Acetabulum Fractures

The acetabulum is formed by a portion of the innominate bone. It lies at the point where the ilium, ischium, and pubis are joined by the triradiate cartilage, which later fuses to form the innominate bone. The acetabulum is enclosed by the anterior and the posterior columns like the two limbs of an inverted Y (see the images below).

The anterior column comprises the anterior border of the iliac wing, the entire pelvic brim, the anterior wall of the acetabulum, and the superior pubic ramus. The posterior column makes up the ischial portion of the bone, including the greater and lesser sciatic notch, the posterior wall of the acetabulum, the majority of the quadrilateral surface, and the ischial tuberosity. The roof of the acetabulum is the thick weightbearing portion and forms a separate fragment in bicolumnar fractures. The thin quadrilateral plate forms the medial wall or the floor of the acetabulum.

The innominate bone is irregular in shape and has differing thickness in cross-section in different areas. The posterior column and sciatic buttress provide the best purchase for screws. The areas suitable for implant placement are shown in the images below.[8]

An intimate knowledge of the nerves and vessels in the area is essential for preventing iatrogenic complications at the time of surgery. Details of the relevant anatomy are elaborated further in the discussion on surgical approaches (see Treatment).

Fractures of the acetabulum occur as a result of the force exerted through the head of the femur to the acetabulum. The femoral head acts like a hammer and is the last link in the chain of forces transmitted from the greater trochanter, knee, or foot to the acetabulum. The position of the femur at the time of impact and the direction of the force determine the type and displacement of the fracture.

Point of impact and resulting fracture patterns

Although it is difficult to pinpoint the exact relation between the point of impact and the mechanism of injury in acetabulum fractures, certain relations are well recognized. These can help in understanding the forces involved in creating the fracture, the direction of displacement, and the fracture patterns involved.

Force applied to greater trochanter in axis of femoral head

The point of impact of the femoral head is decided by the degrees of adduction and abduction and rotation of the femur.

With the hip in neutral adduction-abduction, external rotation of the hip predisposes to anterior-column injury, and internal rotation predisposes to posterior-column injury. Rotations and associated fractures are as follows:

• Neutral - Central/anterior column
• External (~25°) - Anterior column
• External (~50°) - Anterior lip
• Internal (~25°) - Transverse/T-shaped/bicolumnar, depending on the degree of force applied
• Internal (~50°, extreme) - Posterior column with transverse element

With the hip in neutral rotation, the greater the degree of adduction of the femur, the higher the level of the fracture (greater involvement of the roof). The greater the degree of abduction, the lower (more inferior) is the fracture line. Positions of the femur and associated fractures are as follows:

• Neutral adduction-abduction - Transverse or T-shaped fracture beginning at the inner margin of the roof of the acetabulum
• Increasing adduction - Transverse or T-shaped fracture with increasing involvement of the roof of the acetabulum
• Increasing abduction - Transverse or T-shaped fracture with progressively inferior shift of the fracture line

Force applied to flexed knee in axis of femoral shaft

Acetabulum fracture morphology depends on the degrees of flexion or extension and adduction or abduction. The degree of hip rotation generally does not contribute significantly to the fracture pattern.

With the hip flexed to 90°, positions of the femur and associated fractures are as follows:

• Neutral adduction-abduction - Posterior wall
• Maximum abduction - Posterior column with transverse element
• Mild (~15°) abduction - Posterior column
• Adduction - Posterior dislocation of the hip, with or without posterior-wall fracture

With different degrees of hip flexion, positions of the femur and associated fractures are as follows:

• Increasing flexion - Progressively lower involvement of the posterior column
• Decreasing flexion (< 90°) - Involvement of the posterosuperior portion of the acetabulum

Force applied to foot with knee extended

Positions of the femur with associated acetabulum fractures are as follows:

• Hip extended (eg, fall from a height) - Transtectal transverse fracture
• Hip flexed (eg, frontal collision in a vehicle, with force transmitted through the foot pedal) - Depending on the position, similar to force acting through a flexed knee

Force applied to lumbosacral region

A force applied to the lumbosacral region is a rare cause of acetabular fractures.

In actuality, however, it is very difficult to pinpoint the exact site of impact and the mechanism of injury. These mechanisms are important, in that they help in understanding the acting forces, the direction of displacement, and the fracture patterns involved.

Classification

Elementary fracture patterns

Various classifications of acetabular fractures have been propounded, but the easiest system is that of Judet and Letournel, who categorized acetabular fractures according to the fracture morphology as elementary fracture patterns.[3, 4] These have only one fracture line and include the following:

• Posterior-wall fractures
• Posterior-column fractures
• Anterior-wall fractures
• Anterior-column fractures
• Transverse fractures

Posterior-wall fractures (see the images below) typically involve the rim of the acetabulum, a portion of the retroacetabular surface, and a variable segment of the articular cartilage. The articular cartilage may also be impacted. Impacted articular cartilage should be diagnosed preoperatively on computed tomography (CT); these impacted fragments require elevation at the time of surgery.

Extended posterior-wall fractures can involve the entire retroacetabular surface and include a portion of the greater or lesser sciatic notch, the ischial tuberosity, or both. The ilioischial line, however, remains intact on the anteroposterior (AP) view.

Posteriocolumn fractures include only the ischial portion of the bone. The entire retroacetabular surface is displaced with the posterior column. As the vertical line separating the anterior column from the posterior column traverses inferiorly, it most commonly enters the obturator foramen. An associated fracture of the inferior pubic ramus is present.

Sometimes, the fracture line traverses just posterior to the obturator foramen, splitting the ischial tuberosity. The ilioischial line typically is displaced and disassociated from the teardrop. However, when a large portion of the quadrilateral surface remains intact with the posterior column, the teardrop and a portion of the pelvic brim displace with the posterior column.

Anterior-wall fractures (see the images below) are uncommon injuries and often occur in conjunction with anterior dislocations.

Low anterior-column fractures involve only the superior ramus and pubic portion of the acetabulum. High anterior-column fractures can involve the entire anterior border of the innominate bone. The pelvic brim and iliopectineal line are displaced. Medial translation of the entire roof or a portion of the roof is typical of displacement of a high or intermediate anterior-column fracture.

Transverse fractures (see the image below) divide the innominate bone into two portions. A horizontally displaced fracture line crosses the acetabulum at a variable level. The innominate bone is then divided into a superior part and a lower part. The superior part is composed of the iliac wing and a portion of the roof of the acetabulum. The lower part of the bone, the ischiopubic segment, is composed of an intact obturator foramen with the anterior and posterior walls of the acetabulum.

Letournel further divided transverse fractures into the following three subtypes:

• Transtectal, in which a transverse fracture line crosses the superior acetabular articular surface
• Juxtatectal, in which a transverse fracture line crosses at the junction of the superior acetabular articular surface and superior cotyloid fossa
• Infratectal, in which a transverse fracture line crosses through the cotyloid fossa

Associated fracture patterns

Associated acetabulum fracture patterns are the more complicated fracture patterns and include the following:

• Anterior with posterior hemitransverse
• Posterior-column with posterior-wall
• Transverse with posterior-wall
• T-shaped
• Both-column

Anterior with posterior hemitransverse fractures combine an anterior-wall or anterior-column fracture with a horizontal transverse component, which traverses the posterior column at a low level. The distinction between the associated anterior-column and associated posterior hemitransverse and T-shaped patterns is often subtle. In the anterior plus posterior hemitransverse fracture, the anterior component typically is at a higher level and is more displaced than the posterior component.

The posterior-column with posterior-wall pattern (see the images below) divides the posterior column into a larger posterior-column component and an associated posterior-wall component. The ilioischial line typically is displaced and disassociated from the teardrop.

The transverse with posterior-wall pattern (see the image below) combines a normal transverse configuration with one or more separate posterior-wall fragments. A fracture of the inferior pubic ramus typically is not seen.

A T-shaped fracture (see the images below) is similar to a transverse fracture except for the addition of a vertical split along the quadrilateral surface and acetabular fossa (the stem of the T), which divides the anterior column from the posterior column. An associated fracture of the inferior pubic ramus typically is present.

In both-column fractures (see the images below), the anterior and posterior columns are separated from each other, and all articular segments are detached from the intact portion of the posterior ilium, which remains attached to the sacrum. A fracture of both columns is associated with the spur sign, in which the fractured edge of the intact posterior iliac wing is seen prominently relative to the medially displaced articular segments on the obturator oblique radiographic view. This sign is pathognomonic of an injury to both columns.

AO-ASIF classification

The classification developed by the Arbeitsgemeinschaft für Osteosynthesefragen–Association for the Study of Internal Fixation (AO-ASIF)  is more comprehensive (see the image below). This can be simplified as follows:

• Type A fractures - Involving either a single wall or column (anterior or posterior)
• Type B fractures - Include both anterior and posterior columns but not bicolumnar fractures (transverse, T-shaped, anterior with posterior hemitransverse type injuries)
• Type C fractures - Bicolumnar fractures, with the roof as a separate fragment

In 2018, the AO and the Orthopaedic Trauma Association (OTA) published an updated classification system applicable to acetabular fractures.[9]  In this classification, acetabular fractures would first be labeled by the number of the bone involved (62 in the case of the acetabulum) and then be divided into the following three main types:

• Type A - Partial articular, isolated column and/or wall fracture 
• Type B - Partial articular, transverse-type fracture
• Type C - Complete articular, associated both-column fracture

Each of these main types is further divided into various groups.

Type A is divided into three groups: (1) posterior-wall fracture, (2) posterior-column fracture, and (3) anterior-column or -wall fracture. These groups are further divided into subgroups as follows:

• A1.1 - Simple fracture
• A1.2 - Multigragmentary fracture
• A2.1 - Through the ischium
• A2.2 - Through the obturator ring
• A2.3 - With associated posterior-wall fracture
• A3.1 - Anterior-wall fracture
• A3.2 - High anterior-column fracture (exiting along iliac crest)
• A3.3 - Low anterior-column fracture (exiting below anterior superior iliac spine [ASIS])

Type B is divided into three groups: (1) transverse fracture, (2) T fracture, and (3) posterior hemitransverse fracture with anterior column. These groups are further divided into subgroups as follows:

• B1.1 - Infratectal
• B1.2 - Juxtatectal
• B1.3 - Transtectal
• B2.1 - With infratectal transverse component
• B2.2 - With juxtatectal transverse component
• B2.3 - With transtectal transverse component
• B3.1 - Associated with anterior wall 
• B3.2 - High anterior-column fracture (exiting along iliac crest)
• B3.3 - Low anterior-column fracture (exiting below ASIS)

Type C is divided into three groups: (1) high anterior-column fracture (exiting along iliac crest), (2) low anterior-column fracture (exiting below ASIS), and (3) fracture involving the sacroiliac joint.

More detailed descriptions of these fractures may be achieved by using one or more "universal modifiers," which may be appended to the fracture code. Further information on the current AO/OTA classification is available on the AOTrauma Web site.

Pediatric acetabular fractures

Pediatric acetabular fractures are classified as follows:

• Type A - Small fragments are typically seen with dislocations
• Type B - Linear fractures with a stable hip, these fractures generally occur with pelvic fractures and are the only type in which the force exerted is not through the femoral head but through the pelvis; type B fractures are also generally stable and often do not require any specific treatment
• Type C - Linear fractures with hip instability
• Type D - These are central fracture dislocations, and they have the poorest prognosis, even after operative treatment; a variant is the Walther fracture, which is a fracture through the acetabulum and ischium, which displaces medially

Pediatric acetabular fractures are important, in that the triradiate cartilage remains open until the age of approximately 12 years. Therefore, if the acetabulum is injured before its closure, growth arrest may result, leading to a shallow acetabulum and progressive subluxation of the hip.[10]  Conversely, in patients older than 12 years, the chance of significant growth disturbance is minimal.

Bucholz et al recognized two main types of physeal disturbances with triradiate cartilage injuries, as follows[11] :

• Type I or II Salter-Harris injuries - These have a good prognosis for continued acetabular growth
• Type IV Salter-Harris (crush) injuries - These have a poor prognosis, with premature closure of the triradiate cartilage because of formation of a medial osseous bridge

Dora et al monitored 10 patients with posttraumatic acetabular dysplasia and reported that all 10 patients demonstrated marked retroversion averaging 27°, whereas the contralateral acetabuli showed 23° of anteversion; the average center-edge angle was 9.5°.[12]  The hip joint typically was in a lateral and caudal position, and a significant posterolateral deficiency was present.

The exact incidence of acetabular fractures in various parts of the world is not known. Studies at level I trauma centers have shown an admission rate for pelvic and acetabular fractures of 0.5-7.5% (see Table 1 below).

Table 1. Relative Frequency of Acetabular Fracture Types in Various Studies (Open Table in a new window)

Peltier reported an incidence of 24% acetabular fractures in his series of adult pelvic fractures.[15] Reed documented that approximately 5-10% of pediatric pelvic injuries involve the acetabulum.[16]

In a meta-analysis that included 8389 fractures from 8372 patients over the period between 2005 and 2020, Kelly et al found that the mean patient age had risen from 38.6 years to 45.2; that the proportion caused by road traffic accidents had fallen from more than 80% to 66.5%; and that the proportion of fractures caused by falls had risen from 10.7 to 25.8%.[17] They also noted that the number of anterior column-based fractures had increased significantly, whereas the numbers of other fracture patterns had fallen. Functional outcomes after acetabular fracture appeared to remain similar.

Factors in the injury pattern that affect prognosis include the following:

• Force of energy - High-energy versus low-energy trauma
• Location - Instability allowed with superior-roof, posterior-wall, and column fractures
• Degree of articular comminution of both the acetabulum and the femoral head
• Degree of initial displacement
• Associated injuries

Treatment factors that affect the prognosis are the quality of the reduction, which ideally restores congruity, and the quality of fixation, which ideally restores stability.[18]

The prognosis can also be affected by complications such as the following:

• Avascular necrosis (AVN)
• Metal in the joint
• Chondrolysis
• Sepsis
• Heterotopic ossification
• Neurovascular injury

Studies have confirmed the positive association between the accuracy of reduction and a better long-term result.[13, 19]  However, many series have shown that even when these goals are achieved, posttraumatic arthritis still occurs in as many as 30% of patients.[5, 13, 20, 21, 22]  Contributing factors may include the following:

• Imperfect reduction
• Osteochondral defects in either the acetabulum or the femoral head
• Chondrolysis due to articular trauma at the time of injury
• AVN of the femoral head or the acetabulum

Once symptomatic posttraumatic arthritis has developed, options for salvage generally are limited to total hip arthroplasty and arthrodesis.

The nature and mechanism of injury help predict the fracture pattern and the associated injuries. The premorbid level of function and status of the joint should be established. In the presence of preexistent arthrosis, a total hip replacement may be a better option than open reduction of the acetabular fracture.[23, 24]

Associated injuries are also important to assess. Patients often have multiple traumatic injuries, and a high likelihood of associated injury exists (in as many as 50% of patients).[25]  One must diligently look for these injuries; some are subtle and can be missed.

Assess the following:

• Vital parameters - Life-threatening injuries to the chest, abdomen, and cranium must be the first priority; the basic principles of trauma care and resuscitation apply because many acetabular fractures are associated with severe trauma
• Associated injuries - Associated limb injuries may be in the form of a  patella or upper tibial fracture or a  posterior cruciate ligament (PCL) injury, indicating the mechanism of injury; associated femoral shaft fractures may also be present, which could have a bearing on the management of the acetabular fracture; associated concomitant  pelvic fractures may be present in up to 20% of patients
• It is also important to exclude injury to the  bowel and the urinary tract, in that such injuries influence decision-making about an open reduction of the acetabular fracture

The local orthopedic examination includes an assessment of the following:

• Position of the lower limb - In a posterior dislocation, it is adducted, flexed, and internally rotated; in an anterior dislocation, it is is abducted and externally rotated; eversion of the iliac wing, with the anterior superior iliac spine (ASIS) on the affected side being more laterally placed, is a subtle clue to a central dislocation
• Skin - Including local wounds, abrasions, and closed degloving injury
• Morel-Lavele lesion - A closed degloving injury occurring over the greater trochanter, in which the subcutaneous tissue is torn from underlying fascia creating a cavity, which places this tissue at risk for infection and/or poor healing
• Abduction and adduction of the hip - To detect instability (manual traction can aid in determination of vertical instability)
• Limb-length inequality - May be a subtle clue to the presence of incarcerated intra-articular fragments
• Neurologic examination - To exclude preoperative sciatic/lateral popliteal nerve palsy

The complicated anatomy of the acetabulum necessitates clear-cut visualization of the fracture fragments and their relationships with each other and the rest of the pelvis if anatomic reconstruction of the acetabulum is planned. The following imaging modalities can be used:

• Plain radiographs - Pelvis with both hips (anteroposterior [AP] view), Judet views, and, if required, inlet and outlet views of the pelvis (in cases with concomitant pelvic injury)
• Computed tomography (CT) - Plain and with three-dimensional (3D) reconstructions

Doppler ultrasonography (US) or venography may be performed in cases where deep vein thrombosis (DVT) is suspected.

Laboratory studies that may be helpful include the following:

• Hemoglobin and hematocrit levels
• Type and crossmatch blood
• Routine evaluation of fitness for anesthesia and major surgery

Pelvis with both hips

This is an essential radiograph and may depict the following:

• Associated pelvic-ring fractures independent of the acetabular fracture passing through the iliac wing, the obturator foramen, or the sacrum
• Dislocation through or disruption of one or more joints in the pelvic ring
• Bone quality
• Rarely, a bilateral acetabular fracture
• The acetabular fracture itself

This view enables visualization of the six fundamental radiologic landmarks of the acetabulum, as follows:

• Borders of the anterior wall (acetabulo-obturator line) and posterior wall of the acetabulum
• Roof or dome of the acetabulum
• Teardrop of Köhler
• Ilioischial line of Duverney-Parent
• Pelvic inlet
• Innominate line

Judet views

In the obturator oblique technique, the injured hip is raised to 45°, and the beam is centered over a point one fingerbreadth below and medial to the anterior superior iliac spine. In a correctly taken obturator oblique, the anterior and posterior iliac spines are superimposed, the iliac wing is seen in section as narrow as possible, and, correspondingly, the obturator foramen is seen as large as possible. Features to be studied include the following:

• Pelvic brim
• Articular surface, especially the posterior lip
• Obturator foramen and the anterior column
• Iliac wing in section
• Junction of the anterior and posterior columns as seen as a line just above the roof

In the iliac oblique technique, the uninjured hip is elevated to 45°, with the injured part resting on the table. The beam is centered one fingerbreadth below the level of the anterior superior iliac spine (ASIS) and at the midpoint of a transverse line from the ASIS to the midline. In a correctly positioned iliac oblique, the iliac wing is seen widely spread out and the obturator ring is as thin as possible. Features to be studied include the following:

• Anterior lip of the acetabulum
• Posterior column and posterior border of the iliac bone
• Iliac wing

Interpretation of films

Interpretation of the plain films is based on understanding the normal radiographic lines of the acetabulum and what each line represents. Disruption of any of the normal lines of the acetabulum represents a fracture involving that portion of the bone. Displacement of the articular surface is inferred by displacement of these normal lines of the acetabulum.

On the AP view, the inferior three fourths of the iliopectineal line represents the pelvic brim and is a landmark of the anterior column. The superior fourth of this line is formed by the tangency of the x-ray beam to the superior quadrilateral surface and the greater sciatic notch. The ilioischial line is formed by the tangency of the x-ray beam to the posterior portion of the quadrilateral surface and is therefore a radiographic landmark of the posterior column.

The teardrop and the ilioischial line both result from the tangency of the x-ray beam to a portion of the quadrilateral surface. Thus, they are always superimposed in the normal acetabulum. Separation of the teardrop and the ilioischial line indicates rotation of the hemipelvis or fracture of the quadrilateral surface.

The roof of the acetabulum is a radiographic landmark resulting from the tangency of the x-ray beam to the subchondral bone of the superior acetabulum. Interruption of the radiographic line of the roof is indicative of a fracture involving the superior acetabulum.

The anterior rim is the lateral margin of the anterior wall of the acetabulum and is contiguous with the inferior margin of the superior pubic ramus. The posterior rim is the lateral margin of the posterior wall of the acetabulum. Inferiorly, the posterior rim is contiguous with the posterior horn of the acetabulum.

In most cases, the fracture can be classified properly from plain films alone. Plain films are usually best for assessing the congruence between the femoral head and the roof of the acetabulum.

Measurement of roof-arc angles

Roof-arc angles are used to assess the size of the intact portion of the acetabulum.[26, 27, 28, 29]  These angles are made on the AP, obturator, and iliac oblique radiographic views.

A vertical line is drawn to the geometric center of the acetabulum. Another is drawn through the point where the fracture line intersects the radiographic roof of the acetabulum and again to the geometric center of the acetabulum. The angle drawn in this way represents the medial, anterior, or posterior roof arc as seen on the AP, obturator oblique, or iliac oblique view, respectively. The roof-arc measurements roughly describe the position and orientation of the acetabular fracture and, therefore, the intact portion of superior acetabular articular surface.

A similar determination can be made from the CT scan (see Computed Tomography below). The CT scan of the superior acetabular articular surface from the vertex to 10 mm inferior to the vertex is equivalent to an area described by all three roof-arc measurements of 45°. At 10 mm below the acetabular vertex, the subchondral bone appears as a ring or arc.

If nonoperative treatment is to be considered, the head should remain congruous with the roof of the acetabulum on the three views of the pelvis with the patient out of traction, and all roof-arc measurements should be more than 45°, or there should be no displaced fracture lines involving the superior acetabular articular surface in the superior 10 mm of the acetabulum on CT.

Vrahas et al, in a cadaveric study, concluded that fractures that have a medial roof-arc angle of 45° or less, an anterior roof-arc angle of 25° or less, or a posterior roof-arc angle of 70° or less across the weightbearing portion of the acetabulum should be treated operatively.[7]

Roof-arc measurements are not commonly used. This technique is most applicable to the anterior column and less applicable to the posterior column. Roof-arc measurements are particularly helpful in evaluating the anterior-column component of a T-shaped fracture. If the anterior-column component is low (< 10 mm of the acetabular vertex), only the posterior portion of the fracture must be addressed surgically.

The use of CT for acetabular fractures has revolutionized the imaging of a particularly difficult area and, with 3D reconstruction, has enormously facilitated the visualization of the fracture anatomy, the degree of comminution, and associated fracture patterns; it has also helped in the preoperative planning of the surgical reconstruction.[30, 31, 32, 33, 34, 35]

It is important to have sections taken at 2- or 3-mm intervals; incarcerated fragments may be missed if sections are taken at 5-mm intervals.

3DCT is an invaluable tool for demonstrating the overall fracture orientation in displaced fractures, as well as for deciding the choice of operative approach to the fracture.[36] Because of smoothening artifacts, however, it may not depict minimally displaced fractures. A study by Meesters et al found that 3DCT was feasible and reproducible for the assessment of acetabular fractures and that it correlated with clinical outcome.[37]

Special views are available that enable selective study of the details of the acetabular fracture after computer subtraction of the femoral head from the image. These provide unrestricted access for visualization of the fracture.

Axial images are more sensitive than plain radiographs for demonstrating the following:

• Location and extent of the acetabular fracture
• Degree of comminution, rotation of the fragments, and impaction of the weightbearing dome and the posterior wall
• Intra-articular/incarcerated fragments (see the image below)
• Injury to the femoral head
• Minimally displaced iliac-wing fractures and quadrilateral plate fractures that may have been missed on plain films
• Pelvic hematoma
• Sacroiliac joint integrity
• Rarely, a dislocation that is missed on a plain radiograph

Postoperatively, CT is an invaluable investigative tool whenever joint penetration by a fixation device is suspected (see the image below).

Indications for open reduction and internal fixation (ORIF) in patients with acetabulum fractures include the following[38, 39] :

• All displaced fractures (>2 mm articular step)
• Intact roof-arc angle less than 30°
• Failure to achieve or maintain concentric reduction by closed means
• Fractures that have a medial roof-arc angle of 45° or less, an anterior roof-arc angle of 25° or less, or a posterior roof-arc angle of 70° or less across the weightbearing portion of the acetabulum, according to Vrahas et al, on the basis of a cadaveric study; persistent instability after closed reduction ^[7]
• Incarcerated intra-articular fragments or impaction of the articular surface
• Emergency ORIF if associated vascular injury or sciatic palsy develops after a closed reduction

Nonoperative treatment should be considered in the following circumstances:

• Undisplaced fractures
• Displaced fractures if the following conditions are met: (1) A large portion of the acetabulum remains intact and the femoral head remains congruous with this portion of the acetabulum; (2) a secondary congruence is present after only moderate displacement of a both-column fracture and the patient presents late (>3 weeks after injury)
• Small posterosuperior-wall fractures that are associated with a stable hip joint and a congruent reduction; careful follow-up is needed to monitor for signs and symptoms of late instability in the initial months after injury
• A posterior-wall injury that is minimally displaced or nondisplaced and is part of a more complex pattern requiring an ilioinguinal approach
• If surgery is contraindicated

Contraindications for surgery include the following:

• General - Severe systemic illness or secondary multiorgan failure secondary to polytrauma; systemic infections or sepsis
• Local - Local infection; extreme  osteoporosis
• Surgical intervention may be carried out in these cases to facilitate a salvage procedure later.
• Relative - Severe comminution; preexisting arthrosis

Future and controversies

As techniques improve, imaging is being used more and more in the treatment of acetabular fractures. Brown et al reported the use of computer-generated three-dimensional (3D) computed tomography (CT) moving images for preoperative planning and screw/pin insertion, as well as the use of stereolithography (wax or plastic 3D model of bony anatomy) to develop a computer-generated "clip-on" interpositioning template for accurate placement of plate and screws. These technologies provide precise information about the fracture patterns and allow effective preoperative planning and accurate fixation of acetabular fractures.[40] Citak et al reported on virtual 3D planning of acetabular fracture reduction.[41]

The best modality for preoperative deep venous thrombosis (DVT) prophylaxis remains controversial; multiple options are available, but the current trend is to use sequential compression devices for prophylaxis in the preoperative period. Similarly, the best form of prophylaxis against heterotopic ossification remains controversial; however, indomethacin appears to be used most frequently at present.

Nonoperative therapy consists of the following:

• Resuscitation of the patient - Basic and advanced life support
• Diagnosis - Clinical and radiologic, once the patient stabilizes
• Treatment of associated life-threatening head, chest, abdominal, or other injuries
• Urgent reduction of dislocations

Gentle closed reduction of posterior dislocations is done on an emergency basis. Management of central fracture-dislocations involves the use of heavy longitudinal skeletal traction with an upper tibial or lower femoral Steinmann pin and, if required, lateral skin traction at the upper thigh. (Reduction under general anesthesia may be necessary. This is maintained with skeletal traction. The authors do not recommend the use of an upper femoral pin for lateral traction, because this acts as an infective focus and may preclude surgery.)

Preoperative evaluation

A preoperative evaluation is used either to exclude other injuries or, if other injuries are present, to formulate a treatment plan for them. The preoperative evaluation consists of the following:

• Ensure that the patient is medically stable for surgery
• Type and crossmatch an adequate amount of blood; there can be significant bleeding at the time of surgery
• Plan preoperatively with plain radiography (anteroposterior [AP] and both Judet oblique views) and CT, and keep a bone model handy at the time of surgery; with advances in technology, it is possible to generate a model of the fracture pattern and preoperatively plan the position of interfragmentary screws
• Determine the timing of surgery - The ideal time for surgery is between days 3 and 10 after injury

With regard to the optimal timing of operative treatment, it is best to wait 2-3 days after the injury so that the initial bleeding from the intrapelvic vessels subsides. However, it is not advisable to wait for too long, because surgery becomes more complicated 2-3 weeks after the injury. If the surgery is performed beyond 3 weeks, the chances of obtaining a good result decrease significantly.[42]  

Intraoperatively, various difficulties are possible, including the following:

• Increased blood loss because of disruption of the forming soft callus
• Loss of definition of the fracture lines that can cause difficulty in obtaining a good reduction
• Difficulty in identification of vital structures, thereby giving rise to increased chances of neurovascular damage and other complications
• Contraction of the soft tissues, leading to difficulty in mobilization of the fracture fragments

However, in a retrospective review investigating the timing of surgical intervention for fractures of the acetabulum and the influence of timing on perioperative factors, Dailey et al found that whereas both-column and anterior-column posterior hemitransverse fractures were associated with greater estimated blood loss, longer operating times, and longer hospital stays than posterior-wall fractures, no differences in these parameters were noted when early fixation (≤ 48 hr) was compared with late treatment (>48 hr).[43]

Choice of surgical approach

The choice of approach usually is dictated by the fracture anatomy, but it also depends on the personal preference and experience of the operating surgeon (see Common Surgical Approaches and Extensile Surgical Approaches below). Guidelines for the choice of approach are as follows[38, 44, 45] :

• Anterior fracture, cephalad to iliopectineal eminence - Iliofemoral
• Anterior fracture, patients with complex injuries requiring exposure of the symphysis or quadrilateral plate - Ilioinguinal
• Posterior wall/column - Kocher-Langenbeck ^[46]
• Transverse with posterior lip - Kocher-Langenbeck or transtrochanteric
• Transverse without posterior lip - Depending on the rotation of the fracture
• T-shaped - Depending on the fracture pattern, ilioinguinal/Kocher-Langenbeck/combined/extensile
• Both columns - Ilioinguinal, modified ilioinguinal/combined/extensile

Of these exposures, the ones commonly performed are the following:

• Ilioinguinal exposure for anterior-column or T-shaped or bicolumnar fractures with mild comminution in the posterior column
• Kocher-Langenbeck exposure for posterior-column injuries.

Isaacson et al investigated the use of the modified Stoppa approach for the treatment of acetabulum fractures with regard to three outcomes: hip function, complications, and quality of fracture reduction and percentage of fractures that united.[47]  They concluded that for a variety of acetabular fractures, this approach yields good functional outcomes with minimal complications.

Bastian et al compared the modified Stoppa approach with the pararectus approach for for patients with acetabular fractures involving the anterior column.[48]  They found that the latter facilitated surgical access in the false pelvis, provided versatility for fracture fixation in the posterior pelvic ring, and afforded the surgeon the option to extend the approach without a new incision.

Kwak et al evaluated the use of an anatomic suprapectineal quadrilateral surface (QLS) plate through the modified Stoppa approach (n = 16) to treat superomedially displaced acetabular fractures and compared surgical outcomes with those of fixation with the conventional reconstruction plate in a modified ilioinguinal approach (n = 23).[49] They found that the operating time was shorter and blood loss was less in the QLS plate fixation group.

Arthroscopy has been used in certain cases of acetabular fractures to remove intra-articular loose fragments. However, potentially fatal complications, such as intra-abdominal compartment syndrome due to extravasation of fluid under pressure, have been reported with its use.48 Arthroscopy may be appropriate for reduction and fixation of certain acetabular fractures in carefully selected patients.[50]

Kocher-Langenbeck approach

The ideal indication for the Kocher-Langenbeck approach (see the images below) is an isolated fracture of the posterior wall and/or column with or without dislocation (types A1 and A2 on the Arbeitsgemeinschaft für Osteosynthesefragen–Association for the Study of Internal Fixation [AO-ASIF]  classification). The approach can also be used in types B1 and B2 fractures on the AO-ASIF classification. This approach can be used when the major rotation and displacement are posterior.

The patient is placed in the lateral or prone position. The lateral position is more common with most surgeons because it allows easy maneuverability of the limb.

The prone position is used particularly with the transverse or T-type fractures, where, if a lateral position is used, the femoral head tends to keep the fracture surfaces apart because of gravity. This creates difficulty in reduction. The advantages of the prone position in this situation are that it requires one assistant fewer and that it facilitates relaxation of the sciatic nerve. The hip should be kept extended and the knee flexed throughout the procedure to avoid any tension on the sciatic nerve.

The incision starts at the posterior superior iliac spine (PSIS), proceeds to the greater trochanter, and then continues distally along the femur as necessary. The fascia lata and the gluteus maximus fascia are divided in line with the incision. The maximus is split along its fibers, with care taken to protect the inferior gluteal nerve. The insertion of the gluteus maximus on the femur may be divided partially or completely to increase exposure.

The gluteus medius, the external rotators, and the sciatic nerve are now seen. The short external rotators are incised close to the greater trochanter, with care taken to avoid cutting the quadratus femoris so as to protect the ascending branch of the medial circumflex femoral artery. The plane between the external rotators and the capsule of the hip joint is developed carefully by gentle dissection.

The gluteus medius and minimus are raised subperiosteally from the ilium and retracted with a Steinmann pin. The superior gluteal vessels and nerve, which emerge from the inner pelvis in this area, must be protected.

The fracture fragments usually are found attached to the capsule, which forms the only soft-tissue attachment to the fragments and, hence, their only source of blood supply. Care should be taken not to denude the attachment.

The entire posterior column and the posterior wall of the acetabulum are now exposed from the top of the notch to the ischial tuberosity. Retraction of the gluteus medius may not be adequate for fixation of some high posterior column or transverse fractures. To increase the exposure of the roof of the acetabulum, a trochanteric osteotomy may be carried out (see the image below).

Ebraheim et al reviewed 30 patients in whom a sliding trochanteric osteotomy was used as an adjunct procedure for treating acetabular fratures.[51]  They concluded that the technique was reliable for providing adequate exposure of the dome of the acetabulum without associated complications that can occur with standard oblique osteotomy.

Another alternative is to do a "trochanteric flip," in which the abductor and the vastus lateralis, in continuity with a small medallion of the trochanter (which is osteotomized in a sagittal plane), are retracted anteriorly to expose the dome of the acetabulum. The advantage of this over a routine trochanteric osteotomy is that the abductors and the vastus lateralis remain in continuity through the trochanter, enabling easy restoration of the anatomy.

A careful arthrotomy, if needed, can be performed. By flexion and external rotation of the hip with lateral traction and by retraction of the fragment, an excellent view of the entire cavity is possible. Soft-tissue release of the inner surface of the quadrilateral plate can be performed through the sciatic notches subperiosteally, if necessary, after the ischial spine is osteotomized (especially in late fractures).

A constant vessel exists within the gluteus muscle 1-2 cm from the sciatic notch, which, if not taken proper care of while retracting or dissecting, tends to produce troublesome bleeding.

In a study of patients with posterior-wall fractures and late revision surgery with the Kocher-Langenbeck approach, three of the four patients eventually required total hip arthroplasty (THA).[46]  The authors concluded that if salvage procedures are delayed more than 3 weeks, THA is more likely to be ultimately required, especially in older patients. Older age, posterior-wall involvement, and femoral head lesion/subluxation have been associated with the need for THA after acetabular fracture.[52]

In a study that included 70 elderly patients (52 men, 18 women, median age, 79.0 years; range, 65-104) with acetabular fractures, Rommens et al found that ORIF resulted in excellent outcomes at short-term (median, 30 months) follow-up when anatomic reduction could be achieved.[53] In the presence of negative predictive factors, they did not regard ORIF as a definitive solution but, rather, as involving the construction of a stable socket for secondary THA.

Collinge et al concluded that acetabular fractures reduced and stabilized using the Kocher-Langenbeck approach had a higher rate of radiographic residual fracture displacement if treated in the lateral as compared with the prone position.[54]

Ilioinguinal approach

Described by Letournel, the ilioinguinal approach (see the images below) is suitable for the following fracture types:

• Anterior-wall fractures
• Anterior-column fractures
• Combined anterior-column fractures with posterior hemitransverse extension
• Types A3 and B3 fractures (AO-ASIF) where the major rotation and displacement are anterior
• Both-column fractures

The ilioinguinal approach provides exposure of the entire inner table of the innominate bone from the symphysis pubis to the anterior aspect of the sacroiliac joint, including the quadrilateral surface and the pubic rami.

Merits of this approach include the following:

• Excellent visualization of the entire anterior column of the acetabulum
• Less incidence of heterotopic ossification as compared with the posterior approaches
• Rapid postoperative rehabilitation is possible

Dangers of the ilioinguinal approach include injury to the iliac vessels, lymphatic system, femoral nerve, and lateral cutaneous femoral nerve.

The patient is positioned supine. If a combined approach (anterior and posterior) is planned, the floppy lateral position is then preferred. The incision is placed 2 cm above the inguinal ligament and parallel to it, from the midline to the anterior superior iliac spine (ASIS), and then curved along the anterior two thirds of the iliac crest.

The origin of the abdominal muscles from the iliac crest is erased sharply and retracted medially. The iliacus origin from the inner pelvic wall is now seen. The iliacus origin is then erased subperiosteally, and the dissection is carried out posteriorly and inferiorly to expose the anterior sacroiliac joint and pelvic brim.

Through the medial part of the incision, the external inguinal ring is identified, and the spermatic cord (in females, the round ligament) is protected with a rubber catheter. The external oblique aponeurosis is incised 1 cm proximal to the ring, with the ring kept intact and the lateral 5 mm of the aponeurosis left near the ASIS to protect the lateral cutaneous femoral nerve. Care should be taken to protect the inferior epigastric artery.

The distal flap of the external oblique aponeurosis is raised to reach the reflected part of the inguinal ligament. This ligament is incised along its length so as to leave 1 mm of the ligament attached to the internal oblique and transversus abdominis origins and the transversalis fascia.

The next step is to identify the iliopectineal fascia, which divides the iliopsoas with the femoral nerve (lacuna musculorum) from the external iliac vessels (lacuna vasorum). This is the most dangerous and most important part of the approach. The iliac vessels are retracted, the iliopectineal fascia is identified and then cut with blunt-tip scissors from lateral to medial, and the cut is continued laterally behind the psoas. Next, the psoas with the femoral nerve is retracted as a unit after a rubber catheter is inserted around them.

After the iliac vessels are dissected with the associated lymphatic tissues as a single unit, along with the areolar tissue around them (to protect the lymphatics and prevent postoperative limb swelling), these tissues are held together with a third rubber catheter. Take care to identify the obturator vessels and nerve. Be aware of the abnormal origin of the obturator artery as an anatomic variant. If found to be present, the abnormal vessel must be ligated. The periosteum on the inner surface of the pelvis along the quadrilateral plate is cleared.

The exposure is now established through three windows, as follows:

• Retracting the psoas medially allows exposure of the internal iliac fossa, the pelvic brim, and the anterior sacroiliac joint; this exposure is facilitated by flexing and internally rotating the hip to relax the iliopsoas
• The middle window is created by retracting the psoas laterally and the vessels medially; this allows the superior pubic ramus and the quadrilateral plate to be visualized
• The medial window is seen by retracting the vessels laterally and the spermatic cord medially; this maneuver provides access to the remainder of the pubic ramus, the pubic symphysis, and the quadrilateral surface; the most medial part can best be visualized with lateral retraction of the spermatic cord

If necessary, the inguinal ligament and the sartorius from the ASIS, the tensor fasciae latae, and the gluteal muscles from the lateral surface of the ilium can be released to aid exposure.

The entire anterior column is now easily visualized. Useful access to the posterior column can be obtained through the second (middle) window by manipulating the quadrilateral plate. The interior of the joint can be visualized by distracting the fracture fragments. Intra-articular visualization can be improved by combining the iliofemoral approach (the distal part of the approach) with this procedure.

Before closure, drains are left in the retropubic space and internal iliac fossa. All structures are repaired.

Iliofemoral approach

Letournel modified the Smith-Petersen approach to define the iliofemoral approach for the acetabulum. This procedure is indicated for anterior-column fractures in which the fracture line does not extend medial (caudal) to the iliopectineal eminence.

The patient is positioned supine. If combined with a posterior approach, a floppy lateral position is preferred. The incision is made on the iliac crest, from the middle of the crest to the ASIS, and then along the sartorius. The periosteum is sharply raised from the iliac crest, and the iliopsoas is stripped from the interior of the ilium. The lateral cutaneous nerve of the thigh is identified and protected.

The interval between the sartorius and the tensor fasciae latae is developed to expose the rectus femoris if exposure of the hip joint is required. The exposure can be extended along the lateral aspect of the ilium by stripping the gluteal muscles to see the anterior aspect of the hip joint and anterior inferior iliac spine. The exposure can be improved as needed with division of the sartorius and inguinal ligament insertion and the direct head of the rectus femoris, which is part of the hip joint capsule.

An advantage of this approach is easy access. No dissection of the femoral vessels, as in the ilioinguinal approach, is required. A disadvantage of the approach is limited anterior column access. Another disadvantage is that medial to the iliopectineal eminence, the exposure should be established with the ilioinguinal approach, which usually limits fixation options to screws or short plates in this approach. Also, injury to the lateral cutaneous nerve of the thigh is difficult to prevent with this approach.

Combined approach

When access to both columns is required, a combined approach is used.[55, 56, 57, 58]  This involves the combination of one anterior and one posterior approach (described above), under the same anesthesia.

The patient is placed in the floppy lateral position and is rocked back and forth as needed. The anterior approach is more difficult, in that the procedure with this approach is best performed with the patient in the supine position. Technical details of exposure remain the same as for the individual approaches.

An advantage of a combined procedure is that the entire posterior wall and column (with or without trochanteric osteotomy), the entire anterior wall and column, the sacroiliac joint, and the pubic symphysis can be visualized. The disadvantages inherent in a single extensile approach (eg, the incidence of heterotopic ossification, weakness of abductors, and jeopardy for the vascularity of the abductors) are lower with a combined approach. A disadvantage of a combined approach is that the entire fracture is not visualized through a single approach.

Extended iliofemoral approach

Letournel developed an extended iliofemoral approach that provides complete exposure of the inner and outer tables of the ilium and the acetabulum. This is an extended approach for difficult transtectal transverse, T-type, and both-column fractures with posterior wall involvement.

The patient is placed in the lateral position. Keep the hip extended and the knee flexed throughout the procedure to prevent traction injury to the sciatic nerve. The inverted J–shaped incision starts at the PSIS, courses along the iliac crest to the ASIS, and then turns distally parallel to the femur on the anterolateral aspect of the thigh.

The periosteum over the iliac crest is sharply incised; the gluteal muscles and the tensor fasciae latae are elevated from the outer aspect of the iliac bone. The fascia lata over the tensor fasciae latae is opened, the muscle is retracted posteriorly, and the rectus femoris, which lies beneath it, is identified. The ascending branch of the lateral circumflex femoral artery, which is found between the rectus femoris and the vastus lateralis, is identified and ligated.

The tendons of the gluteus minimus and the gluteus medius are cut in the midportion, and tag sutures are inserted at the cut ends. The piriformis and the obturator internus are cut and tagged, with care taken to preserve the quadratus femoris and the underlying ascending branch of the medial circumflex femoral artery. Alternatively, the insertion of these external rotators can be osteotomized.

The entire posterior column can now be seen with a retractor inserted near the sciatic notch. This also brings into view the ischial spine and tuberosity.

The reflected head of the rectus femoris is elevated from its origin to aid exposure of the hip joint. The abdominal muscle origin from the iliac crest, sartorius origin from the ASIS, and the iliacus from the inner table of ilium are erased to expose the anterior column of the acetabulum. The capsule is incised along the rim of the acetabulum to allow intra-articular exposure as the femoral head is pulled laterally.

During closure, the rectus femoris, the sartorius, the fascial layers of the hip abductors, and the tensor fasciae latae are reattached to the iliac bone by transosseous sutures. The gluteus minimus and medius tendons are repaired. The short external rotators are also reattached.

An advantage of this approach is that it is a lateral approach to the innominate bone, which allows excellent simultaneous exposure of both columns. A disadvantage is that the extensive stripping of muscles from the lateral side of the ilium that is required impairs the vascularity of the abductors.

Although this disadvantage has been studied through in-vivo and cadaveric studies, definite evidence of muscle necrosis and significant weakness as a result of this approach has not been proved to be an invariable consequence, but heterotopic ossification is much more common in this approach.[59, 60]  This is understandable, in view of the extensive attachment of the abductors to the ilium. Injury to the femoral nerve has also been documented.

Reinert et al modified the extended iliofemoral approach to allow later reconstructive procedures (Maryland approach).[61]  The incision is positioned more laterally and is T-shaped. The hip abductor muscles are mobilized by an oblique osteotomy of the origin and the insertion. Rigid bone-to-bone reattachment allows early rehabilitation with less risk of failure than when the abductors are reattached through soft tissue.

Some authors have prescribed a preoperative arteriogram (as in the extended iliofemoral approach) if a displaced fracture is present at the sciatic notch to prevent necrosis of the hip abductors, in view of the stripping required for exposure.

Triradiate approach

Mears and Rubash have described an extensile approach to the lateral aspect of the ilium, the entire anterior column and wall, the entire posterior column and wall, the anterior aspect of the sacroiliac joint, and the inner iliac wall.[44, 45]  This procedure is referred to as the triradiate approach (see the image below) and is indicated for transtectal transverse fractures, T-shaped fractures, and both-column fractures with posterior-wall involvement. This approach is an alternative to the extended iliofemoral approach.

The patient is placed in a lateral position. A Y-shaped incision is made, the posterior segment of which is the same as in the Kocher-Langenbeck approach. The anterior limb of the Y starts at the greater trochanter from this incision at an angle of 120° and extends beyond the ASIS to the front of the abdomen.

The fascia lata is cut along the longitudinal part of the incision. The interval anterior to the tensor fasciae latae is developed by dissecting it from the fascia, and then the muscle along with the abductors is stripped from the lateral aspect of the ilium. The gluteus maximus is split along the posterior limb of the incision parallel to its fibers. A trochanteric osteotomy is performed. The short external rotators' insertion on the femur is erased.

The rest of the posterior exposure is obtained by retracting the muscles from the greater sciatic notch. The anterior incision is developed as in the ilioinguinal approach by dividing the sartorius and the rectus femoris and opening the external oblique aponeurosis and dissecting through the three windows available beneath the inguinal ligament.

During closure, the muscles—especially the abductors, the tensor fasciae latae, the rectus femoris, and the sartorius—are reattached. The trochanteric osteotomy is fixed, and the three fascial limbs of the triradiate incision are closed, beginning with a single apical suture.

Overview

Reducing acetabular fractures is one of the most challenging tasks the orthopedic surgeon faces.[62, 63]  Often, because of the high velocity of the injury, comminution is extensive, and piecing all the fracture fragments together is similar to solving a jigsaw puzzle. It requires patience and skill. One tends to improve with experience, but the learning curve is fairly steep.

Analysis of the fracture pattern, displacement of the fragments, and meticulous preoperative planning go a long way in easing the difficulties faced in the surgical treatment of acetabular fracture. A hip with a malreduced acetabular fracture is doomed to a posttraumatic arthrosis. It is therefore essential to obtain anatomic reduction in order to ensure longevity of the hip. There has been a good correlation between the accuracy of the reduction and good long-term clinical outcomes.

Reduction in acetabular fractures usually proceeds from the periphery to the center—that is, in a centripetal fashion. The articular surface is reconstructed to the mold of the peripherally reconstructed innominate bone. Thus, it is easy to understand the need for perfect alignment of the peripheral fracture lines; a small peripheral step may lead to significant articular incongruity and may necessitate revision of fixation.

It is also important to appreciate that the malalignment of any one column precludes anatomic fixation of the other column in injuries involving both the columns. For this reason, the authors recommend simultaneous anterior and posterior approaches as opposed to staged procedures for fractures that require an anterior and a posterior approach.

In reduction and fixation of acetabular fractures, the need for a thorough knowledge of the local anatomy, both normal and pathologic, cannot be overemphasized. This knowledge is helpful not only for avoiding injury to surrounding vital structures (eg, the femoral neurovascular bundle) and intra-articular hardware but also for placing screws in the areas that provide the best purchase and thereby ensuring ensure stable fixation of the fracture.

Provisional fixation usually is established by means of Kirschner wires (K-wires) and, sometimes, cerclage wires. Definitive fixation is established with screws and plates.

The primary fixation usually is by means of an interfragmentary screw. This is usually a 3.5-mm cortical screw used as a lag screw or a 4-mm cancellous screw. Screws measuring 6.5 mm are used rarely but can provide excellent hold. The exact nature and placement requires careful preoperative planning and depends on the fracture pattern.

Because of the curvaceous pelvic anatomy, implants that are too rigid must be avoided because implants must be molded perfectly to avoid malreduction. The 3.5-mm reconstruction plate, either curved or straight, is ideal for this purpose. It is thin and easily contoured in both planes, so it can be applied perfectly to the pelvis. The curved plates are slightly thicker and have a sloping undercut screw hole, allowing more oblique placement of the screw through the plate. Preoperative virtual simulation and 3D printing appear to be promising as means of facilitating plate molding.[64]

The other types of plates that can be used in special situations include spring plates, spike (spring hook) plates, and cerclage wires.[4, 32]

In cases with comminution of the quadrilateral plates, especially near the dome or above the fovea, the hip tends to subluxate despite fixation of the anterior and posterior columns. In this situation, a plate placed buttressing the medial wall can control the medial migration. This is usually a reconstruction or a small fragment T-plate with a sharp right-angle bend going over the pelvic brim down to the quadrilateral surface. It is overcontoured to function almost like a spring and hold the comminuted medial wall.

A spike plate or spring hook plate is a one-third tubular plate cut through a hole at the end, creating two small spikes that help hold a small fragment of a comminuted posterior lip.

The use of cerclage wires through the greater sciatic notch or, sometimes, the lesser sciatic notch, around and over the anterior aspect of the pelvis at the level of the anterior inferior iliac spine, is a very effective technique for provisional fixation in certain fracture patterns.

This technique is useful in some difficult-to-hold posterior column fractures, transverse, T-shaped, and both-column fractures in which the posterior fracture line exits high in the sciatic notch, providing a beak for the cerclage wire to hold. The use of cerclage wires, however, does entail slightly more dissection of the outer table when the ilioinguinal approach or an extensile approach (not often used) is followed. These wires may be left as definitive fixation.

Technical tips

A femoral distractor (see the image below) can be used to facilitate visualization and identification of structures for reduction.

A Schanz screw can be used on a T-handle in the ischial tuberosity to manipulate the posterior column. This technique is especially useful in transverse fractures.

Holes may be drilled into the outer cortex of the pelvic bone to obtain purchase for reduction holding clamps.

K-wires can be used to temporarily hold reduction. This technique is especially useful when there is no place to apply pointed reduction holding clamps.

Reduction and stabilization of common fracture patterns

Posterior-wall or lip fracture

For posterior-wall or lip fractures (see the images below), after exposure by a Kocher-Langenbeck approach, the fracture hematoma is washed out and the fracture site cleaned. The interior of the joint is inspected, and loose bodies, if any, are washed out. Anatomic reduction and temporary stabilization with K-wires is carried out. The fracture is stabilized with 3.5-mm lag screws (or 4-mm cancellous screws) with washers, and a neutralization plate is applied.

In about 25% cases, the articular cartilage is impacted. This must be derotated and elevated and the metaphyseal defect filled with cancellous bone graft (usually from the greater trochanter) before the wall fragment is addressed. A subchondral screw usually is used to support the reconstructed articular surface.

In a highly comminuted posterior-wall fracture, it may not be possible to lag each individual fragment with a lag screw. In this situation, the use of spring hook plates (two-, three-, or four-holed one-third tubular plates with the ends cut off and the prongs bent to create hooks) is recommended. These plates are affixed in a loaded fashion underneath the buttress plate more medially but with the spring-loaded lateral hooks providing a buttressing effect to the comminuted posterior wall.

Posterior-column fractures

Posterior-column fractures generally result in medial displacement and internal rotation of the distal fragment (as seen from the back). Therefore, after cleaning the fracture site, the reduction of the displaced posterior column is facilitated by correcting the rotation by using a Schanz screw in the ischium and a small bone hook or pelvic reduction clamps for correcting the medial displacement. Adequacy of the reduction is confirmed by digital palpation of the quadrilateral surface and the smooth contours of the greater and lesser sciatic notches.

Once reduction is obtained, the column is stabilized by using an accurately contoured 3.5-mm (preferably flexible) reconstruction plate from the sciatic buttress down to the ischium. The distal portion of the plate should go low enough on the ischium to permit the most distal screw to be placed into the ischiopubic ramus. Screw placement in the central area of the posterior column is avoided to prevent intra-articular placement. Usually, two screws distally and two or three screws proximally are sufficient for adequate fixation.

Transverse fractures

A Kocher-Langenbeck approach can be used for fractures with a major posterior displacement or associated with posterior-wall fractures (see the image below). In these fractures, it is necessary to reduce not only the posterior-column but also the anterior-column displacement and malrotation. Generally, it is advisable to reduce the column first, check the articular surface continuity, and rule out articular penetration by hardware before fixing the wall fracture.

The reduction is carried out in a fashion similar to that in a posterior-column fracture.

The adequacy of the anterior reduction is confirmed by digital palpation of the quadrilateral plate to the iliopectineal line. If the anterior column is still displaced, it is corrected with a pusher or a pelvic reduction clamp in the greater sciatic notch. A 3.5-mm reconstruction plate is then placed on the medial border of the posterior column, from the sciatic buttress to the ischium, and fixed with 3.5-mm screws. It is vital to overcontour the posterior plate slightly in order to prevent the anterior column from opening up on application of the posterior plate.

A posterior-to-anterior lag screw is then inserted across the obliquity of the transverse fracture line into the anterior column. The starting point of this screw is approximately three fingerbreadths above the acetabulum and requires a significant retraction of the abductor musculature.

This screw starts proximal to the thin part of the quadrilateral plate and runs parallel to the plate, taking purchase in the anterior column. Its position in the anterior column is checked on the obturator oblique view and its extra-articular placement confirmed on the iliac oblique view intraoperatively. It is important to avoid excessive anterior penetration with the drill bit so as to prevent damage to the femoral vessels, which are stuck down there by the iliopectineal fascia.

Mehin et al, in a study of five cadaveric acetabula with transverse acetabular fractures, found that the locking plate construct was as strong as plate plus interfragmentary lag screw for repair of transverse acetabular fractures. The authors feel that locking plates may provide an advantage in that fractures may be displaced during lag-screw tightening.[65]

T-shaped fractures

Reduction of T-shaped fractures (see the image below) with a single nonextensile approach is somewhat more difficult than it is for transverse fractures. When one uses the posterior approach, the reduction of the posterior column is carried out as outlined for posterior-column fractures (see above), ensuring that none of the screws cross into the anterior column.

Indirect reduction of the anterior column is then attempted by using a bone hook to pull the displaced anterior column into the acute angle created by the intact anterior column and the reconstructed posterior column. The bone hook or a pusher on the quadrilateral plate controls the rotation of the anterior column.

Reduction is confirmed by palpation of the quadrilateral plate, and the anterior column is stabilized to the reconstructed posterior column with posterior-to-anterior lag screws. A finger is placed on the quadrilateral surface, and the hip is taken through a range of movement to rule out intra-articular hardware penetration.

With the anterior approach, the anterior column is reduced first, and indirect reduction of the posterior column is attempted through the quadrilateral plate by using a small bone hook or a cerclage wire, after establishing lateral traction using a Schanz screw in the femoral head. Fixation is carried out using cerclage wires or an anterior-to-posterior lag screw.

Anterior-column or -wall fractures

With the ilioinguinal approach, the fracture site is cleaned and the reduction is carried out in a centripetal fashion. The iliac crest fracture is reduced by using a pointed reduction holding forceps or a specially designed pelvic reduction clamp. The gliding hole for lag-screw fixation can be created before reduction to ensure optimal screw placement in the thin iliac crest.

The crest can be stabilized by using a lag screw or 3.5-mm reconstruction plates. The column is then stabilized to the crest temporarily with a K-wire, later to be replaced by a 3.5-mm lag screw into the sciatic buttress through the lateral window of the ilioinguinal approach. The wall fracture is then addressed through the middle window and reduced. Finally, the superior pubic rami and displaced pubic body fractures are reduced through the medial window.

A 3.5-mm reconstruction plate is molded along the iliac fossa, across the iliopectineal eminence to the pubic tubercle and the body of the pubis. The symphysis needs to be crossed only if an associated symphyseal disruption is present or if fractures are present in the pubic body. It is essential that the plate be perfectly contoured; otherwise, tightening down the plate may result in malreduction of the column fracture.

Cortical screws 3.5 mm in length are then placed in the pubis and the pubic tubercle medially and in the area of the sciatic buttress and the quadrilateral plate proximal to the acetabulum to provide stable fixation of the anterior column to the posterior column (anterior-to-posterior lag screws). These screws start at the pelvic brim superior to the acetabulum and are directed from proximal to distal into the posterior column paralleling the quadrilateral surface, aiming for the ischial spine.

Care must be taken to avoid intra-articular placement of these screws; therefore, it is important to appreciate the location of the acetabulum relative to the fixed pelvic landmarks; that is, inferior to the anterior inferior iliac spine and under the iliopubic eminence.

Both-column fractures

The ilioinguinal approach is the best approach for both-column fractures (see the image below). Anterior-column reduction is performed from the iliac crest to the symphysis. This provides an anatomic template for the subsequent reduction of the posterior column. Usually, the anterior column piece of the both-column fracture is externally rotated and shortened. A Schanz screw in the femoral head is used to apply traction, with the hip flexed to correct the shortening and external rotation. The anterior column is thus reduced to the intact iliac wing and stabilized.

The posterior column, which usually is medially rotated and displaced, is then reduced to the anterior column by using the Schanz screw in the femoral head for anterior and lateral traction. Pelvic reduction clamps—with one tine on the outer surface of the ilium and the other tine through the lateral or middle window—on the quadrilateral plate or the posterior column helps achieve reduction. Reduction may also be achieved by means of a small bone hook or a cerclage wire. The posterior column is stabilized with anterior-to-posterior lag screws.

The reduction is checked radiographically, and the hip is taken through a range of movement to look for intra-articular placement of hardware.

Percutaneous fixation

Percutaneous fixation is a relatively recent addition to the armamentarium of the acetabular surgeon.[66, 67, 68, 69, 70, 71]  This technique is recommended for use by experienced acetabular surgeons in certain unstable minimally displaced fracture types in elderly persons or, particularly, in those at high surgical risk due to comorbid factors.

Fixation is carried out using 4.5-mm cannulated screws under fluoroscopic control. The technique usually involves the use of two screws in the anterior inferior iliac spine, directed posteriorly, perpendicular to the fracture surface, toward the greater sciatic notch or just superior to it. On the obturator view, the insertion site of each screw is centered along the midaxis of the anterior inferior spine; in the iliac view, the screw is directed posteriorly across the fracture site. This permits fixation of high anterior or posterior column fractures.

Percutaneous fixation of the posterior column, though rarely done, has been reported, using insertion of the screw into the ischial tuberosity.

These techniques are useful only in experienced hands; the complexities of the local anatomy and the small target zones for proper screw insertion preclude their widespread use.

The results from one study suggest that closed reduction and anterior-to-posterior supra-acetabular percutaneous screw fixation, followed by full weightbearing immediately postoperatively, may be a safe and reasonable alternative for anterior-column acetabulum fractures, with earlier return to work-related or recreational activities.[72]

Mauffrey et al described a case involving flexible 3D laparoscopic-assisted reduction and percutaneous fixation of an acetabular fracture in a young obese patient.[73] They did not recommend routine use of this approach but suggested it as a possible alternative for a small patient subset.

Quadrilateral surface comminution

An anterior-column fracture with comminution of the quadrilateral surface and central migration of the femoral head is one of the most difficult acetabular fractures to stabilize, in that there is always a tendency for late central migration of the head because of the lack of support there. Reconstructing the quadrilateral surface is extremely difficult.

Different techniques have been described to this end. One is the use of a contoured reconstruction or T-plate (spring plate), bent at right angles to buttress the quadrilateral surface, as described by Tile and by Matta et al (see the image below).[32, 38]  Tile also described the use of an inner table iliac crest autograft, fixed with heavy wires or braided cables to reconstitute the quadrilateral surface.[32]

Total hip replacement in acetabular fractures

For total hip replacement in acetabular fractures, Weber et al reported a 10-year follow-up study with a survival rate of 78%, with noncemented cups doing better than cemented ones.[74]  (See the image below.)

Bellabarba et al compared the results of arthroplasty in patients who had had prior operative treatment of their acetabular fracture with those in patients who had had prior closed treatment of their acetabular fracture.[75]  The average duration of follow-up was 63 months. Operating time, blood loss, and perioperative transfusion requirements were significantly greater in the patients with posttraumatic arthritis than in the patients with nontraumatic arthritis.

Of the patients with posttraumatic arthritis, those who had had ORIF of their acetabular fracture had a significantly longer index procedure, greater blood loss, and a higher transfusion requirement than those in whom the fracture had been treated by closed methods.[75]  Two of the 15 patients with a previous ORIF required bone grafting of acetabular defects, compared with seven of the 15 patients treated by closed means.

The Kaplan-Meier 10-year survival rate, with revision or radiographic loosening as the end point, was 97%; results were similar to those of the patients who underwent primary THA for nontraumatic arthritis.[75]  The only failure occurred in a patient with an unsupported acetabular discontinuity. They concluded that plate fixation is required in conjunction with acetabular reconstruction in such patients.

Mears and Velyvis assessed the role of acute total hip replacement in a selected group of patients with a displaced acetabular fracture and complicating features that greatly diminished the likelihood of a favorable outcome after open reduction and internal fixation.[23]

In this study, 57 patients underwent an acute THA for a displaced acetabular fracture.[23]  Mean follow-up was 8.1 years, and mean time from injury to arthroplasty was 6 days (range, 1-20 days). Mean patient age at arthroplasty was 69 years. Indications for the acute arthroplasty included intra-articular comminution and full-thickness abrasive loss of the articular cartilage, impaction of the femoral head, and impaction of the acetabulum that involved more than 40% of the joint surface and included the weightbearing region.

At the latest follow-up, mean Harris hip score was 89 points (range, 69-100).[23]  Of the 57 patients, 45 (79%) had an excellent or good outcome, six had heterotopic bone formation, and one had symptomatic grade IV ossification. In the initial 6 postoperative weeks, acetabular cups subsided an average of 3 mm medially and 2 mm vertically; all then stabilized, and none were loose at the latest follow-up. Six patients had excessive cup medialization, but none had late loosening or osteolysis. No cup or stem had late clinical or radiographic evidence of loosening.

The authors prefer a posterior approach with a generous incision. Identification and mobilization of the sciatic nerve is an important step. In cases with central dislocation, the head may be incarcerated and may have to be removed piecemeal; however, whenever possible, the authors prefer to excise the head en bloc and use it as bone graft to fill all of the defects. Only the implants that interfere with reaming need to be removed at surgery. Displaced large fragments must be realigned and stabilized, if possible, by using standard fracture fixation techniques.

The authors prefer uncemented cups (only if at least 75% contact exists in between the host bone and the cup) to cemented cups. It is essential to have a large inventory of implants available because larger cups may be necessary if the acetabulum is reamed to get a better fit for the cup. Larger deficiencies may require the use of acetabular reinforcement rings, cages, or even allograft.

Acetabular deficiency and distorted local anatomy may result in difficulty in proper orientation of the cup; this must be guarded against. Selection of a proper neck length and version of the prosthesis is essential to maintain optimal soft-tissue tension around the hip and reduce the chances of dislocation.

Dislocations reportedly occur more frequently after total hip replacement for acetabular fractures than after routine total hip replacements, possibly as a result of malorientation of the components or improper soft-tissue balance around the hip. The infection rate is increased, possibly because of prolonged surgery, increased blood loss, and preexistent infection. Nerve damage occurs because of difficulty in identification of the nerves tied down in scarred fibrous tissue. Loosening of the prosthesis, myositis ossificans, and other complications are possible.

Boraiah et al found that in 18 patients (mean age, 71 years) who underwent combined open ORIF and THA for acetabular fractures (one transverse, one anterior-column posterior hemitransverse, one both-column, and 15 posterior-wall), only one patient required revision surgery, because of failure of the acetabular component. The authors concluded that in appropriately selected patients, ORIF/THA can be an acceptable treatment approach.[76]

The goals of postoperative management are to maximize the functional status of the patient, facilitate early return to function, and detect complications quickly and manage them appropriately.[8, 72]

General measures

Acetabular surgery can be long and complicated and may involve significant bleeding. It is, therefore, important to adequately replace fluid volume and monitor the electrolyte balance. Blood should be given to maintain the hemoglobin level above 8-9 g/dL.

Pain relief is one of the most important aspects of the postoperative management of patients who have undergone acetabular surgery, given that the surgical procedure can involve a great deal of dissection. The best way to provide pain relief is by means of continuous epidural infusion of opiates. This decreases the need for systemic administration of analgesics significantly.

The authors recommend intravenous antibiotics for 72 hours postoperatively in uncomplicated cases. These should be broad-spectrum and provide gram-positive and gram-negative coverage.

The authors routinely recommend the use of indomethacin, 25 mg three times daily for 6 weeks, for the prevention of heterotopic ossification. The authors have no experience with the use of radiation for this purpose.

The authors do not use anticoagulation, except in individuals at high risk, because they have rarely encountered significant DVT in the Indian population. The authors do, however, encourage the use of elastic stockings, sequential compression devices (SCDs), and active ankle mobilization. In patients at high risk, standard DVT prophylaxis must be used. The risks of development of a wound hematoma and protection against pulmonary embolism (PE) must be weighed carefully in selecting patients for anticoagulant prophylaxis.

Nutrition is an often-neglected aspect of rehabilitation, especially in patients with multiple injuries. These patients have sustained severe trauma and tend to go into severe negative nitrogen balance, unless nutrition is specifically assessed. They often may have associated abdominal injuries that preclude enteric feeding. These patients must be put on parenteral hyperalimentation to ensure the best nutritional status to heal.

Patients often are unable to void spontaneously and require a urinary catheter. Care must be taken to prevent the catheter from becoming a source of sepsis, and, therefore, the catheter should be removed as soon as possible.

Bowel care is important. Patients may also be constipated and may require a high fluid intake, high-fiber diet, and stool softeners. An enema may be justified if these measures are unsuccessful.

Local measures

Patients with simple fractures, such as a posterior-lip fracture, need not be put on traction but should be confined to bed on the first postoperative day. Patients with more complex injuries may have to be put on gentle (2- to 3-kg) traction until pain subsides, usually in about 10-14 days.

A longer period of immobilization may be indicated if the fixation is not deemed stable at the time of surgery. A longer period of immobilization may also be indicated in extensile approaches; in these patients, the rehabilitation, especially abductor strengthening, may also have to proceed at a slower pace.

The posterior drains usually are removed at 48 hours. The retropubic drain should stay in place longer, for 72-96 hours. The drains may be removed earlier if they drain less than 10 mL/day.

Scrotal elevation may be required for some patients in whom there has been excessive handling of the spermatic cord, which may lead to significant scrotal edema.

Exercises may include the following:

• The patient must be taught static quadriceps exercises preoperatively and must start them again postoperatively as soon as he or she is comfortable
• The patient must also begin ankle mobilization and, especially, dorsiflexion exercises on postoperative day 1; this not only prevents the development of a postural foot drop but also helps in circulation of blood in the lower limb and guards against development of DVT
• The patient should also begin with upper limb–strengthening exercises to make crutch walking easier during rehabilitation
• Dynamic quadriceps exercises may be started as soon as the patient can sit up with his or her legs dangling by the side of the bed, usually in 5-7 days

Sutures are usually removed after 10-12 days; ilioinguinal wounds may sometimes take longer to heal.

Early complications

Death

Death may result from associated injuries or from thromboembolic phenomena, such as massive pulmonary embolism. The overall reported mortality is in the range of 0-2.5%. Mortality may be increased in patients older than 60 years, as seen in Letournel's series (5.7%).

Infection

Factors predisposing to infection include the following:

• Presence of wounds/friction abrasions near the operative site or at a distance
• Extensive exposure with a lot of soft-tissue stripping and devascularization
• Prolonged surgery
• Hematoma formation (especially in the retropubic space)
• Operating room atmosphere

Prophylactic measures include the following:

• Early and aggressive treatment of wounds/infective foci
• Prophylactic preoperative antibiotics the day before surgery and continued postoperatively, especially with the ilioinguinal approach ^{[3, 4]}
• Use of multiple suction drains to prevent hematoma formation, along with meticulous attention to hemostasis intraoperatively
• Early recognition and evacuation of hematomas

Management consists of the following:

• Early recognition
• Vigorous antibiotic therapy
• Thorough surgical debridement and removal of all necrotic debris
• Removal of all loose metallic implants

If infection communicates with the joint, cleaning and draining the joint are essential. Overall reported mortality is in the range of 0-2.5%. Mortality may be increased in patients older than 60 years, as seen in Letournel's series (5.7%). If the hip shows evidence of infective arthritis, excision arthroplasty may be required.

Nerve damage

Nerves involved can include the following[77, 78, 79] :

• Sciatic nerve
• Lateral cutaneous nerve of the thigh
• Femoral nerve
• Superior gluteal nerve
• Pudendal nerve

The nerve most commonly injured is the sciatic nerve, either the peroneal component alone or both the posterior tibial and the peroneal components. Causes include direct trauma by a fractured fragment and direct trauma at the time of surgery. Sciatic nerve damage is also associated with traction.

Prevention includes proper preoperative evaluation of sciatic nerve function, extreme vigilance about placement and use of retractors, and keeping the knee flexed and the hip extended while operating by the posterior approach. Intraoperative somatosensory evoked potential (SSEP) and spontaneous electromyographic (EMG) monitoring can also be used. (Routine use of these modalities has been questioned.) Proper positioning of the drill and screws near the greater sciatic notch is important, as is prevention of external rotation of the limb postoperatively.

If a nerve palsy develops, it is best treated with an ankle-foot orthosis. Recovery of the sciatic nerve is still possible for up to 3 years after injury. Iatrogenic nerve palsies are often a form of axonotmesis. EMG can be helpful in determining reinnervation of affected muscle groups. Tendon transfer procedures to correct foot drop should not be performed during the initial 3 years. About 60-75% of patients recover enough to have satisfactory function.[4]

Injury to the lateral cutaneous nerve of the thigh usually occurs as an iatrogenic injury following the ilioinguinal or extensile approaches. Most resolve spontaneously if the nerve is not avulsed.

Injury to the femoral nerve is extremely rare. It is seen only if excessive lateral traction is given to the iliopsoas compartment during manipulation of the fracture in an ilioinguinal approach.

The superior gluteal nerve is at risk in fractures that exit high in the greater sciatic notch and during the posterior approach, especially if blind coagulation of bleeding is attempted in this area.

The pudendal nerve may be injured because of pressure from the perineal post of the traction table. About 90% of patients with these injuries recover spontaneously.

Vascular injury

Vessels that may be involved include the following:

• Superior gluteal artery
• Femoral artery
• Femoral/external iliac vein

The superior gluteal artery is the vessel most commonly involved. The injury may be due to the injury itself, especially in fractures exiting near the roof of the greater sciatic notch. It may also result from iatrogenic damage during dissection in the region of the roof of the greater sciatic notch.

The femoral artery may be damaged by a misplaced posterior-to-anterior lag screw as reported by Johnson et al.[80] Probe et al also reported a case of femoral arterial thrombosis after excessive manipulation of the artery during an ilioinguinal approach.[81] This necessitated immediate exploration and thrombectomy.

Helfet et al reported the perforation of the femoral vein by a sharp fracture fragment from the anterior column during attempts at fracture reduction.[78] The patient recovered fully following immediate vascular repair.

Thromboembolism

Thromboembolism is one of the most significant complications of acetabular fractures. The prevalence of PE in the acute setting is 1-5%; significant incidence is 4%, according to Judet and Letournel.[3, 4] The reported risk of PE is 4-7%.

The emboli usually originate from the proximal large veins of the lower limb. A large discrepancy exists between the prevalence of clinically evident DVT (2.3-5%) and DVT detected on vascular testing (up to 60%). However, routinely used methods such as Doppler ultrasonography (US) are not good tools for detecting proximal DVT. Therefore, some form of anticoagulant prophylaxis (most often, low-molecular-weight heparin [LMWH] and mechanical compression devices) is often recommended, especially in high-risk patients.

Inferior vena cava (IVC) filters are recommended in patients with positive findings on duplex US and in high-risk groups (ie, those with contraindications for chemical thromboprophylaxis, a history of malignancy, obesity, or a previous history of DVT).

Malreduction

Malreduction is an important and, in most cases, preventable complication that compromises the eventual result. Every possible attempt must be made to achieve an anatomic reduction after surgery.

Fixation failure

Risk factors include marked comminution, severe osteoporosis, use of lag screws or plates alone, and early/unguarded ambulation. This can lead to disastrous consequences.

Intra-articular hardware

Judet and Letournel reported an incidence of 0.9% of complications associated with hardware.[3, 4] Preventive measures include a thorough knowledge of the local anatomy (eg, avoid placing screws underneath the iliopsoas during an ilioinguinal approach).[82] To prevent this complication, intraoperative fluoroscopy and CT can be used to detect intra-articular hardware (see the image below).

Kendorff et al concluded that 3D fluoroscopic imaging provides more detailed and accurate information about implant placement and articular reduction than standard fluoroscopy and that results are comparable to those achieved with CT.[83] Evaluating the hip range of movement for restriction and crepitus following insertion of screws near the joint is also a preventive measure.

Late complications

Avascular necrosis

Judet and Letournel reported an incidence of 6.6% for avascular necrosis (AVN).[3, 4] The incidence of AVN of the femoral head after a central fracture dislocation is only 1.6%, whereas that following an anterior dislocation is 1.5% and that following a posterior dislocation is 7.5%. Salient points include the following:

• Femoral head necrosis is practically impossible to prevent
• The trauma of the accident always determines the future of the femoral head in preserving or destroying all or part of its vessels
• Whatever the quality of reduction, AVN may occur
• Intraoperative avoidance of stripping of periosteum helps decrease the incidence of anterior column and posterior wall osteonecrosis
• Incidence of AVN is lowest if reduction is performed within the first 24 hours; however, necrosis is far from inevitable, even if reduction takes place after 24 hours
• Surgery does not augment femoral head necrosis; however, a relation may exist with acetabular osteonecrosis
• Time of presentation is mostly from 3-18 months
• The clinical course and radiologic course are extremely variable, and any correlation may exist between the two
• Medical treatment does not influence the course, and once diagnosis is confirmed, management is along conventional lines

A prospective study by Maini et al suggested that a complete tear of the obturator externus, the piriformis, or both is a strong predictor of future development of AVN of the femoral head in patients with acetabulum fractures.[84]

Posttraumatic osteoarthrosis

The incidence of osteoarthrosis in the literature is 3-48%. The common causes of osteoarthrosis include malunion (articular incongruity and AVN of the femoral head).

Heterotopic new bone formation

The incidence of heterotopic new bone formation (see the image below) with various approaches is as follows:

• Kocher-Langenbeck approach - 19% (10.5% Brooker grade III or IV)
• Ilioinguinal approach - 9% (2% Brooker grade III or IV)
• Double approaches - 50-60% (35% Brooker grade III or IV)

Risk factors include the following[85] :

• Male sex
• Increased body mass
• Greater age
• Intensive care unit (ICU) admission and length of stay
• Non-ICU hospitalization for longer than 10 days
• Mechanical ventilation required for 2 days or longer
• Abdominal or chest injuries
• Associated head injury
• T-shaped fractures
• Pelvic ring injuries
• Hip dislocation
• Extensile approaches, especially those involving an osteotomy of the greater trochanter
• Stripping of the external iliac fossa

The Brooker classification is a grading of severity of heterotopic ossification around the hip. The various grades are as follows:

• Brooker grade I - Isolated islands of bone
• Brooker grade II - Mild bony projections separated by more than 1 cm
• Brooker grade III - Large bony projections from both acetabular and femoral sides, separated by less than 1 cm
• Brooker grade IV - Severe (bridging from femur to acetabulum)

Salient points include the following:

• The amount of heterotopic ossification appears to be directly related to the trauma to the hip abductor musculature, whether at the time of the injury or subsequently at surgery
• Radiography reveals a significant amount of ectopic bone in many patients, but muscle function and range of motion are satisfactory; in other patients, rotation and abduction are limited; however, if patients can fully extend the hip to the neutral position and have satisfactory flexion of at least 90°, they may be happy with the result and have no desire for further surgery to excise the bone
• Heterotopic ossification commonly is assessed on the AP pelvis view and can be misleading; when excision is being considered, 45º oblique views of the pelvis or CT can be used to clarify the extent and location of heterotopic ossification about the hip
• Whenever possible, surgery for excision of ectopic bone should be delayed for 15-18 months after injury; if it is performed at this time, no problem with recurrence usually exists, and motion can be expected to return to more than 80% of normal (if no arthritis is present); ectopic bone spontaneously regresses over several years in some patients, and thus, if the indications for bone excision are equivocal, it may be best to wait, with the hope of some spontaneous regression of the ectopic bone and improvement of motion

Prophylaxis may include the following measures[82, 86, 87] :

• Indomethacin, 25 mg three times daily for 6 weeks starting on postoperative day 1, reduces the overall incidence of heterotopic ossification and, especially, reduces the incidence of Brooker grade III and IV ossification
• Radiation therapy, 7 Gy in a single sitting, has also been shown to be effective in decreasing the incidence and severity of heterotopic ossification
• A combination of radiation and indomethacin may also be useful

Nonunion

Nonunion is a rare complication of acetabular fractures.

Chondrolysis

Chondrolysis is defined as early (6-12 months) postoperative progressive joint space narrowing without alteration of the femoral head or acetabular bone, in association with painful hip motion.[2] The prevalence is 1%, according to Judet and Letournel.[3, 4, 5] The authors have had no patients who developed this complication. It is important to rule out intra-articular hardware and infection before reaching this diagnosis. Treatment is mainly supportive, and the prognosis is poor.

Certain negative outcomes related to the injury are inevitable. These include death, posttraumatic nerve injury, thromboembolic phenomena, and AVN. However, a number of preventable complications may result secondary to the surgical intervention: infection, iatrogenic nerve injury, fixation failure, and malreduction. Avoidance of such complications greatly improves clinical results after these devastating injuries.

Radiography

Postoperative radiographs are usually obtained at the completion of the operation for preliminary confirmation of the reduction. A minimum of an AP pelvis radiograph is obtained in the operating room; the iliac oblique and obturator oblique views can be obtained in the operating room or later. After gait training and before discharge, another AP pelvic radiograph generally is obtained to confirm that loss of reduction has not occurred during ambulation. A single AP pelvis radiograph is obtained at each follow-up examination.

Mobilization protocol

On postoperative day 1, static quadriceps exercises are started.

On day 2 or 3, continuous passive motion (CPM) is started, with range limited to about 60° for the first 3 days to avoid tension on the wound.

On days 3-7, dynamic quadriceps exercises are performed. Once pain has subsided, the patient may begin gait training on a walker or axillary crutches. Toe-touch weightbearing is permitted. The patient is encouraged to ambulate with a step-through gait and a heel-to-toe motion. Active flexion, extension, and abduction exercises while standing are encouraged.

Physical therapy is directed toward regaining muscle strength at the hip, especially in the abductors; this has been shown to correlate well with the final functional outcome. Active abduction and passive adduction are avoided for 4 weeks in patients treated with an extended iliofemoral approach.

For 8-12 weeks postoperatively, weightbearing is limited. Full weightbearing ambulation is permitted only after the fracture unites, usually by about 12 weeks, with gradual discarding of walking aids as tolerated.

After about 1 year, if no complications are present, return to sporting activity may be advised.

For patient education resources, see Total Hip Replacement.