Minimally Invasive Total Hip Arthroplasty Technique

Updated: Oct 01, 2018
  • Author: Derek F Amanatullah, MD, PhD; Chief Editor: Erik D Schraga, MD  more...
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Technique

Approach Considerations

Among the first alternatives to the transtrochanteric approach to total hip arthroplasty (THA) were the conventional posterior and lateral approaches. [62] These early alternative approaches sought to limit disturbance to osseous and soft-tissue anatomy, thereby avoiding unnecessary complications (eg, trochanteric nonunion). [63, 64] The conventional posterior and lateral approaches were nevertheless reported to be associated with nerve injury. [65]

Beginning in the 1990s, these conventional surgical approaches were further modified to limit the amount of soft-tissue dissection and minimize damage to healthy surrounding structures. Minimally invasive THA (MIS-THA) actually is not a single approach but a collective term that encompasses multiple distinct minimally invasive surgical (MIS) approaches. For example, the surgeon may use a single mini-incision, which is usually shorter than 10 cm, or may prefer to use two incisions, each of which is shorter than 5 cm (see the image below).

Minimally invasive total hip arthroplasty. Shown a Minimally invasive total hip arthroplasty. Shown are skin incisions for direct anterior (black), miniposterior/lateral/anterolateral (dark blue), conventional posterior (dark blue plus red extensions), direct superior (green), and SuperPATH (purple) approaches to hip. Conventional posterior incision is usually 10-25 cm long. Single incisions for minimally invasive approaches are usually less than 10 cm long. In two-incision approach, both incisions are usually less than 5 cm long.

Basic approaches currently employed for MIS-THA include the following [3] :

  • Direct anterior approach (eg, modified Smith-Petersen) - Performed in the supine position and uses the internervous plane between the femoral and superior gluteal nerves
  • Anterolateral approaches (eg, modified Watson-Jones) - Performed in the supine or lateral position and divides the anterior portion of the gluteus medius
  • Direct lateral approach (eg, modified Hardinge) - Performed in the supine or lateral position and uses the intermuscular interval between the tensor fasciae latae (TFL) and the gluteus medius
  • Posterior approach (eg, modified Southern) - Performed in the lateral position and divides the gluteus maximus and the short external rotators (eg, piriformis, superior gemellus, obturator internus, inferior gemellus, and quadratus femoris) of the hip
  • Piriformis-sparing posterior approach - Performed in the lateral position and divides the gluteus maximus, the iliotibial band, and the short external rotators of the hip (eg, superior gemellus, obturator internus, inferior gemellus, and quadratus femoris) except the piriformis
  • Direct superior approach – Performed in the lateral position and divides the gluteus maximus and the short external rotators of the hip (e.g., piriformis, superior gemellus, obturator internus, and inferior gemellus) while leaving the iliotibial band and quadratus femoris intact
  • Two-incision approach - Combines an anterior approach to the acetabulum with a posterior approach to the proximal femoral shaft
  • SuperPATH approach – Performed in the lateral decubitus position and divides the gluteus maximus, medius, and minimus

The choice of operative approach depends on surgeon preference and experience. Any small incision during MIS-THA should be used as a mobile window, so that pressure is not exerted on any single surgical area long enough to compromise muscle and soft tissue. Specialized instruments (see Periprocedural Care) and trained assistants facilitate MIS-THA enormously. Such instruments keep the assistants’ hands out of the operative field while generating less tension on the soft tissues.

Some authors recommend using fluoroscopy to verify the correct location of the skin incisions; others consider this measure unnecessary. [60, 66] Given the decreased visualization characteristic of MIS-THA, surgeons may find high-technology computer navigation, custom guides, or robotics extremely useful for correctly positioning the components. [67] However, the precise role of these technologies in MIS-THA remains to be demonstrated.

In some cases, it may prove necessary to osteotomize the femoral neck in situ or piecemeal rather than dislocating the hip and removing the femoral head en bloc. [8, 59]

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Direct Anterior Approach

The anterior approach uses the internervous plane between the femoral nerve (lateral border of the sartorius) and the superior gluteal nerve (medial border of the TFL). The space between the TFL and the sartorius is developed by splitting the fascia of the anterior TFL and then sliding medially. Access to the joint capsule is achieved through the interval between the TFL and gluteus medius muscles and the rectus femoris muscle of the quadriceps femoris.

Because this approach requires no splitting of muscles or formal cutting of tendons, it is considered the optimal MIS-THA approach. [3, 21] According to its proponents, the direct anterior approach is the only true MIS-THA technique because the hip joint is closest to the anterior skin and the overlying fat tissue is thin in this part of the thigh.

An advantage to the anterior approach is that the operation is done with the patient in the supine position, which means that a bilateral procedure can be performed without any need for redraping or repositioning. Carefully selected and otherwise healthy patients may be candidates for simultaneous bilateral elective THA.

To avoid transecting branches of the lateral femoral cutaneous nerve (LFCN), the skin incision is placed more laterally than in the traditional Smith-Petersen approach (see the images below). The proximal femur can be easily exposed by extending the incision distally, and proximal femur fractures are easy to access.

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct anterior approach. Photograph of right anterior thigh after draping on fracture table. Note metal spar with square holes; this device attaches to fracture table and allows elevation of femur during femoral preparation.
Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct anterior approach. Left femoral head is dislocated anteriorly before osteotomy of femoral neck.
Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct anterior approach. View of proximal femur and right hip in supine position, showing lesser trochanter femoral neck resection marked with pen.
Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct anterior approach. Proximal femoral exposure and rasp is introduced into femoral canal facilitated by fracture table via metal spar elevating femur anteriorly.
Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct anterior approach. Insertion of acetabular component after acetabular component reaming in supine position.
Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct anterior approach. Circumferential view of acetabular component is shown with visual confirmation of orientation. Insertion guides and radiographs also may be used to assess positioning.

Kennon et al described a direct anterior MIS-THA in the supine position using accessory portals as needed. [20] In addition to the primary incision in line with the femoral neck, a distal lateral or a posterior superior accessory portal is created to allow the introduction of a reamer or a broach. Preparation of the femur can be difficult with this approach. Even though both cemented and uncemented implants have been performed safely, cementless components are generally preferred by most authors.

Michel et al described a “MicroHip” procedure that represents a modification of the Smith-Petersen approach. [68] This operation is performed with the patient in the lateral decubitus position, using standard instrumentation on a regular operating table without placing any traction on the leg. Regardless of patient positioning, the use of the intermuscular plane is thought to contribute to faster recovery as compared with a conventional muscle-splitting approach.

The direct anterior approach has the advantage of preventing injury to muscles and their attachments to the pelvis and femur, thereby helping restore their normal tension and the dynamic muscular stabilization of the hip joint immediately after the procedure is completed. Patients do not require hip dislocation precautions postoperatively.

In cadaver studies, this assumption has not held true. [37, 36, 47] Surgeons do not routinely repair posterior structures if they release during the direct anterior approach, whereas repair is routine with the other approaches.

A potential disadvantage of the direct anterior approach is that it is more technically demanding and requires extensive knowledge of hip-joint anatomy in the supine position. Additionally, the LFCN is at risk and, rarely, the femoral nerve. Potential complications associated with fracture table use include intraoperative femoral and ankle fractures. The major contraindications for direct anterior MIS-THA are related to previous acetabular fracture associated with posterior heterotopic ossification (HO), pelvic deformity, or posterior acetabular defects for which extensive posterior access may be necessary.

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Anterolateral Approach

In the anterolateral approach, the skin incision proceeds from the anterior tubercle of the greater trochanter and angles toward the anterior superior iliac spine. Like the anterior approach, this approach uses the plane between the gluteus medius and the TFL and usually only requires elevation of the anterior third of the gluteus medius. [59, 69] Abductor muscle function is maintained, and the posterior capsule is left intact.

Bertin et al reported on anterolateral MIS-THA and noted decreased muscle damage and difficulty with achieving femoral exposure and obtaining consistent acetabular component positioning. [59]

Pflüger et al reported on anterolateral MIS-THA and noted that the gluteal insufficiency or dehiscence seen with the conventional anterolateral approach was eliminated by preserving the muscle attachments. [28]

The anterolateral approach provides good visualization of the acetabulum. Compared with the direct lateral approach, it results in less abductor weakness; compared with the posterior approach, it yields lower dislocation rates. Sectioning of muscle and tendon or the greater trochanter is not required for implantation of components.

The anterolateral approach places the superior gluteal nerve at risk during proximal dissection. [15]

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Direct Lateral Approach

The direct lateral approach was initially described by Kocher and subsequently modified by Hardinge and Millikan et al. The anterior one third to one half of the gluteus medius is released from the greater trochanter. The procedure can be performed with the patient in a supine, semilateral, or  lateral decubitus position.

The skin incision runs from a point 2 cm proximal to the greater trochanter to a point located 5-8 cm distally along a line parallel to the long axis of the femur. There is no true internervous plane, and the dissection involves splitting the gluteus medius and the vastus lateralis. After the TFL is incised, the gluteus medius fibers are cut to expose the joint capsule. [32]

Division of the gluteus medius is limited to 5 cm proximal to the greater trochanter or 4 cm proximal to the superior acetabulum; further extension places the superior gluteal neurovascular bundle at risk for injury. Division of the abductor musculature may be manifested in a prolonged or even permanent limp after surgery. The extent of denervation of the abductors after the direct lateral approach is controversial.

The main disadvantage of the direct lateral approach is the necessity of detaching the gluteus minimus and a portion of the gluteus medius from the greater trochanter, which can lead to a delay in functional recovery or, in some cases, incomplete healing of the abductor musculature back to the greater trochanter. Damage to the superior gluteal nerve can cause a limping gait due to impaired abduction.

In most studies, the direct lateral MIS-THA has failed to show significant improvements over other approaches, aside from a slight reduction in hospital stay. However, some authors have reported favorable outcomes for this approach in comparison with a conventional direct lateral approach to THA.

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Posterior Approach

The posterior approach (also referred to as the posterolateral approach by some authors) is the workhorse for conventional THA. [62, 69] It is the most commonly used approach among US surgeons and is technically the easiest, requiring only one assistant.

An 8-cm incision is made over the posterior trochanter, the gluteus maximus, and the capsule. The dissection proceeds to the gluteus maximus fascia and the TFL. The TFL is incised laterally, and the fibers of the gluteus maximus are split in line with the muscle fibers. The short external rotators (eg, piriformis, superior gemellus, obturator internus, and inferior gemellus) are elevated as a single flap from the femur and reflected posteriorly; this, along with the posterior hip capsule, is repaired at the completion of the operation.

Posterior MIS-THA uses the same plane of dissection as the conventional posterior approach but is designed to minimize the soft-tissue dissection. [60, 70] The gluteus maximus split should be kept to a minimum, and release of the gluteus maximus tendon insertion and quadratus femoris muscles should be avoided. Anterior capsular release is critical: releasing the anterior capsule facilitates femoral mobilization and easy delivery of the femur into a small wound. [58]

The following four differences in muscle damage have been observed between posterior MIS-THA and conventional posterior THA:

  • In posterior MIS-THA, no incision is made in the TFL
  • In posterior MIS-THA, the gluteus maximus muscle is split less than 6 cm, whereas in conventional posterior THA, this muscle is split 10-12 cm
  • In posterior MIS-THA, the gluteus maximus tendon is not released, whereas in conventional posterior THA, this tendon is released and repaired
  • In posterior MIS-THA, the quadratus femoris muscle is not released, whereas in conventional posterior THA, this muscle is released and repaired

With posterior MIS-THA, the femoral preparation is compromised in relation to what it would be with conventional posterior THA because the quadratus femoris muscle is kept intact and the lesser trochanter is not visible, but the acetabular landmarks are the same and are in the visual field. For both the posterior MIS-THA and the conventional posterior THA, meticulous posterior capsular closure with the short external rotator reattachment is critical. This repair reduces the risk of postoperative dislocation from 3% to 0.85%. [71]

Curved inserters facilitate correct acetabular cup positioning and help avoid a more vertical inclination of the acetabular component. Femoral components must be aligned with the posterior cortical bone of the neck for correct version, and the lateral edge of the stem must be under the tip of the greater trochanter to avoid a varus position.

Posterior MIS-THA does result in less pain and better function in the first 3 months than conventional posterior THA does. In gait studies, the posterior incision yields results equivalent to those of the anterior approach.

The major disadvantage of the posterior approach is the cutting off of the external rotators of the joint and opening of the posterior hip capsule (which may result in posterior hip dislocation). Intraoperative damage to the inferior gluteal nerve may lead to a limp as a result of impaired abduction. In cadaver studies, abductor muscle damage occurred in every posterior MIS-THA despite direct visualization and placement of retractors to protect the gluteus medius and gluteus minimus muscles. [37, 36]

A major factor in the pathogenesis of thromboembolic disease during THA is intraoperative distortion of the femoral vein as a result of retraction and limb positioning, which is thought to be especially likely with any posterior approach.

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Two-Incision Approach

Two-incision MIS-THA uses the direct anterior approach, which facilitates osteotomy of the femoral neck, preparation of the acetabulum, and insertion of the acetabular component. The anterior incision is about 5 cm long, passing obliquely from the intertrochanteric line to the center of the femoral head, which are identified with fluoroscopy (see the image below).

Minimally invasive total hip arthroplasty: two-inc Minimally invasive total hip arthroplasty: two-incision approach. Photograph of right hip in supine position showing outlines of anterior superior iliac spine and greater trochanter. Dotted line marks anterior incision.

The superficial plane between the TFL and the sartorius and the deeper plane between the rectus femoris and the TFL are the same as in the direct anterior approach.

A second incision is placed posteriorly to prepare the femur and allow insertion of the femoral component. This incision is 3-4 cm long and is made in line with the femoral canal. The gluteus maximus fascia is split superficially, and a direct pathway to the femoral canal is found with blunt dissection posterior to the abductor tendons and anterior to the piriformis tendon, as in blind nailing of femur fractures (see the image below).

Minimally invasive total hip arthroplasty: two-inc Minimally invasive total hip arthroplasty: two-incision approach. Surgeon can guide femoral broaches through small posterior incision while palpating through anterior incision.

Irving developed a double-incision technique without fluoroscopy, adopting both the posterior approach and the direct anterior approach. [51] The method has been described without fluoroscopy by other authors as well.

The incidence of proximal femoral fractures is three times higher with two-incision MIS-THA than with conventional THA. This difference is related to several factors, including the direction and magnitude of forces delivered to the broach and implant, the loss of visual and tactile feedback, and an increased tendency toward component malalignment. As in the direct anterior approach, injury to the LFCN can lead to lateral thigh numbness.

In one study, patients undergoing two-incision MIS-THA recovered slower than those undergoing posterior MIS-THA, as measured by mean time to discontinue use of a walker or crutches, discontinue use of all ambulatory aids, and return to normal daily activities. [72] Substantially more muscle damage occurs to the gluteus medius and minimus muscles in two-incision MIS-THA than in posterior MIS-THA. The location of the gluteus medius muscle damage typically is along the posterior border of the muscle belly proximal to the tendinous portion of the gluteus medius.

Two-incision MIS-THA also damages the short external rotators. Patients appeared to be more satisfied with the appearance and functional results of posterior MIS-THA than with those of two-incision MIS-THA. [72] It should be noted, however, that several other authors have obtained exactly the opposite results, with dramatically better clinical outcomes and a significant patient preference for two-incision MIS-THA.

The difficulty inherent in the two-incision approach is reflected in the longer mean operating times associated with this procedure. As a result, many surgeons are reluctant to learn two-incision MIS-THA.

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Direct Superior Approach

In the direct superior approach, the skin incision proceeds from the posterosuperior corner of the greater trochanter, extending proximally in line with the fibers of the gluteus maximus. The gluteus maximus fascia is incised sharply, exposing the gluteus maximus muscle. (See the image below.)

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct superior approach. Gluteus maximus fascia is incised sharply to expose gluteus maximus muscle.

These fibers are divided longitudinally with a Cobb elevator, and the deep fascia of the gluteus maximus is gently divided, exposing pericapsular fat. The piriformis tendon is detached close to its insertion. (See the image below.)

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct superior approach. Gluteus maximus muscle fibers are divided longitudinally, and deep gluteus maximus fascia is divided to expose pericapsular fat; prirformis tendon is detached close to its insertion.

The capsule is then incised in the inferior aspect of the wound, and the capsulotomy is extended posterior and superior to the superior acetabulum. (See the image below.)

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct superior approach. Capsule is incised in inferior aspect of wound; capsulotomy is extended posterior and superior to superior acetabulum.

The hip is dislocated, the femoral neck is osteotomized with an oscillating saw, and the femoral head is removed. (See the image below.)

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct superior approach. Hip is dislocated, femoral neck osteotomized, and femoral head removed.

A sharp curved Hohmann retractor is placed over the anterior acetabular rim. A second bent 90º Hohmann retractor is then placed at the inferior margin of the acetabulum. A 90º handheld retractor is placed in the superior aspect of the wound to delineate the margin between the superior labrum and the superior capsule. A 90º sharp Hohmann retractor is placed deep to the superior capsule and gently tapped into the ilium. An optional retractor is placed on the posterior aspect of the acetabulum. (See the image below.)

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct superior approach. Sharp curved Hohmann retractor is placed over anterior acetabular rim; second bent 90-degree Hohman at inferior margin; 90-degree handheld retractor in superior aspect of wound; and 90-degree sharp Hohmann deep to superior capsule. Optional retractor may be placed on posterior aspect of acetabulum.

The acetabular labrum is excised, and the acetabulum is reamed with a 55º angled acetabular reamer. The leg is placed in 40º flexion, 40º adduction, and 40º internal rotation. A 90º handheld retractor is placed in the inferior aspect of the wound to retract the quadratus femoris away from the proximal femur.

Minimally invasive total hip arthroplasty: direct Minimally invasive total hip arthroplasty: direct superior approach. Acetabular labrum is excised; acetabulum is reamed. Retractor is placed in inferior aspect of wound to retract quadratus femoris away from proximal femur.

A 90º Hohmann retractor is then placed over the superior femoral neck. A third retractor is placed under the calcar to expose the proximal femur. A box chisel may be used to remove the bone from the lateral neck. The acetabulum is reamed under direct vision to a size 1 mm smaller than the anticipated hemispheric implant. A single hand-powered reamer is used in femoral preparation to locate the direction of the femoral diaphysis. Hand reaming is performed to lateralize the proximal femoral canal. Sequential broaching is performed with an offset handle until maximal cortical contact in the mediolateral dimension is obtained.

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Piriformis-Sparing Approach

A piriformis-sparing MIS-THA is performed by one surgeon with one or two assistants. No specialized instruments are required. The patient is placed in the lateral decubitus position. Leg lengths are noted and the leg positioned in 45° of flexion at the hip and 90° of flexion at the knee. Landmarks for the skin incision are identified, with the tip, the anterior border, and the posterior border of the greater trochanter forming an equilateral triangle with sides of approximately 4-6 cm.

A 6-cm incision is made, starting one fingerbreadth anterior to the posterior corner of the triangle and extending cranially and posteriorly at an angle of 30° to the long axis of the femur, so that two thirds of the incision is distal to the tip of the greater trochanter and one third proximal. In all but the very slimmest of patients, the incision is extended distally if there is inadequate access to the acetabulum or proximally if better access to the femur is desired. In nonobese patients, an incision of 7-10 cm is the norm. In obese or highly muscular patients, longer incisions are needed, and the surgeon should not hesitate to extend the incision in such cases.

Once the femoral head has been dislocated, the neck is osteotomized. A Hohmann retractor is placed just distal to the lesser trochanter to retract the distal part of the quadratus femoris distally and provide better visualization of the calcar (for accurate positioning of the osteotomy site); a second Hohmann may be required to prevent fascia lata from sliding over the greater trochanter.

After the neck is cut, the proximal femur is retracted anteriorly with a curved Hohmann retractor placed in front of the anterior column. The anterior capsule may have to be released if it is tight, though this is seldom necessary in a routine osteoarthritic hip. A second curved Hohmann retractor is placed under the transverse ligament to hold the inferior capsule out of the way, and a Norfolk and Norwich retractor is placed in the proximal part of the wound between the fibers of the gluteus maximus (superficially) and the posterior capsular flap (deep).

The retractor positions at this stage are crucial to obtaining good exposure of the acetabulum. Occasionally, the Norfolk and Norwich retractor fails to retract the posterior capsular flap (with stay sutures attached) adequately, thus obscuring the view of the posteroinferior edge of the acetabulum. In this case, a pointed Hohmann retractor may be placed carefully between the acetabular margin and the posterior capsule to retract the latter posteriorly.

The labrum is excised with a long-handled scalpel, with care taken to preserve the capsule and piriformis. If the piriformis or the superior capsule obscures the view into the roof of the acetabulum (eg, with a valgus femoral neck), these structures may be retracted by means of a Charnley pin fixed into the ilium. With correctly placed retractors, adequate soft-tissue release, a correctly located incision, and, in the obese patient, a sufficiently long incision, the view into the acetabulum should be good, with a 360° view of the acetabular margin.

The inferior capsule may be incised to facilitate entry of the reamers. The acetabulum is then reamed in the normal manner, and the cup is inserted (40-45° of abduction and 25° of anteversion). Care is taken to prevent the reamers from exerting leverage on the femur or retractor and thereby contributing to the creation of an eccentric socket.

The femur is presented by flexing, adducting, and internally rotating the hip; the incision “mobile window” is moved appropriately. A Hohmann retractor is placed medially (just proximal to the lesser trochanter) to afford access to the femoral canal. A second retractor may be placed under the femur to elevate it. A Langenbeck retractor is often required to prevent fascia lata from subluxating over the greater trochanter. At this point, the intact piriformis tendon may be seen and palpated as a tight cord exiting its insertion and passing posteriorly.

The femur is then prepared with broaches, placed in 20° of anteversion. With an overhanging greater trochanter, the piriformis tendon may be damaged by the broach if care is not taken. In obese patients, retraction of the proximal part of the incision with a Langenbeck retractor is required to prevent skin abrasion from the femoral broaches. With trial components in place, hip stability is tested, leg lengths are checked, and the definitive components are inserted. This approach does not preclude normal balancing of the hip when required (eg, capsulotomy, tendon release, or osteophyte removal).

Closure commences with repair of the posterior capsule, which is sutured to the back of the greater trochanter (by using the stay sutures already in place) through two drill holes in the bone. At this stage, the entire posterior envelope has been reconstructed. The remaining tissues are closed in layers. Neither a hip abduction wedge nor a pillow is used. Patients are mobilized without restrictions. [45]

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SuperPATH Approach

The SuperPATH approach was developed to promote early mobilization and greater range of motion, physiologic gait kinematics, and improved pain control. It is a hybrid of the superior capsulotomy (SuperCap) approach and the percutaneously assisted total hip (PATH) technique.

Preparation of the hip in situ allows the operative leg to rest on a Mayo stand during the entire procedure, obviating the need for a second assistant. Additionally, because the hip is not dislocated, the interval between the gluteus medius and the piriformis is utilized, and the piriformis can be preserved in a majority of cases.

Using the percutaneous accessory portal for acetabular preparation ensures that visualization of the wound is not obscured by tooling. This allows the procedure to be done safely through the smaller window created by an intact piriformis. The accessory portal also provides in-line access to the cup, simplifying the insertion of screws and facilitating impaction of bone-ingrowth components. [73]

As is the case for the SuperCap and PATH techniques, any available implant can be used for the SuperPATH technique, including both press-fit and cemented styles for either femoral or acetabular components. This allows the surgeon to make the choice of implant on the basis of the patient’s disease and deformity, without being unduly influenced by the choice of incision. [73]

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Complications

The complication rate is twice as high for surgeons who perform fewer than 50 MIS-THAs a year. Complications after MIS-THA are more common in the following individuals:

  • Patients older than 65 years
  • Patients with a body mass index (BMI) higher than 30 kg/m 2
  • Women with osteoporosis
  • Patients with altered femoral or acetabular anatomy

Common adverse events include the following:

  • Dislocation
  • Damage to the sciatic nerve, femoral nerve, or LFCN
  • Impaired postoperative wound healing
  • Hematoma
  • Infection
  • Venous thrombosis or thromboembolism

The most common errors during MIS-THA are vertical positioning of the acetabulum due to noncentric drilling and varus placement of the femoral stem, leading to a higher incidence of early or late dislocation. Proximal femoral fractures, fractures of the greater trochanter, and torsional fractures of the femoral shaft and its condyles are associated with problems related to femoral head dislocations. Damage to the sciatic nerve or the femoral nerve can occur.

Less significant risks include skin rupture caused by excessive tension from the hooks and impaired postoperative wound healing. The incidence of hematomas, as well as superficial and deep infection, is also higher. Early or late dislocation of the hip-joint endoprosthesis is more likely after MIS-THA. It has been suggested that the greater retraction pressure associated with MIS techniques causes muscle and wound damage and poor healing, though there is little clinical evidence to support this suggestion.

The reason for the high probability of complications after MIS-THA may be that only one surgery team member has good access to the treated area; this restricted access limits assistant support and also inhibits the transfer of experience from surgeon to surgeon. The use of a special set of instruments can facilitate implantation of the endoprosthesis and reduce the number of complications.

Because the posterior approach carries an increased risk of posterior dislocation, it is reasonable to be especially alert for this complication with this procedure. However, a study of 1000 hips treated with miniposterior MIS-THA reported a posterior dislocation rate of 1.2%, compared with 5.8% for the standard posterior approach. [4, 74] Despite sufficient soft-tissue mobilization in properly selected patients, limited surgical visualization may necessitate conversion of MIS-THA to conventional THA in a minority (< 10%) of patients. [32]

Because the two-incision technique uses unique dissection planes, it has a significant learning curve that results in a higher-than-anticipated complication rate. [40] One study found that the rate of complications did not decrease over a surgeon’s first 10 cases, which suggested that the learning curve may be longer than expected. [52]

The two-incision technique is supposed to spare cutting muscles and tendons, though cadaveric studies of 10 hips showed that in every case, the abductors, external rotators, or both were injured. [36] Moreover, unlike standard mini-incisions, which use large dissection planes, the two short incisions have limited extensibility. Given the increased level of skill and experience required to perform the two-incision approach safely and correctly, many surgeons feel that this approach is best left to high-volume surgeons who receive specialized training. [3]

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