Wrist Fractures and Dislocations

This review covers primary fractures and dislocations involving the wrist region. The wrist is composed of the anatomic region between the forearm and the hand. Its ability to place the hand in 3-dimensional space is essential for normal daily function of the upper extremity. Over the last few decades, significant advances have occurred in the understanding of wrist anatomy, pathophysiology, and carpal kinematics. Even so, some wrist injuries remain a diagnostic enigma, while others remain frustrating to treat either conservatively or with operative intervention.

Frequency

In the Western world, the most common orthopedic fractures are distal radius fractures. Peak incidence is found in young men and postmenopausal women.[1]

Approximately 14% of all hand fractures are carpal fractures. Scaphoid fractures are by far the most common of the carpal fractures, estimated at 70-79%. Fractures of the triquetrum make up an estimated 14% of all carpal fractures, trapezial fractures make up 2.3%, and hamate fractures make up 1.5%. Lunate, pisiform, and capitate fractures combine for 3% of all carpal fractures. Trapezoid fractures are rare, encompassing 0.2% of all carpal fractures.

Injuries occur more commonly in young, active, and energetic males and are also common in osteoporotic elderly persons. The demographics may vary by season, as fractures in children seem to be more common in the warmer months while those in adults increase in the colder months. The overall incidence of these fractures appears to be increasing over time.

One retrospective study on carpal fractures in Singapore found that the prevalence of carpal fractures in this population was consistent with findings of studies in other countries. Isolated scaphoid and other carpal fractures were more common in men compared with women (male-to-female ratio of 13:1), and the mean age of those experiencing these fractures was 26 years. Military conscription was identified as an at-risk activity predisposing to carpal fracture.[2]

Most wrist fractures and dislocations are a result of axial loading on the outstretched palm and extended wrist, usually from a fall on outstretched hand (FOOSH), motor vehicle accident, or sports contact injury. Most result in fractures of distal radius, scaphoid, and other carpal bones. Higher-impact injuries from falls or severe motor vehicle accidents can lead to more complex fracture/dislocation patterns of the wrist (ie, perilunate fracture/dislocation).

Scaphoid Fractures

Fractures of the scaphoid represent the most common carpal fracture, accounting for 60-70% of all carpal fractures. Fracture of the scaphoid has been explained as a failure of bone caused by a compressive tension load, by torsion, or by rotation forces. This is usually seen in a FOOSH type injury and is typically characterized by dorsiflexion and ulnar deviation. However, with dorsiflexion (95-100°) and radial deviation (10°), the scaphoid becomes trapped between the volar edge of the radius proximally and the trapezium and trapezoid distally at the level of the radioscaphocapitate ligament, thereby fracturing the scaphoid through impaction.

The most common site of fracture within the scaphoid is the anatomic waist (70-80%). These fractures may be stable or unstable, depending on the orientation of the fracture line (see below). Of scaphoid fractures, 15-20% occur at the proximal pole, while 10-15% occur through the distal pole of the scaphoid.

Several classification systems have been proposed for scaphoid fractures.

Russe described scaphoid fractures on the basis of orientation, including horizontal oblique, vertical oblique, and transverse fractures. The vertical oblique fracture is considered to be the least stable and most likely to require surgical intervention.

One of the other commonly employed classification systems was described by Herbert. In this system, the author combines fracture anatomy, stability, and chronicity of scaphoid fractures in an alphanumeric system (below).

• Type A fractures are stable acute fractures, including fracture of the tubercle (A1) and incomplete fractures of the scaphoid waist (A2).

• Type B fractures are unstable and include distal oblique fractures (B1), complete fracture of the waist (B2), proximal pole fractures (B3), and transscaphoid perilunate fracture dislocation of the carpus (B4).

• Type C fractures are characterized by delayed union.

• Type D fractures are characterized by established nonunion and either fibrous union (D1) or pseudarthrosis (D2).

The diagnosis of fracture displacement or instability includes the following:

• Translation or gap at the fracture site ≥1 mm on any x-ray view

• Greater than 15° dorsal angulation of the lunate with respect to the radius

• Carpal height ratio of the affected side less than the opposite side by at least 0.03

• Scaphoid length >1 mm shorter than the contralateral side

Understanding that the carpal configuration is in carpal rows is useful (see Relevant Anatomy). The carpus can be thought of as a 3-bar linkage system, with the radius, proximal row (ie, lunate, triquetrum), and distal row (ie, hamate, capitate, trapezoid, trapezium) aligned in a linear fashion (see image below).

The scaphoid acts like a bridge between the proximal and distal rows and provides carpal stability. Under compressive forces, the scaphoid flexes. The counterbalance to this is the natural extension of the triquetrum. Both bones try to influence the lunate through their respective ligamentous attachments, but in opposite directions (see image below).

Once scaphoid integrity is lost, an imbalance occurs and the lunate extends and assumes a dorsal tilt (see DISI below). Through the scapholunate ligament complex, the proximal pole of the fractured scaphoid also assumes an extended (dorsal) position. However, the distal fragment of the scaphoid is still loaded by the overlying trapezium and trapezoid, which causes the fragment to flex in a volar direction, thereby leading to the so-called humpback deformity.

With the loss of colinearity, the entire carpus becomes unstable and subject to collapse. The lunate and proximal row lie dorsal, thus the term dorsal intercalated segment instability (DISI). These forces result in a large gap at the fracture site and an increased incidence of delayed union, malunion, and nonunion.

The blood supply of the scaphoid is largely interosseous and oriented in a distal to proximal direction. Therefore, with fractures of the scaphoid waist and, especially, the proximal pole, this tenuous blood supply can become interrupted, thereby predisposing the proximal pole to avascular necrosis (AVN) with an incidence approaching 100%. Fractures of the middle third are similarly associated with a 30% incidence of avascular necrosis, while less than 15% of distal pole fractures lead to avascular necrosis.

Lunate Fractures

Lunate fractures account for approximately 1% of all carpal fractures (excluding Kienböck disease). Lunate fractures may also occur with axial loading to the dorsiflexed wrist. However, lunate fractures are correlated more with ulnar deviation of the wrist during impact.

Lunate fractures can be difficult to diagnose; therefore, they may be difficult to treat.

Lunate fractures are thought to invariably precede Kienböck disease, which occurs when the lunate undergoes avascular necrosis. This eventually leads to collapse of the carpus in a predictable, progressive pattern and, ultimately, pancarpal arthritis.

Five types of lunate fractures have been described, based on location and vascular supply.

1. Palmar pole (most common) fractures (affect the palmar nutrient artery)

2. Osteochondral (chip) fractures of the proximal articular surface (do not affect vascularity)

3. Dorsal pole fractures (may affect the dorsal nutrient artery)

4. Sagittal-oblique through the body

5. Coronal split of the body

Type 1 fractures result from hyperextension and compression from the capitate and radius; the radiolunate and lunotriquetral ligaments pull in radial and ulnar directions, respectively. The distal palmar pole is avulsed by the lunotriquetral ligament.

Type 2 fractures may be a result of Kienböck disease but may also result from shearing related to lunate dislocation or subluxation.

Type 3 fractures result from shear force as the capitate dislocates dorsally in perilunate dislocation or from avulsion of the scapholunate ligament in acute rotatory subluxation of the scaphoid.

Type 4 fractures result from shear forces induced from a radial carpal fracture dislocation.

Type 5 fractures result from hyperextension as the short radiolunate ligament avulses the palmar pole while the capitate forces the lunate into extension. This also happens in palmar perilunate dislocation as a shear force.

Kienbock Disease

In 1910, Kienböck described lunate collapse as the result of progressive vascular compromise resulting from repetitive wrist sprains and contusions. They are now understood to be characteristic lesions from failure of the lunate fractures to unite (often the dorsal pole).

The incidence and progression of Kienböck disease relies on a combination of "at-risk" factors. These include ulnar (minus) variance, lunate geometry, lunate vascular pattern, triangular fibrocartilage complex compliance, intraosseous pressure gradients, vocational loading, and underlying congenital and developmental disorders.

All factors are pathophysiologically important, each to varying degrees. However, describing and understanding the concept of ulnar variance is the most relevant clinically.

Ulnar variance refers to the distance between the articular surfaces of the radius and ulna (with a standard anteroposterior radiograph, the shoulder is abducted to 90º and the palm of the hand is on the radiograph plate). Ulnar-minus infers that the ulna is relatively short with respect to the radius and the articulating surface, and vice versa. Inequality in the length of the forearm bones leads to differential stress-loading of the lunate, which is one of the factors leading to the disease process.

During impact on a dorsiflexed and ulnarly deviated wrist, a short ulna contributes to the stress forces across the lunate and contributes to fracture, thus explaining the correlation with ulnar-minus variance and the incidence of Kienböck disease.

This concept forms the basis of various surgical procedures designed to unload the lunate by transferring the load to more lateral carpal columns in the treatment of Kienböck disease.

Kienböck disease is best divided into 4 stages based on radiological progression of the disease.

• Stage I: Radiographic findings are normal, but the bone scan findings are positive for disease. MRI shows a decreased signal on T1- and T2-weighted images.

• Stage II: Sclerotic changes and fractures are visible on radiographs; however, carpal integrity is intact.

• Stage III (A and B): This stage occurs when the lunate collapses and the capitate migrates proximally. In stage IIIA, no fixed carpal derangement is noted. In stage IIIB, decreased carpal height, ulnar migration of the triquetrum, scapholunate dissociation, and flexion of the scaphoid are noted.

• Stage IV: This stage is associated with additional carpal degeneration and generalized arthritis.

A study by Rhee et al indicated that the severity of Kienböck disease is influenced by lunate morphology, with lunates bearing a medial hamate facet (type II lunates) offering more protection against the disease than lunates without this feature (type I lunates). The study involved 106 wrists, including 75 with type I lunates and 31 with type II lunates. The investigators found that Kienböck disease tended to be significantly more advanced at presentation in the type I lunate wrists than in those with type II lunates. In addition, type I lunates had a higher rate of coronal fractures than type II lunates (77% vs 58%), and type II lunates seemed to be more resistant to scaphoid flexion deformities.[3]

Triquetrum

Triquetral fractures are the second most common carpal fracture. These fractures are usually not seen in isolation, and the most common presentation is with other carpal injuries that are boney, ligamentous, or both (ie, perilunate fracture dislocation). The vascular supply of the triquetrum contains rich vascular networks and numerous intraosseous anastomoses, making nonunions exceptionally rare. Triquetral fractures may be divided into 3 types based on radiographs.

1. Dorsal cortical fractures (most common)

2. Body fractures

3. Volar avulsion fractures

The mechanism of chip fractures has been debated. Some think the mechanism is due to avulsion of the conjoined insertion of the dorsal intercarpal or dorsal radiocarpal ligaments with hyperextension and radial deviation, while others think it is due to direct impact from the ulnar styloid or hamate with wrist hyperextension.

Trapezium

The trapezium fracture is the third most common carpal fracture. Five types of trapezial fractures exist and are based on radiographic findings.

1. Vertical transarticular (most common) - Most likely due to axial force along the thumb metacarpal bone

2. Horizontal - Due to direct shearing forces

3. Dorsal radial tuberosity - Due to vertical shearing forces

4. Anteromedial ridge - Due to anteroposterior crush injury

5. Comminuted

Trapezoid

The trapezoid fracture is rare. Standard radiographs often fail to demonstrate trapezoid fractures. A computed tomography (CT) or magnetic resonance imaging (MRI) scan may be needed to diagnose a fracture of the trapezoid. Two types of trapezoid fractures exist.

1. Dorsal rim

2. Body

These fractures are rare and are usually associated with fracture dislocation that involves dislocation of the index metacarpal or the trapezoid itself. The force is usually axial along the index metacarpal bone.

Capitate

Capitate fractures are thought to occur with a frequency of less than 1%. The proximal pole is entirely intra-articular and without soft tissue attachment. These fractures are usually identified on CT or MRI, using a high degree of suspicion. Capitate fractures can be categorized into 4 types.

1. Transverse (axial body; most common)

2. Transverse (axial proximal pole)

3. Coronal oblique

4. Parasagittal

Types 1 and 2 occur with extreme dorsiflexion. The transverse fracture of the neck of the capitate in conjunction with a fracture of the waist of the scaphoid has been referred to as the scaphocapitate syndrome. Malrotation of the proximal capitate (rotating with the proximal scaphoid fracture fragment) fracture usually occurs, and many believe that this represents a variant of the perilunate pattern of injury. The other types of capitate fractures occur as a result of hyperextension, axially loading injuries, or both.

Hamate

Hamate fractures are most common in stick- or bracket-handling sports (eg, golf, baseball, tennis). The vascular supply is most tenuous at the waist of the hamate hook. Two types of hamate fractures exist.

Hook fractures

See the list below:

• Avulsion (tip)

• Waist

• Base

Body fractures

See the list below:

• Proximal pole

• Medial tuberosity

• Sagittal oblique

• Dorsal coronal fractures

Hook fractures have several causes. Fractures can result from a direct blow or from repetitive contusions with a handle (golf, baseball) or racket (tennis, squash). Indirect avulsions through forceful pull of the flexor carpi ulnaris (FCU) and avulsion through the pisiform hamate ligament can cause hook fractures, as can a crush injury. Because of the tenuous vascular supply, nonunions of the hook of the hamate are common.

Body fractures can result from severe wrist fracture-dislocation, a direct blow to the ulnar aspect of the hand, anteroposterior crush injury, or transcarpal-carpal metacarpal dislocations, resulting in dorsal coronal fractures with posterior subluxation of the fourth and fifth metacarpal bones.

Pisiform

Often regarded as a proximal carpal bone, it is truly a sesamoid bone within the FCU tendon substance. Pisiform fractures fall into 4 broad categories.

1. Transverse (most common)

2. Parasagittal

3. Comminuted

4. Pisotriquetral impaction

The most common mechanism is a fall or impaction directly on the pisiform (or hypothenar eminence) with the wrist extended. Active firing of the FCU simultaneously with the direct impaction may result in transverse avulsion fractures; also ADM co-contraction may cause ulnar border avulsion fractures.

Perilunate Dislocation and Fracture Dislocation

Seven percent of carpal injuries fall into this category. Cooney et al classified carpal dislocations to 5 categories.[4]

1. Dorsal perilunate dislocation (lesser arc injuries)

2. Transcarpal fracture dislocation (greater arc injuries)

3. Radiocarpal dislocation

4. Longitudinal (axial dislocation)

5. Isolated carpal dislocation

These transcarpal injuries result from more extreme hyperextension injuries of the wrist such as violent motor vehicle accidents or high-impact falls. The position of the wrist and magnitude and direction of the fall or impact determine the fracture/dislocation pattern.

Fracture dislocations, or greater arc injuries, are twice as common as pure ligamentous dislocations (lesser arc).

The pathophysiology focuses on zones of vulnerability where most carpal fractures and dislocations occur. The potential lines for cleavage around the lunate can be divided into a lesser arc and a greater arc (see image below). The lesser arc is the ligamentous zone surrounding the lunate bone, and injury to this zone results in perilunate dislocation. The greater arc consists of the bony structures surrounding the lunate, including the scaphoid, trapezium, capitate, hamate, and triquetrum. Combined fracture and ligament disruption to this zone results in a typical perilunate fracture-dislocation pattern.

Perilunate dislocations

Lesser-arc injury is best understood within the context of progressive perilunate instability. This concept describes a predictable sequence of ligamentous injury leading to perilunate and lunate dislocation as described by Mayfield et al.[5]

• Stage I includes scaphoid dissociation from tearing of the scapholunate interosseous and volar displacement of the radioscaphoid joint.

• Stage II includes dorsal dislocation of the capitate with dissociation at the lunocapitate joint.

• Stage III (perilunate dislocation) includes lunotriquetral ligament disruption. The lunate remains aligned with the radius, while the rest of the carpus is displaced, usually dorsally.

• Stage IV (volar lunate dislocation) is complete ligament disruption. The capitate remains aligned with the radius, while the lunate is squeezed out in a volar direction.

Perilunate (stage III) and lunate dislocations (stage IV) display different dislocation patterns and alignments, yet they are understood to be manifestations of the same progressive disease.

Perilunate fracture dislocations

Greater-arc injuries are characterized by complete loss of contact between the lunate and head of the capitate and one or more fractures of bones surrounding the lunate.

Several potential patterns for disruption are possible. In all cases, disruption occurs through the greater arc, while the dorsal intercarpal ligaments remain intact; thus, the distal carpal row is displaced dorsally and proximally over the proximal row.

The maximum point of force may be initiated at the radial styloid and extend through the scapholunate interosseous ligament through to the lunotriquetral joint. Alternatively, the point of maximum force may begin at the scaphoid waist and tear through ligaments until the capitate, hamate, triquetrum, and distal scaphoid are carried away from the lunate and proximal scaphoid.

Alternatively, if the force is directed through the scaphoid, this may then be propagated interosseously, fracturing the capitate and tearing through to the triquetrum. In all cases, the triquetrum can fracture directly or tear at the lunotriquetral ligament.

Simply, the carpal fractures can be classified into 3 stages.

• Stage I is transscaphoid dislocation.

• Stage II includes transcapitate dislocation in addition to stage I features (transscaphoid, transcapitate perilunate).

• Stage III consists of transscaphoid, transcapitate, and transtriquetral (body or avulsion) with or without hamate disruption.

Axial Dislocation and Fracture Dislocation

This describes global disruption of the carpus into longitudinal patterns parallel to the long axis of the limb. Injuries occur in industrial accidents in which machinery applies high-energy force combined with dorsal and palmar compression to the hand.

The incidence of axial carpal disruption has been estimated at 1.4-2.08% of patients with carpal fracture dislocations or subluxations. Variables include magnitude, velocity, duration, and angle point of application of force. Parallel compression results in dislocation, whereas pressure under more oblique angles also results in fractures. In addition to universal tearing of the flexor retinaculum, important intercarpal ligament tears (eg, palmar hamate-capitate, palmar capitate-trapezium) disrupt the normal springlike integrity of the carpal arch. The wrist can split into 2 or more columns, usually with the metacarpals displacing along with the corresponding carpal bones.

Garcia-Elias et al described 2 major groups of injuries in this category.[6]

Axial ulnar

See the list below:

• Transhamate, peripisiform

• Perihamate, peripisiform

• Perihamate, trans-triquetrum

Axial radial

See the list below:

• Peritrapezoid, peritrapezium

• Peritrapezium

• Trans-trapezium

Most fractures are of the axial-ulnar type, in which injury is often at or around the hamate and capitate (see figure A in the image below). An ulnar column is created that is displaced proximal and ulnar. Axial-radial dislocation occurs when the ulnar carpus remains aligned but the radial carpus is displaced (see figure B in the image below). Usually, the trapezium is dislocated along with the first metacarpal, or a combined trapezoid-trapezial dislocation can occur with the first, second, and third metacarpals. In the axial radial dislocation, combined axial-radial-ulnar dislocation has also been reported.

Isolated Carpal Dislocations

Isolated carpal dislocations are extremely rare and a challenge to treat.

Lunate dislocations are the most common type and occur in the context of progressive stage IV perilunate instability.

Dislocation is almost always in a palmar direction. The rare dorsal dislocation occurs during wrist flexion injury.

Scaphoid dislocation occurs with forceful dorsiflexion while an object is grasped and the wrist is ulnarly deviated. The 2 clinical types that have been reported are isolated anterolateral dislocation of the proximal pole of the scaphoid and scaphoid dislocation associated with an axial derangement of the capitohamate joint.

Triquetral dislocations occur in a palmar and dorsal direction. Palmar dislocation can contribute to carpal tunnel pressures and lead to median nerve compression.

Pisiform dislocation occurs with injury directly to the ulnar carpus or hyperextension traction of the flexor carpi ulnaris that tears the pisohamate or pisometacarpal ligaments.

Trapezoidal dislocations may occur from a dorsal blow to the second metacarpal during wrist flexion. Because of the pyramidal shape of the trapezoid and the weak dorsal ligaments, the trapezoid is usually dislocated in a dorsal direction.

Trapezium dislocations occur in dorsal and palmar directions. They occur with crush injuries either alone or with radial-axial dislocations.

The hamate may be dislocated in both dorsal and palmar directions. Direct, indirect, or a severe crush-type trauma usually manifests as axial dislocation.

Most patients with wrist injuries present with a history of a fall on an outstretched palm and extended wrist.

Scaphoid fractures

This usually manifests as pain and swelling of the radial wrist after a traumatic event, usually a fall on the outstretched hand or a motor vehicle accident. The classic presentation is swelling in the anatomic snuffbox, although this is not specific to scaphoid fractures alone.

Physical examination may reveal a limited range of motion. Palpation in the anatomic snuffbox (interval between the extensor pollicis longus ulnar/dorsal and the abductor pollicis longus and extensor pollicis brevis radial/volar) often elicits pain. Tenderness is usually found upon radial deviation and flexion of the wrist, and pain is usually found with the Watson maneuver. Another useful sign may be pain with scaphoid compression via axial load to the first metacarpal. Patients not uncommonly present with diminished grip strength when compared to the contralateral wrist. Patients may present with pain and tenderness months after a traumatic event; in this situation, the pain is often a vague and aching pain, usually on the radial side of the wrist.

Lunate fractures

Uncomplicated lunate fractures usually manifest as simple wrist sprains or can remain painless. Upon palpation, dorsal tenderness may be observed between the Lister tubercle and the third metacarpal base.

Most fractures are difficult to diagnose, and patients may not present until avascular necrosis has already occurred. The patient presents with chronic wrist pain and tenderness localized dorsally over the lunate. Diffuse swelling and grip weakness may be observed. Disease progression involves stiffness, clicking, crepitation, and grinding, with increasing pain as time passes after the inciting traumatic event.

Triquetral fractures

Triquetral fractures are most commonly associated with other carpal injuries and can be seen with both perilunate and axial ulnar injury. Isolated fractures are seen less frequently. They can result from a fall with the wrist in extension and ulnar deviation. Direct impaction by the ulnar styloid and a direct blow to the dorsum of the wrist are common mechanisms of injury. Patients typically present with ulnar-sided wrist pain and decreased range of motion and grip strength secondary to pain. The lunotriquetral shear test may elicit pain, though this is not necessarily specific for a triquetral fracture alone, as a tear in the lunotriquetral ligament may also elicit pain.

Trapezium fractures

These fractures are usually associated with other carpal bone fractures, as well as fractures of the first metacarpal and the radius. Dislocation in isolation is very rare.

Symptoms may include the presence of localized tenderness and swelling following the injury. Fractures of the wrist are tender immediately distal to the tuberosity of the scaphoid. The tenderness of the body fracture of the trapezium is more easily elicited anterior or dorsal to the tendon of the abductor pollicis longus, about 1cm distal to the tip of the radial styloid. Range of motion in the wrist may be pain free, but pinch strength specifically is weak and painful. Fractures of the trapezial ridge may be associated with symptoms of carpal tunnel syndrome secondary to median nerve compression.

Trapezoid fractures

This type of fracture is rare, as the trapezoid is well-protected by strong ligament attachment with the trapezium, capitate, and index metacarpal and also by the bony geometry of the carpometacarpal articulation.

Trapezoid fractures are usually associated with trapezoid and index metacarpal dislocations, as in axial pattern fracture dislocation. Palmar dislocation is also possible.

Capitate fractures

Isolated capitate fractures are often undisplaced, but most of the fractures can be found in combination with other major carpal bones, especially the scaphoid (scaphocapitate syndrome). Diagnosis depends on a degree of suspicion, which should be present when evaluating a scaphoid fracture.

Hamate fractures

Fracture of the body or the hook of the hamate can present similarly.

Usually, the patient experiences pain on the ulnar half of the wrist and localized swelling and tenderness over the dorsal ulnar projection of the body of the hamate. These injuries should be suspected for ulnar wrist pain in golf, tennis, baseball, and squash players. Patients may also complain of symptoms of ulnar nerve compression (Guyon canal), including weakness and decreased subjective sensation to the ulnar-innervated digits.

Pisiform fractures

This type of fracture is very uncommon. About half of pisiform fractures occur in association with other upper extremity injuries that can delay the diagnosis of pisiform fractures. They are most commonly caused by a direct blow to the hypothenar eminence.

Perilunate dislocation

Patients have generally diffuse tenderness with significant loss of motion and pain. Initial mild swelling increases significantly over time. The patient can have good active wrist extension, but flexion is usually limited. Crepitation also can be present.

Palpation reveals disruption of the normal bony contour. In a person with a dorsal perilunate injury, the capitate can be identified as dorsal swelling. Volar perilunate dislocation can manifest with median neuropathy.

Perilunate fracture dislocation

Compared to other injuries, patients present with more severe pain that is incapacitating. The wrist is swollen, and patients cannot flex their fingers. The pathognomonic feature is dorsal and palmar pain upon palpation, not isolated to a single area. Again, median nerve compression is common and, therefore, requires a careful neurologic examination.

Axial dislocation and fracture dislocation

The manifestations of injuries can range from open laceration and denudement to closed injury. Patients have extreme pain, swelling, and tenderness in the wrist. Combined injury and dislocation of the metacarpals and phalanges is common. Serious neurovascular compromise and a variety of ligamentous and tendon disruptions may be evident upon careful examination.

Isolated carpal fractures

Isolated carpal fractures also manifest as wrist pain and tenderness. Bruising may be evident over the trapezium, scaphoid, and hamate hook in the palm.

Tenderness to palpation and swelling over the ulnar wrist suggest triquetral or pisiform fracture, which is more volar with pisiform fractures and dorsal with triquetral fractures. Also, pain with forceful wrist flexion suggests triquetral fracture.

Dull aching over the hypothenar eminence and ulnar nerve palsy suggest hamate fracture (see image below). The hamulus is usually tender. Progressive grip weakness, pain with flexion, and lateral movement of the little finger also can be present, especially with nonunion at the injury site.

Isolated carpal dislocations

Isolated dislocations manifest similar to the other injuries, and symptoms are localized to the area of dislocation. Palpation may reveal a bony mass.

Scaphoid fractures

Type A and other stable, nondisplaced fractures can be treated using closed methods. Short arm casting is usually sufficient, with 95% union in 11 weeks. All higher-grade and other unstable fractures are treated with open reduction and internal fixation (ORIF).

Generally, operative indications include a radiolunate angle greater than 15°, a scapholunate angle greater than 60°, or a greater than 1-mm displacement of the scaphoid. All proximal pole fractures should be treated by ORIF due to the predictably high rates of nonunion. Avascular necrosis of the proximal scaphoid should be treated with ORIF, usually with a vascularized bone graft (see image below).

Lunate - Acute lunate fracture

Early diagnosis of lunate fractures is an uncommon occurrence. If discovered, immobilization is usually sufficient for healing. Displaced fractures (>1 mm) and transverse fractures require ORIF to optimize bony union.

Kienbock disease

With stage I, immobilization in a short cast for up to 3 months may be sufficient. This may provide an opportunity for the lunate to revascularize. If no improvement is observed in 3 months, radial shortening for ulnar-minus variance is recommended. This operation significantly reduces the axial load on the lunate (redistributing it to the radioscaphoid and ulnocarpal joints) and allows for spontaneous or indirect revascularization. Otherwise, neutral or the ulnar-plus variety should be directly revascularized with a vascular bone graft, usually the 4,5 extensor compartment artery (ECA). This corticocancellous graft taken from the distal radius at the base of the fourth compartment perfuses based on the retrograde flow from the intercarpal arch.

For stage II and IIIA, treatment is similar to stage I disease. In addition to revascularization, stage II/IIIA ulnar-plus/neutral fractures may benefit from capitate shortening or radial wedge osteotomy.

For stage IIIB, scaphocapitate fusion or other limited fusions (ie, triscaphe or STT fusion) may maintain some degree of functional wrist mobility. Necrotic or fragmented lunate should be excised.

For stage IV, salvage procedures are necessary, either proximal row carpectomy or total wrist fusion. Patients whose goal is simply pain relief and return to heavy manual labor may benefit most from a total wrist fusion.

Perilunate dislocation

Dorsal perilunate and palmar lunate dislocations are different manifestations of the same injury, and treatment remains essentially the same.

Closed reduction and casting is rarely satisfactory and is not currently recommended as definitive treatment. Initial closed reduction has the benefit of immediate restoration of anatomy and alleviating pressures on the median nerve in the carpal tunnel. In this case, postreduction radiographs are essential and only perfect alignment is acceptable. A scapholunate angle greater than 60° or a scapholunate gap greater than 4 mm indicates significant residual scaphoid subluxation. Any malalignment or instability compromises the outcome and mandates ORIF. However, most surgeons now prefer initial operative management and direct ligament repair as the standard of care.

Perilunate fracture dislocation

Perilunate fracture dislocation is an indication for operative intervention. Closed reduction and percutaneous fixation is still performed, but this is generally considered to have a poor outcome and is currently not recommended. Direct primary repair of the extrinsic and intrinsic ligaments of the wrist needs to be performed. The potential for median nerve compromise also warrants operative intervention.

Isolated carpal fractures (not including the scaphoid)

Triquetral fractures usually heal well with simple cast or splint immobilization for 3-6 weeks. Nonunion is extremely rare.

Pisiform fractures also heal well with splinting for similar periods. Complications are rare.

Regarding the hamate, any intra-articular fracture with displacement at the capitohamate, triquetrohamate, or hamatometacarpal joints greater than 1 mm requires ORIF. This may be performed through a dorsal approach and the hamate secured with either screw fixation (headless compression) or with percutaneous K-wires. Stable nondisplaced fractures typically heal with cast immobilization.

Fractures at the base of the hamate hook usually heal well if diagnosed and treated within 2 weeks of the injury. These are usually best treated with cast immobilization. The more distal fracture (more volar in location) tends not to heal as well. Any fracture of the base that is older than 14-21 days, failed conservative treatment, or is a more distal acute fractures of the hook should be treated by direct hamate hook excision. This has been shown to provide adequate pain relief and adequate predictable functional outcomes (see image below).

For the trapezium and trapezoid, fractures greater than 1 mm displacement at the carpometacarpal or scaphotrapeziotrapezoidal joint require ORIF. Otherwise, thumb spica cast/splinting is adequate.

With capitate fractures, undisplaced injury to the body may be treated with cast immobilization. Intra-articular fractures of the proximal pole require ORIF for optimal outcome.

Isolated carpal dislocations

For scaphoid dislocation, closed reduction or open reduction with associated ligament repair has been advocated. The latter method is preferred because direct ligament attachment and, therefore, subsequent anatomic healing may be achieved. Kirschner wire (K-wire) fixation is usually needed in either case.

Triquetral dislocations do well with closed reduction or open reduction. Any displacement larger than 1 mm requires ORIF. Consideration of an open procedure should be given to volar avulsion fractures, as rupture of the lunotriquetral ligament may be an associated finding.

Pisiform dislocations require only simple excision.

For trapezoidal and trapezium dislocations, closed reduction with percutaneous pin placement can be attempted; however, more accurate reduction may be achieved with an open reduction and direct fixation or percutaneous K-wire fixation.

Hamate fracture/dislocations have been successfully treated with closed and open reduction techniques with mixed success. Simple excision has also been described; however, this may leave the patient with residual pain. A limited intracarpal arthrodesis would likely lead to a more predictable functional outcome.

Axial dislocation and fracture dislocation

Treatment of axial dislocations requires immediate recognition and reduction to ensure proper healing.

Examination for soft tissue and neurovascular injury is critical. After adequate anesthesia, intravenous antibiotics, and debridement of frankly necrotic tissue, closed reduction can be attempted and pin fixation performed. Failure to reduce, poor reduction alignment, or tendinous/neurovascular injury require operative reduction and fixation.

Bone anatomy

The wrist is composed of 8 bones, including the scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezoid, and trapezium (see image below).

The largest bone of the proximal row is the scaphoid, which serves as a stabilizing link between the proximal and distal carpal rows. Its name is derived from the Greek word skaphos, which means boat, because of the resemblance in shape. Almost the entire surface of the scaphoid articulates with surrounding bones and is, therefore, covered almost entirely with cartilage. The distal convex surface articulates with the trapezoid and trapezium.

The medial surface has 2 facets. The larger, more distal medial facet is concave and articulates with the capitate. The more proximal medial facet is also concave and articulates with the lateral lunate surface. The lateral scaphoid surface is large, convex, and articulates the radius at the scaphoid fossa. The scaphoid tubercle is the only nonarticulating surface and is found distally on the palmar aspect of the scaphoid. This prominence serves as a pivot point for the flexor carpi radialis tendon and as an attachment point for the radioscaphocapitate and the scaphotrapeziotrapezoid ligaments.

The lunate sits like a cup, holding the capitate (and a small component of the radial and proximal hamate) in its distal biconcave surface. The proximal surface is convex and articulates primarily with the radius and with the triangular fibrocartilage complex (TFCC) more medially. The lateral (radial) surface of the lunate articulates with the scaphoid, while the medial (ulnar) surface articulates with the triquetrum. The hornlike palmar and dorsal nonarticulating surfaces serve as ligamentous attachment points and function to stabilize the head of the capitate in place. Viegas classified lunates into 2 types based on their distal articulation. Type 1 lunates articulate with the capitate distally, while type 2 lunates articulate with the capitate and with the hamate by way of a small distal ulnar/medial facet. This may have some clinical significance in terms of midcarpal stability patterns.

The triquetrum also has 4 articulating surfaces. The distal surface has a radial convex and an ulnar concave formation, which both articulate with the hamate. The lateral (radial) surface articulates with the lunate and proximally serves as the insertion site for the lunotriquetral interosseous ligament and the vascular penetration into the triquetrum. The small convex proximal surface articulates with the TFCC. The palmar aspect of the triquetrum contains an oval-shaped surface that articulates with the pisiform through cartilaginous structures. The dorsal triquetrum has a transverse ridge and is the attachment point to the highly relevant dorsal radiotriquetral, dorsal lunotriquetral, and dorsal intercarpal ligaments.

The pisiform is a sesamoid type bone that solely articulates with the triquetrum on its small, flat, oval, dorsal articular surface. The remaining surface is round and rough and is the site of attachment for the flexor carpi ulnaris tendon. Ligamentous connections at this site attach the pisiform to the hook of hamate and the base of the fourth and fifth metacarpals.

The trapezium has 4 articulating surfaces. The distal saddle-shaped surface articulates with the first metacarpal, while the more ulnar (medial) distal surface articulates with the base of the second metacarpal. Medially, the trapezium articulates with the trapezoid and, proximally, with the distal scaphoid.

The trapezoid is trapezoidal. Distally, the wedge-shaped facet articulates with the second metacarpal. In some cases, an additional facet may articulate with the third metacarpal. The radial surface articulates with the trapezium, the ulnar surface articulates with the capitate, and the proximal concave surface articulates with the distal scaphoid. The palmar and dorsal aspects receive ligamentous attachments.

The capitate is the largest and most prominent bone in the wrist. The proximal head articulates with the scaphoid radially, the hamate ulnarly, and the lunate proximally. The distal body articulates with the trapezoid laterally through cartilage and articulates medially with the hamate through an interosseous ligament. The distal capitate articulates with the styloid process of the third metacarpal, the entire base of the third metacarpal, and, often, the proximal medial facet of the fourth metacarpal.

The hamate articulates distally with the fourth and fifth metacarpal bases. The oblique medial surface articulates with the triquetrum, while the lateral surface articulates with the capitate. The palmar nonarticulating projection is known as the hamulus and is the site of attachment of the flexor retinaculum, pisohamatum ligament, and the muscular origin of opponens digiti minimi.

Ligament anatomy

Several ligamentous complexes exist in the wrist. They can be classified as follows:

Extrinsic carpal ligaments are divided into superficial extrinsic radial carpal ligaments, deep extrinsic radial carpal ligaments, and deep extrinsic ulnar carpal ligaments.

Superficial extrinsic radial carpal ligaments are as follows:

• Radioscaphoid (palmar)

• Radiocapitate (palmar)

• Long radiolunate (palmar)

• Radiotriquetral (dorsal)

Deep extrinsic radial carpal ligaments are as follows:

• Short radiolunate

• Radioscapholunate

Deep extrinsic ulnar carpal ligaments are as follows:

• Ulnotriquetral

• Ulnolunate

• Ulnocapitate

Intrinsic carpal ligaments include the following:

• Scapholunate interosseous ligament

• Lunotriquetral interosseous ligament

• Distal carpal row interosseous ligament

• Dorsal intercarpal ligaments

• Palmar intercarpal ligaments

The palmar ulnocarpal ligaments comprise the other group of capsular ligaments that cross the carpus in a palmar direction. This includes the ulnolunate, ulnotriquetral, and ulnocapitate ligaments. Collectively, they originate from the palmar radioulnar ligament, which contributes to the formation of the triangular fibrocartilage complex (TFCC).

Dorsally, the capsule of the wrist is primarily composed of the dorsal intercarpal and dorsal radiocarpal ligaments. The dorsal radiocarpal ligament connects the radius, lunate, and triquetrum. The dorsal intercarpal ligament connects the triquetrum to the scaphoid and trapezoid. These structures can be dissected together to provide a radial flap when access to the dorsal carpus is required. This technique, commonly referred to as a capsular-sparing capsulotomy, allows excellent exposure and may result in reduced postoperative scarring and stiffness.[7]

The palmar midcarpal ligaments are the main stabilizing ligaments of the carpus and appear as a continuous flat sheet of ligament, which converges at the capitate. Its most important components include the scaphotrapezium, trapezoid, scaphocapitate, triquetrocapitate, triquetrohamate, and pisohamate ligaments.

The short ligaments between the bones are known as interosseous ligaments. The interosseous ligaments in the proximal row include the scapholunate, lunotriquetral, and pisotriquetral ligaments. The ligaments in the distal row include the trapeziotrapezoid interosseous ligament, trapeziocapitate interosseous ligament, and capitohamate interosseous ligament.

The palmar radioulnar ligament and dorsal radioulnar ligament (which sends fibers to the flexor carpi ulnaris subsheath) contribute to the formation of the triangular fibrocartilage complex. This articular disk is interposed between the ulnar head and carpal bones, and its thickness is inversely proportional to positive ulnar variance. See Kienböck disease in the Pathophysiology section.

Blood supply

The carpal wrist receives vascularization primarily from the dorsal and palmar carpal plexi (see image below). The radial artery, ulnar artery, and posterior branch of the anterior interosseous artery contribute branches that form the dorsal radiocarpal arch and the dorsal intercarpal arch. The dorsal radiocarpal arch is positioned over the radiocarpal joint and supplies the proximal carpal row, whereas the intercarpal is more distal and supplies the distal carpal arch.

In the palmar aspect, the radial, ulnar and the anterior branch of the anterior interosseous artery contribute to the formation of palmar radiocarpal and palmar intercarpal arches. In addition, the deep palmar arch supplies the distal carpal row through the recurrent ulnar and recurrent radial branches.

Vascularization at risk (tenuous carpal vascular supply)

The scaphoid is exclusively supplied by the radial artery, which sends a dorsal, proximal, and distal branch to the distal third of the scaphoid (see image below). The distal and proximal branches come off the superficial palmar branch of the radial artery (20-30% of scaphoid blood supply), and the distal branch comes off the dorsal radiocarpal branch of the radial artery (70-80% of scaphoid blood supply). These vessels flow retrograde through an interosseous artery to supply the proximal pole of the scaphoid. For this reason, fractures of the scaphoid waist lead to a severed blood supply and a high incidence of avascular necrosis of the proximal pole.

The lunate receives blood dorsally and volarly. Dorsally, the radial artery contributes small vessels with origination from the intercarpal arch. In the palmar direction, the lunate receives branches from (1) the anterior division of the anterior interosseous artery, (2) the palmar carpal branches of the radial and ulnar arteries, and (3) a recurrent branch from the deep palmar arch. In some instances, the lunate receives vascularization only from the dorsal components and thus is susceptible to avascular necrosis after lunate fracture. Gelberman et al found that 20-30% of lunates have a single nutrient vessel that enters the lunate either volarly or dorsally, while the remaining 70-80% have multiple nutrient arteries, shaped in the form of X or Y, that enter the lunate either volarly or dorsally.[8] See Kienböck disease in the Pathophysiology section.

The capitate receives blood from branches of the dorsal radiocarpal and intercarpal arches and dorsal branch of the anterior interosseous artery. On the palmar aspect, branches are from the palmar radiocarpal arch and deep palmar arch and a direct contribution from the recurrent ulnar artery. The blood vessels combine to form a plexus distally and supply the head of the capitate through retrograde interosseous vessels. Thus, the proximal capital may also be vulnerable to avascular necrosis.

Innervation

The wrist and carpal capsules are innervated by branches of the posterior and anterior interosseous nerves; superficial branch of the radial nerve; dorsal, lateral, and perforating branches of the ulnar nerve; palmar cutaneous of the median nerve; and the medial and lateral antebrachial cutaneous nerves of the forearm. These nerves play a significant role in the pathophysiology of chronic wrist pain and, therefore, also in the management of nerve-specific denervation techniques.

At this time, there are no known absolute contraindications to the initiation of treatment for most wrist fractures and dislocations.

Radiographic examination is essential for diagnosis and for the classification of all carpal fractures and dislocations. All diagnosed fractures should be carefully examined for evidence of contaminant fractures and for dislocations that are less obvious than the primary injury. Improper positioning of the wrist for radiographs is a common cause of failure to make the correct diagnosis; thus, proper radiographic technique is crucial. All wrist injuries should include 4 views, posteroanterior (PA), lateral, and supinated and pronated obliques. In addition, all wrist injuries should have scaphoid/navicular views because of the relative frequency of scaphoid fracture.

Radiography

The 4 essential views (ie, PA, lateral, supinated and pronated obliques) identify 97% of fractures. The lateral view is used to assess the degree of scaphoid fracture angulation. On PA views, radial displacement of a fractured scaphoid usually obliterates the linearity of the radial radiolucent soft tissue pad known as the navicular fat stripe sign.

The scaphoid view or navicular view is recommended. This is a PA radiograph with the wrist extended 30° and deviated ulnarly 20°. This view helps to stretch out the scaphoid and is also used for assessing the degree of scaphoid fracture angulation.

A clenched-fist radiograph has also been useful for visualization of the scaphoid waist. This may also assist in demonstrating dynamic scapholunate instability.

Initially, the fracture is not recognizable on a radiograph. Treatment is initiated with immobilization in a thumb spica cast for 2 weeks (allowing for resorption at the fracture site) and then evaluation with repeat radiography.[9]

Bone scan, CT scan, ultrasound, and MRI

In addition to radiographs, bone scans, CT scans, and ultrasonograms[10] have also been reliable in the early (< 24 h) detection of occult nondisplaced scaphoid fractures.

In emergent management, the bone scan is useful to help detect high-probability fractures not visible on standard radiographs (see image below).

CT scans are particularly useful for identifying malalignments within the carpus and in the diagnosis of more obscure distal osteocartilaginous fractures.

A study by Gilley et al indicated that scaphoid fracture displacement can be better diagnosed CT scanning than with radiography. The investigators found that CT scans revealed displacement in 26-34% of scaphoid fractures that appeared nondisplaced on radiographs.[11]

MRI has emerged as a useful adjunct in the detection of occult scaphoid fractures as well as nonunions.[12] Dorsay has found that MRI performed in patients with high degree of suspicion reduced the time interval for casting and allowed an earlier return to function.[13] MRI with gadolinium enhancement remains the criterion standard in the diagnosis of scaphoid nonunions with or without avascular necrosis.

Radiography

See Lunate fracture in the Pathophysiology section for classification based on radiographic findings. Fractures of the lunate are difficult to diagnose with radiographs; thus, additional CT scan and MRI studies are recommended. Radiography is perhaps more useful after deterioration to Kienböck disease.

The 4 routine views of the wrist are recommended; also include carpal tunnel views. The initial lunate fracture is often difficult to diagnose based on radiographic findings. Fracture lines and fragmentation become evident only weeks later.

During stage IIIB, the collapsing carpus undergoes scapholunate dissociation, which results in flexion of the scaphoid and a ring sign often also seen with progressive perilunate instability, which is discussed further below.

MRI (T1- and T2-weighted images)

Avascular necrosis of the lunate shows the hallmark signal reduction of the lunate.

This is useful in the early stages when initial radiographic findings are normal but clinical findings are suggestive (stage 1).

CT scan

CT scan studies are useful for all stages of disease, particularly in the acute fracture setting.

Bone scan

These may show early changes, but the findings are nonspecific and lead to false-positive and false-negative results.

Radiography

In addition to the 4 basic views, PA traction views can also aid in diagnosis and classification. Clenched-fist anteroposterior (AP) views have been shown to help diagnose the more dynamic scapholunate dissociation. Approximately 20% of perilunate injuries are misinterpreted on initial radiographs.

The ring sign may be seen with PA/AP views. In scapholunate dissociation (stage I), ligament instability results in permanent flexion of the scaphoid and a foreshortened appearance on AP/PA cross-section. This end-on projection of the distal pole of the scaphoid produces the classic signet ring sign (also observed in stage IIIB Kienböck disease).

The Terry-Thomas sign may be seen on AP/PA views. Pathognomonic for perilunate instability, this radiologic sign means a gap is present between the lunate and scaphoid, which is considered abnormal if larger than 3 mm on the radiograph.

The spilled-teacup sign may be seen on the lateral view. Normally, the kidney-shaped lunate holds the head of the capitate with its concave surface and articulates with the distal radius with its proximal convex surface. With lunate dislocation (stage IV), the lunate usually flips volarly on its volar radiolunate ligament hinge so that its concavity faces the carpal tunnel. This provides the appearance of a cup turned downward and is referred to as the spilled-teacup sign on lateral-view radiographs.

CT scan, bone scan, MRI: These are useful in the setting of subtle acute, delayed, late, or dynamic carpal instability presentations.

Standard PA (for fracture pattern) and lateral radiographs (for identifying displacement of the carpus)

Typically, these views are sufficient. Traction radiographs also are often helpful.

A delay in diagnosis is not unusual, especially in persons with polytrauma in whom the injury is overlooked.

Poorly taken initial radiographs are usually to blame; radiographs are often misinterpreted, and the fracture is treated as a Colles fracture.

CT scan

This is recommended for late diagnosis and when routine films are difficult to interpret.

Very late presentation after many years includes carpal tunnel syndrome and ruptures of the flexor tendons.

Radiographs

AP, lateral, radial, and ulnar deviation views are used for carpal fractures.

Trapezium, trapezoid, pisiform, and hamate fractures benefit from the addition of carpal tunnel views.

CT scan

Moreover, the trapezium, trapezoid, pisiform, and hamate fractures also may benefit from the addition of a CT scan.

Radiographs

With lateral and AP views, projections are minimal. Possible trapezoidal, trapezium, and pisiform dislocations should have oblique views.

CT scan

This is indicated for all complicated presentations.

Radiographs

AP views allow assessment of the type of axial dislocation (radial vs ulnar).

Lateral radiographs allow a determination of the direction of dislocation.

Additional traction views and CT scan

These may be necessary for a full assessment of the intercarpal ligamentous and carpal articulative derangements.

Scaphoid immobilization

Scaphoid immobilization includes a thumb spica cast to the interphalangeal joint to inhibit motion at the fracture site. Most include the metacarpophalangeal joint in the cast, leaving the interphalangeal joint either included or not. A long arm cast just above the elbow may also be used to prevent supination and pronation, thereby inhibiting any pronation/supination motion, which theoretically limits motion at the fracture site. As with inclusion of the thumb in the cast, controversy exists over whether to immobilize above or below the elbow. Careful indentation molding over the capitate (dorsally) may be used to depress the distal carpal row, thereby promoting anatomic fracture reduction.

Lunate immobilization

The initial treatment of Kienböck disease stage 1 may be initiated with a period of casting, especially in young patients. However, this has never really been shown to alter progression of disease, especially in symptomatic patients. Most believe that surgical intervention is required in the treatment of symptomatic Kienböck disease, regardless of stage.

Surgical therapy varies by location.

Open reduction and internal fixation is indicated for unstable fractures or fractures presenting with more than 1 mm displacement. Operative intervention can also be considered for nondisplaced stable fractures to reduce the amount of time off work or sports.

A volar approach is adequate for most fractures, especially distal pole and waist fractures. A curvilinear skin incision that crosses the wrist obliquely allows access to the scaphoid tubercle between the radial artery and flexor carpi radialis tendon.

The radiocarpal capsule is reflected over the scaphoid tuberosity to the scaphotrapezium joint. If necessary, the fracture is reduced and a K-wire is drilled down one side through the fragments to stabilize the fracture. If using a Herbert screw, a Huene jig is used to secure the fragments in proper alignment, and a hole is tapped, followed by fixation using a Herbert screw (see image below). Alternatively, another K-wire (0.045 in) is placed down the central axis of the scaphoid (checked with fluoroscopy) and a cannulated, headless compression screw of appropriate length (3-4 mm shorter than the length of the scaphoid) is inserted. Care is taken not to overdrill the distal cortex with the leading edge of the screw. Again, alignment is critical, and variations in technique are common.

The capsule is repaired, and the skin is closed subcuticularly. Postoperative casting as described above is used for 3-4 weeks to minimize fracture motion. Gentle range of motion exercises are then commenced.

Percutaneous (either dorsal or volar approach) techniques have also been described including with or without arthroscopic assistance.

The dorsal approach allows the best access. The superficial radial nerve is identified and then carefully protected. The third compartment in incised and EPL retracted radially. The interval between the first and second compartment is incised in a J-type fashion and the fractured proximal pole of the scaphoid identified. Care is taken not to injure the scapholunate ligament.

Careful ulnar deviation of the wrist then exposes the proximal scaphoid. A K-wire is drilled in a proximal to distal direction down through to the distal scaphoid tuberosity. One or two additional parallel K-wires can be used to prevent fracture displacement or rotation during screw placement. The technique of screw placement is as described above for the volar approach, and the choice of cannulated headless compression screw is at the surgeon's discretion. The screw is overdrilled for full insertion into the scaphoid. Closure and treatment as in the palmar approach completes the procedure.

Application of a short arm cast is the most commonly used method of immobilization. No consensus has been reached on the type of cast, length of cast, or period of immobilization needed to prevent nonunion.

Open reduction of the lunate can be approached either through a dorsal or palmar incision. The use of cannulated headless compression screws likely represent the most common fixation devices presently used, though K-wire fixation may still be beneficial. Dorsal fractures may require repair of the radiotriquetral or dorsal radiolunotriquetral ligaments, while volar fractures may require repair of the lunotriquetral ligament.

Radial shortening

This may be performed with a dorsal or volar approach. It may be the procedure of choice in patients with ulnar-negative variance.

The dorsal approach requires a 10-cm incision over the dorsoradial aspect of the radius. Exposure is gained between the radial artery and flexor carpi radialis.

A compression plate and 2 screws are applied to the distal radius. After marking the level of osteotomy, one of the distal screws is removed and the plate rotated away. Two parallel cuts are made approximately 2-3 mm apart. The fragment is removed, the ends are realigned, and the plate is rotated back and secured proximally and distally. After closure, a short arm plaster cast is applied for 4-6 weeks.

The volar approach is through a longitudinal radiopalmar incision. The radial artery is protected and dissection is carried out ulnar to this structure down to the pronator quadratus. The periosteum is then incised along the brachioradialis insertion and the radius exposed subperiosteally. Shortening and fixation is as described for the dorsal approach.

A lateral radial closing wedge osteotomy has also been advocated, especially in patients presenting with ulnar-neutral variance.

Revascularization procedures

These procedures may be combined with other procedures aimed at unloading the lunate, such as joint leveling or intercarpal fusions, as an adjunct to allow the lunate to heal while maintaining a functional range of motion.

Originally described by Hori in 1979 and modified by others, the efficacy of the procedure remains controversial. A dorsal approach is preferred, with adequate exposure of the lunate. Necrotic bone within the lunate is curetted and packed with iliac or radial corticocancellous bone. A dorsal metacarpal arteriovenous pedicle is then implanted into the lunate. A corticocancellous bone graft from the ulnar side of the second metacarpal may also be incorporated. More recently, vascularization from the fourth and fifth extensor compartment artery (ECA) with a corticocancellous graft liberated from the dorsal distal radius has been described.[14] This relies on retrograde flow from the dorsal intercarpal arch from the fifth ECA to the fourth ECA.

This is fusion of the scaphoid, trapezium, and trapezoid into a single bony unit, while the external dimensions of the original bones are maintained. The procedure begins with a dorsal transverse incision at the radial styloid. The articular and subchondral surfaces of the bone are removed using a rongeur.

Two K-wires are passed percutaneously and through the trapezoid. The spacer is placed into the scaphotrapezoid joint, and the scaphoid is reduced (with the wrist in full radial deviation and 45° dorsiflexion) to maintain external dimension of the bones. The pins are driven into the scaphoid, and the spacer is removed. The scaphoid should be in about 60º of flexion in relation to the long axis of the radius. The radial styloid (< 1 cm) should be removed with an osteotome to prevent styloid-scaphoid impingement.

Harvested corticocancellous bone is packed into the joint spaces between the scaphoid, trapezoid, and trapezium. The wrist capsule and extensor retinaculum is realigned and closed with sutures. The pins are cut beneath the skin level, and the skin incisions are closed. A long arm plaster cast is applied with the wrist in slight extension and radial deviation and the elbow at 90°. It is removed in 3-4 weeks.

Scaphocapitate arthrodesis

This approach is similar in dissection to that of STT arthrodesis. With a radioscaphoid angle of 50-60º, the articular and subchondral bone is removed with a rongeur between the scaphoid and capitate. One or two compression screws or interosseous staples may be used to provide fixation with or without cancellous bone graft. Postoperatively, the treatment course is similar to the STT fusion.

Capitate shortening

The capitate is exposed through a standard dorsal wrist exposure and ligament-sparing capsulotomy. At about the midpoint of the capitate body, a microsagittal saw is used to create an osteotomy. The proximal body is shortened 3 mm and the capitate is reduced and fixated with K-wires, interosseous staples, or headless compression screws. Capitate shortening with capitohamate fusion has also been described in reducing the load on the lunate.

The patient is placed supine, and the elbow is flexed to 90°. Continuous longitudinal traction in finger traps with 10-15 lb of weight for 10 minutes allows relaxation of the muscles. This usually requires intravenous sedation to aid in adequate relaxation.

Manual retraction is applied while the thumb of one hand applies pressure to the volar aspect of the wrist (stabilizing the lunate). The other hand maintains longitudinal traction while extending the wrist. As the wrist is gradually flexed, the capitate can snap back into the concavity of the lunate.

Proper cast application requires a 3-point support system with reduction pressure applied at the dorsal capitate, distal radius, and in a palmar direction over the pisiform. Postreduction radiographs are necessary to assess alignment. Closed reduction alone is currently not recognized as standard of care treatment. Once bony anatomy has been restored, the patient should ideally undergo operative intervention to repair the soft tissue structures (scapholunate and lunotriquetral ligaments) within 10 days of the trauma.

Numerous combinations of lesser- and greater-arc disruptions are observed, and these require operative modifications based on the injury pattern.

Combined palmar and dorsal approach

Dorsally, a longitudinal incision is made between the dorsal third and fourth compartment. The extensor retinaculum is elevated, and the extensor pollicis longus is retracted. A longitudinal capsular (or capsular-sparing, if the traumatic tissues permit) incision is then performed, and flaps are elevated. Dorsal radiocarpal and intercarpal ligaments are usually preserved.

In the palmar aspect, an extended carpal incision is used and the transverse carpal ligament is incised. The flexor tendons and median nerve are usually retracted radially. Any unreduced component (lunate) can now be addressed with the aid of longitudinal traction. Again in the palmar aspect, a percutaneous K-wire is placed through the radius into the lunate to maintain reduction. A K-wire is then passed through the lunotriquetral joint. Any disrupted lunotriquetral ligament is then repaired.

Next, the midcarpal region is inspected again and further reduction is performed as necessary.

On the dorsal side, any scaphoid dissociation is reduced. To maintain the reduced position, K-wires are placed from the scaphoid to the lunate and from the scaphoid to the capitate. The scapholunate interosseous ligament is inspected and repaired to the scaphoid (using the ligament rim or with drill holes or even suture anchors) with nonabsorbable suture. If the ligament is avulsed from the lunate, a similar technique is used. The carpus is inspected for any further damage.

Usually, the horizontal rent in the volar capsule is also repaired with nonabsorbable suture. Incision sites and soft tissue are repaired in both the dorsal and palmar aspects.

Compression and a long arm splint are applied. Sutures are removed in several days, and a full long arm cast is applied. A short arm cast can be applied at 6 weeks, and pins can be removed at 6-8 weeks, followed by splint application. Follow-up care with a physiotherapist begins thereafter.

Closed reduction and fixation of these injuries is not recommended.

Transradial styloid fracture

Usually, only a dorsal incision is needed. The carpus is entered near the Lister tubercle. The radial styloid is reduced and fixed with K-wires or a screw. The capsule is incised, and the lunate is reduced and pinned to the distal radius. The scaphoid is then reduced and fixed to the lunate. Any necessary repair to the triquetral bone or ligaments is performed last.

Transscaphoid perilunate fracture (stage I lesion)

A dorsal longitudinal incision is made over the extensor compartments, and soft tissue is retracted. With capsular retraction, the lunate is exposed, reduced, and pinned to the proximal scaphoid with a K-wire. The lunocapitate and lunotriquetral joints are reduced and pinned. Appropriate ligamental repair is made at this time.

Next, a distally extended carpal tunnel incision is made, with retraction and exposure of the radial palmar carpal ligaments. If not torn, the radioscaphocapitate and radioscapholunate ligaments are incised. The scaphoid is held with a K-wire. Once reduction of the fracture is achieved, it is fixed either with a Heune jig and a Herbert screw or, alternatively, with another headless compression screw (see image below). Finally, the injured ligament disruptions are repaired as described above. A long arm thumb spica cast is recommended for at least 6 weeks, longer for comminuted fractures.

Transscaphoid transcapitate (stage II lesion)

A similar initial dorsal approach is used as described above. Once the lunate is reduced, no pinning to the scaphoid is necessary. The capitate fracture is reduced, aligned, and percutaneously fixed to maintain alignment. At this point, a compressions screw is inserted in a retrograde fashion.

The lunate is now pinned to the distal radius. The proximal and distal scaphoid are pinned and fixed with a Herbert screw. A palmar incision is now performed, and palmar radiocarpal ligaments are repaired.

Triquetral, pisiform, and hamate fractures heal well with cast immobilization and rarely require surgical intervention. ORIF for hamate fractures is performed with K-wires or screw fixation. ORIF for capitate fractures is performed with the screw inserted proximal to distal.

Scaphoid

Closed reduction can be attempted with the wrist in traction and pressure over the scaphoid while the wrist is in ulnar deviation. If successful, pin fixation may be adequate; however, open reduction and repair is recommended. Open reduction has the benefit of allowing assessment and repair of the scapholunate interosseous and scaphotrapezium ligaments. A K-wire is fixed to the scaphotrapezium and scapholunate joints.

Other

Most of the other carpal dislocations require similar operative reduction, K-wire fixation, and ligamental repair. Casting is recommended for 8 weeks.

Treatment requires proper anesthesia (eg, axial block) and radical debridement of dead tissue. The injury is reduced as much as possible, and further operative intervention is almost always required. Preoperative antibiotics are given.

Operative (ORIF)

Surgical repair is via a dorsal approach. Further reduction is performed (if required), and K-wires are used to fix the positions. A variety of screws and small plates are used for fixation.

Ligamentous structures are salvaged and repaired as much as possible. Then, tendons and neurovascular structures are repaired, often requiring grafts. Loose skin closure with grafting or flap transfer is performed. K-wires remain for 6 weeks, and casting for immobilization remains for even longer. Extensive physiotherapy and occupational therapy is required for full return of function.

Scaphoid fracture

The first complication encountered with scaphoid fractures is failure to initially recognize and treat the injury. Suboptimal radiographs are usually to blame. This, along with insufficient reduction and inadequate or early mobilization, result in dreaded complications. These include delayed union, nonunion, malunion,[15] avascular necrosis of the scaphoid, progressive carpal instability (dorsal intercalated segment instability), and late degenerative changes.

Clinically, all manifest as weakness, chronic pain, and limited motion of the hand. Osteosynthetic techniques such as Russe bone grafting and, more recently, vascularized bone grafts during operative repair have been described, with successful prevention of these complications.

Operative complications include sensory neuritis, displaced grafts and recurrence of deformity, and carpal collapse from instability after palmar capsule ligament injury. Capsular stiffness after surgery and casting is common but improves with physiotherapy and time.

Late salvage procedures include radial styloidectomy, scaphoid excision and 4-corner fusion, proximal row carpectomy, midcarpal arthrodesis, and total wrist fusion.

Lunate fracture and avascular necrosis

The most relevant complication of lunate fractures is associated with the relative difficulty in diagnosing the injury based on findings from simple radiographs. Unrecognized injury and repetitive strain may lead to Kienböck disease and, ultimately, arthritic, painful degeneration of the wrist.

Tearing of the palmar radiolunate ligament during injury to the proximal pole can result in a dorsal and ulnar shift in the position of the lunate and a palmar tilt of the proximal fragment. Complications such as carpal tunnel syndrome and radiocarpal arthrosis, in addition to nonunion and Kienböck disease, can occur.

Important complications of the radial shortening procedures include neurovascular injury and delayed union and nonunion at the osteotomy site.

Complications of arthrodesis include infection, hematoma, transient neurapraxia, scapholunate instability, and nonunion. However, these are relatively rare.

Perilunate dislocation and fracture dislocation

Similar to most carpal injuries, failure to recognize these dislocations and fracture dislocations is the earliest complication. A late presentation of chronic injury may require salvage procedures.

Perilunate injury can result in median nerve compression and neuropathy. This usually resolves with reduction, but it may require carpal tunnel release if chronic in nature. Avascular necrosis of the scaphoid and lunate can occur and is treated within the context of individual injury. The lunate usually has good blood supply, and ischemia is often only transient; the development of Kienböck disease is exceptionally rare.

A significant complication may be carpal instability within or between carpal rows (dissociative and nondissociative, respectively) and, ultimately, painful arthrosis. This requires a limited intercarpal arthrodesis, total arthrodesis, or, possibly, an implant wrist arthroplasty.

Chronic perilunate dislocations are difficult to manage. Early dislocation can be operatively reduced and repaired, but late dislocations may require proximal row carpectomy, 4-corner fusion, or total wrist arthrodesis.

Isolated carpal fractures

Complications with triquetral fractures are rare. The most significant concern is ulnar carpal instability. Arthrosis can result from untreated triquetral fracture, and simple excision is suggested.

Hamate fractures can be complicated with ulnar neuropathy, tendon rupture, and a weak grip.

Complications of capitate fractures include avascular necrosis, malrotation of the distal fragment, and arthrosis.

Isolated carpal dislocations

Most carpal dislocations do well if treated appropriately; complications are rare. Undiagnosed palmar triquetral dislocations can manifest as carpal tunnel syndrome, at which point excision is recommended.

Late presentation of trapezoid dislocation may include avascular necrosis. Arthrodesis is recommended over excision because the latter may lead to metacarpal migration and subsequent carpal arthritis.

Axial dislocation and fracture dislocation

Axial fractures and dislocations can be complicated by associated neurovascular, muscular, and/or tendinous injury. These are more common with axial ulnar dislocation. Later complications, after treatment, include tendon and nerve adhesions, stiff joints, rotational deformities of the finger, fibrous contraction of the thenar eminence (axial radial), and carpal instability.

Most wrist injuries have a positive outcome if diagnosed and treated early. Complications and late presentation can lead to devastating degenerative changes in the wrist.

A study by Bae et al found that pediatric patients with scaphoid fractures achieved excellent functional outcomes by median 6.3-year follow-up, whether they were treated with casting or surgery. The study involved 63 patients (aged 8-18 years at treatment), including 39 with acute scaphoid fracture and 24 with chronic fracture nonunion; six of the acute fractures and 20 of the nonunions were treated with surgery, with the rest undergoing casting. All bones in the study healed successfully; patient outcomes were the same for casting and surgery, with over 95% of patients reporting wrist function equal or superior to that of the general population. However, presentation with chronic nonunion was found to independently predict an outcome level below that in acute fracture, although chronic nonunion patients still achieved a median level of function comparable to that in the general population.[16]

A literature review by Jauregui et al indicated that in adolescent and preadolescent patients, surgical treatment with or without bone grafting is effective in healing scaphoid fracture nonunions. The study included patients under age 18 years with scaphoid fracture in whom cast immobilization had produced no clinical or radiographic improvement in over 3 months. The investigators reported that surgery using nonvascularized bone graft led to a 94.8% union rate, compared with 94.6% for patients who underwent rigid fixation without grafting. Both groups of patients showed significant improvement in range of motion and grip strength.[17]

A literature review by Pradhan et al indicated that persistent pain and functional limitations are often reported up to a year and a half after wrist fracture. The investigators concluded that current rehabilitation protocols for patients with wrist fracture have limited effectiveness, finding rehabilitative exercise/manual therapy to have only small effects with regard to functional improvement and pain reduction.[18]

Arthroscopy

An important trend in the management of wrist fractures and dislocation is the use of wrist arthroscopy. Arthroscopy, though initially intended as a diagnostic tool, has increasing application as a therapeutic tool also. This includes soft tissue repair (interosseous ligaments and the TFCC) as well as bony repair (ORIF of scaphoid). Its benefit will lead to more accurate reduction of structures and, potentially, less down time for patients. This is an active field of study and growth and appears to have tremendous potential.

Revascularization

Revascularization techniques such as vascular bone grafting for avascular necrosis of the scaphoid and lunate have been described and developed by a variety of researchers. Although successes have been reported using these methods, a final consensus has not been reached on the efficacy of these techniques. However, the use of these techniques continues to grow; they are becoming important tools among practicing hand surgeons' current armamentarium.

Salvage

Regarding Kienböck disease, researchers have not yet determined which salvage procedure is the most efficacious for end-stage carpal collapse. However, weighing the benefits of pain management versus the loss of function, or vice versa, may ultimately remain the patient's burden. Certainly, proximal row carpectomy, if available, is at the top of the list. Total wrist fusion is an alternative option.

Electrical stimulation

Pulsed electromagnetic stimulation with small, implanted electrodes has been described for the treatment of scaphoid nonunion sites. This osteosynthetic technique remains controversial but is advocated by some in instances in which alternate methods of treating nonunion have failed.