Hand injuries account for up to 15% of sports injuries and are common in contact sports and in sports with a high risk of falling. Appropriate management requires knowledge of the type of injury, demands of the sport and position, competitive level of the athlete, future athletic demands and expectations, and the role of rehabilitation and protective splints for return to play. Management of the athlete requires aggressive and expedient diagnostic intervention and treatment. This article describes ligamentous injuries to the thumb, including thumb carpometacarpal dislocations, thumb metacarpophalangeal dislocations, collateral ligament injuries and interphalangeal dislocations, their evaluation, treatment and outcomes.
Key points
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Injuries to the hand account for up to 15% of all sports injuries and are common in contact sports and in sports with a high risk of falling.
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Ligamentous injuries to the thumb include thumb carpometacarpal dislocations, thumb metacarpophalangeal dislocations, and collateral ligament injuries and interphalangeal dislocations.
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Management requires knowledge of the type of injury, demands of the sport, competitive level, future athletic expectations, and the role of rehabilitation and protective splints for return to play.
Introduction
Injuries to the hand account for up to 15% of all sports injuries and are common in contact sports such as football and in sports with a high risk of falling such as skiing, biking, in-line skating and gymnastics. In many sports, the thumb is one of the most frequently injured areas. Appropriate management requires knowledge of the type of injury, demands of the specific sport and position played, competitive level of the athlete, future athletic demands and expectations, and the role of rehabilitation and protective splints for return to play. In contrast with the nonathlete, management of the athlete often requires more aggressive and expedient diagnostic intervention and treatment to minimize time away from sport while also ensuring safe return to competition. This paper describes ligamentous injuries to the thumb including thumb carpometacarpal dislocations, thumb metacarpophalangeal dislocations, collateral ligament injuries and interphalangeal (IP) dislocations, their evaluation, treatment and outcomes.
Introduction
Injuries to the hand account for up to 15% of all sports injuries and are common in contact sports such as football and in sports with a high risk of falling such as skiing, biking, in-line skating and gymnastics. In many sports, the thumb is one of the most frequently injured areas. Appropriate management requires knowledge of the type of injury, demands of the specific sport and position played, competitive level of the athlete, future athletic demands and expectations, and the role of rehabilitation and protective splints for return to play. In contrast with the nonathlete, management of the athlete often requires more aggressive and expedient diagnostic intervention and treatment to minimize time away from sport while also ensuring safe return to competition. This paper describes ligamentous injuries to the thumb including thumb carpometacarpal dislocations, thumb metacarpophalangeal dislocations, collateral ligament injuries and interphalangeal (IP) dislocations, their evaluation, treatment and outcomes.
Thumb carpometacarpal joint dislocation
The thumb trapeziometacarpal joint consists of the concavoconvex articular surfaces of the thumb metacarpal base and the trapezium oriented in opposition to one another with perpendicular axes similar to 2 reciprocally opposed saddles. The joint is stabilized by its capsule and the palmar oblique, intermetacarpal, dorsal–radial, and dorsal oblique ligaments. The primary restraints to dorsal subluxation and dislocation are the palmar oblique ligament and dorsoradial ligament.
Injuries to the thumb carpometacarpal joint may be complete or partial. Partial injuries are far more common and result in varying degrees of joint subluxation. Complete injuries with dislocation of the thumb carpometacarpal joint are relatively rare and occur when a flexed metacarpal is loaded axially. Dislocations are invariably dorsal and result in tearing of the dorsal radial ligament and volar oblique ligament. Physical examination typically reveals an adducted thumb with dorsal subluxation that reduces with a palmar directed force or thumb extension. Evaluation with standard posteroanterior and true lateral radiographs must be performed to evaluate for associated fractures (ie, Bennett fracture–dislocation) and may show dorsoradial subluxation of the metacarpal. Evaluation of the thumb carpometacarpal joint is best obtained with a Robert view in which the forearm is fully pronated with the dorsum of the thumb on the cassette and the x-ray beam angled 15° from distal to proximal ( Figs. 1 and 2 ). Posteroanterior stress radiographs with the radial aspect of the distal phalanges pressed firmly together are often helpful to access for instability and allow comparison with the contralateral uninjured joint ( Fig. 3 ).
Treatment should consist of immediate reduction and assessment of joint stability. If the joint is well-reduced and stable after reduction, immobilization in a thumb spica cast for 4 to 6 weeks may be sufficient to maintain reduction and prevent long-term instability. Frequently, however, the joint remains unstable and open reduction, repair of the dorsoradial ligament and K-wire fixation of the joint is indicated. If reduction is delayed beyond 3 weeks or there is persistent instability, ligament reconstruction with a strip of the flexor carpi radialis as described by Eaton and colleagues is advised.
A dorsoradial incision is made along the proximal half of the first metacarpal curving ulnarward proximally around the base of the thenar eminence parallel with the distal flexor crease of the wrist. The carpometacarpal joint of the thumb is exposed subperiosteally and the distal part of the flexor carpi radialis is isolated. A 6-cm distally based strip of the flexor carpi radialis is harvested from the radial side of the tendon and freed proximally, ensuring that it remains attached to the base of the second metacarpal distally. The thumb metacarpal is then reduced on the trapezium and secured with a K-wire ensuring that its path will not interfere with the site through which the tendon transfer will eventually pass. A hole is drilled transversely through the base of the thumb metacarpal ulnar to the extensor pollicis brevis tendon exiting near the volar beak. The harvested tendon strip is passed through this tunnel deep to the abductor pollicis longus tendon and sutured to the periosteum near its exit. It is then looped around the flexor carpi radialis near its insertion and sutured to the base of the thumb metacarpal ( Fig. 4 ).
Postoperatively, the thumb is immobilized for 4 weeks in extension and abduction. Treatment of traumatic dislocations of the thumb carpometacarpal joint when instability is present remains a subject of debate. Simonian and Trumble retrospectively compared closed reduction and percutaneous pinning with early ligamentous reconstruction. One-half of the patients (4/8) initially treated with closed reduction and percutaneous pinning were noted to have unsatisfactory results secondary to recurrent instability and degenerative arthritis and were converted to early (within an average of 7 days of injury) ligamentous reconstruction as described. At follow-up, these patients were noted to have good pain relief and well-preserved grip strength and range of motion (ROM). Other studies have demonstrated favorable results with good pain relief, stability, and improvements in pinch strength after ligamentous reconstruction in the setting of persistent instability.
Thumb metacarpophalangeal joint dislocation
The soft tissue stabilizers of the thumb metacarpophalangeal joint include paired collateral ligaments and the volar plate. The collateral ligament complex is composed of a proper and accessory collateral ligament. The proper collateral ligament arises from the lateral condyles and inserts on the volar aspect of the proximal phalanx. The accessory collateral ligaments arise more volarly and insert on the volar plate and sesamoids.
Thumb metacarpophalangeal dislocations are typically dorsal and occur secondary to a hyperextension injury with associated injuries to the collateral ligaments, volar plate, and capsule. Dislocations are classified as simple (reducible with closed techniques) or complex (irreducible with closed techniques) and present with a hyperextension deformity and metacarpal adduction. Complex dislocations often present with puckering of the palmar skin overlying the metacarpal head and imply interposed soft tissue, most often the volar plate, which has avulsed proximally, or the flexor pollicis longus. Radiographic evaluation should include standard posteroanterior and true lateral radiographs to evaluate for associated fracture–dislocation.
Reduction is accomplished under local anesthetic block with wrist flexion to relax the flexor tendons, gentle recreation of the deformity (ie, hyperextension), and a palmar-directed force on the proximal phalanx to reduce it onto the metacarpal head. Longitudinal traction should be avoided because displacement of the flexor pollicis longus to the ulnar side of the metacarpal head, in conjunction with the radial sided adductor musculature, can produce a “noose” around the metacarpal head. Longitudinal traction serves to tighten this noose converting a reducible dislocation into an irreducible one.
Dislocations that cannot be reduced by closed means require open reduction, most commonly via a dorsal or volar approach. The dorsal approach uses the interval between the extensor pollicis brevis and longus and offers the advantage of minimal risk to the neurovascular bundles whereas the volar approach with a Bruner incision has the advantage of allowing direct visualization of structures that may be impeding reduction (ie, volar plate, sesamoids, and flexor pollicis longus). Either approach may be used based on surgeon preference. After reduction the thumb is immobilized in a dorsal block splint with the metacarpophalangeal joint in 10° more flexion than the point of instability. Each week thereafter it is extended 10° until terminal extension is obtained. Few studies have evaluated the long-term outcome of thumb metacarpophalangeal joint dislocation, but patients can expect to have a stable, albeit possibly stiff, joint. If, after reduction, the joint remains unstable and there is evidence to suggest complete collateral ligament rupture, operative repair is indicated, as discussed.
Thumb metacarpophalangeal joint ulnar collateral ligament injuries
Commonly known as skier’s thumb , acute injuries to the thumb metacarpophalangeal joint ulnar collateral ligament (UCL) can be partial or complete tears and are common in skiers and other sports that place the thumb at risk for forced radial deviation/abduction. Patients typically present complaining of pain with tenderness, swelling, and ecchymosis along the ulnar aspect of the thumb metacarpophalangeal joint.
Patients with suspected UCL injuries should undergo radiographic evaluation with standard posteroanterior and true lateral radiographs before physical examination to rule out associated fracture and prevent displacement of a nondisplaced fracture. Physical examination should include evaluation for the presence of a Stener lesion. Originally described in 1962, a Stener lesion presents as a palpable mass over the ulnar aspect of the joint and occurs as the distal insertion of the UCL avulses from the proximal phalanx and retracts proximal and dorsal to the adductor aponeurosis. Present in 80% or more of cases, recognition of the presence of a Stener lesion is of paramount importance because it prevents reapproximation of the ligament to its insertion site and warrants surgical intervention. Of note, however, inability to palpate a mass does not definitively rule out a Stener lesion ( Fig. 5 ).
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