Gamekeeper Thumb

Updated: Apr 18, 2016
  • Author: Michael A Secko, IV, MD; Chief Editor: Trevor John Mills, MD, MPH  more...
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Overview

Background

Gamekeeper's thumb was originally described by Campbell in 1955 when he reported chronic laxity of the ulnar collateral ligament (UCL) of the thumb in 24 Scottish gamekeepers. The injury occurred as gamekeepers sacrificed wounded rabbits and other small game by breaking their necks between the ground and their thumbs and index fingers.

Today, this injury is more a result of delayed treatment of an acute injury. The alternative term skier's thumb was popularized by Gerber et al and has become more synonymous with an acute injury. A significant proportion of these injuries are a result of fall or blows to the thumbs. One of the common mechanisms is a skier landing against the ski pole or ground while the thumb is abducted causing a valgus force on the thumb.

Gamekeeper’s thumb, or skier’s thumb, may constitute up to 50% of hand injuries in skiers. It may also be seen in patients with rheumatoid arthritis, those who have been in a motor vehicle accident, and athletes of other sports with injuries resulting from a fall onto an outstretched hand with an abducted thumb. MRI can establish the integrity of the ulnar collateral ligament. MRI can also distinguish between a Stener lesion and a nondisplaced or minimally retracted tear. Ultrasonography is also considered safe and accurate. [1]

Complete UCL tears require surgical intervention. Gamekeeper's fractures are usually treated conservatively, but those involving more than 30% of the joint surface and those that are malrotated or displaced should not be manipulated. Those fractures are indications for surgical intervention. [1]

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Pathophysiology

The metacarpophalangeal (MCP) joint is a diarthrodial joint with the metacarpal head stabilized by ligamentous and musculotendinous attachments. The thumb MCP joint is capable of motion predominately in flexion and extension with a limited degree of rotation. The ulnar collateral ligament provides static stabilization of the thumb MCP joint. The UCL consists of both a proper ligament and an accessory ligament. The proper is taut in flexion, while the accessory is taut in extension.

The dynamic stabilizers are the intrinsic and extrinsic muscles of the thumb or most notably the adductor pollicis muscle. Dorsally, this muscle expands to form the adductor aponeurosis lying superficial to the UCL.

Chronic laxity of the UCL results from repetitive lateral stress applied to the abducted MCP joint, in particular, the stabilizing ligaments on the ulnar side of the thumb MCP joint. Subsequent instability of the first MCP joint can result from the chronic laxity of the UCL and moreover, lead to functional disability such as weakness of pincer grasp and arthritis.

An acute injury results from a sudden forced abduction stress at the MCP, particularly a fall against a ski pole or the ground. The distal attachment on the proximal phalanx is the most frequent site of rupture. The UCL may even avulse a small portion of the proximal phalanx at its insertion site. The rate of associated fractures in the skeletally mature varies from 23-50% of patients treated operatively.

A Stener lesion occurs when the ruptured end of the UCL retracts and becomes abnormally displaced proximal to the adductor aponeurosis and may be palpated clinically on the ulnar side of the MCP joint. Proper anatomical alignment and healing becomes impeded because the adductor aponeurosis becomes interposed between the sites of insertion on the proximal phalanx with the ruptured end. This lesion can also be associated with a fracture as well.

In the pediatric population, epiphyseal fusion of the proximal phalanx occurs in those aged 16-18 years. Ulnar collateral ligament ruptures of the thumb MCP joint in children are usually associated with epiphyseal fractures (Salter-Harris III) of the proximal phalanx.

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Epidemiology

Frequency

United States

The incidence is increased in skiers. This common injury can also be sustained while playing football or rugby. Some instances of skier's thumb injuries are reported in sports with direct ball-to-thumb impact, such as volleyball. Gripped object sports cannot be implicated as the lone risk factor since thumb injuries are not common in sports such as lacrosse, hockey, or tennis. Ulnar collateral injuries have been reported in cases of people falling on outstretched hands with the thumb without reports of gripping any handle.

Skier's thumb is the most common upper extremity injury in skiing and is second only to medial collateral ligament (MCL) injury of the knee. Reported injury rates in downhill skiing vary between 2.3 and 4.4 per 1000 skiing days. Of these, between 7% and 9.5% are injuries to the UCL.

The incidence of Stener lesion–diagnosed definitively during surgery—was first noted in 64% of patients with clinical UCL injuries. Subsequent studies report between 14% and 87% of patients.

Mortality/Morbidity

Disruption of the UCL leads to instability of the first MCP joint. This results in poor pincer grasp and opposition and can ultimately lead to degenerative arthritic changes and difficulty carrying on the activities of daily living secondary to chronic pain.

If the diagnosis is missed or the injury is not treated properly, enduring pain, weak pincer grasp, or arthritis may result.

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