Orthopedic Surgery for Gamekeeper's Thumb
- Author: Matthew Hannibal, MD; Chief Editor: Harris Gellman, MD more...
History of the Procedure
Gamekeeper's thumb is a clinical instability of the first metacarpophalangeal (MCP) joint caused by an insufficiency of the ulnar collateral ligament (UCL) in the MCP of the thumb. Because the stability of the thumb is important for prehension, treatment is directed toward optimizing the healing of the ligament to restore its full function.[1, 2, 3, 4, 5]
The common name for this condition, originally coined in 1955, derived from the observation that this injury was most often associated with Scottish gamekeepers, especially rabbit keepers. In these individuals, the injury was work-related, occurring as game animals (eg, rabbits) were sacrificed. The animals' necks were broken between the ground and the gamekeeper's thumb and index fingers; this placed a valgus force onto the abducted MCP) joint, leading to UCL injury and to instability accompanied by pain and weakness of the pinch grasp.
Currently, this type of injury is typically more acute. The most common mechanism is a skier landing on the ground with his or her hand braced on a ski pole, causing a valgus force on the thumb. The alternative term skier's thumb reflects the acute nature of the injury.[8, 9, 10, 11, 12]
Gamekeeper's thumb is a common injury. The incidence is increased in skiers, but it does not depend on the type of ski pole used. No sex-related proclivity exists.
Gamekeeper's thumb is caused by a valgus force that is directed on the MCP joint of the thumb and produces a failure of the UCL. Falls on an abducted thumb and the fall of a skier against a planted ski pole are common mechanisms. (For a discussion of the anatomy of the MCP joint and the UCL, see Relevant Anatomy.)
Chuter et al, over a 10-year period, studied 127 patients who underwent surgical repair of an acute thumb UCL rupture for clinically unstable injuries or displaced avulsion fractures. Most of the injuries (≥66%) were hyperextension or abduction injuries. The most common cause was a fall (49%), followed by sports injuries (skiing injuries accounted for only 2.4% of injuries). More than 99% of patients had a UCL rupture confirmed at surgery. Other findings included avulsion fractures (21%), dorsal capsular tears (57%), and dorsal capsule infolding (29%).
A Stener lesion occurs when the adductor aponeurosis becomes interposed between the ruptured UCL and its site of insertion at the base of the proximal phalanx. Thus, the distal portion of the ligament retracts and points superficially and proximally. A rupture of the proper and accessory collateral ligaments must occur for this injury to happen. The UCL no longer contacts its area of insertion and cannot heal.
Occasionally, failure of the UCL avulses a small portion of the proximal phalanx at its insertion, leading to a gamekeeper's fracture ; this injury can be subtle or obvious, and it can involve a substantial portion of the articular surface of the proximal phalanx. However, a lump or mass over the ulnar aspect of the MCP joint of the thumb does not necessarily imply a fracture; it may be the result of the Stener lesion.
The injured thumb should be evaluated for swelling and pain at the ulnar aspect of the MCP joint. Ecchymosis is frequently seen. A palpable mass on the ulnar aspect of the MCP joint may represent the retracted ulnar collateral ligament stump that is displaced proximally and dorsally relative to the adductor aponeurosis. The uninjured thumb should be evaluated first to assess its range of motion (ROM) and valgus stability in both extension and 30º flexion.
The range of flexion and extension of the thumb MCP joint varies considerably. The variation of normal joints can include ROMs of 5-115º of flexion and extension. In full extension, valgus laxity averages 6º and increases to an average of 12º in 15º of flexion.
The accessory collateral ligament may remain intact, and gross instability may be absent. The thumb should be placed in 30° flexion and tested for valgus instability in this position. However, this maneuver should be performed only after radiographic findings rule out a gamekeeper's fracture.
Although a gamekeeper's fracture is a contraindication to stress testing, a nondisplaced avulsion fracture is not. If the patient's pain is severe, the joint may be anesthetized with a lidocaine injection before the stress testing.
A laxity of 30º or one that is 15º more than that on the uninjured side represents a ruptured proper collateral ligament in this position (the proper collateral ligament runs from the metacarpal head to the volar aspect of the proximal phalanx).[13, 9] A supination deformity of the MCP joint, which may be visualized, can be associated with the volar subluxation of the MCP joint and suggests instability.
A Stener lesion can be present only when both the proper collateral ligament and the accessory collateral ligament are ruptured. In more than 80% of complete ruptures of the UCL, a Stener lesion is present, whether it is palpable or not. Stress testing with the thumb in the extended position is the best test for determining the competence of the accessory collateral portion of the UCL.
Again, valgus laxity of more than 30º or a laxity that is 15º more than that on the uninjured side suggests rupture of this portion of the ligament.[13, 9] If valgus laxity of the MCP joint is present in both the flexed and extended positions, complete UCL rupture should be suspected.
Nonsurgical treatment can be considered for partial tears of the UCL — that is, grade I or grade II tears. These tears usually involve an isolated rupture of the proper collateral ligament.
Complete ruptures of the UCL can be determined by means of physical examination, including stress testing. Radiographic stress testing can be performed, but the evaluating surgeon should perform these tests because radiographic stress test findings can be misleading.
In pediatric gamekeeper's thumb, the injury usually involves a Salter-Harris type III fracture of the thumb proximal phalanx. If the fragment is displaced by less than 2 mm, nonsurgical management is indicated. For greater displacement, the fracture should be opened and reduced.
Occasionally, significant ligamentous injury may occur without immediate gross instability, which can be masked by swelling and muscle spasm. At this point, a repeat examination can be performed after 1 week; if the swelling persists and motion has not been regained, surgical fixation may be considered.
The MCP joint is a diarthrodial joint that is primarily involved in flexion and extension. The static restraints and some dynamic stabilizers provide joint stability.
The static restraints include the proper collateral ligament (mostly in flexion), the accessory collateral ligament (mostly in extension), the palmar plate (mostly in extension), and the dorsal capsule (limited, in flexion). The dynamic stabilizers include the thumb intrinsic and extrinsic muscles. The adductor mechanism is particularly important here because it inserts onto the extensor expansion through its aponeurosis, which lies superficial to the UCL.
The UCL is a 4- to 8-mm × 12- to 14-mm band that originates from the metacarpal head and inserts into the medial aspect and base of the proximal phalanx of the thumb. Occasionally, when the UCL is strained, it avulses the bone at its insertion and leads to a gamekeeper's fracture.
In gamekeeper's thumb, no absolute contraindications to surgery exist. Relative surgical contraindications include the following:
The patient is too infirm to tolerate surgery, regardless of whether a complete UCL tear is present
In a child, gamekeeper's thumb with less than 2 mm of displacement of the Salter-Harris type III fracture
Chronic instability of the thumb due to a chronic UCL rupture
Chronic instability of the thumb due to a chronic UCL rupture is difficult to treat, and repair using the capsuloligamentous structures of the ulnar border of the MCP joint has had limited success. Even surgical repair that is performed 6 weeks after the complete UCL rupture has had limited success. Essentially, the longer a complete rupture of the UCL exists, the smaller the possibility of stability restoration with anatomic repair (see Complications).
Some surgeons have reported success with the dynamic transfer of a tendon (eg, the adductor pollicis) from its insertion on the ulnar sesamoid to the ulnar base of the proximal phalanx. Other surgeons have reported success with the use of static tendon transfers, which have the theoretical advantage of an inherent blood supply if some continuity of the tendon with its musculotendinous unit is preserved.
MCP fusion has been recommended by some surgeons in cases of chronic gamekeeper's thumb; in some cases, this procedure is reserved for use in patients who have concomitant osteoarthritis.
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