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Skiers thumb

Skiers thumb

The leading injury hazard for skiers is knee damage. Second only to this, however, is damage to the thumb, accounting for up to 9.5% of all ski injuries according to some studies (1,2) .

The thumb has an extensive range of movements and lends great dexterity to the hand, thanks mainly to the existence of its metacarpophalangeal (MCP) joint. The MCP is a very mobile hinge joint which relies on a delicate system of articulating elements, tendons and ligaments for its stability. It is one of these key stabilisers, the ulnar collateral ligament (UCL), that is the source of the problem in the injury known as skier’s thumb.

UCL injury was first described by Campbell in 1955 (3) , but in a very different context. Laxity of this ligament was noticed to be widespread among British gamekeepers, causing the phenomenon to become known as ‘gamekeeper’s thumb’. It was found to be the manoeuvre of breaking rabbits’ necks between the ground and the thumb and index finger that resulted in repeated strain to this ligament at the MCP joint. Over time the gamekeepers would develop a distinct weakness in their pincer grip between thumb and forefinger.

Today this problem is more often the result of an acute injury or a delayed presentation of an acute traumatic injury; and Gerber et al (4) have coined the alternative term of ‘skier’s thumb’ in keeping with the shifting pattern of injury occurrence.

For its stability the MCP depends on the muscles (notably the adductor pollicis muscle) and static ligaments around the joint. The UCL is on the ulnar aspect of the MCP joint. It is typically 4 to 8mm in width and 12 to 14mm in length (5) . It is made up of two parts: a proper and an accessory ligament. The proper ligament is taut in flexion of the MCP joint, and relaxed in full extension; with the reverse being the case for the accessory ligament. So it is in flexion of the MCP joint that the UCL proper provides maximum lateral stability.

UCL injury may be chronic or acute. Chronic laxity results from repeated valgus (away from the body) stress applied to the MCP joint. This leads to instability of the MCP joint and associated functional disability such as the weakenedpincer grip.

Acute injury results from a forced valgus stress at the MCP joint causing the UCL to rupture (see Figure 1, below). The injury may also include an avulsion fracture (where bony fragments break off at the origin or insertion of the ligament). This classic skiing injury has been linked to the use of the ski pole handle strap, where the thumb is forced into abduction and hyperextension against the ski pole. Several studies have looked into the design of ski poles and it seems that no type of ski pole handle in common use today has been able to eliminate the risk of thumb injuries, even those featuring modified strapless grips (1, 6) .

Other sporting contexts for UCL injuries include break-dancing and football; but the mechanism of injury remains the same.

Injury management

The diagnosis of UCL injury will often be linked to a history of combined hyperextension and forced abduction to the thumb. Typically, a client will present with an acutely painful MCP joint, swelling and a weak pincer grip. Avulsion fractures may show up on imaging. In cases where diagnosis is not certain, ultrasound and MRI will identify UCL tears (7, 8) .

Strains and partial UCL tears are best treated conservatively. Simple thumb immobilisation in a plaster cast or thumb splint for four to six weeks has yielded good results (9) .

Complete UCL tears, avulsion fractures and instability of the MCP joint will usually need surgical exploration and repair. The aim is to restore anatomy, strength and stability to the MCP joint with minimal compromise to the range of motion of the thumb. However, some surgeons advocate conservative management of complete UCL rupture, and studies have reported comparable results between surgical and non-surgical approaches (10, 11) . [077-FIG1]

Injuries that have been neglected will eventually lead to chronic pain, instability and premature arthritis of the thumb. Attempts to repair such chronic UCL damage does not yield such good results. Treatment options include ligament reconstructive surgery (using tendon grafts) or fusion of the MCP joint.

Post-operative protocols vary, but inevitably involve a period in which the thumb is immobilised in a plaster cast, followed by a strict physiotherapy regime to restore mobility.

Conclusion

Even though there is some controversy as to how best to manage UCL injuries, the sports therapist who suspects such an injury should seek a referral for their client to a specialist orthopaedic/hand surgeon. Because of the possible complications of long-term chronic instability, disability and inevitable degenerative changes to the joint, UCL injuries are best managed in a specialist environment.

References

1. Engkvist O, Balkfors B, Lindsjö U. ‘Thumb injuries in downhill skiing’. Int J Sports Med. 1982; 3(1):50-5.

2. Campbell JD, Feagin JA et al. ‘Ulnar collateral ligament injury of the thumb; treatment with glove spica’. Am J Sports Med. 1992; 20:29-30.

3. Campbell CS. ‘Gamekeeper’s thumb’. J Bone Joint Surg Br. 1955; 37:148-9.

4. Gerber C, Senn E, Matter P. ‘Skier's thumb. Surgical treatment of recent injuries to the ulnar collateral ligament of the thumb's metacarpophalangeal joint’. Am J Sports Med. 1981; 9(3):171-177.

5. Ebrahim FS, De Maeseneer M et al. 'US diagnosis of UCL tears of the thumb and Stener lesions: technique, pattern-based approach, and differential diagnosis'. Radiographics. 2006; 26:1007-1020.

6. Primiano GA. ‘Skier’s thumb injuries associated with flared ski pole handles’. Am J Sports Med. 1985; 13:425-7.

7. Romano WM, Garvin G, Bhayana D, et al. ‘The spectrum of ulnar collateral ligament injuries as viewed on magnetic resonance imaging of the metacarpophalangeal joint of the thumb’. Can Assoc Radiol J. 2003;54(4):243-248.

8. Bronstein AJ, Koniuch MP, von Holsbeeck M. ‘Ultrasonographic detection of thumb ulnar collateral ligament injuries: a cadaveric study’. J Hand Surg [Am]. 1994; 19(2):304-312.

9. Coonrad RW and Goldner JL. ‘A study of pathological findings and treatment in soft-tissue injury of the thumb metacarpophalangeal joint’. J Bone Joint Surg Br Am. 1969; 50:439-451.

10. Landsman JC, Seitz WH Jr, et al. ‘Splint immobilization of gamekeeper's thumb.’ Orthopedics. 1995; 18(12):1161-1165.

11. Sollerman C, Abrahamsson SO et al. ‘Functional bracing versus plaster cast for ruptures of the ulnar collateral ligament of the thumb. A prospective randomised trial of 63 cases’. Acta Orthop Scan. 1991; 62:524-526.

 

Skiers thumb