Ulnar collateral ligament of thumb injury
Acute UCL injury of the thumb, or skier's thumb, is caused by an acute valgus (radially directed) force on an abducted thumb, resulting in partial or complete rupture of the UCL. This injury is commonly the result of skiing, sporting, bicycle, or motorcycle accidents.
A notable variant of acute thumb MP joint UCL injury known as a Stener lesion occurs when the adductor pollicis aponeurosis becomes interposed between the avulsed UCL and its insertion at the base of the proximal phalanx, resulting in inadequate healing and persistent laxity or instability. This variant has been reported to occur in 64%-88% of complete ruptures; thus, distinguishing between complete and partial rupture on examination is critical.
Chronic instability of the thumb MP joint UCL can result from untreated acute ruptures, failure to recognize a Stener lesion, or chronic repetitive stress to the ligament. This injury is often referred to as gamekeeper's thumb, a diagnosis originally used to describe Scottish gamekeepers who fractured the necks of rabbits between their thumbs and index fingers.
Classic history and presentation: Typical presentation includes tenderness, ecchymosis, and swelling along the ulnar border of the thumb MP joint. Pinch grip and valgus stress across the thumb MP may cause pain and instability. Avulsion fracture of the ulnar base of the proximal phalanx, and less commonly of the metacarpal head, can be an associated finding on x-ray.
Patients with chronic instability typically present with thumb pain, swelling, and weakness that is exacerbated by forceful pinch activities. Laxity or gross instability can similarly be seen on valgus stress.
Risk factors: Risk factors for acute injury include activities that predispose to acute UCL injury, such as cycling, skiing, and ball-handling or stick-handling sports. Risk factors for chronic injury include undiagnosed Stener lesions or activities that predispose to chronic, repetitive UCL stress.
S53.30XA – Traumatic rupture of unspecified ulnar collateral ligament, initial encounter
405275001 – Rupture of ulnar collateral ligament of thumb
Differential Diagnosis & Pitfalls
- Thumb fracture
- Stenosing tenosynovitis of thumb (trigger thumb)
- Gout or other inflammatory arthropathy
- Septic arthritis
- Radial collateral ligament injury of the thumb (uncommon)
- Thumb dislocation (including injuries to additional stabilizing structures of the thumb)
- Wrist sprain or fracture