Woman with pain.
Gamekeeper's thumb was named after the chronic injury gamekeepers experienced while using their abducted thumb to apply pressure to the necks of the animals. The pressure applied to the abducted thumb would result in the avulsion of the ulnar collateral ligament. More recently, a similar injury has been seen with skier's as they fall against an anchored ski pole. Again the force of the body falling against the pole is applied to an abducted thumb and results in an avulsion or tear of the ligament.
The tear may be accompanied by an avulsion fracture or also by an injury called a Stener lesion. The Stener lesion is identified when the two torn ends of the ulnar collateral ligament are separated by the proximal adductor aponeurosis. By separating the torn ligament, the injury is not able to hear and surgery is required. A Stener lesion may be identified using MR or ultrasound. As the Gamekeeper's thumb injury may only be a soft tissue injury, it may not be always seen on radiography. A partially torn ulnar collateral ligament or a nondisplaced injury may be splinted and heal with time. A displaced lesion >2 mm with or without a Stener lesion will usually require surgical intervention.
Radiologic overview of the diagnosis:
- Avulsion fragments uncommonly seen on radiograph (12% of UCL injuries)
- Nondisplaced to minimal displacement (< 2 mm) avulsion fracture of proximal phalanx base suggest ulnar collateral avulsion without Stener lesion
- Incomplete rupture or complete rupture without a Stener lesion: On T1WI - Hypo intensity to intermediate signal intensity within the ulnar collateral ligament with or without avulsed bone fragment. The ulnar collateral ligament remains deep to overlying hypo intense adductor aponeurosis. The ulnar collateral ligament remains in line with the long axis of the thumb. On T2WI - Hypo intense ligament with central inhomogeneity. May reveal surrounding edema.
- Stener lesion: On T1WI - retracted mass of the ulnar collateral ligament trapped beneath the adductor aponeurosis. The ulnar collateral ligament will likely be directed superficial in relation to the adductor aponeurosis. On T2WI - may show the "yo-yo on a string" where the ulnar collateral ligament is retracted and coiled (the yo-yo) adjacent to the linear aponeurosis.
- Gamekeeper's thumb (Skier's thumb) is the tear of the ulnar collateral ligament with or without an avulsion of its attachment on the proximal phalanx of the thumb.
- May require surgical intervention if displaced >2 mm or associated with Stener's lesion: separation of the torn ligament by the adductor aponeurosis.
- Avulsion fracture rarely seen on radiography. Diagnosis best made with MR or ultrasound.
- Avulsion fragment displaced <2mm strongly suggests against Stener lesion.
- https://my.statdx.com/STATdxMain.jsp?rc=false#dxContent;ulnar_collateral_ligament_tear,_thumb_dx. 08/30/2011
- http://en.wikipedia.org/wiki/Gamekeeper%27s_thumb. 08/30/2011
- http://emedicine.medscape.com/article/1240710-overview#showall. 08/30/2011