The Unstable Thumb - Metacarpo-phalangeal joint (MCP Joint)

The thumb ligaments are commonly injured, and are often the result of falls or sports injuries. The commonest type of injury is a collateral ligament injury, often referred to as “skier’s thumb.” This is characterised by pain, weakness and instability of the ligament, on the inner (ulnar) aspect of the thumb MCPJ joint. Injuries can be partial or complete, and new or old. Most partial injuries are managed in a splint with supervised physiotherapy, whereas most complete injuries are managed with surgical repair. If the repair is done within the first few weeks after injury the repair is usually direct suturing of the ruptured ends of the ligament, or re-insertion of an avulsed ligament back into bone. If the injury is more than 6 weeks old, generally a tendon graft is required to reconstruct the ruptured ligament.

How is the diagnosis made?

Usually this is made by taking a careful history and examination. X-rays are generally requested to exclude a fracture. Occasionally an ultrasound scan is requested to help determine whether  the ligament injury is partial or complete.

What is the recovery period and prognosis?

These injuries, whether managed in cast or with surgery, require a splint for 4 to 6 weeks, and usually necessitate time of work, and often driving, due to poor grip. The prognosis of an appropriately treated collateral ligament injury is usually excellent, albeit with some stiffness of the joint, which can persist long term. The return to sport is generally at 8 -12 wks dependent on the type of injury