Ulnar Collateral Ligament Injury of the thumb meta-carpo-phalangeal Joint

Ligaments are the thick bands of connective tissue that stabilize joints in the hand. There is a ligament either side of the joint at the base of the thumb: the radial collateral ligament stabilizes one side of the joint, the ulnar collateral ligament the other side. Injury to the ulnar collateral ligament (UCL) of the thumb is usually the result of a sudden force across the thumb (Skier’s thumb).

Assessment of whether the ligament is completely torn, or partially torn, is critical
The meta-carpo-phalangeal (MCP) joint normally has about 5 degrees of laxity to lateral stress in full extension and 15 degrees of laxity to lateral stress when flexed. If the UCL is damaged there will be more laxity. Patients will find it difficult to make a strong pinch grip due to a loss of stability at the base of the thumb.

The UCL will usually tear away from the attachment to the proximal phalanx, less commonly a tear is found in the middle of the ligament, or at the attachment to the metacarpal bone.

Complete or partial tears

UCL injuries can be complete, or partial tears.
A complete tear of the UCL almost invariably needs surgery. A complete tear can be associated with the interposition of a thin sheet of connective tissue (the adductor aponeurosis) between the avulsed ligament and its point of avulsion from the bone of the proximal phalanx of the thumb (this is called a Stener lesion, the interposition of the adductor aponeurosis stops the ligament from healing without surgery).

Partial UCL tears can be treated conservatively using a splint.
A moulded thermoplastic splint can be used to protect the partially torn UCL for a period that usually lasts up to six weeks.

Complete disruption of the UCL is usually treated with surgery
Complete disruption of the UCL treated by surgery. The ligament is reattached using a small metal bone-anchor. The repair can be protected with a splint allowing movement of the thumb MCP joint within hours of surgery (and potentially allowing an early return to training for competitive sportsmen or women).

Surgery is performed as a day case using either a short general anaesthetic or a regional block (local anaesthetic injected around the nerves to the arm).

Diagnosis

Diagnosis is usually confirmed in clinic
The diagnosis and assessment of the injury is usually made from the patients account of the injury. Some patients may need injection of local anaesthetic into the hand to in-order help the assessment, some may need an ultrasound scan.

A complete tear is commonly associated with 15 degrees more laxity and a lack of affirm end-point with stress across the MCP joint (when compared to the uninjured thumb).

Chronic UCL Tears

Chronic UCL injuries can be treated by reconstruction of the ligament using a tendon graft.
Chronic injuries to the UCL (months or years old) cannot routinely be repaired: the UCL is reconstructed using a tendon graft (usually the palmaris longus tendon). The results of this operation are similar to UCL repair, the thumb is partially immobilised in a splint for up to six weeks after surgery.

Return to sport

After a successful repair, and with an appropriate splint in place (usually covered in Elastoplast tape) rugby players can return to competitive sport in 25 days (but should continue to wear the splint during training and competition for 3 months).

Surgery is usually done under a short general or regional (arm) anaesthetic. The procedure lasts less than one hour, patients go home the same day.

There are many injuries that can have surgery safely delayed, I do not think this is appropriate for this injury. There have been no long-term studies looking at the incidence of osteoarthritis or the duration of an athletic career after this injury. The short-term prognosis, after appropriate assessment and treatment seems excellent.