10.1 Ulnar Collateral Ligament Repair

Acute rupture of the metacarpophalangeal joint (MCPJ) ulnar collateral ligament (UCL) also known as Skier thumb is a result of forced abduction that can further result in a UCL tear. The primary role of the MCPJ of the thumb is flexion and extension. The joint is stabilized by the UCL and radial collateral ligament (RCL), the volar plate, and the dorsal capsule. The collateral ligaments consist of a strong proper collateral ligament and a weaker accessory collateral ligament.

To test for joint stability, one should test by fully flexing the MCPJ and should apply valgus stress to the thumb to test the proper collateral ligament. Laxity of over 35 degrees with no clear endpoint signifies rupture (Fig. 10‑1). Full extension of MCPJ with a valgus stress test assesses the accessory collateral ligament. One should make a comparison with the uninjured contralateral thumb.

If there is a midsubstance UCL rupture, a direct repair can be performed; however, in some cases Mitek mini anchor repair is warranted. The sequence of repair in both scenarios is illustrated in Fig. 10‑2, Fig. 10‑3, Fig. 10‑4, Fig. 10‑5, Fig. 10‑6, Fig. 10‑7, Fig. 10‑8, Fig. 10‑9, Fig. 10‑10, Fig. 10‑11, Fig. 10‑12, Fig. 10‑13, Fig. 10‑14, Fig. 10‑15, Fig. 10‑16, Fig. 10‑17, Fig. 10‑18, Fig. 10‑19. For an avulsion fracture of the UCL, one must assess the size of the bony fragment. If large, this can be fixed with a tension band K-wire technique (Fig. 10‑20).