Purpose: This study presents an autograft technique for the surgical management of chronic posttraumatic instability of the thumb metacarpophalangeal (MCP) joint by using a bone-retinaculum-bone graft from the second compartment of the extensor retinaculum. Methods: The bone-retinaculum-bone graft was harvested from the second compartment. The graft ends were fixed into the host site with screws. Fourteen patients (12 ulnar, 2 radial collateral ligament tears) had the procedure. All patients were reviewed by an independent observer using objective and subjective criteria, the mean follow-up time was 20 months. Results: Results were satisfactory overall (8 excellent, 4 good, 1 fair, 1 poor that subsequently was fused). All patients returned to their former jobs. All but one had a clinically stable first MCP joint; grasp was 87%, pinch was 80%, MCP joint range of motion (ROM) was 91%, and interphalangeal joint ROM was 98% of the unoperated side. Conclusions: Early results are encouraging. This procedure preserves ROM of the MCP and interphalangeal joints of the thumb, improves strength, and gives the stability required for proper thumb function.