Restoration of the first dorsal interosseous muscle.

Motor dysfunction of the 1st dorsal interosseous (DIO) muscle is typically observed in low and high ulnar nerve palsy. This causes weak thumb-index pinch, which can be disabling for the patient. Various reconstructive techniques have been described; however, the choice often depends on the surgeon's experience, the presence of associated neurovascular and musculotendinous injuries, as well as the requirements of the palliative surgery schedule. Nerve transfers can be proposed when patients present early in the course of the disease. Tendon transfers are often a last resort when late presentation occurs. Tendon transfers must follow general principles: the insertion is made on the 1st DIO terminal tendon; the tension must be adjusted in a neutral position to avoid excessive tension, and immobilization is maintained for 4 weeks. Although many transfers are possible, the extensor pollicis brevis transfer is our preferred option. This donor does not require additional tendon grafting, has a direct line of pull close to that of the 1st DIO and is not often used for other reconstructive purposes.