Emergency repair of extensor tendon central slip defects with Oberlin's bypass technique: feasibility and results in 4 cases with more than 5 years of follow-up.

Treatment of soft tissues defects in the central slip of the extensor tendon at the proximal interphalangeal (PIP) joint is challenging because of the potential for stiffness and boutonniere deformity. The bypass procedure proposed by Oberlin for secondary injuries is an attractive solution. This salvage procedure uses a free tendon graft (palmaris longus) that is intercalated between the extensor indicis proprius muscle and the base of the middle phalanx. This study reports on the first cases of acute central slip defect treated in an emergency setting. Four patients with an average age of 37 years (range 11-69) were treated by the same surgeon using the bypass procedure. Clinical evaluations consisted of measuring the active range of motion in the PIP joint, QuickDASH, Total Active Motion (TAM) and strength with a Jamar® dynamometer. All patients had reintegrated their injured finger into their body image within three months. At the last follow-up, the average active mobility was 0-5-76.5°. The functional outcomes were similar at nine months, with an average mobility of 0-13-72°. The two patients who were working at the time of injury were able to return to work in the third month. Various procedures such as tendon plasty, transfer or graft have been described in the literature for posttraumatic chronic boutonnière deformity. In cases where significant defects exist not only in the tendon, but the bone and skin, the bypass procedure is an effective approach to achieving satisfactory functional outcomes.