Resection of Fourth-to-Fifth Metacarpal Synostosis and Fascial Interposition for Creation of a Functional Grip/Pinch...

Fourth-to-fifth metacarpal synostosis, present in a majority of Apert hands, flattens the metacarpal arch, restricts metacarpal descent, may prevent opposition of border rays, and negates any functional flexion. Restoration of position and mobility with arthroplasty changes the plane of flexion and enables both pinch and grip. This report summarizes the evolution of the authors' technique over 5 decades.

In a cohort of 184 Apert patients (368 hands), the presence, anatomy, and level of metacarpal synostosis with a classification was determined. The present technique consists of incision along the ulnar border of the hand, wide excision of the skeletal coalition, release of dorsal structures, and soft-tissue interposition. Data consisted of clinical records, serial molds, radiographs, and occupational therapy records. Follow-up ranged from 3 to 44 years.

A total of 147 patients (80% of hands) had bilateral fourth-to-fifth metacarpal synostoses, the extent of which correlated with the Apert hand classification. In 72 patients, the synostosis was resected and cadaveric fascia interposed. Synostosis refusion occurred in 38 hands, all of which were treated early in the series and in patients younger than 6 years old. Despite refusion, the position of the fifth digit had improved, and the flat transverse arch was in a more curved or cupped posture. The distance between the opposing border rays was always improved, and a new grip and pinch mechanism created.

Aggressive ostectomy of synostosis and fascial interposition places the ulnar side of the hand in a much more functional position. In conjunction with thumb lengthening, opposition between the thumb and fifth finger becomes a clinical reality in children with Apert syndrome.

Therapeutic, IV.