An Evolution of the Surgical Management of Synpolydactyly: A Case Series of 21 Hands

Synpolydactyly is a rare congenital anomaly characterized by syndactyly and polydactyly in the central hand. Limited treatment guidelines exist for this complex condition.

A retrospective review of synpolydactyly patients was conducted at a large, tertiary pediatric referral center to describe our surgical experience and evolution of management. The Wall classification system was used to categorize cases.

Eleven patients (21 hands) with synpolydactyly were identified. Most of the patients were White and had at least one first-degree relative who also had synpolydactyly. The Wall classification yielded the following results: 7 type 1A hands, 4 type 2B hands, 6 type 3 hands, and 4 uncategorizable hands. Each patient had an average of 2.6 surgeries and an average follow-up time of 5.2 years. The rates of postoperative angulation and flexion deformities were 24% and 38%, respectively, with many of these cases also demonstrating preoperative alignment abnormalities. These cases often required additional surgeries including osteotomies, capsulectomies, and/or soft tissue releases. The rate of web creep was 14% with 2 of these patients requiring revision surgery. Despite these findings, at the time of final follow-up, most patients had favorable functional outcomes, were able to engage in bimanual tasks, and were able to perform activities of daily living independently.

Synpolydactyly is a rare congenital hand anomaly with a significant degree of variability in clinical presentation. The rates of angulation and flexion deformities as well as web creep are not insignificant. We have learned to prioritize correcting contractures, angulation deformities, and skin fusion, over simply trying to delete the "extra" number of bones as this may destabilize the digit(s).