Purpose: To report a congenital anomaly of the middle finger.
Method: Nine patients (16 digits) are reported with congenital flexion deformity of the metacarpophalangeal (MCP) joint of the middle finger. Three patients (4 digits) had isolated deformities to the middle finger and in 6 the deformity was part of congenital ulnar drift (CUD) of the hand. Three patients had Freeman-Sheldon syndrome, 2 had nonsyndromic CUD, and 1 had arthrogryposis multiplex congenita. In CUD patients the middle finger had substantially greater flexion deformity of the MCP joint in comparison with other digits. Seven patients were treated surgically and 2 were treated nonsurgically. Five of the surgical patients had bilateral middle finger involvement.
Results: During surgery on 12 digits sagittal band hypoplasia of varying degrees was encountered in all patients and in all patients the extensor tendon of the middle finger was underdeveloped and often ulnarly displaced. Longitudinal imbrication of the remnants of the extensor tendon and centralizing the tendon if necessary by radial sagittal band reefing improved MCP joint flexion deformity.
Conclusions: Congenital middle finger-in-palm deformity in our patients was caused by sagittal band and extensor tendon hypoplasia.