A comprehensive approach to surgical management of the type IIIA hypoplastic thumb.

In order to adequately identify pathologic anatomy and effectively reconstruct 14 type IIIA hypoplastic thumbs, a comprehensive clinical evaluation and surgical approach was employed. Eleven patients had congenital differences in the forearm, while all patients had anomalies in the wrist, hand, and digits. In addition to well-described interconnections between the flexor pollicis longus and the extensor pollicis longus, and thenar muscle hypoplasia, the authors observed duplication of musculotendinous units, anomalous muscles between the thumb and index rays, and abnormal insertions or dense adhesions along tendons as proximal as the forearm level. Successful reconstruction required an extended approach from the digit to the forearm, through which division of abnormal connections, reorientation of tendons, and lysis of adhesions was performed. Opposition transfer was needed in only 8 of the patients after the other pathologies were treated. Web-space deepening and ulnar collateral ligament reconstruction was performed when indicated. Improvement in function and appearance was achieved.