gms | German Medical Science

Objectives/Interrogation: A rare case presentation of an 14-year old healthy boy of Ethiopian descent presented with a duplicated thumb on his right hand consisting of a non-functioning hypoplastic radial and a fully developed functional ulnar component.

The presented case report should demonstrate a case of rare congenital deformities; usually hand surgeons in the western hemisphere are not confronted with.

In the current geopolitical situation more often refugees from less developed countries seek advice for their congenital deformities in a very late presentation. This case attempts to describe such a rarely seen deformity, discusses the classification and treatment options.

Methods: After thorough discussions with the patient and explaining the options with the help of an interpretor, we decided to undergo a resection/ reconstruction procedure. During surgery the hypoplastic radial component was resected and the metacarpal head reduced to match the proximal ulnar phalanx. Tendons were dissected proximally. Followed by radial collateral ligament anatomic transosseus. In order to avoid a painful neuroma the remaining nerves of the removed radial component were dissected, crushed and buried into an intraosseus drillhole.

Results and Conclusions: At three months follow-up the patient showed no metacarpophalangeal joint instability, a satisfying motion of the thumb as well as intact sensation, was pain free and pleased with the result. Postoperative X-Rays revealed a normal joint alignment.

To our knowledge this is only the second case of thumb polydactyly with metacarpophalangeal joint symphalangism and a single interphalangeous joint reported in the world literature and certainly the latest presentation. Al-Qattan, 2010 mentioned this rare anomaly in one case in his study of 228 hands without providing further details. One patient with metacarpophalangeal symphalangism and two distal phalanges radially was described by Afshar, 2007 whereas a few patient reports of interphalangeous symphalangism of the thumb as well as cartilaginous symphalangism in children can be found in the literature. According to Zuidam et al our presented case would be named Type IV S (Symphalangism) u (ulnar).

Our reported case is unique in that it is the only case of thumb metacarpophalangeal symphalangism with a near-normal single distal phalanx. Previously reported cases showed either two distal phalanges (Afshar, 2007), a slightly deformed interphalangeal joint (Al-Qattan, 2010) or symphalangism in more distal joints of the thumb.