Rigid Digits or Symphalangism

Abstract

Rigid digits or symphalangism is a rare autosomal dominant trait which can be traced back through many family pedigrees. Symbrachydactylism can involve either the proximal interphalangeal or the distal interphalangeal joints. Brachydactylism has been a useful tool and contributed much to the development of medical genetics. Although the aetiology is unknown, our clinical observations tend to support the theory that a lack of motion in the foetus causes symphalangism.

Rigid digits fall into three main groups. Group one is composed of single and multiple true symphalangism. Group two comprises the most common type, symbrachydactylism. Group three involves a large group in which symphalangism and syndactyly are associated.

The literature reports the association of rigid digits with Apert's, Poland's, Mobius', Marchesanie's, Nievergelt-Pearlman's syndromes, and diastrophic dwarfism. We report the association of symphalangism with gargoylism and dysplasia epiphysealis multiplex.

The treatment of symphalangism of the proximal interphalangeal joint has been uniformly unsuccessful. Because of dissatisfaction with fusions, manipulations and various arthroplasties, we are attempting to develop a new silicone rubber cap for arthroplasty use in children. As yet this method of treatment must be considered strictly experimental.