An Assessment of the Relationship Between Congenital Transverse Deficiency of the Forearm and Symbrachydactyly

Purpose: A relationship between symbrachydactyly and transverse deficiency has been suggested but has not been critically investigated or established by scientific studies. The purpose of this investigation was to evaluate a large group of patients with transverse deficiency of the forearm for clinical and radiologic features typically seen in patients with symbrachydactyly. Methods: A retrospective review of the medical records of 291 patients with a diagnosis of upper-extremity transverse deficiency at the level of the forearm was performed. Patient charts, photographs, and radiographs were evaluated for manifestations of symbrachydactyly; specifically, we clinically assessed for the presence of nubbins and skin invaginations and radiologically assessed for hypoplasia of the proximal radius and ulna. Results: Two hundred seven patients had soft tissue nubbins at the end of their amputation stumps including 38 with the additional finding of skin invagination at the distal end. Another 36 extremities had a skin invagination alone. Twenty-nine of the extremities without nubbins or skin invaginations had hypoplasia of the proximal radius and ulna. Thus, 272 of the 291 extremities with transverse deficiency had manifestations of symbrachydactyly. Conclusions: The majority of patients with the diagnosis of transverse deficiency have soft tissue nubbins, skin invaginations, or hypoplasia of the proximal radius and ulna at the end of their amputation stumps. These clinical and radiologic features support the concept that transverse deficiency through the forearm represents a proximal continuum of symbrachydactyly.