Congenital Contracture of the Ulnar Digits and Its Differentiation From Ischemic Contracture

Purpose To describe the clinical features, radiologic findings, differential diagnosis, and surgical treatment of a congenital flexion deformity of the middle, ring, and little fingers. The cause of the condition is the aberrant origin of the flexor digitorum profundus, leading to a congenital contracture of the ulnar digits. Methods We reviewed 8 patients with congenital contracture of the ulnar digits. The mean age at the time of surgery was 14 years. An examination revealed a flexion contracture of the middle, ring, and small fingers. Plain radiographs, 3-dimensional computed tomography, magnetic resonance imaging, and ultrasound were used to characterize bony and soft tissue pathology. Surgical treatments included resection of the aberrant origin and a muscle-sliding procedure. Results Bony prominence on the proximal ulna was seen in the plain radiographs and/or 3-dimensional computed tomography. A cord that extended from this bony prominence to the tendons of flexor digitorum profundus was revealed in the magnetic resonance imaging. The bony prominence and the cord were also seen using ultrasound. The median time of patient follow-up was 1.7 years. A simple resection of the tendinous origin only resulted in a release in 2 patients who were 4 years old. Older patients required a further muscle-sliding procedure. The average grip strength ratio on the contralateral side was 82%. Conclusions Congenital contracture of the ulnar digits is a new congenital flexion deformity involving the middle, ring, and small fingers. Bony prominence on the proximal ulna is the key finding for establishing its diagnosis and distinguishing it from an ischemic contracture. We recommend treating this surgically at 12 years of age or older after the phase of rapid growth of the extremities. We recommend the resection of the aberrant origin, combined with a muscle-sliding procedure, as the treatment of choice, even for young patients. (Copyright (C) 2022 by the American Society for Surgery of the Hand. All rights reserved.)