Supernumerary flexor carpi ulnaris--case report and review

Area of Science:

• Anatomy
• Surgical Reconstruction
• Medical Case Study

Background:

• Anomalies of the Flexor Carpi Ulnaris (FCU) muscle are infrequent, typically involving variations in tendon insertion or accessory bands.
• The Digastric FCU, characterized by two distinct muscle bellies and tendons, is an exceptionally rare variant with limited documented cases.
• Previous literature lacks reports on the clinical utilization of this specific anatomical variation.

Observation:

• An incidental finding of an anomalous FCU muscle during surgery for complex Post Volkmann's ischemic contracture deficits.
• The identified anomalous FCU presented with two separate muscle bellies and tendons.
• Each distinct FCU tendon was surgically employed for specific functional reconstruction.

Findings:

• The anomalous FCU muscle was successfully utilized in a surgical procedure, representing the first reported clinical application of a Digastric FCU.
• Postoperative outcomes demonstrated independent functional recovery of the thumb (opposition) and index finger (flexion).
• A novel classification system for supernumerary FCU anomalies is proposed, categorizing them into Type 1 (Split Tendons), Type 2 (Digastric FCU), and Type 3 (Accessory FCU).

Implications:

• This case highlights the potential reconstructive utility of the Digastric FCU anomaly in managing complex hand deficits.
• The proposed classification may aid in standardizing the description and understanding of FCU variations.
• Further research into the embryological basis and clinical applications of FCU anomalies is warranted.