Anatomical study of the pre-retinacular fat pad of the wrist: application to a new surgical approach to the carpal tunnel

INTRODUCTION: Decompression of the median nerve in the carpal tunnel by section of the flexor retinaculum is the generally accepted treatment for carpal tunnel syndrome and is usually effective in relieving the symptoms. Following postoperative observations we proposed the hypothesis that incisional pain following open carpal tunnel release could be partly explained by injury to the fat pad situated between the palmar carpal ligament and the flexor retinaculum. METHOD: We performed an anatomical study on 20 fresh adult latex injected upper limbs. RESULTS: The sus-retinacularis fat pad is a real anatomical structure, clearly delineated and located inside a defined fibrous space with its own innervation from the ulnar nerve. It lies in the path of the normal carpal tunnel approach. DISCUSSION: Although most postoperative scar tenderness is attributed to neuroma formation because of injury to transverse branches of the palmar cutaneous nerves, we nevertheless consider that injury to the preretinacular fat pad also plays a part. We propose a modified approach to the carpal tunnel. This is a safe and simple method which respects the integrity of the sus-retinacularis fat pad so as to minimise the extent of scar tenderness.