Anatomical Variations of the Extensor Carpi Ulnaris Groove: A New Computed Tomography-based Evaluation

Abstract

INTRODUCTIONThe morphology of the extensor carpi ulnaris (ECU) groove is likely related with the pathology of ECU-related injuries. The fibro-osseous ECU subsheath reportedly prevents subluxation of the ECU tendon and works with the extensor retinaculum to prevent tendon bowstring. 1,2)Volar subluxation of the tendon during supination is prevented by the transverse fibers of the medial wall of the subsheath.3) A shallow ECU groove might lead to ECU tendon instability and subluxation, and deepening the ECU groove 2-3 mm with a power bur has been recommended to improve the congruency of the tendon and groove.3-5) However, there have been few studies regarding the ECU groove morphology, 6,7) and the ideal morphology of the ECU groove remains unknown. Furthermore, the shape of the ECU groove has not been discussed previously. The purpose of this study was to evaluate the morphology of the ECU groove, including Background: This study aimed to develop a classification that precisely describes the extensor carpi ulnaris (ECU) groove morphology.

A new comprehensive Classification Scheme for ECU Tendon Problems at the Wrist

“…Type U was present in 44%, Type M in 37% and Type R in 19% of patients. Type R ECU groove, which lacks a medial bony buttress, might be also more prone to ECU-related injuries 12 .…”

“…Despite the increased amount of available information about ECU instabilities, there are new records [12][13][14] in the literature describing anatomical variations which are not involved in classification schemes [8][9][10]. Hand surgeons have to cope with these "anomalies and variations" during surgical operations.…”

“…Since the time of the most recently-published classification, many articles have been published providing descriptions of ulnar anatomy variations [12,13]. ECU tendon instability was also recorded in healthy individuals.…”