Conservative Treatment of an Acute Traumatic Extensor Carpi Ulnaris Tendon Subluxation in a Collegiate Basketball Player: A Case Report (Case Report) (Report‪)‬

Ulnar-sided wrist pain is a common complaint among athletes that can result from either acute or chronic injury mechanisms. Numerous complex structures can be damaged, contributing to the enigmatic nature of this problem. Possible sources for ulnar-sided wrist pain include triangular fibrocartilage complex injury, lunotriquetral instability, distal radioulnar joint injury, extensor carpi ulnaris (ECU) injury, flexor carpi ulnaris tendinopathy, and pisotriquetral joint injury. (1) Therefore, it is critical for the clinician to understand the anatomy of this region. The anatomy of the sixth dorsal or extensor compartment is complex, consisting of a fibro-osseous tunnel between the capitulum and the styloid process of the ulna. (2-4) The ECU tendon is situated in this groove and is held in place by a subsheath, which lies inferior to the extensor retinaculum. (3,5,6) The extensor retinaculum attaches to the pisiform and triquetrum and therefore has no direct attachment to the ulna and so does not play a role in stabilizing the ECU. (3) As the ECU tendon passes through the sixth dorsal compartment to its attachment at the base of the fifth metacarpal, an ulnarly directed obtuse angle is formed, resulting in translational stress with muscular contraction. (7) Disruption or attenuation of the subsheath is caused by supination, ulnar deviation, and flexion as the angle becomes more acute, placing increased stress on the restraining subsheath. (2,4-12) Once the subsheath is damaged, the ECU tendon can sublux and slide under the intact extensor retinaculum. (3) Further wrist complica tions can occur because an intact ECU tendon and subsheath also play a role in stabilizing the distal radioulnar joint?