ECU Tendon Subluxation: “Snapping Wrist” Syndrome

MRI finding of ECU tendon rupture.

The extensor carpi ulnaris (ECU) tendon is involved in many pathologies seen in golf, hockey, tennis, and baseball athletes. Injury to the tendon may be acute, chronic, or anatomical based. The tendon sits in the ulnar groove and may encounter subluxation, dislocation or rupture with or without ulnar sided wrist pain.

Repetitive microtrauma or a traumatic forceful wrist flexion, supination, or ulnar deviation can lead to damage. Chronic subluxation can lead to ECU tendonitis. Acute injury can cause a rupture or further degeneration of the wrist subsheath.

Clinical Manifestations:

ECU injury presents with ulnar-sided wrist pain. Palpating the ECU groove will likely elicit pain and tenderness for the patient if the ECU is involved in the mechanism of injury. Subluxation of the tendon in the ulnar groove will proved a snapping sensation with passive supination and ulnar deviation of the wrist.

This type of injury is frequently misdiagnosed in high-trained athletes. Middorsal wrist injuries that are misdiagnosed can delay return to play. The addition of an accessory tendon is a rare but important finding that can explain a snapping wrist without injury. When diagnostic measures fail to show ECU tendon damage, an accessory of the extensor pollicus brevis may be the source of the snapping sensation (Subramaniyam SD, et al 2017).

Hand Anatomy Review and Clinically Relevant Disorders by Compartment

(Source: OrthoBullets)


Conservative treatment involves immobilization with pronation and radial deviation. ECU subsheath reconstruction and arthroscopy is indicated if conservative treatments fail. 50% of surgical cases also find a TFCC tear. 

Reference Links:

Accessory Tendon Case Study:

Summer Trusty, B.S., M.S. Summer Trusty, B.S., M.S. Summer Trusty, has worked as a physical therapy technician at the Orthopedic Center for Sports Medicine (OCSM). She has worked directly with post-operative patients, professional athletes, and traumatically injured patients. She has monitored multiple patients per hour and provided rehab exercise protocols to her patients. Among her duties, Summer applied post therapy treatment protocols including ice, electrical stimulation, heat, and cervical/lumbar traction. Her current goal is to attend medical school so that as a physician, she can treat her patients for the reason they are visiting the doctor, while also encouraging positive preventive medicine. As a physician, Summer expects to utilize her experiences in overcoming non-medical barriers to provide the highest quality of care to her community.

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