Review Question - QID 217394

This patient most likely has a subluxing extensor carpi ulnaris (ECU) tendon secondary to rupture of the ECU subsheath given the mechanism, pain characteristics, and negative radiographic findings.

The ECU tendon is an important ulnar-sided wrist structure that is contained within the ECU subsheath, or 6th dorsal compartment. The subsheath primarily keeps the ECU tendon located during supination, and when torn, allows the ECU tendon to subluxate during supination, leading to dorsoulnar pain and snapping. The ECU tendon will usually reduce with pronation. Management initially involves splinting with the forearm in pronation and slight wrist extension/radial deviation to leave the ECU in a position of minimal angulation relative to the ulna. In cases that are refractory to conservative care, repair or reconstruction of the subsheath may be undertaken to stabilize the tendon.

Iorio et al. described a case report of a 19-year-old college tennis player with ulnar wrist pain accompanied by a snapping sensation. The authors note that despite nonoperative management with bracing, stretching, and strengthening, she remained tender over the ECU tendon and was noted to have subluxation of the tendon on examination and dynamic ultrasound. They go on to discuss their favored treatment algorithm which included two months of nonoperative measures, followed by ECU subsheath reconstruction +/- ulnar groove deepening.

Ruchelsman and Vitale reviewed indications, anatomy, and technique for ECU subsheath reconstruction. They note that associated pathology must be identified and treated appropriately at the time of surgery. They proceed to discuss the technique or ECU subsheath repair and reconstruction, typically performed using a radially based extensor retinacular sling of tissue.

DaSilva et al. published a review on determining the etiology of ulnar-sided wrist pain. They review a variety of different contributing conditions as well as their associated physical exam and imaging findings. They go on to discuss nonoperative and operative management strategies, noting that wrist arthroscopy is becoming increasingly more valuable in treating ulnar-sided wrist pain.

Figures A & B represent the AP and lateral radiographs of a normal wrist without fracture or other abnormality.

Incorrect Answers:
Answer 2: In cases of TFCC tear, deep, foveal ulnar-sided wrist pain is present and worsened with ulnar compression of the wrist.
Answer 3: Ulnar abutment syndrome is seen in cases of positive ulnar variance where the ulna pathologically impacts the carpal bones, most commonly the lunate.
Answer 4: Lunotriquetral ligament tears create a VISI deformity and are usually demonstrated on exam with pain when 'shucking,' the lunotriquetral joint.
Answer 5: An injury to the dorsal radioulnar ligament often causes instability of the DRUJ, and this patient demonstrated no DRUJ instability on exam.