Subluxation of the Extensor Carpi Ulnaris Tendon Associated with the Extensor Digitorum Tendon Subluxation of the Long Finger
A twenty-year-old male patient presented to our clinic with pain of the right wrist and the long finger MP joint. Two years earlier, the patient slipped on his hand. After injury, he did not received any evaluation or treatment, but he felt a snapping of the ulnar side of the wrist in forearm rotation and dorsal side of the long finger MP joint in MP flexion. At that time, the symptoms improved spontaneously after several weeks without specific treatment, three months earlier, after heavy lifting, he had persistent symptoms despite the conservative treatment including short arm splint for 4 weeks. A physical examination revealed painful ECU dislocation in forearm rotation and painful extensor tendon subluxation at the long finger MP joint in MP flexion. He showed generalized ligament laxity according to the Beighton and Horan criteria but did not have any symptoms in the contralateral hand.\nPlane radiography did not reveal any fracture or abnormality. Ultrasonography and magnetic resonance imaging (MRI) were performed to confirm the subluxation and identification of the associated pathology. In dynamic ultrasonography, the sagittal band (SB) was subluxated ulnarly as the long finger MP joint was flexed more than 70°. In addition, the ECU was subluxated volarly in forearm supination with tendon attrition at the level of the ulnar styloid process where the ECU groove exists. MRI revealed longitudinal splitting approximately 5 cm at the level of the ulnocarpal joint and dislocation of volar half slip of the ECU tendon on T2 axial plane image ().\nThe patient had been in military service. He required surgical treatment for rapid return to his previous work. Therefore, surgical treatment was performed.\nWith the patient under general anesthesia, the long finger MP dorsum was approached longitudinally. The radial SB did not reveal any definitive rupture but diffuse thinning was observed. The extensor tendon slipped off the metacarpal head ulnarly as the joint flexed intraoperatively. The redundant radial SB was augmented using a cross-stitch with a 6-0 prolene suture (). This effectively prevented any additional slippage of the extensor tendon of the long finger.\nWith an approximately 4 cm longitudinal incision in the ulnar styloid area, the ECU sheath on the ECU groove was approached protecting the dorsal ulnar nerve sensory branch. Neither the ECU sheath nor extensor retinaculum was ruptured but the space within the ECU tendon compartment was dilated because of its redundancy at the ulnar styloid process. An ECU tendon dislocation in an ulnar and palmar direction was confirmed with the forearm in supination and the wrist in palmar flexion. The fibro-osseous sheath of the ECU groove was incised at the ulnar border and elevated radially. The ECU tendon surface showed no longitudinal tear unlike the MRI finding. The ECU groove was deepened approximately 2 mm using a curette. Two small FASTak (Arthrex Inc., Naple, FL, USA) suture anchors were inserted at the ulnar border of the ECU groove just proximal to ulnar styloid and 1 cm apart proximally. The overlying ECU sheath was advanced to the underlying periosteum reducing the enlarged sheath volume with a horizontal mattress tie (). A long arm splint with MP extension at neutral forearm rotation was applied for 4 weeks and the wrist motion was allowed thereafter. A removable splint was applied for an additional 2 weeks. Vigorous activities were restricted for an additional three months. At the 1-year follow-up, the long finger MP joint, wrist and forearm showed normal motion with no pain (). He returned to his previous activities without a recurrent dislocation of the ECU tendon and long finger extensor tendon.