Abstract
Objective: Injury of the finger extensor tendon in the opisthenar is commonly seen in dialysis patients, but the pathology of this condition remains to be elucidated. This study was designed to determine the cause, incidence, and symptoms of finger extensor tendon injury on the opisthenar and investigate what patients would be candidates for surgery. Subjects: This study included fifty patients (seventy-one hands) with swelling on the dorsal side of the wrist joint and, as confirmed by ultrasound examination, hyperplasia of the extensor tenosynovium. Results: 1) Injury of the finger extensor tendon on the opisthenar developed in patients who had undergone dialysis over 15 years or longer. The prevalence was increased as dialysis persisted for a longer duration; 2.7% for a dialysis duration of 10 to 19 years, 34.9% for 20 to 29 years, and 82.8% for 30 years or longer. 2) For subjective symptoms, swelling was noted in twenty-six patients, pain in five patients, and restricted finger extension in three patients. Approximately half of patients had no subjective symptoms. 3) Ultrasonography was useful as an adjunctive diagnostic method for injury of the finger extensor tendon. 4) In five patients treated surgically, the synovium, extensor retinaculum, and tendon were collected during surgery for histopathologic examination, suggesting the presence of amyloid deposition. 5) Dialysis amyloidoses, including carpal tunnel syndrome, amyloid bone cyst, and amyloid shoulder arthropathy, were complications in 94% of the patients with injury of the finger extensor tendon on the opisthenar. Discussion: Injury of the finger extensor tendon on the opisthenar represents stenosing tendosynovitis that develops as a result of amyloid deposition in the tenosynovium and extensor retinaculum. Clinical observation and ultrasonography are useful in the diagnosis of this disease. As the disease progresses, swelling and pain on the opisthenar as well as hypertrophy of the tendon occur. The characteristics in the end-stage of this disease include degeneration of the tendon and restricted range of motion in the fingers. In the advanced stage, which is associated with tendon hypertrophy and tenosynovial hyperplasia, aggressive surgical treatment is indicated.
