Closed rupture of extensor tendon resulting from untreated Kienböck disease: A case report and a review of the literature

Abstract

Rationale: Spontaneous closed extensor tendon rupture is a rare complication of Kienböck disease with only 23 cases reported in the English literature.

Patient concerns: We present a case of painless attritional rupture of the extensor tendons of the right fourth finger in a 69-year-old woman with Kienböck disease and review reported cases of Kienböck disease with subcutaneous closed tendon rupture.

Diagnoses: Physical examination had shown mild painless swelling of the dorsum of the right hand. Plain radiographs showed a dorsally displaced fragment of collapsed lunate bone fracture (Lichtman grade IIIb). Although surgery was recommended, the patient did not desire surgery because she had no pain and no interference with the activities of daily living. Six months later, however, the patient returned to our hospital with complaints of loss of spontaneous extension of the fourth finger. CT and MRI showed aseptic necrosis and large dorsally displaced fragments of the lunate under the extensor tendons of the fingers, suggesting a subcutaneous fourth extensor tendon rupture.

Interventions: Surgery was performed to achieve functional recovery of the ring extensor and to prevent further subcutaneous tendon rupture. The extensor digitorum communis (EDC) of the ring finger was found to be ruptured and the EDCs to the third and fifth fingers were frayed due to attrition from the protrusion of the dorsal fragmented lunate bone. Inspection of the floor of the compartment revealed that the dorsally displaced fragment of the lunate bone had perforated the wrist capsule and protruded into the fourth compartment. The dorsal and volar fragments of the lunate bone were excised completely and scaphocapitate arthrodesis followed by the reconstruction of the fourth extensor tendon was performed.

Outcomes: A year after the surgery, radiography showed complete union of the scaphocapitate arthrodesis. The joint motion reached 45% of normal without any pain and there was full active extension of the fourth finger.

Lessons: Because dorsally displacement of collapsed lunate bone fragments is a risk factor for attritional closed rupture of tendons, radiography, and MRI are essential to diagnose and to treat any closed tendon rupture.

Figure 1

Presenting anteroposterior (C) and lateral (D) radiographs at the third visit of our hospital, showing a collapse of the lunate bone and a protruded dorsal fragment of lunate bone (arrowhead) from previously asymptomatic Kienböck disease.

Figure 2

Closed rupture of the extensor digitorum communis of the right fourth digit as a result of Kienböck disease in a 69-year-old woman. Initial oblique (A) and lateral (B) clinical photographs 3 years prior to presentation at our hospital, showing apparent active extension lag of the fourth finger (arrowhead).

Figure 3

Coronal (A) and sagittal (B) computed tomography (CT) of view of the right wrist, showing a collapsed and separated lunate. Two large fragments of the lunate bone are displaced dorsally and volarly with more marked protrusion of the dorsal fragment (arrowhead).

Figure 4

Magnetic resonance imaging (MRI) of the right wrist, showing the collapsed and fragmented lunate bone, which has a low signal intensity on a T1 (A) and T2-weighted images (C). Axial MRI of the right wrist, showing a dorsal fragment (asterisk) which had a signal intensity isointense to other carpals. The fragment is surrounded by a diffuse low-intensity area, which indicates the extensor tendons, on a T1 (B) and T2-weighted image (D).

Figure 5

Perioperative photograph. Exposure of the fourth dorsal compartment revealed the inflamed synovium around the ruptured extensor digitorum communis (EDC) of the ring finger (asterisk) (A). Inspection of the floor of the compartment reveals that the dorsally displaced lunate bone fragment (asterisk) had perforated the wrist capsule and protruded into the fourth compartment (B).

Figure 6

(A) anteroposterior and (B) lateral radiographs of the right wrist at a year postoperatively, showing the established scaphocapitate arthrodesis.

Figure 7

Lateral clinical photographs at a year postoperatively, showing 45° of extension (A), 30° of flexion (B).

Figure 8

oblique (A) and lateral (B) clinical photographs at a year postoperatively, showing full active extension of the fourth digit.