Comments on “Flexor Tendon Rupture Due to Previously Undiagnosed Kienböck Disease: A Case Report”

To the Editor:

We read with interest the article by Turner et al in the 2017 issue of HAND.³ The authors reported a case of flexor tendon rupture due to Kienböck disease and stated that no prior cases have been reported. However, flexor tendon rupture associated with Kienböck disease has indeed been previously reported. In 1942, James reported a case of rupture of the flexor pollicis longus (FPL) and flexor profundus tendons of the index finger secondary to Kienböck disease.¹ Niwa et al reported 6 cases of closed tendon rupture as a result of Kienböck disease and also reviewed 11 reported cases in English and 48 cases in Japanese.² According to their article, flexor tendon rupture has been reported in a total of 14 cases.²

Recently, we also encountered a case with FPL rupture caused by Kienböck disease in a 74-year-old woman without marked wrist pain. Plain radiographs revealed Lichtman stage IV, and computed tomography (CT) showed protrusion of the collapsed lunate fragment toward the volar side (Figure 1). In intraoperative findings, the joint capsule was perforated by lunate fragments, as in previous reports^1,2 (Figure 2). The FPL appeared to rupture just above this lesion as a result of friction. Turner et al did not clearly demonstrate the intraoperative findings of the joint capsule, and it is likely that the same mechanism affected the flexor tendon rupture.

Figure 1.

(a) Anteroposterior radiograph showing the collapsed and fragmented lunate, suggestive of stage IV Kienböck disease and (b) CT showing the collapsed lunate fragment protruding into the volar side.

Figure 2.

The volar joint capsule is pierced by the volar fragment of the lunate (arrow). The proximal tendon stump of the flexor pollicis longus is held by the tendon clamp. The median nerve is held by surgical tape.

Of course, it is important to take plain radiographs in the assessment of a patient presenting with closed flexor tendon rupture.³ In addition, closed rupture of the flexor tendon should be recognized as a complication in patients with asymptomatic Kienböck disease.