Revisiting spontaneous rupture of the extensor pollicis longus tendon: eight cases without identifiable predisposing factor.

INTRODUCTION Rupture of the extensor pollicis longus (EPL) tendon has been reported in the setting of distal radius fracture, chronic inflammatory arthritis, following steroid injection, and with excessive or repetitive activities. Truly, spontaneous EPL rupture, without an identifiable predisposing factor, has rarely been reported. METHODS We present a retrospective case series of eight patients with spontaneous EPL rupture who were treated in our institution. RESULTS The majority of the cases were female (75 %, n = 6), and the nondominant (75 %, n = 6) hand was most commonly involved. No identifiable predisposing factor could be identified in four patients. While four patients reported a history of a fall, radiographs failed to demonstrate skeletal abnormality in all four cases. No additional pathology could be identified at the time of surgery. Patients were treated using tendon transfer (n = 7) or interpositional graft (n = 1). There has been no case of clinical recurrence in the mean of 74.8 months (range 23-140 months) follow-up period. CONCLUSION The EPL tendon is at risk for spontaneous rupture even in the absence of identifiable predisposing risk factor. Rather than pure mechanical irritation, vascular and metabolic factors may also play a substantial role in the etiology of this uncommon diagnosis.