Spontaneous Rupture of the Extensor Pollicis Longus Tendon With Repair and Contralateral Prophylactic Decompression: A Case Report and Review of the Literature.

Ruptures of the extensor pollicis longus (EPL) tendon are known to occur primarily from local mechanical causes at Lister's tubercle. Other reasons for ruptures have been proposed including local steroid or even distant steroid injections that might have weakened the tendon, leading to rupture. There have been rare cases in the literature that describe ruptures without any known causes. Here, we describe a case with no known risk factors and with a spontaneous EPL rupture on one side and subclinical tendinopathy on the other. The patient had the EPL repaired on the ruptured side and subsequent prophylactic decompression of the contralateral side. The side without the rupture had preoperative ultrasound and magnetic resonance imaging, and a synovial biopsy was interpreted as showing tendinopathy.