Spontaneous index finger extensor tendon rupture in a SNAC wrist

We present two recent cases of spontaneous rupture of both index finger extensor digitorum communis and extensor indices proprius tendons caused by a dorsal carpus osteophyte. Both patients had a history of scaphoid fracture non-union with evolution to scaphoid non-union advanced collapse (SNAC) of the wrist. These two cases were treated surgically with a 3-corner arthrodesis, and an interposition of a fragment of one of both ruptured tendons together with a tendon transfer of a supernumerary extensor digitorum communis of the third finger. The interposed tendon fragment was sutured with a Pulvertaft weave proximally and end-to-end distally. The supernumerary tendon was added as reinforcement to this construction. At 6-month and 14-month follow-up, the patients had a slight decrease in range of motion and functionality without hindering the activities of daily living and a great improvement in strength. Isolated extension of the index finger was possible minimum 6 months postoperatively. Spontaneous tendon ruptures of the finger extensors are not common but were described earlier in literature. Recent literature described that underlying cause of a spontaneous tendon rupture should always be corrected in order to prevent or at least delay future ruptures. To our knowledge, this is a rare type of complication and this kind of treatment has never been reported in literature.