Mini All-Suture Anchors for Repairing the Central Slip of the Extensor Tendon at the Proximal Interphalangeal Joint: A Biomechanical Investigation

PURPOSE:This study evaluated 1.0-mm mini suture anchors for repairing the central slip of the extensor mechanism at the proximal interphalangeal joint. Studies have reported a requirement for central slip fixation to withstand 15 N during postoperative rehabilitation exercises and 59 N during forceful contraction. METHODS:Index and middle fingers from 10 matched pairs of cadaveric hands were prepared with 1.0-mm mini suture anchors with 2-0 sutures or threaded with 2-0 sutures through a bone tunnel (BTP). In total, 10 index fingers from unmatched hands were prepared with suture anchors and fixed to the extensor tendons to evaluate the tendon/suture interface response. Each distal phalanx was secured to a servohydraulic testing machine, and ramped tensile loads were applied to suture or tendon until failure. RESULTS:All anchors for the all-suture bone tests failed because of pullout from the bone (Mean failure force = 52.5+/-17.3 N). Three anchors from the tendon-suture pull out test failed by pullout from the bone and seven failed at the tendon/suture interface (Mean failure force = 49.0+/-10.1 N). CONCLUSIONS:The 1.0-mm mini suture anchor provides enough strength for early short-arc motion, but it may not be adequate for forceful contraction in the early postoperative rehabilitation stage. CLINICAL RELEVANCE:The site of fixation, the type of anchor, and the type of suture used are key factors to consider for early range of motion, after surgery.