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

Abstract

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. 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. 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). 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. 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.