INITIAL FAILURE STRENGTH OF OPEN AND ARTHROSCOPIC BANKART REPAIRS

Surgical repair of recurrent anterior shoulder instability requires secure fixation of the separated inferior glenohumeral complex to bone. Many techniques of fixation are in use for both arthroscopic and open repair. The specific aim of this study was to compare the initial failure strength of eight repair techniques using a previously described canine model of Bankart repair. Intact capsule-to-bone complexes failed at the bony interface at 236 N. Traditional Bankart repair failed at 122.1 N (2 sutures) and 74.7 N (1 suture), Acufex TAG rod (Acufex Microsurgical, Mansfield, MA) at 143.5 N (2 sutures) and 79.8 N (1 suture), transglenoid suture technique (2 sutures) at 166.6 N, Mitek GII (Mitek, Norwood, MA) (1 suture) at 96.4 N, Zimmer Statak (Zimmer Inc, Warsaw, IN) (1 suture) at 95.2 N, and Acufex bioabsorpable Suretac at 82.2 N. The two-suture repairs were statistically equivalent in strength to each other, as were the one-suture repairs and the Suretac device. Two-suture repairs were significantly stronger than the one-suture repairs (P < .01) failure. In the single-suture specimens, failure occurred by suture breakage in 46% (18 of 39) of specimens and soft-tissue failure around the suture in 54% (21 of 39), Failure in the two-suture techniques primarily occurred by soft-tissue failure (23 of 25) and this proved a statistically significant difference (P < .003). No device broke or pulled out of bone. Our results indicate that in a soft-tissue-to-bone repair model (1) pullout of suture anchors is a rare event and suggests that pullout strength of suture anchors should not be the sole basis of comparison of one device to another in Bankart repairs; (2) suture techniques and anchor devices that allow for two sutures exhibit a stronger initial pullout strength than one-suture techniques and devices; (3) suture anchor techniques are equivalent in strength to suture-alone techniques; and (4) all repair techniques are significantly weaker than undisturbed (control) specimens indicating that the ultimate outcome of a Bankart repair, open or arthroscopic, is dependent on physiological repair of soft-tissue to bone. Further study is required to document the strength of soft-tissue-to-bone repair with time. These results are repair specific. Soft-tissue-tobone repair in other areas, i.e., rotator cuff, may show different failure mechanics.