INITIAL FAILURE STRENGTH OF OPEN AND ARTHROSCOPIC BANKART REPAIRS

Surgical repair of recurrent anterior shoulder instability requires se cure 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 fail ure strength of eight repair techniques using a previously described c anine 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 Micr osurgical, 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 (Mit ek, Norwood, MA) (1 suture) at 96.4 N, Zimmer Statak (Zimmer Inc, Wars aw, IN) (1 suture) at 95.2 N, and Acufex bioabsorpable Suretac at 82.2 N. The two-suture repairs were statistically equivalent in strength t o each other, as were the one-suture repairs and the Suretac device. T wo-suture repairs were significantly stronger than the one-suture repa irs (P < .01) failure. In the single-suture specimens, failure occurre d by suture breakage in 46% (18 of 39) of specimens and soft-tissue fa ilure around the suture in 54% (21 of 39), Failure in the two-suture t echniques primarily occurred by soft-tissue failure (23 of 25) and thi s proved a statistically significant difference (P < .003). No device broke or pulled out of bone. Our results indicate that in a soft-tissu e-to-bone repair model (1) pullout of suture anchors is a rare event a nd 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 ex hibit a stronger initial pullout strength than one-suture techniques a nd devices; (3) suture anchor techniques are equivalent in strength to suture-alone techniques; and (4) all repair techniques are significan tly weaker than undisturbed (control) specimens indicating that the ul timate outcome of a Bankart repair, open or arthroscopic, is dependent on physiological repair of soft-tissue to bone. Further study is requ ired 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.