Initial fixation strength of massive rotator cuff tears: in vitro comparison of single-row suture anchor and transosseous tunnel constructs.

PURPOSE The purpose of this study was to compare the in vitro repair integrity of massive rotator cuff tears fixed with transosseous tunnel and single-lateral row suture anchor techniques. METHODS A 5 x 2-cm crescent-shaped rotator cuff tear was created in 6 matched pairs of cadaveric shoulders. Paired shoulders were repaired with 3 transosseous tunnels and 6 Mason-Allen sutures or with 3 screw-in suture anchors and 6 simple sutures. The repairs were cyclically loaded at physiologic forces along the respective directions of pull when the arm was in 90 degrees of scapular plane elevation. Gap formation and repair displacements were monitored with digital video imaging at 3 sites for each repair. RESULTS There was no significant difference between the maximal gapping of the repair constructs. After 4,000 cycles, the mean maximal gapping at any position along the repair was 6.2 +/- 2.99 mm in the transosseous tunnel construct and 4.9 +/- 1.27 mm in the suture anchor repair construct (P = .40). Gapping was significantly less in the anterior region when compared with the posterior region of the repair (P = .015). CONCLUSIONS There is no difference in cyclic loading of transosseous and single-row suture anchor repair techniques. Significantly greater gap formation occurs at the posterior aspect of repairs of massive rotator cuff tears in this in vitro model. CLINICAL RELEVANCE Initial fixation strength of single-row suture anchor repairs is equivalent to that of transosseous repairs. Further research is required to determine the unknown clinical significance of increased posterior repair gap formation.