Biomechanical comparison of double-loaded suture anchors using arthroscopic Mason-Allen stitches versus traditional transosseous suture technique and modified Mason-Allen stitches for rotator cuff repair.

BACKGROUND

In recent studies objective evaluations have demonstrated that arthroscopic rotator cuff repairs can have higher failure rates than open repairs. Thus, there is a need for a stronger tissue-holding stitch for arthroscopical repair. The purpose of this study was to compare the biomechanical properties of traditional open transosseous suture technique and modified Mason-Allen stitches versus double-loaded suture anchors and arthroscopic Mason-Allen stitches in rotator cuff repair.

METHODS

In 20 sheep shoulders the infraspinatus tendons were dissected from their insertion and were randomized to 2 repair groups: (1) repair with transosseous suture and modified Mason-Allen stitches, (2) repair with double loaded bioabsorbable suture anchors and arthroscopic Mason-Allen stitches: Both groups were coupled with braided, nonabsorbable polyester (Ethibond) suture sized USP No. 2. All repairs were cyclically loaded from 10 to 180N with the use of a materials testing machine. The number of cycles to gap formation of 5 and 10mm at the repair site and the mode of failure were recorded.

RESULTS

The number of cycles to 5-mm gap was mean 634 (SD 106) for group 1 and mean 750 (SD 107) for group 2 (P<0.026). The corresponding values to 10-mm gap were mean 1573 (SD 161) for group 1, and mean 1789 (SD 183 cycles) for group 2 (P<0.012). In group 2 the mode of failure occurred by tissue pull-out, whereas in group 1 the failure occurred by a mixture of suture breakage and pull-out.

CONCLUSIONS

This time-zero study demonstrates that the combination of bioabsorbable suture anchors and arthroscopic Mason-Allen stitches provides strength superior to that of the modified Mason-Allen transosseous suture technique under isometric cyclic loading conditions. However, additional evaluation is needed to examine the effects on the sustained strength of the repair throughout the healing process.