Biomechanical effect of increased number of suture strands on rotator cuff repair in a bovine model.

objectiveThis study aimed to investigate if there was a link between the biomechanical properties and the number of suture strands in repairing a rotator cuff (RC) tear in a bovine model using the transosseous technique.

methodsFifty-four fresh tendons from bovine (mean age: 7.1 ± 0.5 months; range 6.5-7.5 months) and 1 humeral head from porcine (8.5 months) were used in this study. All the specimens had no apparent abnormalities. Using the transosseous structure, the RC tendon was detached from the greater tuberosity and randomly assigned to 3-strand, 4-strand, 5-strand, and 6-strand groups, with the glenohumeral abducted at 0° and 90°. Biomechanical tests were conducted to compare the groups' differences in the failure mode, pull-toextension load in the 1-, 2-, and 3-mm formations, and the maximum load. The analysis of variance test was performed to compare the results. Statistical significance was set at P < .05.

resultsNo significant difference was observed among the groups concerning the tendon characteristics (all P ≥ .05). At 90° shoulder abduction, a significant difference was detected in the load between 3- and 5-strand groups for 1-mm gap formation (P=.049). No statistical differences were noted in the load at the gap displacements in the 1-, 2-, and 3-mm formations at 0° and 90° shoulder abduction (all P > .05). The maximum failure load and extension in maximal tension increased with the number of sutures.

conclusionThe maximum load and ultimate extension increase with the number of sutures at both positions. The number of sutures was not an influencing factor of gap formation. Regarding the tear size and tension of the RC, choosing the appropriate number of strands individually instead of excessively increasing the number of sutures is advocated for RC repair.