Comparison of Biological Augmentation in Rotator Cuff Repair Using Inflamed Versus Noninflamed Bursal Tissue in Rats.

Abstract

To examine how augmentation of a rotator cuff repair with inflamed versus noninflamed bursal tissue affects tendon-to-bone healing in a rat model of rotator cuff repair. A total of 136 Sprague-Dawley rats were randomly assigned to an inflamed or noninflamed bursal tissue application group. After detachment, the supraspinatus tendon was reattached with bursal tissue sewn onto the tendon-to-bone interface. The specimens were analyzed biomechanically 6 and at 7 weeks and immunohistologically at 1 and at 7 weeks after surgery. Immunohistological results showed no significant difference in the percentage of collagen type II in the tendon-to-bone interface at 1 (P = .87) and 7 weeks (P = .42) when using autologous noninflamed bursal tissue in comparison with inflamed bursal tissue specimens. The inflamed bursa group also showed no significant difference in collagen I to III quotient (P = .14) after surgery in comparison with noninflamed bursa groups after surgery. Biomechanical assessment showed that tendon stiffness (P = .87 inflamed versus noninflammed (resp.) P = .1) and the tendon viscoelasticity (P = .12 resp. P = .07) was the same after 6 and 7 weeks when we compared the inflamed bursa with the noninflamed bursa group. There was no significant difference (P = .8 resp. P = .87) in load to failure between in both inflamed and noninflamed bursa groups after 6 and 7 weeks. Autologous inflamed bursal tissue derived from the Achilles bursa and implanted to the tendon-to-bone interface after rotator cuff repair facilitates the same histologic and biomechanical healing response as using a noninflamed bursa interposition in rats. During augmentation of a rotator cuff repair, it is irrelevant whether the bursa tissue is inflamed.