Does demineralized bone matrix enhance tendon-to-bone healing after rotator cuff repair in a rabbit model?

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Background The purpose of this study was to compare the histologic outcomes after rotator cuff (RC) repair between with demineralized bone matrix (DBM) augmentation and without DBM and to evaluate the role of DBM for tendon-to-bone (TB) healing in a rabbit model. Methods Twenty-six adult male New Zealand white rabbits were randomly allocated to the control group (n = 13) or the DBM group (n = 13). A chronic RC tear was generated on the right shoulder of all rabbits. In the control group, RC repair was achieved by a standard transosseous technique. In the DBM group, RC repair was achieved using the same technique, and DBM was interposed between the cuff and bone. After 8 weeks, the RC tendon entheses from all rabbits were processed for gross and histologic examination. Results In the control group, the tendon midsubstance was disorganized with randomly and loosely arranged collagen fibers and rounded fibroblastic nuclei. The TB interface was predominantly fibrous with small regions of fibrocartilage, especially mineralized fibrocartilage. In the DBM group, the tendon midsubstance appeared normal and comprised densely arranged collagen fibers, with orientated crimped collagen fibers running in the longitudinal direction of the tendon. These fibers were interspersed with elongated fibroblast nuclei. The TB interface consisted of organized collagen fibers with large quantities of fibrocartilage and mineralized fibrocartilage. Conclusion DBM augmentation at the RC-to-bone interface enhances TB healing after RC repair.