Native Enthesis Preservation Versus Removal in Rotator Cuff Repair in a Rabbit Model

The purpose of this study was to explore whether preservation of native enthesis during rotator cuff repair (RCR) results in a histologically and biomechanically better rotator cuff-greater tuberosity (RC-GT) connection in an animal model.Thirty-six New Zealand white rabbits were used in this study. The supraspinatus tendons were cut from the footprint to create a rotator cuff tear (RCT) on both shoulders, followed by immediate repair, with a 1 mm thick tendon stump remaining on the footprint. On one side, RCR was performed by attaching the medial rotator cuff to the GT over the footprint stump layer (enthesis preservation [EP] approach). On the other side, the footprint stump and enthesis were fully removed and the footprint was decorticated. The repair was performed by attaching the medial rotator cuff onto the spongy bone surface in the footprint area (enthesis removal [ER] approach). Twelve rabbits were sacrificed at 4, 8, and 12 weeks, of which 6 were used for histological analysis and 6 for biomechanical evaluation.Histological examination revealed that in the EP group, the native enthesis healed well with the reattached cuff tendon, and continuous collagen crossed the tendon-tendon interface area at 12 weeks. However, in the ER group, there was only fibrous scar tissue formation at the tendon-bone interface. Biomechanical testing revealed a significantly higher load to failure (P = .001) of the RC-GT structure in the EP group than that in the ER group at 12 weeks.For acute RCT with remnant enthesis, EP-RCR incorporates the native enthesis functionally in the restored RC-GT connection and enhances the RC-GT connection when compared with ER-RCR at 12 weeks in a rabbit model.This finding justifies a human trial because in RCR with a remnant footprint, the EP technique may be adopted for a better RC-GT connection.