A Biomechanical Model for Augmented Human Rotator Cuff Repairs

Rotator cuff tears affect 40% or more of those over age 60 and are a common cause of pain and disability. Surgical repairs have high failure rates that range from 20 to 90%. Hence, natural and synthetic scaffolds are being developed to mechanically augment tendon repairs and to biologically enhance the intrinsic healing potential of the patient. When used as an augmentation device, scaffolds are believed to provide some degree of load sharing in a manner that decreases the likelihood of tendon re-tear. While significant advances are being made in the development of scaffolds, no studies have investigated the degree of load sharing provided by a scaffold used for rotator cuff repair augmentation. Furthermore, the manner in which loads on an augmented rotator cuff repair are distributed amongst the various components of the repair is not known, nor is the relative biomechanical importance of the various components of the repair. To answer these questions, the objectives of this study are to (1) develop quasi-static analytical models of simplified rotator cuff repairs, (2) validate the models by comparing the predicted model force to experimental measurements of force for human rotator cuff repairs, and (3) use the models to predict the degree of load sharing provided by a scaffold used for rotator cuff repair augmentation.