Background: Despite advances in surgical treatment options, failure rates of rotator cuff repair have continued to range from 20% to 90%. Hence, there is a need for new repair strategies that provide effective mechanical reinforcement of rotator cuff repair as well as stimulate and enhance the intrinsic healing potential of the patient. The purpose of this study was to evaluate the extent to which augmentation of acute repair of rotator cuff tendons with a newly designed poly-L-lactide repair device would improve functional and biomechanical outcomes in a canine model.
Methods: Eight adult, male mongrel dogs (25 to 30 kg) underwent bilateral shoulder surgery. One shoulder underwent tendon release and repair only, and the other was subjected to release and repair followed by augmentation with the repair device. At twelve weeks, tendon retraction, cross-sectional area, stiffness, and ultimate load of the repair site were measured. Augmented repairs underwent histologic assessment of biocompatibility. In addition, eight pairs of canine cadaver shoulders underwent infraspinatus injury and repair with and without device augmentation with use of identical surgical procedures and served as time-zero biomechanical controls. Eight unpaired, canine cadaver shoulders were included as normal biomechanical controls.
Results: At time zero, repair augmentation significantly increased the ultimate load (23%) (p = 0.034) but not the stiffness of the canine infraspinatus tendon repair. At twelve weeks, the poly-L-lactide scaffold was observed to be histologically biocompatible, and augmented repairs demonstrated significantly less tendon retraction (p = 0.008) and significantly greater cross-sectional area (137%), stiffness (26%), and ultimate load (35%) than did repairs that had not been augmented (p < 0.001, p = 0.002, and p = 0.009, respectively).
Conclusions: While limiting but not eliminating tendon repair retraction, the augmentation device provided a tendon-bone bridge and scaffold for host tissue deposition and ingrowth, resulting in improved biomechanical function of the repair at twelve weeks.
Clinical Relevance: The augmentation device, applied in a similar manner as described in the present study, might offer a functional benefit to patients undergoing rotator cuff repair.
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from the National Institutes of Health (T32 AR 050959-01, P30 AR-050953, and R44 AR051260). One or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits of less than $10,000 or a commitment or agreement to provide such benefits from commercial entities (Wyeth and United HealthCare), and one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from commercial entities (DePuy and Tornier). Also, a commercial entity (Synthasome, Inc.) paid or directed in any one year, or agreed to pay or direct, benefits in excess of $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which one or more of the authors, or a member of his or her immediate family, is affiliated or associated.
Investigation performed at the Departments of Orthopaedic Surgery and Biomedical Engineering, Cleveland Clinic, Cleveland, Ohio
- Copyright © 2009 by The Journal of Bone and Joint Surgery, Incorporated
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