COMPARATIVE STUDY
JOURNAL ARTICLE
RESEARCH SUPPORT, NON-U.S. GOV'T
RESEARCH SUPPORT, U.S. GOV'T, NON-P.H.S.
Add like
Add dislike
Add to saved papers

The biomechanical effects of dynamic external rotation on rotator cuff repair compared to testing with the humerus fixed.

BACKGROUND: Biomechanical testing without humeral motion is a standard method for evaluating rotator cuff repair constructs. This cannot elucidate the effects of dynamic external rotation on the repair, which is a common postoperative motion.

HYPOTHESIS: Biomechanical properties and gap formation of rotator cuff repairs will be different when dynamic external rotation is allowed to occur during loading.

STUDY DESIGN: Controlled laboratory study.

METHODS: In 6 matched pairs of human cadaveric shoulders, a commonly used single-row rotator cuff repair was performed. In 6 shoulders, a materials testing machine and a custom testing apparatus that permits cyclic rotation (0 degrees -30 degrees ) were employed (group 1). In contralateral shoulders, the apparatus was fixed to prevent humeral rotation (group 2). All repairs were cyclically loaded from 0 to 60 N at a displacement rate of 1 mm/s for 30 cycles. The constructs were then loaded to failure. Repair strength, gap formation, and strain were compared between groups.

RESULTS: Cyclic loading revealed no difference in linear stiffness between testing conditions. Hysteresis was significantly greater when dynamic external rotation was allowed to occur. With load to failure, there were no differences in yield or ultimate load. Anterior tendon gap formation was greater at end rotation (30 degrees of humeral external rotation) and at yield load, and strain on the posterior tendon was less with dynamic external rotation. With dynamic external rotation, gap formation and tendon strain were significantly greater in the anterior region of the supraspinatus tendon compared with the posterior region.

DISCUSSION: External rotation using postoperative physiologic loads affects gap formation and tendon strain between anterior and posterior supraspinatus tendon regions. Previous testing models without humeral rotation may underestimate gap formation and anterior tendon strain and overestimate posterior tendon strain.

CLINICAL RELEVANCE: Understanding regional differences with respect to these variables, depending on quality of repair, may provide the surgeon a framework from which to prescribe guidelines for postoperative rehabilitation.

Full text links

We have located links that may give you full text access.
Can't access the paper?
Try logging in through your university/institutional subscription. For a smoother one-click institutional access experience, please use our mobile app.

For the best experience, use the Read mobile app

Mobile app image

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app

All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

By using this service, you agree to our terms of use and privacy policy.

Your Privacy Choices Toggle icon

You can now claim free CME credits for this literature searchClaim now

Get seemless 1-tap access through your institution/university

For the best experience, use the Read mobile app