Miller, Robert M.
(2016)
Biomechanical Factors Influencing the Successful Non-Operative Treatment of Rotator Cuff Tears.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
The risk of developing a degenerative rotator cuff tear increases dramatically with age, reaching over 50% in the 7th decade of life. The severe pain and loss of function brought on by rotator cuff tears underscores the importance of swift and effective treatment. Unfortunately, failure rates for treating rotator cuff tears remain high. Unsuccessful treatment may relate to failure to restore joint kinematics or propagation of the rotator cuff tear. Furthermore, it is not clear which types of tears (i.e. geometry and amount of degeneration) will result in propagation. Therefore, the objective of this work was to investigate the effects of exercise therapy and initial tear characteristics on alteration of glenohumeral kinematics and tear propagation. Glenohumeral joint kinematics were measured in subjects with an isolated supraspinatus tear before and after 12 weeks of therapy. Although exercise therapy does not increase sub-acromial space, therapy decreases the overall joint contact path length by 36%, indicating a more stable joint. Cadaveric experiments measured tear propagation for increasing levels of loading using a novel cyclic loading protocol. Anterior supraspinatus tears propagate at lower loads than tears in the middle third (389 ± 237 N vs 714 ± 168 N). Mechanical testing also showed that tendons with pre-existing rotator cuff tears are not more likely to propagate than artificial tears representative of a “traumatic” rotator cuff tear (408 ± 86 N vs 580 ± 181). Histological analysis on cadavers (age 50-80) found no differences in degeneration between intact and torn supraspinatus tendons, indicating that age-related degeneration is a wide-spread phenomenon that can lead to the initiation of rotator cuff tears. Using experimental data, finite element models of supraspinatus tendon were validated and used to predict effects of tear size, location, and degeneration on propagation. Overall, the model found that larger, more degenerative tears in the anterior third of the supraspinatus tendon are most at risk for propagation. These results provide valuable information to improve treatment of rotator cuff tears based on tear characteristics at diagnosis, by focusing on improving joint kinematics and advocating for early treatment of degenerative tears that interrupt the rotator cable structure.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
16 September 2016 |
| Date Type: |
Publication |
| Defense Date: |
23 June 2016 |
| Approval Date: |
16 September 2016 |
| Submission Date: |
13 June 2016 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
275 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Bioengineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Rotator cuff, kinematics, tear propagation, finite element modeling |
| Date Deposited: |
16 Sep 2016 16:14 |
| Last Modified: |
15 Nov 2016 14:33 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/28190 |
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