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Understanding Key Biomechanical Factors that Influence Rotator Cuff Tear Propagation

Ferrer, Gerald Dave A. (2020) Understanding Key Biomechanical Factors that Influence Rotator Cuff Tear Propagation. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The high frequency of rotator cuff tears in an aging population, combined with their capacity to cause pain and limit normal activity, underscores the importance of treating these injuries in a judicious manner. However, high failure rates have been reported for non-operative and surgical treatment. Tear propagation may explain high failure rates of treatment as larger tears are more difficult to treat and are associated with worse clinical outcomes. Abnormal glenohumeral arthrokinematics and localized changes in mechanical properties are factors that explain why some tears propagate more easily than others. Furthermore, clinicians lack a tool to non-invasively quantify tendon mechanical properties. Therefore, the objective of this dissertation is to better understand the role of glenohumeral arthrokinematics and location specific mechanical properties on tear propagation as well as the utility of ultrasound techniques to quantify mechanical properties of tendons through in-vivo, cadaveric, and computational experiments.

Following exercise therapy for 5 subjects with a rotator cuff tear, glenohumeral arthrokinematics for internal/external rotation with the arm at the side did not improve. Abnormal glenohumeral arthrokinematics may be a result of unbalanced force couples, exposing the torn supraspinatus tendon to loads that may promote tendon remodeling that increases the likelihood of tear propagation. Using a subject-specific finite element model of a supraspinatus tendon, tendon remodeling in terms of increased stiffness at the tear tips lead to more tear propagation. Cadaveric experiments showed that quantitative ultrasound measures, which analyze the grayscale echotexture of an ultrasound image, correlates to measures of tendon quality as quantified through histology. Acoustic Radiation Force Impulse (ARFI) imaging a technique where localized radiation forces push onto the tissue, the resulting displacement is measured. The mechanical properties of the tissue can then be inferred. However, our findings suggest that ARFI imaging is limited for high stiffness tissues such as tendons. Despite large differences in tissue modulus, differences in ARFI displacement are minimal. Ultimately, understanding how changes in localized tendon mechanical properties influence tear propagation and the capabilities of currently available ultrasound techniques to measure tendon mechanical properties will enable clinicians to make better treatment decisions for patients with a rotator cuff tear.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Ferrer, Gerald Dave A.gerald.ferrer@pitt.edugaf23
ContributionContributors NameEmailPitt UsernameORCID
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairDebski, Richard E.genesis1@pitt.edugenesis1
Committee MemberAbramowitch, Steven D.sdast9@pitt.edusdast9
Committee MemberKim, Kangkangkim@pitt.edukangkim
Committee MemberMaiti, Spandanspm54@pitt.eduspm54
Committee MemberMusahl, Volkermusahlv@upmc.eduvom2
Date: 2020
Date Type: Submission
Defense Date: 6 March 2020
Approval Date: 30 July 2020
Submission Date: 22 February 2020
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 264
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: No
Uncontrolled Keywords: Shoulder, Rotator Cuff, Finite Element Analysis, Ultrasound, Biplane Fluoroscopy
Date Deposited: 30 Jul 2020 18:00
Last Modified: 30 Jul 2020 18:00

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