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Effect of Rotator Cable Tear Size and Location in Humeral Abduction

Blake, Ryan Jeffrey (2021) Effect of Rotator Cable Tear Size and Location in Humeral Abduction. Master's Thesis, University of Pittsburgh. (Unpublished)

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The rotator cable is described as being a mechanical structure responsible for force transmission from the rotator cuff muscles to the rotator cuff’s humeral insertions. The structure is also said to be responsible for shielding the tissue lateral to it, the crescent area. Preliminary studies at our laboratory have shown contradicting results. A biomechanical, cadaveric study was implemented to determine the mechanical importance of the rotator cable by means of differing tear sizes and locations. It was hypothesized that the entire complex is essential for shoulder function based on abduction strength.
Physiological loading was applied to ten cadaveric specimens using a custom shoulder simulator to simulate abduction in the scapular plane. The specimens were tested under two cutting sequences by sectioning the lateral crescent area into quarters and releasing the quartered sections of tissue in either an anterior-to-posterior or posterior-to-anterior-direction. Both groups then underwent subsequent releases of the insertions of the rotator cable. Abduction strength and rotation torque at the distal humerus were recorded and compared to the native condition.
Abduction strength significantly decreased for the specimens that underwent an initial anterior quarter crescent area release in the anterior-to-posterior direction when three quarters of the crescent area were affected. Continuation of the tear into the posterior and anterior rotator cable insertions also resulted in a significant drop in strength. The initial posterior quarter crescent area release did not show a significance in abduction force loss, but the final release of the entire crescent area and both rotator cable insertions approached significance. The internal rotation torque increased for the anterior group and remained stable for the posterior group. None of the changes were significant.
The results indicate that significant decreases in strength occurred when tears were isolated within the crescent area. If the rotator cable were to transmit load around the crescent area, shoulder function would not be expected to change with an intact cable. Therefore, it can be concluded that the rotator cable is not a specialized mechanical structure solely responsible for force transmission, and the entire complex is needed to support shoulder function.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Blake, Ryan Jeffreyrjb114@pitt.edurjb114
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairSmolinski, Patrickpatsmol@pitt.edupatsmol
Thesis AdvisorSmolinski, Patrickpatsmol@pitt.edupatsmol
Committee MemberMiller, Markmcmllr@pitt.edumcmllr
Committee MemberWang, Qing-Mingqiw4@pitt.eduqiw4
Date: 13 June 2021
Date Type: Publication
Defense Date: 18 March 2021
Approval Date: 13 June 2021
Submission Date: 6 April 2021
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Number of Pages: 58
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Mechanical Engineering
Degree: MS - Master of Science
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: rotator cable, rotator crescent, abduction strength, tear propagation, biomechanics
Date Deposited: 13 Jun 2021 18:49
Last Modified: 13 Jun 2021 18:49


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