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Darcy, Shon Patrick (2003) ESTIMATION OF ACL FORCES BY REPRODUCING AVERAGE KNEE KINEMATICS. Master's Thesis, University of Pittsburgh. (Unpublished)

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A non-invasive, non-contact methodology to estimate forces in the anterior cruciate ligament (ACL) in response to in vivo knee kinematics will allow ACL surgical procedures and rehabilitation protocols to be improved. The specific aim of this study is to evaluate the feasibility of a non-invasive, non-contact methodology for estimating force in the ACL by reproducing average differential kinematics in 6-degrees of freedom (DOF) from one set of porcine knees (source) onto a separate set of porcine knees (target). Differential kinematics are motions of the knee in 6-DOF relative to the passive path of flexion-extension 1. Differential kinematics from a set of source cadaveric porcine knees (n = 8) were recorded in response to an anterior load of 100 N and a valgus load of 5 Nm at 30°, 60°, and 90° of knee flexion. The in situ forces in the ACL of the target knees (n = 8) in response to reproducing average differential kinematics was compared to the in situ forces in the ACL of target knees resulting from the application of the same anterior and valgus loads. There was a significant difference in the in situ force in the ACL between applied loads and average differential kinematics for all flexion angles under anterior loading and at 60° of knee flexion for valgus loading. There was not a significant difference in the in situ force in the ACL for valgus loading at 30° or 90° of knee flexion. Under anterior loads, in situ force in the ACL from reproducing average differential kinematics and applied loads differed by up to 227% in two target knee; although, the anterior tibial translations were identical. These results indicate that average differential kinematics from a random sampling of knees does not account for the 6-(DOF) motion of the knee. This is because variations in knee laxity cause coupled motions to be averaged out of the differential kinematics, artificially constraining the knees' motion. In the future, cadaveric knees will be matched to the group of subject kinematics with similar anterior and internal-external knee laxity to improve estimates of the forces in the ACL.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Darcy, Shon Patrickspd2@pitt.eduSPD2
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairDebski, Richard Egenesis1@pitt.eduGENESIS1
Committee MemberFu,
Committee MemberCham, Rakiéracst46@pitt.eduRACST46
Committee MemberWoo, Savio L-Yslyw@pitt.eduSLYW
Date: 3 September 2003
Date Type: Completion
Defense Date: 29 July 2003
Approval Date: 3 September 2003
Submission Date: 16 July 2003
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Bioengineering
Degree: MSBeng - Master of Science in Bioengineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: Anterior Cruciate Ligament; In Situ Force; In Vivo; Reproducing Kinematics; Robotic/UFS Testing System
Other ID:, etd-07162003-072424
Date Deposited: 10 Nov 2011 19:51
Last Modified: 15 Nov 2016 13:46


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