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Potential of a Bioscaffold to Enhance the Healing of the MCL Following a Mop-End Tear: An Animal Model Study

Papas, Noah Peter (2007) Potential of a Bioscaffold to Enhance the Healing of the MCL Following a Mop-End Tear: An Animal Model Study. Master's Thesis, University of Pittsburgh.

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    Abstract

    Isolated medial collateral ligament (MCL) injuries occur frequently (95,000 per year in the US) and heal with conservative treatment. Long-term clinical outcome is generally excellent because the structural properties of the Femur-MCL-Tibia complex (FMTC) naturally return to normal especially the stiffness. However, the quality of the healing ligament, as described by its histomorphological appearance, as well as biochemical, mechanical, and viscoelastic properties, remain poor [37, 70, 108, 109, 116]. Functional tissue engineering techniques such as the use of extracellular matrix (ECM) bioscaffolds have shown promise in improving healing of soft tissues after injury. In particular, small intestine submucosa (SIS) is especially attractive due to its chemoattractant properties, organized fiber alignment, and natural concentration of growth factors [9, 13, 48]. The objective of this thesis is to use SIS to improve MCL healing in a clinically relevant injury model. Sixteen New Zealand white rabbits were subjected to a mop-end tear (Weiss et al. 1991) in order to simulate a clinically relevant injury, which included damage to the ligament insertion sites, over-stretching of collagen fibers, and a frayed appearance of the torn ligament ends. After 12 weeks of healing, seven rabbits per group were euthanized and subjected to a well-established biomechanical testing protocol [111], including a load to failure test. The remaining rabbits (n=2 per group) were evaluated histologically. It was found that SIS treatment resulted in a marked improvement for the tangent modulus of the healing MCL midsubstance over non-treatment (404 ±120 MPa vs. 273 ± 91 MPa, respectively, p<0.05). However, this difference did not translate into a change in the measured structural properties of the FMTC. Nearly half of the specimens in each treatment group failed at the tibial insertion, this indicates asynchronous healing between the ligament insertion and midsubstance. In conclusion, these results confirm SIS enhances the quality of the healing MCL. SIS positively effects the local healing response of an MCL regardless of injury model. This work provides a basis to explore the effect of applying SIS to ligaments which do not heal well naturally, such as the anterior cruciate ligament.


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    Item Type: University of Pittsburgh ETD
    Creators/Authors:
    CreatorsEmailORCID
    Papas, Noah Peternpapas@vt.edu
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairWoo, Savio L-Y.sly@pitt.edu
    Committee MemberBadylak, Stevenbadylaks@upmc.edu
    Committee MemberAbramowitch, Steven D.sabram@engr.pitt.edu
    Title: Potential of a Bioscaffold to Enhance the Healing of the MCL Following a Mop-End Tear: An Animal Model Study
    Status: Unpublished
    Abstract: Isolated medial collateral ligament (MCL) injuries occur frequently (95,000 per year in the US) and heal with conservative treatment. Long-term clinical outcome is generally excellent because the structural properties of the Femur-MCL-Tibia complex (FMTC) naturally return to normal especially the stiffness. However, the quality of the healing ligament, as described by its histomorphological appearance, as well as biochemical, mechanical, and viscoelastic properties, remain poor [37, 70, 108, 109, 116]. Functional tissue engineering techniques such as the use of extracellular matrix (ECM) bioscaffolds have shown promise in improving healing of soft tissues after injury. In particular, small intestine submucosa (SIS) is especially attractive due to its chemoattractant properties, organized fiber alignment, and natural concentration of growth factors [9, 13, 48]. The objective of this thesis is to use SIS to improve MCL healing in a clinically relevant injury model. Sixteen New Zealand white rabbits were subjected to a mop-end tear (Weiss et al. 1991) in order to simulate a clinically relevant injury, which included damage to the ligament insertion sites, over-stretching of collagen fibers, and a frayed appearance of the torn ligament ends. After 12 weeks of healing, seven rabbits per group were euthanized and subjected to a well-established biomechanical testing protocol [111], including a load to failure test. The remaining rabbits (n=2 per group) were evaluated histologically. It was found that SIS treatment resulted in a marked improvement for the tangent modulus of the healing MCL midsubstance over non-treatment (404 ±120 MPa vs. 273 ± 91 MPa, respectively, p<0.05). However, this difference did not translate into a change in the measured structural properties of the FMTC. Nearly half of the specimens in each treatment group failed at the tibial insertion, this indicates asynchronous healing between the ligament insertion and midsubstance. In conclusion, these results confirm SIS enhances the quality of the healing MCL. SIS positively effects the local healing response of an MCL regardless of injury model. This work provides a basis to explore the effect of applying SIS to ligaments which do not heal well naturally, such as the anterior cruciate ligament.
    Date: 25 September 2007
    Date Type: Completion
    Defense Date: 03 May 2007
    Approval Date: 25 September 2007
    Submission Date: 18 June 2007
    Access Restriction: No restriction; The work is available for access worldwide immediately.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Master's Thesis
    Refereed: Yes
    Degree: MSBeng - Master of Science in Bioengineering
    URN: etd-06182007-144935
    Uncontrolled Keywords: functional tissue engineering; ligament; ligament biomechanics; ligament healing; MCL; medial collateral ligament; QLV; quasilinear viscoelasticity; SIS; small intestine submucosa; tensile testing; tissue mechanics
    Schools and Programs: Swanson School of Engineering > Bioengineering
    Date Deposited: 10 Nov 2011 14:48
    Last Modified: 19 Jun 2012 10:50
    Other ID: http://etd.library.pitt.edu/ETD/available/etd-06182007-144935/, etd-06182007-144935

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