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Scientific Articles   |    
Dynamic Contact Mechanics of the Medial Meniscus as a Function of Radial Tear, Repair, and Partial Meniscectomy
Asheesh Bedi, MD1; Natalie H. Kelly, BS1; Michael Baad, BS1; Alice J.S. Fox, MS1; Robert H. Brophy, MD2; Russell F. Warren, MD1; Suzanne A. Maher, PhD1
1 Sports Medicine and Shoulder Service (A.B. and R.F.W.) and Department of Biomechanics (N.H.K., M.B., A.J.S.F., and S.A.M.), The Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021. E-mail address for S.A. Maher: mahers@hss.edu
2 Department of Orthopaedic Surgery, Washington University School of Medicine, 14532 South Outer Forty Drive, Chesterfield, MO 63017
View Disclosures and Other Information
Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from the Widgeon Point Foundation, the Leo Rosner Foundation, and the Russell F. Warren Chair. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

Investigation performed at The Hospital for Special Surgery, New York, NY

Copyright ©2010 American Society for Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2010 Jun 01;92(6):1398-1408. doi: 10.2106/JBJS.I.00539
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Abstract

Background: 

The menisci are integral to normal knee function. The purpose of this study was to measure the contact pressures transmitted to the medial tibial plateau under physiological loads as a function of the percentage of the meniscus involved by the radial tear or repair. Our hypotheses were that (1) there is a threshold size of radial tears above which contact mechanics are adversely affected, and (2) partial meniscectomy results in increased contact pressure compared with that found after meniscal repair.

Methods: 

A knee simulator was used to apply physiological multidirectional dynamic gait loads across human cadaver knees. A sensor inserted below the medial meniscus recorded contact pressures in association with (1) an intact meniscus, (2) a radial tear involving 30% of the meniscal rim width, (3) a radial tear involving 60% of the width, (4) a radial tear involving 90% of the width, (5) an inside-out repair with horizontal mattress sutures, and (6) a partial meniscectomy. The effects of these different types of meniscal manipulation on the magnitude and location of the peak contact pressure were assessed at 14% and 45% of the gait cycle.

Results: 

The peak tibial contact pressure in the intact knees was 6 ± 0.5 MPa and 7.4 ± 0.6 MPa at 14% and 45% of the gait cycle, respectively. The magnitude and location of the peak contact pressure were not affected by radial tears involving up to 60% of the meniscal rim width. Radial tears involving 90% resulted in a posterocentral shift in peak-pressure location manifested by an increase in pressure in that quadrant of 1.3 ± 0.5 MPa at 14% of the gait cycle relative to the intact condition. Inside-out mattress suture repair of a 90% tear did not restore the location of the pressure peak to that of the intact knee. Partial meniscectomy led to a further increase in contact pressure in the posterocentral quadrant of 1.4 ± 0.7 MPa at 14% of the gait cycle.

Conclusions: 

Large radial tears of the medial meniscus are not functionally equivalent to meniscectomies; the residual meniscus continues to provide some load transmission and distribution functions across the joint.

Clinical Relevance: 

The results of this study support meniscal preservation and repair of medial radial tears.

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    References

    Accreditation Statement
    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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