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The High Variability in Sizing Knee Cartilage Defects
Robert A. Siston, PhD1; David Geier, BS1; Julie Y. Bishop, MD1; Grant L. Jones, MD1; Christopher C. Kaeding, MD1; Jeffery F. Granger, MD1; Tyler Skaife, MD1; Megan May, MD1; David C. Flanigan, MD1
1 Departments of Mechanical and Aerospace Engineering (R.A.S.) and Orthopaedics (R.A.S., D.G., J.Y.B., G.L.J., C.C.K., J.F.G., T.S., M.M., and D.C.F.), The Ohio State University, E305 Scott Laboratory, 201 West 19th Avenue, Columbus, OH 43210. E-mail address for R.A. Siston: siston.1@osu.edu
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Investigation performed at the Departments of Mechanical and Aerospace Engineering and Orthopaedics, The Ohio State University, Columbus, Ohio

Disclosure: One or more of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of an aspect of this work. In addition, one or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.

Copyright © 2013 by The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2013 Jan 02;95(1):70-75. doi: 10.2106/JBJS.K.01406
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Articular cartilage defects of the knee are commonly encountered during arthroscopic examination and are believed to be a precursor to osteoarthritis. While a variety of surgical treatments exist, the defect size, specifically the cross-sectional area, has historically been used as a critical element in choosing one procedure over another. The purpose of this study was to characterize the variability associated with arthroscopic techniques that are used to determine the cross-sectional area of distal femoral articular cartilage defects.


Six orthopaedic surgeons used four measurement techniques to estimate the area of cartilage defects in ten cadaveric knees. The areas of the defects determined by the surgeons were compared against the known areas of the defects that were determined from plastic molds.


Averaged across all approaches, the four measurement techniques yielded highly variable results that underestimated the size of the defects (mean and standard deviation, −0.31 ± 1.22 cm2). There was no difference in the estimated sizes of the defects on the medial or lateral femoral condyles (p = 0.96), but defects on the trochlea (mean, −0.53 ± 1.00 cm2) were less accurately sized than defects on either of the condyles (p < 0.01). The areas of defects that were <2 cm2 were overestimated (mean, 0.21 ± 0.65 cm2) compared with other sizes of defects (p < 0.001), and the areas of defects that were >4 cm2 were underestimated (mean, −0.87 ± 1.83 cm2) compared with other defects (p < 0.001).

Conclusions and Clinical Relevance: 

Our current treatment algorithms rely heavily on the size of a cartilage defect, but only 57% of the measurements in this study would have accurately led to the appropriate surgical procedure. There is a need to evaluate and quantify the size of a lesion more appropriately than current standards allow and potentially revise existing treatment algorithms.

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    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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