HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:
Sign In to gain access to subscriptions and/or personal tools.

This Article Full Text Full Text (PDF) All Versions of this Article: 32/6/1451    most recent 0363546504263234v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Request Reprints Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Guettler, J. H. Articles by Jurist, K. A. Search for Related Content PubMed PubMed Citation Articles by Guettler, J. H. Articles by Jurist, K. A.

Osteochondral Defects in the Human Knee

Influence of Defect Size on Cartilage Rim Stress and Load Redistribution to Surrounding Cartilage

Joseph H. Guettler, MD^*, Constantine K. Demetropoulos, PhD^,*,, King H. Yang, PhD and Kenneth A. Jurist, MD^*

From the ^* Department of Orthopaedic Surgery, William Beaumont Hospital, Royal Oak, Michigan, and the Department of Biomedical Engineering, Wayne State University, Detroit, Michigan

Address correspondence to Constantine K. Demetropoulos, PhD, Harold W. Gehring, M.D. Center for Biomechanics and Implant Analysis, William Beaumont Hospital Research Institute, 3601 W. Thirteen Mile Road, Suite 402, Royal Oak, MI 48073-6769 (e-mail: cdemetropoulos{at}beaumont.edu).

Purpose: To determine the influence of osteochondral defect size on defect rim stress concentration, peak rim stress, and load redistribution to adjacent cartilage over the weightbearing area of the medial and lateral femoral condyles in the human knee.

Methods: Eight fresh-frozen cadaveric knees were mounted at 30° of flexion in a materials testing machine. Digital electronic pressure sensors were placed in the medial and lateral compartments of the knee. Each intact knee was first loaded to 700 N and held for 5 seconds. Dynamic pressure readings were recorded throughout the loading and holding phases. Loading was repeated over circular osteochondral defects (5, 8, 10, 12, 14, 16, 18, and 20 mm) in the 30° weightbearing area of the medial and lateral femoral condyles.

Results: Stress concentration around the rims of defects 8 mm and smaller was not demonstrated, and pressure distribution in this size range was dominated by the menisci. For defects 10 mm and greater, distribution of peak pressures followed the rim of the defect with a mean distance from the rim of 2.2 mm on the medial condyle and 3.2 mm on the lateral condyle. An analysis of variance with Bonferroni correction revealed a statistically significant trend of increasing radius of peak pressure as defect size increased for defects from 10 to 20 mm (P = .0011). Peak rim pressure values did not increase significantly as defects were enlarged from 10 to 20 mm. Load redistribution during the holding phase was also observed.

Conclusions: Rim stress concentration was demonstrated for osteochondral defects 10 mm and greater in size. This altered load distribution has important implications relating to the long-term integrity of cartilage adjacent to osteochondral defects in the human knee. Although the decision to treat osteochondral lesions is certainly multifactorial, a size threshold of 10 mm, based on biomechanical data, may be a useful adjunct to guide clinical decision making.

Key Words: knee • osteochondral defect • contact pressures • cartilage healing • cartilage repair

This article has been cited by other articles:

				C. Mina, W. E. Garrett Jr, R. Pietrobon, R. Glisson, and L. Higgins High Tibial Osteotomy for Unloading Osteochondral Defects in the Medial Compartment of the Knee Am. J. Sports Med., May 1, 2008; 36(5): 949 - 955. [Abstract] [Full Text] [PDF]