Effect of acetabular labral tears, repair and resection on hip cartilage strain: A 7T MR study

Greaves, Laura L.; Gilbart, Michael K.; Yung, Andrew C.; Kozlowski, Piotr; Wilson, David R.

doi:10.1016/j.jbiomech.2009.11.016

« Previous Next »Journal of Biomechanics
Volume 43, Issue 5 , Pages 858-863, 22 March 2010

Effect of acetabular labral tears, repair and resection on hip cartilage strain: A 7T MR study

Laura L. Greaves
- Division of Orthopaedic Engineering Research, University of British Columbia and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada
- Corresponding author at: 130 Forbes Boulevard, Mansfield, MA, 02048, USA. Tel: +18575261555; fax: +15082613650.
Michael K. Gilbart
- Department of Orthopaedics, University of British Columbia, Vancouver and Vancouver Coastal Health Research Institute, BC, Canada
Andrew C. Yung
- MRI Research Centre, University of British Columbia, Vancouver, BC, Canada
Piotr Kozlowski
- MRI Research Centre, University of British Columbia, Vancouver, BC, Canada
David R. Wilson
- Division of Orthopaedic Engineering Research, University of British Columbia and Vancouver Coastal Health Research Institute, Vancouver, BC, Canada
- Department of Orthopaedics, University of British Columbia, Vancouver and Vancouver Coastal Health Research Institute, BC, Canada

Accepted 13 November 2009. published online 16 December 2009.

Abstract

Background

Tears of the acetabular labrum are frequently present in patients with groin pain. While it is clear that the labrum contributes to the surface area articulating with the femoral head, it is not clear whether labral repair yields different load distribution in the hip compared to labral resection.

Purpose

Determine whether labral repair reduces cartilage strain more effectively than labral resection.

Methods

Six human cadaveric hips (mean age 37 years) were loaded in a simulated single-leg stance within the bore of a 7T MR scanner. After cartilage had reached a steady-state thickness distribution, a scan of the cartilage was acquired with a voxel size of 0.1×0.1×0.3mm. This method was repeated for each of six specimens when the labrum was intact, after a surgically simulated labral tear, after an arthroscopic labral repair and after labral resection. Cartilage thickness and strain in an anterosuperior region of interest were measured from the MR scans. A paired t-test was used to compare mean and maximum cartilage strain when the labrum was intact vs. torn, torn vs. repaired and repaired vs. resected. Three-dimensional patterns of cartilage strain distribution were qualitatively compared for the different labral conditions.

Results

For the number of specimens tested we found no change in mean and maximum cartilage strain, and little obvious change in the pattern of cartilage strain distribution after a simulated labral tear. Labral repair caused a 2% decrease in mean cartilage strain compared to a torn labrum (p=0.014). Labral resection caused a 4% and 6% increase in mean and maximum cartilage strain, respectively, compared to labral repair (p=0.02), and the cartilage strain distribution was elevated throughout the region of interest.

Conclusion

Based on our ex vivo findings of increased cartilage strain after labral resection when compared to labral repair, we have demonstrated the associated consequences to the mechanical environment of the cartilage following surgical treatment of the labrum.

Keywords: Labrum, Cartilage, Biomechanics, Hip, Osteoarthritis, MRI, Acetabular labrum, Labral tear, Cartilage strain