2015 ISAKOS Biennial Congress ePoster #1506

Quantitative 3D MRI Reveals Only Limited Intra-Lesional Bony Overgrowth at One Year After Microfracture-Based Cartilage Repair

Matthew Shive, PhD, Toronto, ON CANADA
William David Stanish, MD, FRCS, FACS, AOA, Halifax, NS CANADA
Jose Tamez-Pena, PhD, Monterrey MEXICO
Saara Totterman, MD, Rochester, NY UNITED STATES
Edward Schreyer, BSc, Rochester, NY UNITED STATES
Alberto Restrepo, MD, Montreal, QC CANADA

Piramal Healthcare, Laval, Quebec, CANADA

FDA Status Not Applicable

Summary: For the first time we have demonstrated with sophisticated imaging methods coupled with 3D visualization that BO occurs to only a limited quantitative extent following microfracture-based therapies and comprises either spotty or planar bone. The incidence of BO is partly explained by pre-existing conditions, and a correlation between BO and clinical outcomes at 12 months was not identified.




The clinical evidence for intra-lesional bony overgrowth (BO) following cartilage repair is largely subjective and not well understood. Generally, BO has been related with bone marrow stimulation and microfracture in particular, with reported anecdotal incidence rates ranging widely from 25-70% (Cole, 2011; Kreuz, 2006; Mithoefer, 2005). Clearly, the lack of cartilage repair studies addressing intra-lesional BO directly compounded by a shortage of analytical methods has slowed the understanding of its etiology and natural history. Here, the extent of intra-lesional BO following microfracture-based repair at 12 months was evaluated using sophisticated imaging methods coupled with 3D visualization and represents the first systematic assessment of intra-lesional BO in the context of a randomized clinical trial (RCT).

A multicenter cartilage repair RCT comparing BST-CarGel treatment (Piramal Healthcare (Canada) Ltd.) to microfracture alone enrolled 80 patients with focal lesions on the femoral condyles.(Stanish, 2013) Standardized MRI scans were obtained from each patient at 1 and 12 months post-treatment using 3D fat-suppressed SPGR and 3D-GRE and fat-suppressed Dual Echo Spin Echo sequences. Three-dimensional quantitative and qualitative analyses of BO were performed on repaired lesions using semi-automated morphological segmentation and precise co-registration of 1-month debrided lesion boundaries with 12-month images. The extent of BO was calculated as a ratio of intra-lesional bone volume to the entire original debrided lesion volume. Illustrations of BO were generated using 3D reconstructions of index knees as references.


Limited BO representing only 5.8± 5.7% (range: 0.0-25.5%) of the original debrided lesion volume in lesions was found in 78 patients. The majority (80%) of patients had very little BO (<10%). Qualitative examination of 3D reconstructions revealed that most occurrences of BO carried either spotty (56.4%) or planar (6.4%) morphological features, and the remaining balance (37.2%) was qualitatively unobservable by eye. Pre-existing BO recurred at 12 months in the same intra-lesional location in 36% of patients. No statistical correlations were found between BO and clinical outcomes.


This study systematically quantified and characterized intra-lesional BO in 78 patients who received microfracture-based treatments. No evidence was found to support the incidence of BO currently suggested in the literature, the magnitude of which may be overestimated, hampered by subjective 2D MRI and lack of scoring methodologies. Furthermore, the implication of BO in relation to clinical outcomes is still unknown.