Articular Cartilage Evaluation After TruFit Plug Implantation Analyzed by Delayed Gadolinium-Enhanced MRI of Cartilage (dGEMRIC)

Abstract

Background: Quantitative MRI of articular cartilage has rapidly developed in recent years and provides the clinician with a noninvasive tool to determine the biological consequence of an intervention. Purpose: To evaluate the quality of intra-articular cartilage, using the dGEMRIC scanning technique, 1 year after TruFit implantation. The hypothesis was that implantation of a TruFit plug does not lead to damage at the opposing articular cartilage. Study Design: Case series; Level of evidence, 4. Methods: A total of 13 patients (age, 32 ± 8 years) were evaluated with dGEMRIC at 12 ± 4 months after treatment of an osteochondral lesion by implantation of 1 or multiple TruFit plugs. The dGEMRIC scanning protocol was applied 90 minutes after intravenous Magnevist (0.2 mmol/kg body weight) injection. Different regions of interest (ROIs) were defined: the femur cartilage, cartilage directly surrounding the implanted TruFit plug, the TruFit plug, and the articulating and nonarticulating tibia cartilage. The average dGEMRIC index (T1gd; magnetic resonance imaging relaxation time per ROI) was calculated by a pixel-by-pixel curve fitting using the Levenberg-Marquardt method. Differences between the mean T1gd of the individual ROI for all patients were tested using analysis of variance with post hoc Bonferroni correction. A P value <.05 was considered statistically significant. Results: The average T1gd of the TruFit ROI (385 ± 74 ms) was comparable with those in the femur (409 ± 49 ms) and surrounding (392 ± 64 ms) ROIs ( P ≥ .339). The average T1gds for the articulating (578 ± 133 ms) and nonarticulating (516 ± 118 ms) ROIs were higher compared with the femur (409 ± 49 ms), surrounding (392 ± 64 ms), and TruFit (385 ± 74 ms) ROIs ( P < .002), while no difference was observed between the tibia ROIs ( P = .160). Conclusion: Implantation of the TruFit plug in osteochondral lesions does not damage the opposing or surrounding surface, and newly formed tissue inside the plug has cartilage-like dGEMRIC characteristics 12 months after implantation. The implantation of synthetic TruFit plugs is safe for the opposing cartilage, an item that is frequently discussed when using such materials to treat focal cartilage defects.