MR imaging of BioCartilage augmented microfracture surgery utilizing 2D MOCART and KOOS scores.

objectivesBioCartilage is a novel scaffold-based microfracture augmentation technique that has been shown to aid in chondrogenic differentiation of adult progenitor cells resulting in formation of more hyaline-like cartilage. As this cartilage repair technique becomes more commonplace, it is essential that the musculoskeletal radiologist and orthopedic surgeon gain familiarity with the surgical technique and its post-operative MR imaging findings.

methodsWe present several case studies regarding MRI findings (modified clinical 2D MOCART) and clinical outcome (KOOS) scores in patients who have undergone this novel surgical procedure. For data analysis KOOS scores where dichotomized to scores greater or less than 80, and MOCART scores were dichotomized to scores greater or less than 50. A fisher exact test was then performed to determine if there was any correlation between parameters of the modified 2D MOCART and KOOS scores (Tables 2 and 3).

resultsMarrow elements travel through the microfracture holes and interact with the scaffold created by BioCartilage, rather than creating their own fibrin scaffold, as is typically anticipated from a marrow stimulation procedure. Interestingly, the amount defect fill, presence of an intact surface, intact subchondral bone, or lack of effusion did not correlate with positive outcomes. Parameters that trended towards significance included presence of adhesions and subchondral lamina. Completeness of cartilage interface, homogeneity, and signal intensity also failed to reach statistical significance. In our experience, patients that demonstrated mild repair tissue surface irregularity, but with preservation of greater than 50% thickness compared to surrounding native cartilage, mild irregularity of subchondral plate, with vertical low signal intensity lines (sequela of prior microfracture surgery), and mild or no bone marrow edema pattern demonstrated higher KOOS scores.

conclusionBiocartilage in conjunction with microfracture is an encouraging cartilage restoration technique that promotes regeneration of more robust hyaline-like cartilage compared to the fibrocartilage formed after conventional microfracture. The T2 mapping properties of the repair tissue after successful BioCartilage augmented microfracture surgery are very similar to that of the adjacent native cartilage. Although there appear to be characteristic trends in a successful repair, further research is warranted to elucidate any correlations between specific characteristics of the repair and patient clinical outcomes.