Collagen Augmentation Improves the Quality of Cartilage Repair After Microfracture in Patients Undergoing High Tibial Osteotomy: A Randomized Controlled Trial

Background: The quality of cartilage repair after marrow stimulation is unpredictable. To overcome the shortcomings of the microfracture technique, various augmentation techniques have been developed. However, their efficacies remain unclear. Hypothesis: The quality of cartilage repair and clinical outcomes would be superior in patients undergoing high tibial osteotomy (HTO) with microfracture and collagen augmentation compared to those undergoing HTO with microfracture alone without collagen augmentation for the treatment of medial compartment osteoarthritis (OA) of the knee. Study Design: Randomized controlled trial; Level of evidence, 2. Methods: Twenty-eight patients undergoing HTO were randomized into 2 groups: microfracture alone (group 1, n = 14) or microfracture with collagen augmentation (group 2, n = 14). At 1 year postoperatively, second-look arthroscopic surgery and biopsy of repaired cartilage were performed at the time of HTO plate removal. Biopsy specimens were graded using the International Cartilage Repair Society Visual Assessment Scale II (ICRS II). In addition, imaging outcomes in terms of the magnetic resonance observation of cartilage repair tissue (MOCART) score were assessed based on magnetic resonance imaging (MRI). Finally, clinical outcomes in terms of the visual analog scale (VAS) for pain score, Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) score, and Tegner activity scale score were evaluated. Results: The mean ICRS II score in group 2 was significantly higher than that in group 1 (1053.2 vs 885.4, respectively; P = .002). Group 2 showed greater improvement in tissue morphology, cell morphology, surface architecture, middle/deep zone assessment, and overall assessment compared with group 1 ( P < .050 for all comparisons). Imaging outcomes based on the MOCART score were superior in group 2 compared to those in group 1 on MRI at 1 year postoperatively (64.6 vs 45.4, respectively; P = .001). The degree of defect repair was better in group 2 than in group 1 ( P = .040). Clinical outcomes in terms of the VAS for pain score, KOOS, IKDC score, and Tegner activity scale score were improved in both groups without between-group differences ( P > .100 for all comparisons). Conclusion: The quality of cartilage repair after microfracture with collagen augmentation was superior to that after microfracture alone in patients undergoing HTO. Clinical results after 1 year did not reflect this difference in tissue repair. Therefore, a longer follow-up of the cohort is needed to answer this question.