Injectable Cultured Bone Marrow–Derived Mesenchymal Stem Cells in Varus Knees With Cartilage Defects Undergoing High Tibial Osteotomy: A Prospective, Randomized Controlled Clinical Trial With 2 Years' Follow‐up

Abstract

Purpose: To analyze the results of the use of intra‐articular cultured autologous bone marrow–derived mesenchymal stem cell (MSC) injections in conjunction with microfracture and medial opening‐wedge high tibial osteotomy (HTO). Methods: Fifty‐six knees in 56 patients with unicompartmental osteoarthritic knees and genu varum were randomly allocated to the cell‐recipient group (n = 28) or control group (n = 28). Patients who had a joint line congruity angle of more than 2°, malalignment of the knee from femoral causes, a fixed flexion deformity, or age older than 55 years were excluded. All patients underwent HTO and microfracture. The cell‐recipient group received intra‐articular injection of cultured MSCs with hyaluronic acid 3 weeks after surgery, whereas the control group only received hyaluronic acid. The primary outcome measure was the International Knee Documentation Committee (IKDC) score at intervals of 6 months, 1 year, and 2 years postoperatively. Secondary outcome measures were Tegner and Lysholm clinical scores and 1‐year postoperative Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) scores. Results: The median age of the patients was 51 years, with a mean body mass index of 23.85. Both treatment arms achieved improvements in Tegner, Lysholm, and IKDC scores. After adjustment for age, baseline scores, and time of evaluation, the cell‐recipient group showed significantly better scores. The effect of treatment showed an added improvement of 7.65 (95% confidence interval [CI], 3.04 to 12.26; P = .001) for IKDC scores, 7.61 (95% CI, 1.44 to 13.79; P = .016) for Lysholm scores, and 0.64 (95% CI, 0.10 to 1.19; P = .021) for Tegner scores. Magnetic resonance imaging scans performed 1 year after surgical intervention showed significantly better MOCART scores for the cell‐recipient group. The age‐adjusted mean difference in MOCART score was 19.6 (95% CI, 10.5 to 28.6; P < .001). Conclusions: Intra‐articular injection of cultured MSCs is effective in improving both short‐term clinical and MOCART outcomes in patients undergoing HTO and microfracture for varus knees with cartilage defects. Level of Evidence: Level II, randomized controlled trial.