Anterior-to-Central Cartilage Defects of Arthritic Knee Showed Better Cartilage Regeneration Than Posterior Cartilage Defects Using Mesenchymal Stem Cell Implantation.

Purpose: To analyze cartilage regeneration and clinical outcomes after human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSCs) implantation on the basis of the distribution and location of medial femoral condyle (MFC) cartilage defects.

Methods: Patients who underwent hUCB-MSC implantation for MFC cartilage defects involved in isolated medial compartment osteoarthritis were included. The patients were divided into 2 groups, those with MFC defects located within the anterior-central portion (group A) and those with MFC defects extending to the posterior portion (group P). Cartilage regeneration was assessed using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 scores. MFC cartilage defects were subdivided into anterior, central, and posterior regions. The total, regional MOCART scores, and patient-reported outcomes (PROs) were evaluated.

Results: Overall, 43 patients were included in this study (group A: 31 patients, group P: 12 patients), with 30 of 43 undergoing combined high tibial osteotomy. Cartilage defect size was significantly larger in group P than in group A (7.8 ± 1.9 cm vs 5.7 ± 2.4 cm, P = .009). Group A demonstrated a significantly greater total MOCART score compared with group P (55.0 ± 12.3 vs 40.4 ± 9.2, P = .001). PROs at final follow-up showed significant improvement compared with preoperative values in both groups (all P < .001), with no significant differences in PROs between groups. The mean follow-ups for each group were 29.7 and 32.5 months, respectively. Defect size were significantly associated with the total MOCART score (P = .026) and unsatisfactory outcome (MOCART < 60) (P = .012, odds ratio 2.674). The cut-off value for defect size was 6.3 cm (area under the curve, 0.905; P < .001). In the comparison of regional MOCART scores within each patient, the anterior MOCART score was significantly greater than the central and posterior MOCART scores (P < .001 and P = .004, respectively).

Conclusions: Cartilage defects with osteoarthritis, which is smaller and primarily limited to the anterior-to-central portion showed better MOCART scores after hUCB-MSC implantation.

Level Of Evidence: Level III, retrospective cohort study.