The effect of medial meniscus (MM) status on outcomes following high tibial osteotomy (HTO) combined with cartilage regeneration using human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) remains unclear.

This study aimed to evaluate the effect of preoperative MM status on the outcomes of HTO combined with cartilage regeneration using hUCB-MSCs. Specifically, clinical and radiological outcomes were compared between two groups of patients, which were divided according to their preoperative MM status. We hypothesized that patients with preserved meniscal integrity or those who underwent meniscal root repair would show better clinical and radiological outcomes compared to those with significant meniscal loss or untreated root tears.

A retrospective analysis was performed on 47 patients who underwent HTO with hUCB-MSC implantation. Patients were divided into group P (preserved MM integrity or medial meniscal root repair) and group L (loss of MM integrity, defined as a peripheral rim width <3 mm, unable to maintain hoop function). Clinical outcomes were assessed using the International Knee Documentation Committee (IKDC) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores after a minimum follow-up of 2 years. Cartilage regeneration was evaluated with Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 score and International Cartilage Repair Society (ICRS) Cartilage Repair Assessment (CRA) score from second-look arthroscopy. Correlation analyses were conducted to examine the relationship between preoperative MM extrusion and cartilage repair.

Both groups demonstrated significant improvements in IKDC and WOMAC scores (p < 0.01). No significant differences were observed between groups in IKDC and WOMAC scores at final follow-up (p = 0.21, p = 0.42, respectively). MOCART 2.0 and ICRS CRA scores showed no significant differences between groups (p = 0.35, p = 0.08, respectively). Group P showed higher proportions of favorable outcomes compared to group L, including no major subchondral changes or only minor marrow edema (56% vs. 31.8%) and ICRS CRA grades I or II (84% vs. 72.7%). While these findings suggest potential differences in outcomes, neither comparison reached statistical significance (p = 0.09 and p = 0.48, respectively). Preoperative MM extrusion negatively correlated with MOCART 2.0 and subchondral bone changes (r = −0.24, p = 0.03; r = −0.29, p = 0.02, respectively).

HTO with hUCB-MSC implantation provided significant clinical improvements and effective cartilage regeneration regardless of preoperative MM status. However, preoperative MM extrusion may influence subchondral bone changes, emphasizing the need to consider MM status for long-term outcomes.

III; retrospective comparative study