Knee osteoarthritis (KOA) is a degenerative joint disease that significantly impacts patients' quality of life. Umbilical cord mesenchymal stem cells (UC-MSCs) have emerged as a research focus in regenerative medicine for KOA due to their multilineage differentiation potential, immunomodulatory, and anti-inflammatory properties. However, reports on the clinical efficacy differences associated with varying dosages and injection frequencies of UC-MSCs are still insufficient. This article reports the clinical outcomes and imaging improvements in a 64-year-old female patient with bilateral KOA who received different administration regimens, aiming to provide clinical references for optimizing stem cell treatment strategies.

A 64-year-old female patient presented with bilateral knee pain for over six months and was diagnosed with bilateral knee osteoarthritis. She had not received any targeted treatment previously. To explore the optimal treatment strategy, the patient's bilateral knees received intra-articular UC-MSC injections using different regimens. The right knee received a single high-dose injection; the left knee received a regimen of low-dose, multiple injections. Post-treatment, regular follow-ups were conducted to evaluate joint function and pain severity using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Visual Analogue Scale (VAS). Concurrently, ultrasound and magnetic resonance imaging were used to observe changes in joint structure, and treatment-related adverse events were recorded.

During the treatment and follow-up period, the patient experienced no serious adverse events. Adverse reactions were limited to mild joint swelling within 72 hours post-injection. Regular follow-up showed that osteoarthritis in both knees improved to varying degrees, manifested as decreased WOMAC and VAS scores. Notably, the joint that received the single high-dose injection (right knee) showed superior improvement in function and pain compared to the joint that received the low-dose, multiple injections (left knee). Knee joint ultrasound and MRI evaluations revealed increased articular cartilage thickness in the right knee, while no significant imaging improvements were observed in the left knee.

This case suggests that intra-articular injection of UC-MSCs is a safe and effective treatment for patients with knee osteoarthritis. Different dosage regimens and frequencies may lead to different clinical outcomes: a single high-dose injection may be superior to low-dose, multiple injections in improving clinical symptoms and promoting cartilage repair. This finding supports the hypothesis of a dose-dependent effect in stem cell therapy; however, the specific mechanisms and optimal treatment regimen require further validation through prospective studies with larger sample sizes. This case provides a valuable reference for selecting individualized stem cell therapy regimens for knee osteoarthritis.