Symptomatic Improvement Following Intra-articular Injection of Cultured Autologous Adipose-Derived Mesenchymal Stem Cells in Kellgren-Lawrence Grade 3 Knee Osteoarthritis: A Case Report With One-Year Follow-Up.

Knee osteoarthritis (OA) is a progressive joint disease, and treatment options for cases refractory to conservative therapy can be limited. We present a 67-year-old woman with Kellgren-Lawrence (KL) grade 3 OA of the left knee who received an intra-articular injection of cultured autologous adipose-derived mesenchymal stem cells (ADMSCs) after conservative measures failed to provide durable relief. She had experienced progressively worsening left knee pain over approximately one year; intra-articular hyaluronic acid and platelet-rich plasma (PRP) injections had produced only transient benefit. ADMSCs cultured from autologous abdominal adipose tissue (100 million cells, 97.92% viability) were injected into the left knee joint under ultrasound guidance on Day 1, in accordance with a plan filed under Japan's Act on the Safety of Regenerative Medicine (plan number PB5240089). The pain visual analogue scale (VAS) improved from 8/10 at baseline to 1/10 at approximately 2.5 months and 0/10 at approximately 13 months. The Japanese Orthopaedic Association knee OA treatment score rose from 55/100 at baseline to 90/100 at approximately 2.5 months and 95/100 at approximately 13 months. Joint effusion resolved, and range of motion and gait improved. Serial MRI over the follow-up period showed improvement of the lateral meniscal lesion and an increase in tibiofemoral cartilage thickness. No serious adverse events occurred. As a single, uncontrolled case, causal inference and generalizability are limited. Nonetheless, intra-articular ADMSC injection may be a viable option for conservative-therapy-refractory knee OA and warrants controlled prospective evaluation.