In a two-year trial, surgeons stitched a hard-to-fix meniscus tear and added the patient’s own stem cells. Knee scores rose sharply, pointing to a possible meniscus tear treatment that avoids removing the meniscus.
This article covers emerging musculoskeletal and regenerative-medicine research. It reflects what may be coming in the field, not the treatments ADX or its network physicians currently provide.
Why it matters
The meniscus is a rubbery pad that cushions the knee. Some tears leave a loose flap that will not heal with stitches alone, so surgeons usually cut the torn piece out. Losing part of that cushion can wear the knee down over time. This study tested a meniscus tear treatment that stitches the flap back and adds the patient’s own stem cells to help it heal, so the cushion stays in place.
Summary
A meniscal flap tear leaves a displaced fragment of the fibrocartilage that distributes load across the knee. The authors describe these tears as notoriously difficult to repair: sutured flap tears often retear, so the standard operation is a partial meniscectomy, which removes the fragment and is linked to progression of osteoarthritis. Sekiya and colleagues ran a phase III trial to test whether adding a patient’s own synovial mesenchymal stem cells, taken from the lining of the knee joint, to a sutured repair could allow these tears to be preserved.
The trial enrolled 20 patients at four medical centers, and 19 were treated. The primary group was 15 patients (median age 53) with flap tears of the medial meniscus who had not improved with conservative care and would otherwise have needed a meniscectomy. Surgeons sutured the tear arthroscopically and took a small sample of joint lining during the same procedure. The cells were grown in the patient’s own blood serum, and four to six weeks later a suspension of roughly 83 to 90 million cells was placed on the repair through a needle. Patients were followed for 104 weeks with knee function scores, MRI, X-rays, and a second-look arthroscopy at 52 weeks.
In the primary group, the Lysholm knee score, a 100-point measure of knee function, improved by 53.5 points at 52 weeks (95% confidence interval 48.7 to 58.2). That cleared the trial’s preset target of 22 points, a figure based on gains reported with conventional meniscus treatments. The improvement held at 104 weeks (57.8 points), and pain and KOOS subscale scores improved as well. MRI showed improvement in 12 of 15 patients (80.0%) at 52 weeks. Adverse events were common, mostly pain from the procedures, but none was judged to be related to the stem cell product.
The caveats are significant. The study had a single arm and no comparison group, and the authors state that no definitive conclusion can be drawn about whether the cells add benefit beyond suturing. On second-look arthroscopy, the trial’s preset definition of healing was met in 5 of 14 patients (35.7%); the 71.4% figure reported in the abstract comes from a broader definition applied after the fact. In 10 of the 15 patients, the sutures had cut through the tissue and had to be redone before the cells were applied. X-rays showed no arthritis progression in 9 of 15 patients (60.0%) at 52 weeks. The trial was funded by FUJIFILM Toyama Chemical, some authors are affiliated with the sponsor, and the authors note that two years may be too short to judge long-term meniscus function.
Source: Journal of Orthopaedic Science, Sekiya et al., 2026 (DOI: 10.1016/j.jos.2026.05.011)
Research compiled by ADX AI Agent, reviewed by Sean Gallivan