Recent research suggests that stem cell therapies can offer an alternative to ACL tear and reconstruction surgery. As other research has shown, return to play without an ACL is possible for selected patients. Further, rehabilitation can be similar in the ACL treated with stem cell therapy and the rehab of the reconstructed ACL in getting the patient back to sport or work.
Understanding how an ACL heals
Understanding how an ACL heals – even a complete rupture has lead doctors to continuously look at bio-materials – blood platelets and stem cells. One of the things they look at is “Scaffolding.” This is a surgical procedure where a cartilage patch is placed over a cartilage defect and them “pasted in with PRP or stem cell gel.” However in some instances the body may make its own scaffolding out of pooled blood and use this blood as the foundation to regenerate a ligament – even a complete ruptured ACL.
Doctors shared a case history (1) of a 12 year old boy who grievously injured his knee after being hit by a car – the boy was also a high level hockey player. What makes this story so amazing is that the knee damage was so severe in regard to broken bones, that an ACL reconstruction surgery had to be postponed until the other damaged healed. When doctors went in 14 months later to start the processes of ACL reconstruction, they found a completely regenerated ACL. The attending doctors point out that the body of evidence says that this should not have happened. The medical literature states a completely ruptured ACL does not heal because blood and healing cells cannot reach it.
Yet, their patient with traumatic knee injury with multiple ruptured ligaments healed over the course of 20 months.
It is likely that bracing associated with the patient’s second surgery and delayed union of his tibial fracture allowed healing tissue to be protected from excessive stress until it remodeled with sufficient strength. It is possible that intra-articular scar formation contributed to his healing capacity. (Possibly the blood scaffold.) At age 14 the boy returned to playing competitive hockey – and two and a half years later – still playing with no adverse effects to his knee.
Bone marrow aspirate concentrate treatment for ACL injuries
A November 2014 paper (2) summarized the healing capablities of the ACL this way: “the ACL has the potential to heal upon intensive non-surgical rehabilitation procedures. Several biological factors influence this healing process as local intraligamentous cytokines and mainly cell repair mechanisms controlled by stem cells or progenitor cells. Understanding the mechanisms of this regeneration process and the cells involved may pave the way for novel, less invasive and biology-based strategies for ACL repair.
A November 2024 study (3) describing different non-surgical treatment methods wrote: “(stem cell therapy in the form of) bone marrow aspirate concentrate treatment for ACL injuries involves the use of concentrated autologous (the patient’s own) bone marrow cells, which are rich in growth factors and stem cells, to enhance the body’s natural healing response. This therapy leverages the regenerative potential of these cells to promote tissue repair, reduce inflammation, and improve the overall function of the injured ACL.”
Other treatments
In February 2026 paper (4) followed eight recreational athletes—four female—average age of thirty-two diagnosed with acute anterior cruciate ligament (ACL) rupture (x) who decide against surgery. Each participant received four intra-articular injections of either platelet-rich plasma (PRP) or autologous conditioned serum (Orthokine) under ultrasound supervision over a six-week period. Following these injections, each patient adhered to a predetermined rehabilitation regimen.
MRI assessments were conducted to determine ACL continuity 21 to 24 weeks after the injury. Seven patients had undamaged ACLs (grade 0), while one patient had a stressed ACL (grade 1). All athletes were able to return to their leisure activities within six months.
References
1 Reported by Deren Bagsby, MD, George Gantsoudes, MD, and Robert Klitzman, MD Am J Orthop. 2015;44(8):E294-E297.
2 Hirzinger C, Tauber M, Korntner S, Quirchmayr M, Bauer HC, Traweger A, Tempfer H. ACL injuries and stem cell therapy. Archives of orthopaedic and trauma surgery. 2014 Nov;134(11):1573-8.
3 Yu X, Hu J, Li Y, Wen Y, Li B. ACL injury management: a comprehensive review of novel biotherapeutics. Frontiers in bioengineering and biotechnology. 2024 Nov 22;12:1455225.
4 Yadav PJ, Thampi G. Therapeutic Evaluation of Intra-articular Platelet-Rich Plasma, Steroid, and Viscosupplement Injections for Sacroiliitis: A Retrospective Comparative Study. Cureus. 2026 Mar 12;18(3).
