This is a guest post by Dr. Christopher Centeno, M.D., a specialist in regenerative medicine and the new field of Interventional Orthopedics.
Tearing your ACL and having it surgically replaced seems like a modern sports rite of passage. This major internal knee ligament stabilizes the joint in a front-back direction and is important for also providing position sense to the whole leg and core. Tears in the ligament are common in football, soccer, rugby, and other sports. Surgery for a torn ligament involves removing the damaged ligament and replacing it usually with a donor ligament taken from another part of the body. The down-time until the knee is fully recovered can be between 6 months and a year. More concerning is a recent study that found that two-thirds of athletes didn’t return to their pre-injury level of sports by one year out from the ACL surgery.
The “holy grail” of ACL injury repair has been growing a new ligament inside the joint. Our team began working on using stem cells to treat arthritis and other common orthopedic injuries in 2005 and has more experience with treating and tracking the outcomes of more stem cell patients than any other clinic in the world. Several years ago we asked the question whether an exacting injection of stem cells into the torn ACL would prompt it to heal. The problem back then was that no one had really tried to document how a doctor would place anything via a needle into a ligament buried deep in the knee. Trying this blind in the office would be like hitting a needle in a haystack.
Our team, after about a year of cadaver work and injecting patients under sophisticated imaging technologies like c-arm fluoroscopy and advanced musculoskeletal ultrasound was finally able to reliably inject cells into the ligament tear. However, inventing how to accurately inject the ACL was only the first part, would they heal an ACL tear?
At this point a quick review of ACL tear types is in order. While radiologists have many grades of ACL tears, for our purposes there are three main types of tears: partial, full thickness non-retracted, and complete retracted. The partial tears leave the ligament with some intact fibers or just stretched out. The complete non-retracted tears have the whole ligament involved, but the main fibers of the ligaments are still being held together, so it hasn’t yet been snapped back like a rubber band. Finally, the complete retracted variety is snapped back like a rubber band.
When we first tried injecting the patient’s own stem cells into partial tears, we began to see robust healing of the tear on post-injection MRIs. In addition, patients reported improvements within a few weeks while they went about most of their activities; a stark contrast to big ACL surgeries where the patient would just be just getting off of crutches when our patients where back to full activities. We next tried complete tears that were not retracted. Again, we saw good healing on follow-up MRIs. Finally, we attempted retracted tears up to about 1 cm and were astounded that most of them healed as well!
How does this work? The ACL ligament is unique in that it is covered by a synovial sheath. We believe that in most patients, even with complete retracted tears, this sheath remains intact, acting as a “guide” for our stem cells. As a result of these findings, we are now submitting a case series with sophisticated computerized analysis of the before and after MRI images. It shows that there is good MRI evidence in about 7-8 out of 10 complete tears and improvements in pain and function for 8-9/10 patients. Our clinic has also funded a randomized controlled trial to put more rigor behind what we see clinically.
In summary, we can now heal ACL tears through a simple and highly accurate injection of the patient’s own stem cells. This often results in less down-time and the ability for the patient to keep his or her own ligament intact. We believe, based on our experience, that 10 years from now, most surgical replacements of ACLs will likely be relegated to the dust bin of history. Thus, providing an incredible transformation in the severity of this injury for the athletes and the teams who employ them.