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For years anterior cruciate ligament (ACL) tears and even partial tears spelt the beginning of the end for an athlete at the elite level. Even with today’s advances in knee reconstructions, recent studies show that two-thirds of athletes didn’t return to their pre-injury level of sport one year after knee surgery a re-injury can be up to six times more likely for athletes after ACL reconstruction. New advances treating ACL tears with stem cells could radically change all this.
People come to OCR from a variety of sporting backgrounds – and succeed. Some of the best OCR athletes have been wrestlers, adventure racers, triathletes, Crossfit athletes, and even ex-kayak/surf ski paddlers, thanks to their strong aerobic capacity and their above-average upper body strength. The terrain and the obstacles in OCR and mud runs break up the rhythm of the elite runner so it’s not all in their favor, plus elite runners are often challenged by the strength component required for some obstacles.
The obvious function of the ACL is to stabilise the knee joint in a front-back direction. Less obvious is the fact that it provides position sense (proprioception) to the whole leg and core. Think of the ligament as being rich in position sensors that help guide the muscles of the lower body in accurate movement.
When you rip the ACL out and replace it with a fake one made from a muscle graft, then whack that graft in at a different angle to the original equipment (it is usually implanted at a steeper, almost vertical angle compared to its natural 45-degree angle), then those position sensors don’t work the same. In fact, a study published in 2013 showed that patients with ACL injury had just as much loss of position sense in their good knee as their ACL-injured knee, so what happens on one side seems to impact the other. The upshot? Getting one knee ACL ‘fixed’ surgically appears to markedly increase the chance that the other knee will be injured.
It can go even further than this. A client of mine had an ACL reconstruction using a graft from her semitendinosus. Classic ACL tear – playing hockey, her boot got stuck in the artificial turf, the leg twisted and SNAP! Over the course of the last 10 years and several attempts to resume sport, she has overloaded the non-reconstructed leg and experiences other biomechanical imbalances between legs due to the shortening of her hamstring. The additional load on the ‘good’ leg is not just for raw strength, but also for the stabilisation required to make up for the loss of proprioception on the reconstructed leg. This fits with a study (see paper 2) presented at the 2013 American Orthopaedic Society for Sports Medicine’s Annual Meeting. The study of athletes following ACL reconstruction demonstrated that the women were more than four times greater rate of injury within 24 months than their healthy counterparts. The study concluded that there was a trend for women to be twice as likely to suffer an injury on the opposite knee compared to the previously injured one after an ACL reconstruction. Overall, from the study group 29.5% of athletes suffered a second ACL injury within 24 months of returning to activity, with 20.5% sustaining an opposite leg injury and 9.0% incurring graft re-tear injury on the same leg. A higher proportion of women (23.7%) suffered an opposite leg injury compared to men (10.5%).
The holy grail of ACL recons is to make like a lizard’s tail and grow it back yourself. This overcomes the need to compromise the functionality of other parts of the leg when you take a graft, plus you don’t fiddle with the angle of the ACL and risk upsetting any of its functions for proprioception.
Specialists in regenerative medicine at The Centeno-Schultz Clinic in Colorado have achieved great results by injecting stem cells first into partial ACL tears and then in complete tears that were non-retracted (i.e. the whole ligament is involved, but the main fibres of the ligaments are still being held together, so it hasn’t yet been snapped back like a rubber band).
The first problem was how a doctor would place anything via a needle into a ligament buried deep in the knee. This is now done under sophisticated imaging technologies like c-arm fluoroscopy and advanced musculoskeletal ultrasound.
When researchers first tried injecting the patient’s own stem cells into partial tears, they began to see “robust healing” of the tear on post-injection MRIs. Patients reported improvements within a few weeks while they went about most of their activities – in other words, by the time people who had big ACL surgeries were just getting off of crutches, the stem cell patients were back to full activities. Good healing has also been seen on complete tears that were not retracted. Finally, the treatment was attempted on retracted tears up to about 1 cm – “most of them” healed as well.
The ACL ligament is unique in that it is covered by a synovial sheath – the membrane lining the cavity of bone through which a tendon moves. Researchers believe that in most patients, even with complete retracted tears, this sheath remains intact, acting as a “guide” for stem cells.
So far, the clinic’s case series shows good MRI evidence in about 7-8 out of 10 complete tears and improvements in pain and function for 8-9 out of 10 patients.
This simple and highly accurate injection of the patient’s own stem cells often results in less down-time and the ability for the patient to keep his or her own ligament intact, which in turn would completely transform the severity and flow-on effects of major ACL injuries to athletes.