Most MMA observers are familiar with the story of Dominick Cruz' knee injuries. The short version is that he suffered consecutive ACL tears to the same knee over a very short time frame. His first injury occurred in May of 2012, and was the result of a training injury. He underwent surgical reconstruction of the ACL, using a cadaver allograft. His post-operative rehab progressed to the point where he started working on limited training activities, and in late 2012 he suffered a second ACL tear which again occurred while training. In a December 2012 interview, he stated that he had his knee brace on and "was moving and went to hit a pivot, and the tissue just popped." He underwent a second surgery, this time using his own patella tendon autograft. So at this point, Cruz is about 8 months into his recovery after the second surgery. I want to present a case from a rehabilitation perspective for why Cruz should make a successful return, but first let's take a look at the idea of the cadaver allograft vs. patella tendon autograft in ACL surgery.
The temptation to make a fast return to fighting after ACL surgery, it seems, is too much to resist for some fighters. To this end, it seems that more than a few of them are turning to the cadaver allograft surgery due to the reduced surgical trauma to the knee compared to the traditional patella tendon autograft. (Cruz and Cat Zingano are two that come to mind.) The problem is that the allograft takes longer to incorporate (or "ligamentize") within the knee, and it can be subject to failure in an athlete pushing to return to competition quickly. Cadaver allografts are commonly sterilized using radiation, but the process of irradiation seems to cause a weakening of the structural integrity of the graft. One study from 2007 looked at the success of irradiated cadaver Achilles grafts, where a piece of the cadaver Achilles tendon is used to replace the ACL. The failure rate was so high that the authors discontinued use of irradiated allografts for ACL surgery.
Another study of young, active individuals published in 2010 is striking. Those who had the allograft (cadaver) ACL reconstruction were 4 times more likely to have a graft failure than those who had the autograft (patella tendon) procedure. It's true that this study was not specific to MMA fighters, but I believe the conclusions are relevant because it looked specifically at the young, active (athletic) population. An accelerated return to competition after an allograft ACL reconstruction may place an athlete at increased risk for repeat rupture.
Now back to the original topic- why I think Dominick Cruz will make a successful return to the Octagon. First I will acknowledge a glaring hole in this idea of a "successful return." What will be considered a success for a fighter who, by the time he returns to fight, will have been out of action close to two years, possibly longer? From my perspective as an observer with an interest in rehab and recovery, success means returning to fight, and going on to compete in subsequent fights with no obvious ill effect on his game due to the knee. However, inconsistent fight performance due to a "bum" knee will probably be manifest in a paltry win-loss record a la Mauricio "Shogun" Rua. His multiple knee surgeries have cast a dark cloud on his performance in the Octagon, based on his fight record since his first surgery.
Cruz and his rehab and training team seem to be approaching his rehabilitation differently following the second knee surgery. They are following a strict time-based and performance-based rehabilitation protocol that gradually reintroduces Dominick to the various aspects of MMA training. That's why I think Cruz will make a successful return to fighting. In a recent interview with AXS TV, Cruz gave some specifics on his rehab program.
"What I've learned especially from the first surgery to the second one is, just listen to the stipulations and you'll be fine. Don't do anything extra, don't do anything less... It's just step by step, in 8 week increments. That's all I know of a time table... it's very important that I don't overstep my boundaries with those 8 weeks."
The time-based component of Dominick's rehab is very important because it accounts for the bone-to-bone healing that must occur. This healing cannot be forced, and must be accounted for over time. An overly aggressive rehab program implemented too soon can lead to micromotion of the graft inside the bone tunnel through which it was placed. On the other hand, controlled loading helps the healing process. So as time passes, Dominick's surgeon is allowing progression of his rehab/training in small doses. It's my belief that this is how rehab after ACL surgery should happen every time, regardless of the type of graft used. The incremental, time-based rehab program should serve Dominick well when he does make his return.
1. Rappe, M, Horodyski, M, et al. Nonirradiated versus irradiated achilles allograft. In vivo failure comparison. Am J Sports Med. 2007;35:1653-1658.
2. Barrett, GR, Luber, K et al. Allograft anterior cruciate ligament reconstruction in the young, active patient: Tegner activity level and failure rate. Arthroscopy 2010;26:1593-1601.
3. Muller, B, Bowman KF, et al. ACL graft healing and biologics. Clin Sports Med. 2013;32:93-109.
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