25 September 2013

Manny Machado's Knee Injury: Diagnosis, Treatment, and Future Prospects

"When you hear hoofbeats, think of horses, not zebras."

One of the more famous and memorable sound bites from the medical field, the above quote comes from a former University of Maryland School of Medicine physician, Dr. Theodore Woodward. It was a catchy warning he used to advise his young trainees on the pitfalls of thinking of the exotic instead of the commonplace when looking to diagnose patients.

In some ways, the knee injury Manny Machado sustained was the hypothetical zebra Woodward warned his fellow practitioners against labeling, in place of the more frequently seen horse. It isn't often this way, but for Machado, it really was a zebra, and that is a relief.

As reported earlier today, Machado sustained a tear of his left medial patellofemoral ligament (MPFL) and not either the anterior cruciate ligament, medial collateral ligament, or meniscus, which was originally feared by many and more commonly seen injuries. While the diagnosis is still a significant injury, it is one that is exceptionally rare in baseball, and brings with it a treatment protocol and recovery period that don't typically include surgery or a lengthy rehabilitation. While not seen as frequently as the horses, this zebra of a diagnosis is pretty encouraging and one that should have Machado ready for 2014 spring training without having to go under the knife.

With collective sighs of relieved breathed with the less daunting diagnosis finally divulged, let's turn our attention to what exactly is at hand for Machado and further discuss the MPFL tear and the prognosis. While we previously discussed some general knee anatomy yesterday here at Camden Depot, with the exam results in, we can finally get down to brass tacks and discuss specifics.

Image courtesy of musculoskeletalnetwork.com
As seen in the image, the MPFL runs in an east-west fashion across the medial portion of the knee between the medial border of the patella and the distal portion of the femur at the adductor tubercle; this is immediately superior to the femoral attachment of the MCL. Its primary function is to prevent the lateral migration of patella, providing 50%-80% of the restraining force to lateral patella dislocation. Simply put, the MPFL prevents the patella, or kneecap, from being dislocated outward.

For Machado, this MPFL diagnosis is one that makes sense, especially when his previous injury history is considered, in particular, the left patella subluxation injury he suffered in 2011 while at Class A Delmarva. A subluxation of the patella occurs when the patella is pulled towards the outside of the knee and out of the groove in the femur that it rests on -- called the trochlea -- causing pain and instability of the knee. Often, it can lead to a more severe patellar dislocation and is commonly seen with large valgus external rotation forces on the knee. With patellar subluxation and dislocations also comes increased rates of MPFL ruptures, with rates quoted as high as 90% to 100%*. 

While there have been instances of success with an immediate surgical repair of the MPFL, especially in the professional athlete and in patients with recurrent patella dislocations, surgery does not appear to be indicated in Machado's case. Considering a number of studies looking at surgical versus non-surgical treatment route success rates have show no difference in outcome, the more conservative, physical therapy oriented route that looks to strengthen the muscles in the area, in particular, the quadriceps, and restoring hamstring flexibility is one perfectly suited for Machado, and a return to action, pain and injury free, come spring training.

Overall, the injury to Machado could have been much worse and one where the horse you're expecting isn't as welcome as the zebra you aren't. 

*Reference: Dines, JS, Altchek, DW, Andrews, JR, ElAttrache, NS, Wilk, KE, Yocum, LA. (2012) Sports Medicine of Baseball: Philadelphia, PA.

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