FightMed: What is an ACL tear?

We hear about ACL tears often in MMA, but for those who are not familiar with the intricacies of what this entails, Resident physician David Liang, based in the United States who specializes in Physical Medicine and Rehabilitation (PM&R) gives us some insight.

During UFC on ESPN 11 on 20thJune,Josh Emmett earned a big victory against Shane Burgosin an arguable contender for fight of the year. But even more impressive was how he gave such a performance after tearing his ACL in the first 30 seconds of the fight.

The ACL (anterior cruciate ligament) is the most commonly injured of the four major knee stabilizing ligaments which connect the femur (thigh bone) to the tibia (shin). Its main purpose is to prevent your tibia from moving too far in front of your femur when you extend your leg. You will often hear of football players tearing it after making sharp pivots. But landing after a jump can also do the trick, especially if the knees are locked and pushed inwards. This mechanism will promote forward movement of the tibia, which stresses the ACL a great deal.

Emmett tore his ACL after landing flat on his left foot while his knee was in nearly full extension. He was in the process of returning to an orthodox stance after performing a shift off a right overhand, but was pushed off balance by a frame from Burgos. You can see how the tibia starts to move out in front of the femur as he lands, leading to an instant reaction.

ACL tear infographic

Commonly you will see instability and swelling after an ACL tear. Pain may or may not be present. It's incredible that Emmett was able to fight on with such an injury. But he did lose some power in his normally destructive right hand due to the inability to fully put weight on that left leg. He managed to drop Burgos twice later in the fight, but those came from shifting punches from southpaw.

The post-surgery recovery process will be a long one. Recommendations vary, but the concensus is 9-12 months before a return to full training. And that's not counting how Emmett's docs want to address the additional knee injuries he suffered, including a partial MCL (medial collateral ligament) tear. Success depends on a good surgery and adherence to a well-planned post-operative rehabilitation program. Key would be improving hamstring strength and activation, as a muscular imbalance in favour of the quadriceps is a risk factor for ACL injury.

By: David Liang, MD
Resident Physician and Combat Sports Practitioner

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