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So You've Torn Your ACL...
June 27, 2016
Have you ever wondered why it takes so long to return to sport after an ACL tear? It's usually 9-12 months!
Maybe you've been through this yourself and been frustrated by this long rehabilitation. Maybe you've recently torn your ACL and you're
starting the grueling road to recovery.
Why does recovery take so long?
While most ligaments heal themselves when torn, the ACL doesn't. Researchers from Boston and Rhode Island found in 2013 that this is because chemicals in the environment around the ACL prevent a blood clot from being able to form. This blood clot formation is necessary to provide the framework through which a ligament repairs itself.
So because it doesn't repair itself naturally, it generally will require surgery. Most ACL repairs are performed by taking a piece of tendon from the hamstrings or below the kneecap and using this in place of the ACL. When this happens, the internal structure of the tendon changes over time to become more like a ligament. During this process the tendon graft becomes weaker over the first couple of months as it strips itself down, then builds itself up more like a ligament and becomes stronger.
Rehab needs to be slow until the graft is at a point where it is strong enough to be exposed to increased forces. This is why recovery is so slow compared with other injuries.
Last year a group of AFL physiotherapists and doctors said they believed they could alter the rehab protocol following an ACL repair to get the recovery time down to 7 months, but this is still being worked on.
What other options are there?
In limited circumstances a synthetic graft may be used rather than a tendon graft. This procedure results in faster recovery times (about three months). Because of a higher rate of reinjury compared with a tendon graft, these grafts are rarely performed. If they are performed it is generally only after multiple injuries to the same knee and there needs to be some ACL left attached to both the femur and the tibia.
Some ACL tears will be treated without surgery. This will leave the knee somewhat unstable and so it is very rare for someone planning on returning to sport to be managed without surgery.
How likely am I to do it again?
A recent study found that only 2.5-5% of tendon grafts are reinjured. There does seem to be a genetic component to your likelihood of suffering an ACL tear and so if you've injured one knee you are at an increased risk of injuring the other compared with the general population.
What does rehab involve?
After surgery your initial rehab will focus on restoring movement and reducing pain and swelling. General strengthening of your legs is important as well to make up for your lack of activity.
Cardio exercise like cycling and walking in the pool will be introduced before running to help maintain your fitness.
Exercises to improve your proprioception (awareness of what position your knee is in and how it is moving) are important to get you ready to move on to more sport-specific exercises.
Practice of sport specific activities that place strain on the ACL, such as jumping, landing and changing direction, will be slowly graduated as you're able to in order to prepare you for a return to training.
When you return to training skills will be worked on first, then more complex drills before full-contact drills are reintroduced last.