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ACL Reconstruction: how long is rehab?


How long is rehab following ACL reconstruction?

ACL injuries are a common and often difficult injury to recover from. ACL tears typically occur in younger athletes who play sports which require a lot of cutting, pivoting, acceleration/deceleration. It is estimated that in the USA over 200,000 ACL tears occur annually, many of which are repaired surgically. If you’ve had an ACL tear before, then you know first-hand that the rehab is a challenge. It takes months of effort with lots of ups and downs to ultimately progress back to your sport, and there is a percentage of athletes who never make it back to their previous sport.


Unfortunately, the rate of re-tears of the same ACL or opposite ACL are very high when returning to sport. For athletes who return to a high-risk sport such as football, soccer, or basketball, the risk of injuring their ACL again is 4-5x higher than someone who does not return to one of those sports. The reason for this is complex and multifactorial, but we do have some good information on things we can control to reduce this risk. What stands out most importantly in our current knowledge base is that athletes who do not pass appropriate return to sport (RTS) testing are at a much higher risk for re-injury compared to those who do. Another issue is that athletes with ACL tears are also subject to increased risk of developing knee arthritis and meniscal tears after return. The best way to reduce your risk of further complication is to go through thorough RTS testing with a qualified physical therapist or athletic trainer. Read below for ways to determine if you are ready to return to sport after an ACL-injury.




This criterion is heavily debated. Some surgeons/therapists will clear athletes based on time alone. Many surgeons and therapists who specialize in ACL rehab know that time is definitely not the best way to clear someone for RTS. What we do know is this: for every month after surgery that you wait to RTS, your risk of re-injury reduces by 51% up until month 9. Because of this data, we really shouldn’t be clearing anyone earlier than month 9. In my personal experience, it takes at least this amount of time for most athletes to meet the other guidelines for RTS. For Most athletes the time to return to sport should fall somewhere in the 9-15 month range. So, if you are in month 7 and have  been cleared to return, you may want to think twice and get a second opinion on testing to make sure you aren’t putting yourself into a risky situation.


Graft Choice:

Not all ACL repairs are created equally. The problem facing surgeons during ACL reconstruction is that they need a new material, or graft, to fill in and take the place of the old ACL. Unfortunately, synthetic material doesn’t work well for surgeries like this, because unlike human tissue, synthetic material can only weaken over time, whereas human tissue can be remodeled and strengthened by our bodies over time. Because of this, there are 4 main types of grafts that surgeons use: Patellar tendon graft, hamstring tendon graft, quad tendon graft, or cadaver graft. Patellar tendon and Hamstring tendon are the most common. There are a lot of differences, but to make things simple, all are fairly close except for cadaver grafts.  Initially cadaver grafts were supposed to be a good idea because we could spare the athletes other tendons. But over time it was determined that these actually lead to higher fail rates. At the time of this blog post, current research would say that the other graft types (patellar tendon, hamstring tendon, quad tendon) have similar outcomes in the long-term (>1 year) post-op, so as long as you are using your own tissue for the graft, you are doing the best you can do in terms of preventing a re-tear. If you did have a cadaver graft, it’s likely going to take you longer to return to sport compared to someone who had one of the other graft choices. The good news is that you can modify the other factors below to improve your ability to return to sport safely. Check out this video from The Prehab Guys regarding different graft options.


Quad Strength:

Of the modifiable risk factors, this is perhaps the most important one to nail down. A huge problem for athletes rehabbing from an ACL injury/repair is that the quadriceps muscle on that side typically is very weak compared to the other leg. This problem often persists for months or even years after surgery depending on the quality of rehab and the athlete’s effort. We also know that having the quad on your injured side less than 90-95% strength of your other side significantly increases your risk, not only for another ACL tear but also for knee osteoarthritis in the future. To do this properly, you must be tested with a special machine or some kind of force gauge that will objectively tell you how much force you can create. Unfortunately, most athletes do not get access to proper RTS testing prior to being cleared to go back. Often, providers clear based on time alone (example you’re cleared at 6 months post-op just because it’s been 6 months) which is just not acceptable based on what we know about re-injury rates. 



Lack of hamstring strength is another testing point to use to determine if someone is ready to get back on the field. While not as well established as the quad in the research, the hamstring is a dynamic knee stabilizer which counteracts a lot of the same forces as the ACL. Typically, this is going to be a bigger concern for athletes who have undergone an ACL repair with a hamstring graft, but it should be regularly tested in all individuals going through the rehab process.


Vertical Jump Height:

Vertical jump height is another way to quantify overall functioning of the lower extremity. During this test you will be forced to create a maximum amount of force production to jump, and then also demonstrate force absorption to stick the landing. We are finding that vertical jumping may be correlated to improved performance and reduced risk of injury compared to the previous standard, the horizontal hop. Horizontal hop distance may still be used in RTS, it may just be less ideal compared to vertical.


Psychological Testing:

Throughout the course of rehab, there are a lot of physical ups and downs. Swelling, poor range of motion, pain, weakness are things that are easier for use to see, measure, and change. The psychological aspect is more challenging to see and measure, however that doesn’t mean it isn’t important. Many athletes have doubts about whether they should return after ACL repair. There are fears about re-tearing, not performing well, increasing pain, etc. Your therapist should be checking in regularly to ensure that these issues have been addressed prior to your discharge back to sport. Sometimes the objective physical tests may say you’re ready to return, but you don’t feel that way internally. You need to take a step back and have that discussion with your therapist or trainer prior to return to sport.


If you or someone you know is being frustrated by ACL rehab, please reach out to us. ACL rehab requires hard work and dedication from both patient and provider. To inquire about working with us, click here and leave us some info about your situation. To learn more about other ACL rehab related topics like Blood Flow Restriction Training, click here. 


If you live in Buffalo and may be in need of ACL reconstruction, contact either Excelsior Orthopedics or UBMD Orthopedics for some top notch surgeons.


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