By Guest Blogger Lauren Calamari, PT, DPT
The early days of rehab after ACL surgery are not glamorous. However, they are vitally important for setting up long-term success. Regaining knee range of motion is one of the first post-operative goals. While knee flexion (bending) is important, regaining knee extension (straightening) early on is a key factor for successful recovery. In fact, research shows us that failing to do so can put you at risk for negative long-term outcomes1,2,3. It is important to note that not all surgeries are the same, and many people have additional injuries that are also addressed during surgery. This can change the overall post-operative precautions, including range of motion, so always consult with your surgeon and/or physical therapist about what is best for your knee.
Achieving terminal knee extension (getting all the way to your knees end range of straightening motion) is important for several reasons. It is necessary to have a normal gait (walking) pattern once you can begin walking. It can also help to reduce post-operative swelling. Reducing swelling and attaining full extension allows your quadriceps (thigh) muscles to activate properly. In fact, swelling can “shut down” or inhibit the muscles surrounding your knee. This is called quad inhibition. In turn, quad inhibition will make it harder to diminish lingering swelling. You can see how this can become a vicious cycle! The bottom line is, regaining terminal knee extension as quickly as possible will help lessen these early challenges. Early quad activation will allow you to strengthen your quads adequately as you advance through your rehab process. Sufficient quad strength is essential for a safe return to your prior activity, no matter what that is. Strong quads give your knee stability and can help prevent secondary knee pain as you progress.
You can see why emphasizing knee extension early on is so important! Unfortunately, the first days and weeks following surgery can be exhausting and overwhelming, which can make accomplishing this goal tough. People often feel compelled to rest with their knee slightly bent or sit with a pillow under their knee. While this is more comfortable, it will make knee extension more difficult. During this time, it is easier to focus on a few simple tasks vs. a long list of exercises. So, here are a few simple extension exercises to focus on, which most people can perform right away:
- Heel Prop: Sit with your leg out in front of you and prop your heel on an elevated surface (this could be pillows, the arm of the couch, or the coffee table). Make sure only your heel is on the propped surface and there is space underneath your knee for it to fully straighten – the more elevated your leg is, the better (elevation also helps decrease swelling). Try to relax and let gravity push your knee down.
Try to tolerate this a couple minutes at a time. Over time, work up to 10 minutes of propping, 5 times per day.
- (Assisted) Heel Pop: Not to be confused with the heel prop. This will help with end range extension and quad activation. Sit with your leg out in front of you on a firm, flat surface. Loop a non-stretchy strap (dog leash, towel, fitted sheet will work) around the bottom of your foot. Gently pull on the strap to lift your heel off the ground while trying to squeeze your quad and push your knee down.
You might have to work up to these. Try 10+ squeezes at a time, holding each squeeze/heel pop for at least 5 seconds. Once able, do this several times per day following the heel prop.
- Quad Set: Sit on a flat, firm surface with your leg out in front of you. Squeeze your quad while trying to push the back of your knee down toward the surface. This addresses quad activation, which can be very challenging at first. Sometimes it helps to practice on your other leg!
Try 20+ squeezes at a time, holding each squeeze for at least 3 seconds. It is good to do this right after you finish the heel prop & heel pop.
Performing these exercises is an excellent way to work toward achieving full knee extension after ACL surgery. I encourage everyone to work with a trusted, experienced physical therapist throughout their recovery process, and always consult their surgeon before performing any independent exercise. However, doing these on your own as part of a home exercise program will be an important part of the early rehab process, and will ultimately set you up for long-term success!
Disclaimer: Please consult your physician or health professional before engaging in any physical activity and stop if you experience pain or discomfort.
About Lauren Calamari, PT, DPT
Lauren graduated from the Medical University of South Carolina with her Doctor of Physical Therapy. She earned her undergraduate degree in Exercise and Sport Science from the University of North Carolina at Chapel Hill. She has experience treating middle school, high school, and college athletes, as well as active adults of all ages. Lauren currently works in an outpatient physical therapy clinic specializing in sports-specific treatment in Baltimore, MD. Her other professional interests include writing, education, coaching, and management.
- Delaloye JR, Murar J, Sánchez MG, et al. How to Rapidly Abolish Knee Extension Deficit After Injury or Surgery: A Practice-Changing Video Pearl From the Scientific Anterior Cruciate Ligament Network International (SANTI) Study Group. Arthrosc Tech. 2018;7(6):e601-e605. Published 2018 May 7. doi:10.1016/j.eats.2018.02.006
- Delaloye J-R, Murar J, Vieira TD, et al. Knee Extension Deficit in the Early Postoperative Period Predisposes to Cyclops Syndrome After Anterior Cruciate Ligament Reconstruction: A Risk Factor Analysis in 3633 Patients From the SANTI Study Group Database. The American Journal of Sports Medicine. 2020;48(3):565-572. doi:10.1177/0363546519897064
- Shelbourne KD, Gray T. Minimum 10-year results after anterior cruciate ligament reconstruction: how the loss of normal knee motion compounds other factors related to the development of osteoarthritis after surgery. Am J Sports Med. 2009;37(3):471-480. doi:10.1177/0363546508326709
Having undergone two ACL surgeries myself, I have an affinity towards seeing new exercises to help patients recover from ACL injuries. One of my favorite physical therapists that I follow on Instagram is Dr. Wesley Wang PT, DPT whose bio includes Sports & ACL Physical Therapy. Many of the exercises shown on Dr. Wang’s Instagram posts are athletes in the recovery process performing mid-stage or late-stage exercises. Compared to my own rehab experience, these athletes are performing advanced exercises leading towards return to play. For competitive athletes looking towards returning to play, working with a sports-based physical therapist may provide them with specific exercises to give them the strength and confidence to return to play and avoid re-injury.
One of the things I realize is that many patients don’t know what to expect after ACL surgery. My last ACL surgery was an out-patient procedure. Within 2 days after the surgery, a Continuous Passive Motion (CPM) machine was delivered to my house to start the process of gently flexing and extending my knee. A week after surgery was my first visit to out-patient physical therapy where my therapist evaluated my knee and provided me with the first of many exercises. Early exercises included Quad Set and Active Assisted Knee Flexion. Among the things I found most surprising post-surgery was how quickly my quadricep muscle mass diminished. Of course, this is why physical therapy is important and why it’s necessary to follow through with your home exercises. In total, it was about 6 months before I was close to being back to pre-surgery leg strength.
Each person will have their own unique recovery experience. Patience, hard work and consistently doing your home exercises will help lead to great outcomes.
PT-Helper has added three new exercises in our exercise library based upon Dr. Wang’s Instagram post.
Step Up Plyometric: Stand in front of a step or short box. Raise one foot above the height of the step. In one continuous motion, drop your foot onto the step then push down with your front foot raising your body up above step while driving your rear leg up in front of you. Push off the step with your forward foot such that your foot rises off the step. Return back down with one leg on the step and the other leg off the step. Raise your front foot of the step and repeat.
Heel Elevated Goblet Squat: Stand straight with your feet slightly wider than shoulder width apart, on top of an incline board. Hold a dumbbell or kettlebell with both hands close to your chest, elbows tight against your body. Tighten your core then bend your knees pushing your butt back while keeping your back straight. Straighten your knees to rise to a standing position. Repeat.
Step Shuffle: Stand to the side of a step with one foot on the step and the other foot to the side of the step. Hop from one side of the step to the other side, alternating which foot remains on top of the step. Repeat.
In addition to the exercises listed above, we have many more exercises in our Knee & Hip category available to help you achieve your recovery or fitness goals.