Post-Operative Knee Exercises following ACL Reconstruction (ACLR)

ACL ruptures can be an intimidating injury to rehab. From the initial rupture, we often see our clients struggle with instability, swelling, lack of muscular control, and pain. Fortunately, there is an encouraging body of literature growing on ACL rehab, providing more specific guidance on best management practice for athletes who choose to undergo ALR repair, and also for those who choose to manage their injury conservatively. 

In this blog post, we will explore the importance of a comprehensive post-operative exercise program following ACL reconstruction surgery. Whether you are a professional athlete, weekend warrior, or just working to stay active for general health and wellbeing, this guide will provide you with valuable exercises and rehabilitation tips to support your journey.

1) The Anterior Cruciate Ligament (ACL) and Its Role:

The knee joint is a complex structure, and the ACL is a key component in providing stability and preventing excessive forward movement of the tibia (shin bone) in relation to the femur (thigh bone). Along with the posterior cruciate ligament (PCL), the ACL helps maintain alignment and function of the knee joint during various activities. The ACL is vulnerable to injury due to its location within the knee and its role in resisting forces that could potentially lead to excessive movement or hyperextension.

Following a suspected ACL injury, a physiotherapist or other qualified professional will perform an examination to determine the extent of the injury, and if any other structures are involved. Depending on the results of this exam, the physio may recommend conservative (non-surgical) rehab, further imaging, or referral to a surgeon. 

The good news is that there is no rush for surgery! Spending a few months working through progressive strengthening as part of a conservative management strategy is actually recommended by many surgeons, as it allows time for the knee to calm down and for you to rebuild strength. People often choose not to undergo surgery after conservative treatment if they’re able to cope well (sometimes with bracing assistance). If you do choose to opt for a repair, waiting for surgery does not affect outcomes. Remember, the stronger you go into surgery, the better you’ll come out! 

If you decide with your physio and surgeon to pursue surgery, the focus shifts to rehabilitating the new ACL site to restore its strength and stability. The surgical procedure involves replacing the torn ACL with a graft (often from the patellar tendon or hamstring), which requires careful post-operative care and rehabilitation to optimize healing and functional recovery. Post-operative knee exercises play a crucial role in this process.

2) Causes of ACL Injury:

ACL injuries often occur during non-contact situations, such as sudden deceleration, landing from a jump, or pivoting movements that place excessive stress on the ligament. Sports like soccer, basketball, football, and skiing, which involve cutting, pivoting, and high-impact movements, quite often see athletes with ACL injuries, especially if the athlete lacks sufficient muscle strength to handle the movements. 

To manage risk of ACL injury, athletes should focus on dry-land neuromuscular training that emphasizes quadriceps strength, as well as proper landing mechanics, cutting, and pivoting techniques.The quadriceps, hamstrings, glutes, adductors (groin muscles), and gastrocnemius (calf muscles) are essential structures for helping to stabilize the knee, so exercises targeting these muscles can help provide a layer of protection, by optimizing the dynamic stability within the knee. 

3) The Role of a Physiotherapist in ACLR Rehab:

At Defy, our role is to guide and support you throughout your recovery journey. We’re here to help you get a picture of what your injury involves, guide your decision for the best pathology forward, and tailor the rehab process to your specific needs. A custom rehab plan will include various elements, such as education, hands-on therapy, and exercise programs, all designed to promote strength, stability, and mobility. Remember, ACL surgery is not a quick fix — typically rehab will last anywhere from 9-18 months, and requires consistent effort on your part. 

Education plays a crucial role in understanding the healing process, the importance of following the prescribed rehabilitation program, and the potential challenges you may encounter during your recovery. Hands-on therapy, including manual techniques and modalities, helps manage pain, facilitate muscular activation, and restore joint mobility in the acute phase. Most importantly, the exercise program, which includes a range of exercises targeting different muscle groups and movement patterns, aims to improve muscle strength, flexibility, balance, and functional movements specific to your goals.

4) Post-Surgery Exercises for Knee Rehabilitation:

To assist you in your ACLR recovery, knee exercises are generally categorized into early, intermediate, and advanced stages of rehabilitation, with much overlap between. It is important to note that each individual’s recovery timeline may vary, and exercises should be performed under the guidance of a physiotherapist. Here are some exercises that can support your rehabilitation journey.

Early Stage Exercises:

The goal of early stage rehab is to reduce swelling, restore normal range of motion, and start to “wake up” the muscles after surgery. Some basic exercises include: 

  • Heel slides for knee flexion
  • Quad sets for muscle activation
  • Straight leg raises 
  • Ankle pumps for swelling control
  • Range of motion exercises
  • Gait training to restore normal gait mechanics and reduce compensations 

Intermediate Stage Exercises:

The goal of intermediate exercises is to start to introduce some load into the knee joint and new graft. It’s also to optimize muscular engagement to help restore function and support the healing knee. 

  • Wall sits or Spanish squats
  • Knee Extensions and Hamstring curls
  • Lateral banded walks
  • Step-ups and step-downs
  • Single-leg balance exercises (eyes open, eyes closed, or with perturbations). 
  • Proprioception drills

Advanced Stage Exercises:

In the advanced stages, ACL rehab often looks like a comprehensive lower extremity strength program. Heavier weights are introduced to help load and strengthen the graft and optimize muscular recruitment. As the athlete progresses, more sport-specific tasks like running, cutting, and plyometric exercises are introduced. 

  • Split Squats
  • Barbell and dumbbell squats, leg press and single leg loading. 
  • Deadlifts and Single-leg deadlifts
  • Return to run programming
  • Box jumps, countermovement jumps, and drop jumps.
  • Sport-specific drills to prepare for pivoting and cutting movements 

It is crucial to perform these exercises routinely, progress gradually, and adhere to the prescribed exercise program. Regular attendance at physiotherapy sessions is highly recommended, as it allows your physio to monitor progress, provide hands-on guidance, and make necessary adjustments to your rehabilitation plan. Evidence shows that supervised rehabilitation leads to better outcomes, faster recovery, and reduced risk of complications.

Recovering from an ACL rupture requires a comprehensive approach that includes post-operative knee exercises and proper guidance from appropriate professionals. By understanding the anatomy and function of the ACL, starting rehab immediately, and following a personalized rehabilitation plan, you can optimize your recovery and safely achieve your goals.

At Defy, we are here to support you throughout your ACLR recovery journey. If you have any questions or require personalized rehab programs, do not hesitate to contact us. Our goal is to help you understand every step of the diagnosis and rehab process to help you make an informed decision about your injury, and guide you through a custom rehab program specific to your goals. Take the first step toward a successful ACLR recovery by reaching out to our team today!


1) How do I strengthen my knee after ACL surgery?

Under the guidance of a Physiotherapist, progressively loading your knee is the best way to strengthen. This means starting with smaller exercises geared toward isolating certain muscles, such as quadriceps and hamstrings, and progressing into more functional movements that work multiple muscle groups like squats and lunges. Your strength programming should be individualized based on your surgery, as well as the strength base you are starting with post surgery.

2) What exercises to avoid after ACL reconstruction?

This depends on the details of your ACL surgery. Some individuals have meniscus repairs as part of their surgery, after which the surgeon may restrict knee bending to 90 degrees for a period of time. The surgeon protocol will dictate their comfort with certain exercises. There is controversy about using the knee extension machine, but the most recent literature shows this to be safe at certain ranges and a great way to strengthen the quadriceps. If a hamstring graft was used, there may be restrictions on loading the hamstring for a period of time to allow the site to heal.

3) What is the most important exercise after ACL surgery?

Immediately after ACL surgery, the most important thing is managing swelling through elevating and restoring knee flexion (bending). In conjunction with decreasing swelling, it is key to get the quadricep muscle firing and restore full knee extension both passively and actively. Thirdly, eliminating any gait compensations by using crutches until gait is completely normalized is very important. There are many more important exercises along the long course of ACL rehab, however these are most important immediately following surgery. 

4) How do you exercise your knee flexion after ACL reconstruction? 

Knee flexion, or bending the knee, is best achieved early on by laying down or sitting with the legs out straight and using a strap to assist the heel to move toward the bottom. Over time this will be easier to do without a strap. There are also machines that will do continuous passive motion and repeat the knee flexion movement for you. If a meniscus repair is part of your repair, you will likely receive a flexion limitation from your surgeon for a period of time as part of your rehab protocol.

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