Timeline for knee straightening or lengthening after ACL surgery
More than 200,000 anterior cruciate ligament (ACL) surgeries are performed in the US every year.[1] The anterior cruciate ligament or ACL is one of the four major ligaments in your knee.[2] Aside from a direct blow to the knee, injuries most commonly occur in sports that involve sudden movements, such as a quick stop or changes in direction. Common sports that cause ACL injuries include but are not limited to soccer, American football, basketball and volleyball. ACL reconstruction surgery is surgery that replaces a torn ACL.[2] The torn ligament is removed and replaced with a tendon; a band of tissue that connects muscle to bone. Regaining full extension of the knee, also called range of motion of knee extension or ROM, is one of the most important goals after ACL surgery.[1] Many studies show that people can fully extend their knee and have good results after ACL surgery.[1] However, this does not mean that straightening the knee is easy. That’s why I want to help you answer some frequently asked questions about knee straightening after ACL surgery.
When can I fully extend my knee or knee stretch again?
The goal for full extension or straightening of the knee after ACL reconstruction surgery is usually 8-12 weeks or between months 2 and 3 after your ACL surgery. For most people, the first four weeks are focused on allowing the tendon to regrow and hypertrophy or become larger, while the next four weeks are focused on strengthening the tendon.[4]
Timeline and possible recommended exercises
Please use the following as a guideline and understand that this is based on research-based ACL protocols, but it may not be suitable for you if you have not had standard ACL surgery. Also check with your doctor to make sure these exercises are safe and appropriate for you. You can also learn about a general ACL recovery timeline by reading our previous blog.
The suggested knee extension exercises below should be performed daily if you have had standard ACL surgery.
Immediate Postoperative ACL Surgery Weeks 0-1
Purpose: To control pain, swelling and inflammation. Place weight on the surgical leg if your surgeon gives you permission to do so.
Assignments:
Muscle setting exercises – contract and relax your leg muscles without moving the leg, just squeeze and relax your leg. These are also called isometric exercises.
Single pumps
Straight legs go up
Heel slips
Knee extensions or knee stretches. Normally you will not be able to fully straighten your knee in the first week. When your leg and knee are flat, this is called 0 degrees of knee extension. In the first week you have no knee extension. Your knee may remain bent when you try to straighten it and this is normal in week 1. Typically people lack 10 to 20 degrees of knee extension and this will be ‘-10’, ‘minus 10’ or ‘-20’, called ‘minus’. 20″ degrees of knee extension. The “-” or “minus” indicates that you have not yet reached 0 degrees of knee extension.
Lie on your stomach and bend your knee, unless you have had a hamstring tendon transplant for your ACL
Other tips: cryotherapy, which is the use of ice or other cold therapy, postoperative compression wrappings such as a tensor bandage, and elevation using ice and compression.
ACL surgery Weeks 2-3
Goal: full weight bearing without crutches with a normal gait or gait pattern
Assignments:
Continue with the exercises from phase 1, may increase from -20 or -10 to 0 degrees of knee extension. It’s hard in the second and third weeks, but you have to work hard to reach 0 degrees of knee extension.
Gait training – walking on a treadmill or a flat surface without crutches
Stationary cycling and DO NOT cycle outside
Usually swimming from week 3, as long as the stitches are removed and the scars are healing properly.
ACL surgery Weeks 4-6
Goal: Near full range of motion, double-leg squats, single-leg calf raises
0 degrees or knee extension
Climbing or climbing stairs from week 4
Assignments:
Step-ups – stand in front of a staircase or step stool, place your foot on it, stand up and shift your weight to the thigh and contract your quadriceps muscles
Step-downs – same process as step-ups, but start with your leg on the step and lower your body and leg in a slow and controlled manner.
Calf goes up
Hip extensions
Hamstring stretch
ACL surgery Weeks 7-8
Goal: Near full range of motion or full range of motion, full weight bearing during normal gait
0 degrees or more knee extension. Many people have knee extension of more than 0 degrees. This means that your knee bends backward more than in a straight line, which is normal. Extension greater than 0 is called “plus” or “+” degrees of knee extension. If a person’s knee bends 5 degrees more than a straight line, this is called “+5” or “plus 5” degrees of knee extension.
Assignments:
Continuation of exercises from phase 1 and weeks 4-6
Exercises that place more strain on the surgical leg and exercises with one leg, such as the step up, lunges and single leg sit to stand from a chair.
How can I improve my knee extension ROM after ACL surgery?
Loss of knee extension is a common complication after ACL reconstruction surgery.[5] Before your surgery, it is helpful to know that being able to fully extend your knee will reduce the chance of loss of extension after your surgery. Loss of extension can also lead to abnormal articular cartilage and poor quadriceps movement. These are the muscles in the front of your thigh, making it important to stick to your rehabilitation exercises.[5] Articular cartilage is the tissue that covers the ends of bones where joints form, making it easier for the joints to move. Recommended treatment strategies to achieve full extension include exercises such as extended low-load stretching and calf stretches.[1] Rehabilitation with knee extension often involves weekly progression. Progress in ROM should be monitored and continually assessed to ensure you are achieving your knee extension goals, based on your rehabilitation protocol and the advice of your healthcare provider.[4] In this blog you will also find some practical tips for improving your knee extension and knee flexion after ACL surgery.
Conclusion
ACL reconstruction surgeries are quite common and therefore the rehabilitation process and timeline are very well understood and researched. However, people often worry about the progress of their rehabilitation and especially whether they are achieving their knee’s range of motion at a normal pace. Following or adhering to your rehabilitation protocols or programs is critical to the success of regaining full knee extension. It’s important to remember that not everyone’s timeline will be the same, but 8-12 weeks is the average time to regain full knee extension after ACL surgery.
If you have had ACL surgery and want clear daily, weekly and monthly guidance for your knee extension and daily exercises for your recovery, try our Cuorvate app. Curovate offers video-guided daily exercises, weekly range of motion goals and exercises, progress tracking, the ability to measure your knee and hip range of motion, and in-app chat with a physical therapist.
If you need more tailored help during your ACL recovery, check out our Virtual Physiotherapy page to book your 1-on-1 video session with a physiotherapist.
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