How to rehabilitate your total knee replacement

 Total knee replacement surgery is an effective way to relieve arthritis pain when non-operative measures have failed. A substantial portion of the outcome, however, is based on adequately rehabilitating after surgery. The most important part of the rehabilitation program is regaining normal range of motion. 

This is easier said than done. 

At the time of a properly performed knee replacement surgery, the soft tissues are balanced and the range of motion should be full. That is: all the way straight, to all the way bent. This is something we test during surgery. Then the incision is closed and the healing process begins. Initially, there could be some swelling and acute surgical pain from the incision/surgical approach. Soon this acute pain subsides and stiffness begins. The stiffness is experienced by many patients as pain, especially when moving against the endpoint.

In a prior posting I discussed the tissue planes that need to glide to allow proper motion. Each day that passes after knee replacement surgery, more healing occurs. This process can create connections, or adhesions, between these tissues. After about 6 weeks, enough scar tissue has formed, that most patients are unable to obtain more range of motion by stretching. In other words, at around 6 weeks from surgery no more progress with regard to range of motion is possible. 

The trouble is, in order to regain excellent function, adequate knee range of motion is necessary. Most patients are anxious to walk, ride a stationary bike, and are often quite focused on regaining strength. While these are fine things to do, and I certainly understand this desire, redirecting the focus to stretching appropriately remains my priority during the first 6 weeks postoperatively. Once range of motion is reestablished, all of these activities will be possible. Because we have a limited time to regain this range of motion this needs to be the priority early on. 

Thankfully these stretches are simple. Gently and progressively force the knee straight. And then gently and progressively force the knee bent. Simple! Except when it's not. 

Sometimes, and fortunately it is rare, a patient really struggles to regain range of motion after their total knee replacement. This can be a very frustrating situation for the patient and surgeon alike. 

I recommend stretching early, often, gently, but progressively. It is better to regain motion early than to attempt to catch up when stiffness is setting in. 

The simplest stretches are shown below:

knee extension stretch

This is one of the easiest stretches for extension. Place your ankle on a pillow. Relax your muscles to allow your knee to sag down. Then attempt to push the back of your knee down.  This is a side view of my knee. It is important to note that my kneecap and toes are pointing straight up. This stretch can be held for minutes, gradually relax your muscles more and more, allow gravity to do the work. The longer the stretch the more the viscoelastic tissues will elongate. 

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avoid external rotation when doing knee extension stretch

This is the wrong way to stretch. This is a view of my knee from above. There is a natural tendency to externally rotate as your hips relax. Our goals are not being accomplished if this is allowed to happen. If you find this happening, simply place additional pillows or folded blankets along the outside of your foot and thigh to hold your toes and kneecap pointing up. 

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knee flexion stretch

Now we are working on regaining flexion. In this example we are working on gaining flexion in my right knee (in the back ground of this photo). Here I have placed my left leg in front of my right ankle. I am using my left leg to help bend my stiff right knee more. This works best when done progressively over a period of minutes as opposed to seconds. Use your hamstrings in both legs to try to flex both knees further. 

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deeper knee flexion test using stepstool

For deeper flexion than the previous stretch,  this position utilizes a step-stool to provide deeper knee flexion. As shown, leaning forward and applying pressure with your hands can increase the stretch. 

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Deepest knee flexion stretch done in supine position

This is a stretch that can achieve extreme flexion. This time I am lying on my back. My knee is pointing up toward the ceiling. Flexing the hip relaxes the quadriceps. The hands are used to to pull the leg toward your body. The effect is increased hip and knee flexion. 

Please note: if you have a total hip replacement, be very careful with this position as it can produce significant hip flexion.

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These stretching positions should take care of 90% of total knee replacement patients. These stretches should be done everyday, ideally multiple times per day, with no days off. The longer the stretches can be held, the better. Remember to relax as much as possible while stretching and remember that a little pain is normal an expected. If no pain is encountered, I would recommend pushing a little bit harder. As always, if you have any specific questions about your particular case, discuss with your surgeon. 

​Occasionally we encounter a patient that has a very difficult time regaining motion. I have a few additional recommendations in these cases and will address that situation in an upcoming posting.