The best total knee extension stretch

I previously discussed how important it is to regain full knee extension following total knee replacement. Full knee extension is required for a normal, low energy gait cycle. Anterior knee pain can occur for a variety of reasons, but lack of full knee extension (otherwise known as a knee flexion contracture) will overload the patellofemoral joint (knee cap and femur joint) causing pain. Unfortunately, regaining knee extension after total knee replacement is generally challenging and often uncomfortable. I previously discussed the basic stretches I commonly recommend. Today I demonstrate the prone hang technique. This method uses gravity and relaxation to gently and progressively induce full knee extension.

Knee flexion contracture in prone position

Here I am lying on my stomach. My left knee (closest to the viewer) is held slightly flexed. This demonstrates the appearance of a knee flexion contracture. Remaining in this position for long periods of time (a minimum of 10 minutes 6 times per day) will result in gradual correction of the flexion contracture. The longer you remain in this position the better. Ideally you would spend a half-hour or more in this position several times each day. A long duration, gentle stretch will allow the viscoelastic biologic tissues to elongate.

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Prone hang technique with additional force provided by opposite leg

By placing my opposite foot on the back of my heel and relaxing, my left knee is pushed into a more extended position. In this case, my right leg provides additional weight, helping gravity force my left knee straight. This may be necessary for more resistant cases of knee flexion contracture. 

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Prone hang technique with full knee extension achieved

This is the goal. Full, symmetric extension of both knees. 

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Prone hang technique with additional force provided by sandbag or ankle weight

Here I have placed a sandbag on the back of my ankle to provide additional extension force to my left knee. An ankle weight would also work nicely.  Remember, the goal is to relax and allow the soft tissues (posterior capsule) to progressive elongate. This takes time. I recommend spending at least 10 minutes in this position several times per day. Longer is better, and will result in faster gains. Remaining in this position for 30-60 minutes at a time is challenging but ideal. 

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Time and effort spent regaining full knee extension after total knee replacement will result in better knee function and reduced knee pain for the life of your knee replacement. As with all the stretching techniques I recommend, gentle, progressive, long-duration stretches. Cycling or bouncing the stretch is not necessary and probably irritating/counterproductive. Try to relax as much as possible during the stretch. Remember that some increased pain during and immediately after stretching is normal and expected.

​The sooner you are able to regain full knee extension following total knee replacement the better you will feel, the easier your rehabilitation will be, and the more rapid the restoration of an efficient gait cycle.