Why laying on your stomach isn’t the best way to regain knee extension

(Last Updated On: April 30, 2018)

After a knee surgery, such as meniscus, ACL, or joint replacement, the number one initial priority is regaining knee extension range of motion. That is, the ability to straighten the knee.

A common way to do this is lay on a table with the leg hanging off. The prone leg hang:

This is not a good way to go about it.

1. You can’t see how the knee is doing. You’re trying to regain normal range of motion, correct? The easiest way to do this is look at the good leg and see if the injured leg is symmetrical. You can’t see the good leg when on your stomach!
2. “But you can feel how the knee is doing.” Ha! After a knee surgery the last thing a person has is a solid mind-body connection with the joint. If you have an ACL surgery, you might feel like your knee is three feet off to the side.
3. The foot is going to be hanging below the head. Blood is flowing into the knee. Why deal with this -potentially extra swelling- if we don’t need to? Increasing range of motion is easier if we’re pushing blood out of the knee.
4. If you just had ACL surgery, there is a very good chance you had a hamstring graft. It will feel like the hardest thing in the world to perform a leg curl after such a surgery. You know, because part of your hamstring has been cut off! It’ll take some time to regain that strength. Meanwhile, if you’re in this prone position, and the stretch becomes too much / painful -which is bound to happen at times- good luck trying to curl the leg / bend the knee of the stretch.
   1. You could use the good leg to help alleviate this.
5. Compensation is much harder to correct. Notice the bottom right picture above, how the practitioner is pushing down on the hip. This is to prevent the person from lifting the leg up, lessening the stretch.
   1. If the person feels the need to do this, the stretch is too much to begin with.
   2. What do you do when nobody is around to keep you honest? Regaining this range of motion has to happen more than at one’s 1-3x a week physical therapy sessions.
6. The equipment necessary to do a prone leg hang isn’t always available. I’ll use my surgery experience as an example-
   1. I’m a personal trainer. During the day I was at the gym. There aren’t tables at the gym. Furthermore, I’m 6’4″. I ain’t fitting my whole body on a bench comfortably.
      1. Comfort matters here. When we are doing long duration stretching, trying to loosen up a stubborn joint, relaxation is paramount.
   2. My bedroom was upstairs in the apartment I stayed at. It’s easily conceivable a person avoids stairs for 2-4 weeks after a knee surgery. The bed is going to be the most used / analogous table equipment for this stretch. What if you can’t get to the bedroom, and your living room (the couch you’re sleeping on) doesn’t have anything amenable?

4. and 5. aren’t necessarily deal breakers. They make life harder than necessary, but are plausibly correctable. 6. depends on the individual circumstance; 1., 2. and 3. are a different story. We’re pushing our luck trying to mitigate them, while staying in the prone position.

Someone might argue while on your stomach, while you can’t see the knees, one could use the toes as a barometer e.g. if the uninjured side toes are lower than the injured side, then the knee extension isn’t symmetrical. But again, this assumes no compensation is occurring. Without an objective pair of eyes, it’s risky to accept going based on exerciser’s interpretation.

It’s not so much prone leg hangs can’t work. It’s there’s a better way.

Check out the Regaining Knee Extension manual for how.