ROM (range of motion) information


Nurse Director
Jun 8, 2007
The North
United Kingdom United Kingdom
ROM or Range Of Motion is both flexion (bending) AND extension (straightening)

ROM show.jpg

Range of motion or ROM is a medical/anatomical definition not a mathematical one. The range of 180-360 degrees is not factored in, presumably because the lower leg cannot move in an entire circle!

To measure degrees of flexion using the goniometer, the zero is on the ankle and the 180 on the hip. Thus full extension is 0 degrees. As the foot moves towards to hip, so the numbers go up - the right angle at the knee being (hardly surprisingly) 90 degrees, and so on.

knee ROM small.jpg

Any extension with the knees going backwards (hyper-extension) uses the 0-180 degrees on the opposite arc so a knee is said to have (for instance) -5 degrees of hyper-extension. Here are examples of what (extreme) hyper-extension can look like.

Standing hyper-extension


Laying hyper-extension

hyperextension 2.JPG

These degrees of flexion are required for the following activities:
- 65° to walk,
- 70° to lift an object from the floor,
- 85° for stair climbing,
- 95° for comfortable sitting and standing
- 105° for tying shoelaces.
Range of Motion (ROM) is measured by your surgeon or therapist using a device called a Goniometer. You can purchase one yourself so that you can do the measuring. One of the best places to buy a Goniometer is on Ebay.

When you measure, it is important that you place the Geniometer properly:

As you can see here, when the goniometer is applied to the straight leg, the hinge is to the back of the knee.


This means that when you flex the knee, the hinge remains in that position which can look rather low.



Make sure you 'aim' the upper arm along the femur towards the greater trochanter or hip done, which is more towards the back of the thigh than the front since there's a considerable quantity of muscle in front which can be misleading. The lower arm should end on the outer ankle bone which is the bottom of the fibula. You can see the dots the examiner has placed on these two points.

If you decide to track your ROM closely, remember that this measurement is JUST A NUMBER! The real key is your ability to do the things you want to do in life following your knee replacement. There is no "magic number" that gives you that's personal and something you will have to determine for yourself.

Another point, normal knees usually get from 130 to 150 depending upon the leg. The skinnier it is, the more ROM it can achieve! (Hence mine is currently 'stuck' at 135!) It's rarely to do with the implants as they nearly all will flex to 155 outside the body! It's tissues that block it not scar tissue. Just normal tissue (or fat!).

You can assess your own extension (straightness) yourself using this technique:
1. put your leg on a bench, seat, bed, floor or anything similar but preferably something fairly firm.
2. with not too much pressure, press the back of your knee down - use your leg muscles, not your hand!
3. slide your hand, palm down, under the back of your knee
a) if you can get your entire hand under easily, it's probably about +10 degrees
b) if you can get just your fingers under, it's about +5
c) if you can get your fingers under but it's a push, it's +0
d) if you can't get your fingers under at all, it's -5 or more​

Here's a graphic to explain the degrees involved

I'm 12 months out from my surgery and have some advice based on my experience:
1. Stop going to PT - all it will do is make your knee swell and reduce ROM
2. Don't worry about your ROM
3. Be patient - VERY patient!!!​

Here is my ROM history (more or less):
1 month - 60 degrees
2 months - 80 degrees
3 months - 85 degrees
4 months - 90 degrees
5 months - 90 degrees
6 months - 110 degrees
7 months - 120 degrees
8 months - 125 degrees
9 months - 130 degrees
10 months - 135 degrees
11 months - 140 degrees
12 months - 140 degrees

I spent waaaaay too much time worrying about ROM. I thought I'd be riding my bike a couple months after surgery but it took SIX months!

Looking back on my surgery, if I knew then what I know now, I wouldn't have wasted my time with PT and I wouldn't have worried about ROM.

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