Glossary
Range of motion (knee)
Quick answer
Range of motion is how far the knee straightens (extension) and bends (flexion), measured in degrees with a goniometer. Losing even a few degrees of straightening can cause a limp and pain, so it is measured at every visit before and after surgery, as Doha knee surgeon Dr. Pablo Gelber explains at Aman Hospital.
How it is measured
You lie on your back. The surgeon or physiotherapist lines up a goniometer, a hinged ruler, with the thigh and shin. First you straighten the knee as far as possible, then bend it, sliding the heel towards your bottom. Each knee is measured and compared.
A fully straight knee reads 0 degrees; some people naturally go a few degrees beyond straight. Many healthy knees bend to around 135 to 150 degrees. The surgeon also checks the movement passively, moving the leg for you, to see whether pain, swelling or something mechanical is blocking it.
Why it matters
Loss of straightening is the more troublesome problem. A knee that stays slightly bent makes the thigh muscles work harder with every step, causing tiredness and front-of-knee pain. A sudden block to straightening after a twist may mean a torn meniscus is caught in the joint.
Bending matters for daily life in Qatar: kneeling, sujood, sitting on the floor in a majlis and climbing stairs all need good flexion. After ACL surgery or knee replacement, regaining range early is one of the main goals of physiotherapy, and slow progress can be a sign of stiffness that needs attention.
Frequently asked questions
How much bend do I need for daily life?
Walking needs relatively little bend, stairs need more, and kneeling or floor sitting needs a lot. Your goals guide how hard you and your physiotherapist push for range.
My knee suddenly will not straighten. Is that urgent?
A sudden block after a twist can be a displaced meniscus tear and should be seen promptly by a knee surgeon, ideally within days.
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