Stiffness after total knee replacement

Most total knee replacements will not allow the same range of motion as a normal knee without arthritis. Very stiff knees before surgery often have stiffness after surgery. The expected range of motion after total knee replacement is 0 to 110 degrees but this can vary from patient to patient and some have more and some less motion.

It is normal to have stiffness of the knee immediately after surgery. The important thing is to be able to improve range of motion constantly in small increments early after surgery as most improvement will be in the first 6-12 weeks after surgery. Extension (straight) is more important than flexion (bend) in the early phase of rehabilitation.

Stiffness will generally last for several months after surgery, particularly stiffness after sitting and during the first few paces after getting up. This will improve over time and will mostly be gone after 6-9 months. Discomfort and a stiff feeling in the total knee replacement can continue to improve for up to two years. Unrealistic expectation and lack of information may also lead to unhappiness with progress.

Abnormal stiffness is usually lack of extension to within 10 degrees of full extension and flexion less than 90 degrees after 3 months despite physio. This is unusual and can be caused by several factors. The most common cause is severe stiffness before surgery. The next most common cause if associated with constant low grade pain even at rest in bed at night is a low grade infection. If this is suspected, then an assessment should be done by an experienced knee replacement specialist. Some people develop arthrofibrosis or severe scar tissue in the knee which is unpredictable and can lead to a very stiff knee but mostly pain free after 6-9 months.

Important to note is that unless there is a known reason for stiffness of a total knee replacement after 6 months, further surgery or revision of the knee is not likely to improve the range of motion.