If you are either considering or having a knee replacement, you are not alone. Total knee replacements are one of the most common surgeries in the world. In 2017, there were 754,000 people who had a knee replacements in the United States alone.  By 2025, the number of knee replacements is projected to rise to more than 1.2 million. Knee replacements are an effective way to relieve your knee pain, improve your knee function and help you resume normal activities.  To learn more about knee replacements head over to our blog “What is a total knee replacement?”.
Unfortunately, although a knee replacement may help to resolve the symptoms of knee pain and activity limitation you are currently experiencing, it is unlikely that your knee will function as well as a completely healthy knee. Learn about the recovery timeline after a knee repalcement.
Six months after a knee replacement
One study compared 24 people, 6 months after a total knee replacement, to 17 adults who did not have a knee replacement.  All people included in the study were between the ages of 50 to 85. Some of the tests that were used to measure ability to function were the stair-climbing test, timed up-and-go test, 6 minute walk test, quadricep strength test and knee range of motion test. The stair-climb test is administered to assess your ability to climb stairs. The timed up-and-go test is used to assess your mobility. The 6 minute walk test is used to assess your endurance. Knee range of motion refers to your ability to bend and straighten your knee. The authors found that people who had a total knee replacement performed worse in all these tests compared to people who had never undergone a knee replacement. Therefore, this study showed that 6 months after knee replacement surgery your function will likely be worse than a healthy knee.
One year after a knee repalcement
Another study compared 243 people, one year after a total knee replacement, to 257 people who had never undergone knee replacement surgery.  This was an age matched study, which means only people that were similar in age were compared to each other. If you are wondering if there is an ideal age to undergo a knee replacement read this blog. Everyone was given a comprehensive questionnaire to assess their ability to function and 52% of people who had a knee replacement reported some degree of limitation in doing functional activities, while only 22% of people who had not had a knee replacement reported limitation with their function. Therefore, this study showed that 1 year after knee replacement surgery your functioning will likely be worse than a healthy knee.
Two years after a knee repalcement
Lastly, a third study compared 32 people, two years after a total knee replacement surgery, to 52 healthy knees.  The authors found that people who had a knee replacement had less strength in their knees compared to people who had never had a knee replacement. The authors used two measures of knee strength, isometric extension peak torque and isometric flexion peak torque. Isometric extension peak torque is a measure of how much force you can generate when you straighten your leg, and isometric flexion peak torque is a measure of how much force you can generate when you bend your leg. The results showed that people who had knee replacements had 30.7% lower isometric extension peak torque and 32.2% lower isometric flexion peak torque. Therefore, this study showed that 2 years after knee replacement surgery your functioning will likely be worse than a healthy knee.
Knee replacements are a safe and effective way to relieve your knee pain and improve the overall function of your osteoarthritic knee. However, studies have shown that it is unlikely that your replaced knee will function as well as a fully healthy knee. As always, consult your healthcare provider before making any final decisions. Curious to learn more about knee replacements? In need of an effective guide to your recovery? Try the Curovate app, an evidence-based app that will provide you with a physical therapy plan, guided daily video exercises, and more to assist you along your journey to recovery! Download Curovate today by clicking the links below!
If you need further customized assistance during your knee replacement recovery check out our Virtual Physical Therapy page to book your 1-on-1 video session with a physical therapist.
Blogs related to knee replacement
- 6 Things You Need to Know After A Total Knee Replacement
- What is the Recovery Timeline for a Total Knee Replacement
- Why does my knee feel weird after my total knee replacement? Why does my knee feel heavy after my total knee replacement?
- Knee replacement recovery: After knee surgery can I kneel? How do I sleep? What movements are safe and what should I avoid
2. Singh JA, Yu S, Chen L, Cleveland JD. Rates of Total Joint Replacement in the United States: Future Projections to 2020–2040 Using the National Inpatient Sample. The Journal of Rheumatology. Published online April 15, 2019. doi:10.3899/jrheum.170990
4. Noble PC, Gordon MJ, Weiss JM, Reddix RN, Conditt MA, Mathis KB. Does total knee replacement restore normal knee function?. Clin Orthop Relat Res. 2005;(431):157-165. doi:10.1097/01.blo.0000150130.03519.fb