Most patients have minimal pain by 3 months (or sooner) after knee replacement, and the majority return to the office and report that their discomfort level, activity, and quality of life are all dramatically improved. It is not unusual to have occasional muscle aches and persistent (but usually slight) swelling of the knee and extremity for several months. Depending on numerous factors, including the surgical approach, amount of surgical work needed, and particularly the state of the musculature around the knee before surgery, some persistent limp is usually expected. In some cases, a limp may be persistent for a long time after surgery (most often for a patient who has had significant muscle atrophy - or wasting - from longstanding disuse of the knee prior to surgery).
It is important to remember that while most patients are back working and getting out of the house within 6 to 8 weeks, they are usually continuing to see gains in muscle strength and range of motion for up to a year after surgery.
Returning To Work
There is a wide variation in how soon patients return to work. It primarily depends on what you do and also on your physical condition before surgery.
Obviously, a young person who is in good health aside from a bad knee will be back to work much sooner than a patient who is severely overweight and out of condition, but most everyone gets there eventually if their health is reasonable and they work at the rehabilitation. Partial knee replacement patients tend to recover significantly more quickly than total knee replacement patients, and patients who have had bilateral (e.g., both knee) procedures take a little longer.
Some patients have been back to desk jobs within several weeks. Others who have very physical jobs, such as laborers, may need to take 10 to 12 weeks until they are able to meet the demands of their job. We recommend that everyone returns to work when they can function safely and with reasonable comfort. Each patient is responsible for determining if he or she can safely perform the activities of his or her job (no one else knows what the job entails better than the person who has to perform it).
If there is some accommodation by the workplace (e.g., to allow someone who normally works a standing job to do light duty at a desk for a short while), most patients are back to at least limited work by 6 weeks.
Activities after Knee Replacement
In general, it is best to avoid impact activities after knee replacement. Although some patients do activities such as jogging or contact sports, they usually do so against medical advice. Avoid situations where repetitive impacts or sudden jolts might occur. Impacts will decrease the life of the replacement and increase the likelihood of early loosening, possibly necessitating revision surgery.
Low impact activities such as walking, golf, cycling, swimming, hiking, or ballroom dancing are good sources of activity and cardiovascular exercise, and these activities are well tolerated by joint replacements (assuming your general medical condition allows them). Skiing on gentle slopes is usually safe, although we recommend against downhill skiing that involves significant twisting and turning. Most joint replacements will last for many years with proper care and low impact activities.
Some patients enjoy yoga or pilates, and these activities are usually fine for routine exercise with some modification to accommodate the range of motion recommended by your surgeon. While hip replacement patients do have some range of motion limitations, knee replacement patients are limited by their own ability (e.g., knee replacement patients do not have to be mindful about dislocation like hip replacement patients do).
Sex After Knee Replacement
Another area that patients are often afraid or embarrassed to ask about is sex after any joint replacement. Hip replacement patients have a little more restriction (see that chapter), but knee replacement patients are again generally limited by what they can do.
Generally, sexual activity is safe for both men and women once they feel comfortable enough to resume activities. Most patients can resume sexual activity 4 to 6 weeks after routine knee replacement if they are otherwise healthy enough, often sooner with partial knee replacements.
One area of caution is that of kneeling. Total knee replacement patients in particular find that kneeling is too uncomfortable, although it generally does not result in physical damage to the knee. If you have more creative positions in mind, most things can be accommodated with some common sense and by going slowly. If you have a concern about a particular activity, it is probably best to just ask your surgeon about it rather than do something risky.
Going To The Dentist
In the past, most surgeons have typically recommended the use of prophylactic antibiotics before dental procedures. The reason has been that with dental work, there is often bacteria in the bloodstream for a short while afterwards that (at least theoretically) may lead to infection of the joint replacement. This concept is not limited to prophylaxis after joint replacement surgeries; many cardiologists also recommend antibiotics for patients with heart valve problems for the same reason.
In reality, there are bacteria in the bloodstream on many occasions (such as after brushing your teeth), and the risk of infection of an artificial joint is very low.
There are however some situations in which antibiotics are recommended. The American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) have jointly met and issued some guidelines regarding when antibiotics should and should not be used before dental work. Because this information also applies to knee replacements, there is an appendix with these guidelines at the back of this book.
Longevity of the Implants
Most patients want to have some idea of how long they can expect their knee replacement to last. This is highly variable, however, and there are many factors that contribute to the longevity of the implants used. A good analogy is that of a new car; when two different owners drive a brand new car of identical make and model off the lot, there may be a wide difference in how many years each is able to use the car based on mileage and how they drive.
Impact activities (running, basketball, and other jumping sports) will increase the likelihood of loosening for a knee replacement over time. The repetitive impacts can lead to slow but progressive loosening of the components from the bone.
Patient weight has a significant influence over how long the replacements will last. Heavier patients place a larger load on the implants, but conversely, they often are less active (e.g., take fewer steps in a year).
The type of bearing material used factors into longevity. There is some evidence that hybrid materials (e.g., zirconium oxide on polyethylene rather than traditional cobalt chrome on polyethylene) will last longer, and these more expensive implants are typically employed for younger and more active patients. At this point, however, with most revision surgeries performed in recent years we are typically seeing the surrounding bone wear out (e.g., loosening) before the implants themselves wear out.
If a part of the knee replacement does wear out, it often may be only the polyethylene liner that is worn while the metal components (fixed to the bone) are still good. In this case, most implant designs allow for a relatively quick procedure in which just the liner is exchanged.
Factors unrelated to the implants may shorten their lifespan, such as infection or trauma. I have treated patients who fell or were involved in motor vehicle accidents who fractured the bone around the implant, necessitating wiring or revision. In general, it usually takes the same amount of energy required to break a bone to damage the replacement, however.
Younger patients wear out their replacements more quickly than older patients. For this reason, many surgeons in the 1980's and 1990's recommended waiting as long as possible before replacing joints in young patients. While we still wait until all conservative (nonoperative) treatments are exhausted, we now recognize that the implants and technology have evolved to the point that even young patients can expect years of use before requiring revision surgery, and partial and total knee replacement can now give severely impaired patients their mobility and life back.
Please remember the information on this site is for educational purposes only and should not be used to make a decision on a condition or a procedure. All decisions should be made in conjunction with your surgeon and your primary care provider.