Surgery Benefits

Total knee replacement is one of the most successful of all surgical procedures. Total knee replacement initially got a bad name as compared to total hip replacements. Early designs did not take into account the complicated biomechanics of the knee joint. The implants were designed as fully linked hinges (completely constrained) resulting in high stresses being placed at the point of fixation to the bone. In the 1970's less constrained knee replacements were developed. These designs allowed the stress to be taken up by the ligaments and yet had enough constraint to provide stability. Use of these prostheses and development of more accurate instrumentation has allowed the success rate to increase dramatically. At the present time knee replacements in the appropriate patients, are felt to succeed 95% of the time; these results are actually better than total hip replacement.

A "success" is defined as freedom from pain and restoration of motion as well as function. A successful knee replacement will allow a person to return to the routine activities of daily living. Certain restrictions do apply however. Persons with total knee replacements should not expect to resume jumping or jogging activities (impact loading). Lifting of weights of greater than 20 pounds should be avoided. Multiple repetitive loads such as walking long distances (greater than a mile) should be avoided. Tennis and racketball are not advised but golf, swimming and bicycling are good exercises. There are also some restrictions of motion. Although the leg with a knee replacement can flex up to 120 degrees, it is not advised that you attempt to bend it more. Therefore, it is not possible to squat and kneeling may be painful. An ideal candidate for total knee replacement is a patient who is over 65, not overly active, with normal mental capacity and who is not overweight.

The converse of this represents the so called "high risk patient" for total knee replacement; namely those who are under 65, overweight, very active or, who have had a previously cemented total knee that has failed. The relative success rates and risks in this group are discussed below.

In summary, if you are an ideal candidate, the expected benefits from total knee replacement should offer a 95% chance of relieving your pain and restoring motion and function for routine activities of daily living.