According to the American Academy of Orthopedic Surgeons, AAOS, knee replacements improve the quality of life and decrease knee pain in over 90 percent of people who have them. Although this is a promising statistic, a knee replacement may still restrict you from participating in certain physical activities, in particular high-impact activities such as running. Running after a knee replacement is currently not recommended by orthopedists, and there are several good reasons for this.
Implant Wear
The AAOS places running and jogging into the "dangerous activity after surgery" category and advises against any type of high-impact activity after a knee replacement. The reason for this is that running increases the rate at which your implant wears and may cause loosening of the implant. Instead, orthopedists encourage participation in activities that place a low amount of stress on your knees such as walking, swimming or biking.
Age
As the age at which individuals have a knee replacement gets younger and younger, knee replacements must last for a longer period. The average age range for a total knee replacement is 60 to 80 years of age, according to the AAOS. However, it is not unheard of for an individual 50 years of age or even younger to have a knee replacement. Since running accelerates the wearing of implants, if you are of a relatively young age you will most likely require a second knee replacement later.
Durability
Due to recent advances in technology, several types of materials are available for knee replacements. Most knee implants are made primarily of a metal such as stainless steel and a strong plastic material such as polyethylene. These materials are considered very durable and are associated with a low risk of complications.
Despite this, implants create considerably more friction than a normal joint surface. Over time, excessive wear can cause the release of small metal particles into your joint, which may result in inflammation and break down of the bone. However, this risk is lower for metal and polyethylene combinations than all-metal implants, which are no longer used for knee replacements.
Outlook
Though orthopedists currently advise against running after a knee replacement, a recent study by the AAOS may suggest that high-impact activities need not be avoided. According to a 2010 study, participation in high-impact activities not only had no effect on the wear of total knee replacements, it actually appeared to improve the functional knee scores of participants in the study. In addition, the rate of mechanical failure in the exercise cohort was only 8.5 percent, compared to 11 percent in the control group.
However, when the rate was adjusted for all variables, the mechanical failure rate for the exercise cohort was 10 percent higher than the control group, which suggests there still may be a risk associated with high-impact activities like running. Although the results are promising, the researchers suggest that a longer study is needed to evaluate the long term effect of high-impact exercise.
References
- American Academy of Orthopedic Surgeons; Total Knee Replacement; April 2009
- Hospital for Special Surgery; Joint Replacement: Implant Bearing Surface Materials; Timothy Wright, et al.; November 2007
- American Academy of Orthopedic Surgeons; Does Participation in Not-Recommended Sports Impact ... ?; Dr. Sebastian Parratte; March 2010
