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Muscle Power and Body Weight as Predictors of Success after Knee Replacement Surgery

Predicting success after total knee arthroplasty (TKA) isn't always easy. Patients want to know what to expect and how long it will take to recover. Doctors don't have a lot of research to use when advising patients.

This study looked at the rate of recovery for mobility in the first six months after TKA. The authors set out to find factors that affect results, such as age, weight, type of joint implant, pain, and other medical problems. It's likely that some factors are more important than others. They tried to rank these factors.

Stair climbing and walking speed were used as the main indicators of success. Measures were made one week before and three and six months after the operation. Researchers thought knee strength and range of motion would affect recovery the most. When it was all said and done, two factors were most important. These are quadriceps muscle power and body mass index (BMI). The quadriceps is the muscle on top of the thigh that straightens the knee. BMI is the current way to measure obesity.

Being overweight with decreased muscle power appears to put patients at risk for failing to recover mobility after a TKA. The authors suggest that exercise and weight management will help patients regain stair climbing and walking abilities. They don't know if it's best to strengthen the quadriceps muscle before or after the joint replacement. More studies are needed to answer this question and to show if such a program would give lasting results.

References: Sarah E. Lamb, DPhil, MSc, MCSP, and Helen Frost, MSc, MCSP. Recovery of Mobility after Knee Arthroplasty. In The Journal of Arthroplasty. August 2003. Vol. 18. No. 5. Pp. 575-582.

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