Analysis of factors that affect changes in knee muscle strength and range of motion before and after knee arthroplasty

Background: We investigated the involvement of basic and medical attributes in the changes in knee muscle strength and range of motion from before to after knee arthroplasty. Methods: The study included 545 patients who underwent knee arthroplasty. The muscle strength and range of motion during knee extension and flexion were measured 2 weeks before and after surgery. The amount of change from before to after surgery was calculated by subtracting the preoperative value from the postoperative value. A Wilcoxon test was performed to compare the muscle strengths and ranges of motion before and after surgery. Furthermore, to analyze the factors involved in the changes in muscle strength and range of motion, a multiple regression analysis was performed with inclusion of preoperative values as the control variable. Moreover, the effect of each measured value on the amount of change was confirmed using a stratified graph. Results: The muscle strengths and ranges of motion during knee extension and flexion were decreased after the surgery especially in women. This decrease was less after unicompartmental knee arthroplasty(UKA)than after conventional total knee arthroplasty(C-TKA). In addition, the muscle strengths during knee flexion after surgery decreased as age increased. Furthermore, the decrease in range of motion during knee flexion was less after UKA. Conclusion: Our results show that decline in knee function after TKA tended to occur more frequently in older women and less likely to occur after UKA.

Keyword: multiple regression analysis, surgical procedure, sex, age, preoperative value

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