Knee Muscles Power Evolution in Patients with Total Knee Arthroplasty

Purpose: To measure changes in muscle power from before to 6 months after total knee arthroplasty and to compare outcomes with those from a control group of healthy adults. Material and Methods: 26 patients who underwent a total knee replacement were compared with 12 healthy age-matched adults in a prospective cohort study. Patients’ assessment was performed preoperatively, as well as at 1, 2 and 6 months postoperatively, by the isokinetic method. Healthy adults were assessed once by the same method. Isokinetic evaluation of knee extensor and flexor muscles was performed using a Gimnex Iso 2 dynamometer. After a warm-up protocol, measurements were done at angular velocities of 90 and 180°/sec. Results: Compared to healthy adults, patients performed significantly worse at all evaluation times, for both extensors and flexors of the knee, except for the 6-month evaluation at 180°/sec. One month postoperatively losses from preoperative levels were registered in patients, but without statistically significance, except for extension at 180°/sec. At 6 months postoperatively patients surpassed the preoperative levels, with statistical significance at 180°/sec. Conclusions: Power is an important parameter to follow after TKA, in parallel with peak torque. Increasing muscle power should be one of the central issues to address during postoperative rehabilitation.