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.


Arthroplasty, Muscle strength, Power, Isokinetic, Rehabilitation