Objective measurements of knee of flexor and extensor strength using isokinetic equipment and function after total knee arthroplasty (TKA) were evaluated until postoperative 12 months.

The control group constituted of 15 persons who were of same age and weight without knee problems. Most of the patients (70%) were operated on both knees simultaneously. The patient group consisted of constituted with 20 patients (34 cases). Isokinetic testing (Cybex) of knee flexor and extensor strength of knee and functional evaluation by HSS score was performed preoperatively and at 3, 6, 12 months postoperatively.

The peak torque of the knee extensor and flexor muscle in the patient group was decreased by 17-41% compared to the control group. Especially, the peak torque of extensor was more decreased than flexor muscles. At postoperative 12 months, the peak-torque values of hamstring and quadriceps were able to attain the same strength levels of the preoperative knee. According to the grade of the Hospital for Special Surgery knee rating scales by Insall, 28 cases (82 %) in the patient group could obtain good result at postoperative one year.

Exercises to increase the strength of extensor should be emphasized in the rehabilitation programs after TKA