[Comparison of the effectiveness of isokinetic vs isometric therapeutic exercise in patients with osteoarthritis of knee].

INTRODUCTION Osteoarthritis is a chronic joint disease; isometric exercise leads to the development of mechanical work and isokinetic exercise leads to better joint mobility. OBJECTIVES To compare the effectiveness of isometric versus isokinetic therapeutic exercises in patients with knee osteoarthritis. MATERIAL AND METHODS Quasiexperimental study in a population of 45 to 75 year old patients with a diagnosis of knee osteoarthritis. Group 1 (experimental) was put under isokinetic exercises and group 2 (control) under isometric exercises. The sample size was of 33 patients per group; the allocation to the experimentation or control group was nonrandom, but stratified by degrees of knee osteoarthritis. The effectiveness of the exercise was measured in three dimensions: muscle strength, joint range and pain. The intervention lasted eight weeks and the physical activity was carried out every third day. The statistical analysis included averages, standard deviation, percentage, Chi square test, z test for two populations, t test for two independent populations and twin t test. RESULTS The analysis of muscle strength comparing the categories independently demonstrates differences at 8 weeks; 33.3% of the isokinetic exercise is in the normal category and 15.2% in the isometric exercise (p= 0.04). There was not difference of joint range between groups, despite finding a stage I range in 100.0% of the isokinetic group and 97.0% in the isometric (p> 0.05) group. Pain was milder in the isokinetic exercise group at 8 weeks (p= 0.01) CONCLUSIONS Isokinetic exercises have a greater effectiveness than isometric exercises for muscle strength and pain in patients with knee osteoarthritis. However, other studies with randomized designs are needed.