Comparison of the Effects of Isokinetic, Isometric, and Isotonic Exercises on Knee Osteoarthritis Using Ultrasound

Introduction: This study aims to investigate the effects of different types of exercise on pain, functional capacity, muscle strength measured by an isokinetic dynamometer, and femoral cartilage (FC) thickness measured using ultrasound in patients with knee osteoarthritis (KOA). Methods: Sixty patients were randomized to isokinetic, isometric, and isotonic exercise groups, and exercise programs were completed five days a week over three weeks. The FC thickness for each knee was evaluated in medial, intercondylar, and lateral areas using ultrasound, and muscle strength was assessed by an isokinetic dynamometer. Activity levels were also measured using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). At three weeks from baseline, follow-up clinical measurements of knee muscle strength and FC thickness were performed. Results: A significant decrease was observed in all three groups in post-treatment visual analog scale (VAS) pain scores. In terms of evaluation of WOMAC scores, no significant difference was observed between the groups. In the isokinetic group, a significant increase was detected in extensor and flexor muscle strength measurements at the angular velocities of 60º/s and 180º/s. In the isotonic group, a statistically significant increase was detected in peak torque values of extensor and flexor muscles at 60º/s in the left knee only. Regarding FC thickness, a significant increase was found in the intercondylar area and the lateral condyle measurements of the left knee in the isokinetic group and the intercondylar area measurements of the right knee in the isometric group. In the isokinetic group, a statistically significant decrease was detected in the medial condyle of the right knee. It was observed that isokinetic exercise ended up with a significant increase in FC thickness in the intercondylar area and the lateral condyle of the left knee and a significant decrease in the medial condyle of the right knee. Conclusion: Isokinetic exercise is functionally superior to isometric and isotonic exercise, providing more significant improvements in muscle strength measurements and FC thickness. Further research is needed to determine the interactions among therapeutic exercises in patients with KOA that impact knee cartilage quantities.