Strengthening Hip Rotators and Ankle Muscles Versus Knee Extensors on Knee Osteoarthritis: Randomized Controlled Trial with Triple Blindness

Abstract

Background: One of the leading causes of pain, functional limitations, and impairment in the elderly population is knee osteoarthritis (OA). The impact of strengthening hip rotators in conjunction with ankle muscles on individuals with knee OA has not been well studied. The current study aims to investigate the effect of adding strengthening exercises of hip rotators and ankle muscles to standard knee exercises on pain, function, and knee proprioception in patients with knee OA.
Methods: A triple-blinded, controlled, randomized trial was conducted with 40 patients with knee osteoarthritis, randomly divided into a control and experimental group. The control group underwent strengthening exercises for the knee extensors and stretching exercises for the hamstrings and calf muscles, three times per week for four weeks. The experimental group received the same previous exercises in addition to strengthening exercises for hip rotators and ankle muscles for the same period. Pain intensity during gait, stair climbing, and at night was assessed using a visual analogue scale, and functional disability was assessed using the Arabic version of the Knee Injury and Osteoarthritis Outcome Score questionnaire. Proprioception was assessed using a digital inclinometer by measuring absolute angular error. Finally, isometric muscle strength was measured using a handheld dynamometer for the Knee extensors, hip internal and external rotators, ankle dorsi- and plantar flexors, and ankle evertors and invertors. All measures were taken at baseline and the end of the trial.
Results: within- and between-group comparisons were measured through MANOVA, which revealed a significant reduction in pain intensity during gait (p=0.004*) and significant improvement in knee functional level (pain (p = 0.015*), ADL (p= 0.017*) and QOL (p= 0.046*)) in the experimental group at the end of 4 weeks (p<0.05). There was no significant difference in knee proprioception and muscle strength improvement between groups.
Conclusion: Adding hip rotators and ankle muscle strengthening exercises to knee extensor exercises presented a significant improvement in pain intensity, as well as knee functional level, among patients with knee osteoarthritis.