Exercise induced effects on muscle function and range of motion in patients with hip osteoarthritis

Background and purposePatients with hip osteoarthritis have impairments in muscle function (muscle strength and power) and hip range of motion (ROM), and it is commonly believed that effective clinical management of osteoarthritis should address these impairments to reduce pain and disability. Therefore, the purpose of this study was to compare the short- and long-term effects of 4months of physiotherapist-supervised strength training, physiotherapist-supervised Nordic Walking (NW), or unsupervised home-based exercise (HBE) on muscle function and hip ROM in patients diagnosed with hip osteoarthritis. MethodsSecondary outcome analyses from an observer-blinded three-armed parallel-design randomized controlled trial in 60+-year-old patients with clinical hip osteoarthritis (American College of Rheumatology criteria) who were not on a waiting list for hip replacement. One hundred and fifty-two patients were randomized to either 4months of physiotherapist-supervised, moderate, progressive, strength training (n=50), physiotherapist-supervised NW (n=50), or unsupervised HBE (n=52). Maximal isometric hip and thigh muscle strength and leg extensor power and active hip ROM were assessed at baseline 2, 4, and 12months. ResultsIntention-to-treat-analyses did not show any significant between-group differences for improvements in muscle strength and power or ROM at any time points. Short-term significant (p<.05) increases in muscle strength were present in the physiotherapist-supervised exercise groups and in the long-term for muscle power in the NW-group. All exercise modes resulted in significant increases of ROM but long-term improvements were only shown for NW and HBE. DiscussionFour months of physiotherapist-supervised, progressive, moderate, and strength training was less effective than hypothesized for improving muscle strength and power in patients with hip osteoarthritis who are not awaiting hip replacement. Our results may indicate that in these patients, improvements in disability are not necessarily dependent on improvements in strength and power or ROM.