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Hip Muscle Strength and Muscle Cross Sectional Area in Men with and without Hip Osteoarthritis
MERJA H. AROKOSKI, JARI P.A. AROKOSKI, MIKKO HAARA, MARKKU KANKAANPÄÄ, MINNA VESTERINEN, LEA H. NIEMITUKIA, and HEIKKI J. HELMINEN
ABSTRACT.
Methods. Based on the American College of Rheumatology criteria regarding classification of hip OA, 27 men (aged 47-64 yrs) with unilateral or bilateral hip OA and 30 age matched randomly selected healthy male controls were studied. The maximal isometric hip abductor, adductor, flexor, and extensor strength (Nm) at 0 degree of hip flexion in the supine position was determined with a dynamometer. The isokinetic hip flexion and extension strength (peak torque, Nm) was determined using angular velocities of 60°/s and 120°/s. The subjective severity of hip pain was rated by visual analog scale prior to the muscle strength test. CSA of the pelvic and thigh muscles was measured from magnetic resonance images. Results. The reliability of intraclass correlation coefficients for repeated measures of muscle strength varied from 0.70 to 0.94 in controls and from 0.84 to 0.98 in subjects with OA. Hip isometric adductor and abductor strength was 25% and 31% lower (p < 0.001) in OA subjects than in controls, respectively. The hip isometric and isokinetic flexion strength was 18-22% lower (p < 0.01) in OA subjects than in controls, but extension strength did not differ between groups. In OA subjects, the hip flexion and extension isometric and isokinetic strength values were 13-22% lower (p < 0.05) on the more deteriorated side compared to the better side. CSA of the pelvic and thigh muscles did not differ between the groups. However, in OA subjects, the CSA of the pelvic and thigh muscles was 6-13% less (p < 0.05 to < 0.001) on the more severely affected hip compared to the better hip. Conclusion. Men with hip OA have significantly lower abduction, adduction, and flexion muscle strength than controls. The decrease of muscle size and hip pain may contribute to the decrease of muscle strength in hip OA. Other possible underlying causes of the muscle weakness need to be studied. (J Rheumatol 2002;29:2185-95) Key Indexing Terms:
MUSCLE
From the Department of Physical and Rehabilitation Medicine, Kuopio University Hospital and Kuopio University, Kuopio; the Department of Clinical Radiology, Kuopio University Hospital; the Department of Anatomy, University of Kuopio; and the Nilsiä Health Centre, Nilsiä, Finland. Supported by EVO-grant 5960408 from Kuopio University Hospital and by the North-Savo Fund of the Finnish Cultural Foundation. M.H. Arokoski, MD, Nilsiä Health Centre and Department of Physical Medicine and Rehabilitation, Kuopio University Hospital; J.P.A. Arokoski, MD, PhD, Department of Physical and Rehabilitation Medicine, University of Kuopio and Kuopio University Hospital; M. Haara, MB; M. Kankaanpää, MD, PhD; M. Vesterinen, MB, Department of Physical Medicine and Rehabilitation, Kuopio University Hospital; L.H. Niemitukia, MD, Department of Clinical Radiology, Kuopio University Hospital; H.J. Helminen, MD, PhD, Professor and Chairman, Department of Anatomy, University of Kuopio. Address reprint requests to Dr. M.H. Arokoski, Department of Physical Medicine and Rehabilitation, Kuopio University Hospital, PO Box 1777, FIN-70211 Kuopio, Finland. E-mail: paivarinne@raketti.net Submitted December 4, 2001; revision accepted March 7, 2002. |