0231–424X/$ 20.00 © 2010 Akadémiai Kiadó, Budapest Acta Physiologica Hungarica, Volume 97 (4), pp. 375–384 (2010) DOI: 10.1556/APhysiol.97.2010.4.3 Potential loss of muscle function during dynamic actions caused by signifcantly decreased muscle strength in older women with hip osteoarthritis Ł Trzaskoma 1 , J Tihanyi 1 , Z Trzaskoma 2 1 Department of Biomechanics, Faculty of Physical Education and Sport Sciences, Semmelweis University, Budapest, Hungary, 2 Faculty of Physiotherapy, Jozef Pilsudski University of Physical Education, Warsaw, Poland Received: 13 December, 2009 Accepted after revision: 1 June, 2010 Purpose: The aim of the study was to analyze the results of the hip joint torques within the patients with osteoarthritis (OA). A total of 119 women were divided into 3 groups performing 3 dimensional strength tests. For the measurements a new apparatus was invented and used. Specially designed position was safety and comfortable during testing OA and elderly women. Results: Signifcant differences (p≤0.05) in strength tests were found both between body side and muscle groups in most of the performed tests. The biggest unilateral defcit in OA group was found in muscles most important for gait and weight bearing – 0.55 for both fexors and extensors. Surprisingly no lateral difference was found for the hip joint adductors. Analysis of the correlation coeffcient between the hip joint muscles proved that complex movements needed well-developed coordination between the muscle groups. The most important agonist muscle coordination occurs between hip extensors and abductors – 0.68 to 0.80. Conclusion: Unilateral hip OA affecting older women is directly responsible for signifcantly lower muscle strength when compared with both control groups. Lost of balance and coordination needed for dynamic actions like gait is caused by strength asymmetry of crucial hip muscles as well as near zero correlation between important agonist muscles. Keywords: hip joint muscles, osteoarthritis, isometric strength, three-direction measurements Ageing of the society and sedentary life style as well as lack of physical activity are the most common tendencies observed in all developed countries. Among the consequences are steadily increasing numbers of degenerative changes of joints like for example osteoarthritis (OA). It is a major disabling hip joint disease among elderly people additionally enhanced with commonly concurrent obesity, muscle weakness, prolonged life and connected with its disorders (3). According to Keuttner and Goldberg (7) osteoarthritis is the result of both biological and mechanical destabilizing process that involve the degeneration and abnormal synthesis of articular cartilage at the level of the chondrocytes and the extracellular matrix, as well as the subchondral layer of the bone. Among all the consequences of the osteoarthritis of the hip joint impaired muscle strength seems to be the most crucial for function of that articulation (14). Hip joint is one of the biggest within human body and has to carry out high loads (up to 4–6 times greater than body weight) like stairs climbing or fast walking. One-legged stance, sit to stand and stand to Corresponding author: Dr. Łukasz Trzaskoma, PhD Department of Biomechanics, Faculty of Physical Education and Sport Sciences, Semmelweis University Alkotás u. 44, H-1123 Budapest, Hungary Phone: + 36 1 487 9200/1301, +36 1 487 9263; Fax: +36 1 487 9263 E-mail: lukasz@mail.hupe.hu