[Review of finite element model studies in knee joint biomechanics]

Human knee joints experience very large loads and motions during regular daily, occupational and sport activities. Consequently, they are at high risk of being exposed to injuries and degeneration. Osteoarthritis and ligament injuries often inflict knee joints causing considerable pain and loss of productivity involving thus significant human and economic costs. Hence, biomechanics of human knee joints has been the focus of many investigations with the primary aim to improve understanding of joint function in normal and perturbed conditions. The existing prevention and treatment programs have been based on such studies. Due to inherent costs, limitations, difficulties and ethical concerns associated with in vivo and in vitro cadaveric studies, finite element model studies have been developed as effective, powerful and complementary tools to investigate knee joint biomechanics subject to internal and external mechanical conditions affecting its normal function. The advantage of finite element method in study of joint biomechanics lies in its robustness to incorporate complex 3D joint geometry, intricate boundary and loading conditions and materials with nonhomogeneous and nonlinear properties. This article reviews important model studies, presents their relevant results and discusses some of the promising future directions

[Normalized electromyography of shoulder muscles during selected functional tasks of upper limb in patients with shoulder impingement syndrome]

Precise muscle activity pattern is required to maintain normal shoulder function and any alteration in muscle activity can result in movement impairment. The purpose of this study was to assess normalized electromyography [EMG] of shoulder muscles during selected functional tasks of upper limb in patients with shoulder impingement syndrome. Test group consisted of 15 subjects with shoulder impingement syndrome selected by nonprobability convenient sampling and control group consisted of 15 matched healthy subjects. In each group selected exercises including open kinetic chain with and without external load and closed kinetic chain with axial load were done and during each exercise surface EMG from selected muscle was recorded. There was significant difference between the two groups in the activities of upper trapezius, infraspinatus and three regions of deltoid muscle [P<0.05].changes in normalized EMG were task dependent. Among all selected exercises, D2E showed minimum changes and tripod showed maximum changes in muscle activity domain. Decrease in activity domain of infraspinatus and trapezius muscles in patients with shoulder impingement syndrome causes impairment of shoulder function. D2E with causing minimum changes and Tripod with causing maximum changes in muscles activity domain are suggested respectively as the first and the last activity patterns in the treatment of these patients