Objective: Change of control strategy in osteoporotic people and their focus on the hip strategy, also the occurred postural changes, result in the displacement of center of pressure (COP). This study was carried out to compare the static stability parameters in healthy, osteopenic and osteoporotic women.
Methods: Seventy-one volunteer postmenopausal women aged 48-65 years were divided into three Normal (n=15), Osteopenic (n=26) and Osteoporotic (n=30) groups according to their bone mineral density of lumbar spine. Static balance was evaluated using force plate, in two positions: double leg standing (DLS) and Romberg standing (Rom), with eyes open, for 20 s. Standard deviation of velocity and amplitude of COP displacement in A-P and M-L direction and path length were evaluated.
Results: In DLS, SD of velocity and amplitude for A-P displacement, showed a significant increase in osteoporotic and osteopenic groups in comparison with normal women (P <0.05). In Rom, SD of amplitude for AP displacement, in osteoporotic group showed a significant increase compared with the normal group (P=0.03). Path length of COP displacement in DLS position in osteoporotic and osteopenic groups was significantly more than the normal group (P =0.05). There was a significant negative correlation between bone mineral density and SD velocity and amplitude in AP direction, and also path length in two static positions.
Conclusion: Increase in SD velocity and SD amplitude of COP displacement in A-P direction, that increase with the decrease in bone mineral density, may be due to the change of control strategy mechanisms in osteopenic and osteoporotic women. Investigation of these changes will be necessary to design the therapeutic methods for prevention of falling and bone fracture in osteoporotic patients.