Reduction of hip joint reaction force via medio‐lateral foot center of pressure manipulation in bilateral hip osteoarthritis patients

Abstract

Loading/excessive loading of the hip joint has been linked to onset and progression of hip osteoarthritis. Footwear-generated biomechanical manipulation in the frontal plane has been previously shown in a cohort of healthy subjects to cause a specific gait adaption when the foot center of pressure trajectory was shifted medially, which thereby significantly reduced hip joint reaction force. The objective of the present study was to validate these results in a cohort of female bilateral hip osteoarthritis patients. Sixteen patients underwent gait analysis while using a footworn biomechanical device, allowing controlled foot center of pressure manipulation, in three para-sagittal configurations: medial, lateral, and neutral. Hip osteoarthritis patients exhibited similar results to those observed in healthy subjects in that a medial center of pressure led to an increase in inter-maleolar distance while step width (i.e., distance between right and left foot center of pressure) remained constant. This adaptation, which we speculate subjects adopt to maintain base of support, was associated with significantly greater hip abduction, significantly decreased hip adduction moment, and significantly reduced joint reaction force compared to the neutral and lateral configurations. Recommendations for treatment of hip osteoarthritis emphasize reduction of loads on the pathological joint(s) during daily activities and especially in gait. Our results show that a medially deviated center of pressure causes a reduction in hip joint reaction force. The present study does not prove, but rather suggests, clinical significance, and further investigation is required to assess clinical implications. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1762-1771, 2016.

Positive outcomes following gait therapy intervention for hip osteoarthritis: A longitudinal study

“…The researchers did not know the particular shifts in the biomechanical device elements made for each patient and thus cannot attribute biomechanical changes in the hip joint to specific biomechanical element locations in the present study. In our previous work on both healthy subjects and bilateral hip OA patients, we found a specific location of the biomechanical elements that led to a significantly reduced hip joint force. We described in detail a possible biomechanical mechanism which initiated with shift in foot COP and commenced with the reduction in joint force.…”

“…In these studies, it was reported that when the biomechanical elements of the device are shifted in the transverse plane of the foot, along either the antero‐posterior or medio‐lateral foot axis, the COP shifted accordingly. This was shown in both healthy subjects and knee OA patients, as well as in a cohort of bilateral hip OA patients . In the current longitudinal study, the COP was not measured for several reasons.…”

“…In the current longitudinal study, the COP was not measured for several reasons. At the time of testing session 1, after data was collected for the present study, we conducted a parallel study in which we assessed the effects of seven different COP locations on the biomechanics of the hip joint during gait . This study resulted in lengthy experiments with patients having to walk many times back and forth in the laboratory, in many instances for a duration of time beyond their comfort level.…”

“…Patients were instructed to follow a treatment protocol in which they walk with the device every day for a cumulative period of time which increases gradually over 1 year from 10 min to 2 h or more. By custom‐positioning the device elements, the locus and orientation of the ground reaction force (GRF) is repositioned, thus shifting the foot center of pressure (COP), and hence kinematics and kinetics of the joints of the lower limbs are significantly altered . The convexity of the device elements reduces stability and “forces” the user to adopt the new COP with the associated gait changes.…”

“…By custom-positioning the device elements, the locus and orientation of the ground reaction force (GRF) is repositioned, thus shifting the foot center of pressure (COP), 31,[36][37][38]39 and hence kinematics and kinetics of the joints of the lower limbs are significantly altered. 30,31,[36][37][38] The convexity of the device elements reduces stability and "forces" the user to adopt the new COP with the associated gait changes. The device works on the principle of motor learning, such that by training (walking) in the device for a set period of time daily, patients are retrained to walk with a more normal or beneficial gait.…”