Velocity of the cop as a reliable parameter for early diagnosis of coxarthrosis

INTRODUCTION:: The first symptoms of the degenerative disease of hip joint appear very early when people are about 14 years old. But clinical and X-ray characters manifest themselves insufficiently: temporary slight pains in hip joints on loading, insignificant painfulness along posterior surface of the joint during palpation, slight lameness on the diseased side. The purpose of this study was to try to involve gait analysis in the clinical research of the teenagers with coxarthrosis and to define the parameters which may be used for early diagnosis of coxarthrosis. METHODS:: 38 male military school teen-agers which have no history in the foot disorders and 20 male and 9 female with coxarthrosis were used for study. Plantar pressure distribution measurements were performed with the mini-emed system (Novel, Munich, Germany). Five dynamic records of each foot were made on the pressure platform (28 x 60 sensors, resolution -- 3 sensors/cm(2), sampling frequency -- 16 Hz). Three trials of gait were accomplished by each subject with inserted insoles (99 sensors in each insole) at the distance about 10 m. Novel-win v.95.121 and Novel-ortho v.95.121 packages were used for data analysis. RESULTS:: For the teenagers with coxarthrosis the loading of heel area is significantly less (< = 15 N/cm(2)), maximum force is generally less. Contact time (in percent of roll-over-process) in the forefoot and toes is increased and is equal to 100% very often. The most interesting results are obtained for the curves of the velocity of the centres of pressure versus time. For the controls this curve has one or two maxima (during 50%-70% of roll-over-process when heel, midfoot and sometimes forefoot are loaded), then a short period of insignificant changes of the velocity (up to 88%-94% of roll-over-process when only forefoot and toes are loaded) and last a very short period of its increase (toe-off phase). For the most part of the teenagers with coxarthrosis this curve seems to be monotonous, oscillating near its mean value line. DISCUSSION:: These disturbances may be explained by valgus deviation of the neck of femur and insufficient function of the muscles of buttocks as a consequence of its lever web decrease. The muscle forces (particularly abducted muscles) are decreased (about 10%-15%). These data are consistent with previous reported findings. CONCLUSION:: To compensate for the painfulness in the diseased hip joint the teenagers load rearfoot and forefoot less than in the 'normal' foot, increasing contact time in the forefoot. As a consequence of disturbances in hip joint a pathway of the centre of pressure is longer than in 'norm' and its velocity changes oscillating near the mean value when for 'normal' teenagers three definite intervals of its change are viewed. Therefore the first symptoms of displastic coxarthrosis of teenagers may be revealed from plantar pressure measurements by analysing the character of time dependence the velocity of the centres of pressure and loading of different areas of the foot (force and contact time). Additionally, functional state of hip joint muscles, X-ray and clinical symptoms, heat radiation and laser biophotometry data give an opportunity to define the character of locomotor function disorders.