Effects Of Chronic Lower Back Pain On The Physical Stability Of The Elderly When They Cross Obstacles Of Different Heights

Objective :In the elderly with chronic low back pain(CLBP),the ability of lumbar pelvic coordination is decreased,the muscle strength of lumbar back is insufficient,and the movement of pelvis and lower limbs is limited.As a result,patients with chronic low back pain have poor mobility,impaired balance,impaired posture control and decreased physical stability,which greatly increases the risk of falls.In this study,biomechanical methods were used to explore the changes of body stability of the elderly with chronic low back pain and the healthy elderly when they crossed the obstacles of different heights,and to analyze the similarities and differences of gait between the elderly with chronic low back pain and the healthy people when they crossed the obstacles.In order to provide a theoretical basis for the elderly to better prevent falls,the risk of falls in patients with chronic low back pain was assessed.Methods:In this study,the elderly patients with chronic low back pain(experimental group,n = 16)and the healthy elderly(control group,n = 19)were selected as the study objects.Vicon infrared motion capture system and Kistler three-dimensional force measuring platform were used to measure the movement of two groups of subjects crossing obstacles of different heights simultaneously.The two-way repeated ANOVA statistical method was used to analyze the step length,step speed,step width,stride height,toe distance,heel distance and three joint angles of lower limbs,dynamic indexes such as hip knee ankle moment,body stability indexes such as centroid pressure distance and centroid shaking distance.If there is interaction between groups and different high independent variables,further use simple effect analysis.P < 0.05 was considered to have significant difference.Results:1.Kinematics:The results showed that compared with the control group,the stride length and stride speed of CLBP group were lower in normal walking,and the support time was higher in 30% leg height crossing.The comparison results within the CLBP group showed that compared with normal walking,the stride speed,swing time and support time of CLBP group were lower when crossing 20% and 30% leg length obstacles;Compared with crossing 20% leg length obstacles,the swing time was higher when crossing 30% leg length obstacles.Compared with the swing leg crossing 20% leg length obstacle,the hip flexion angle and the knee flexion angle were larger when the swing leg crossing 30% leg length obstacle;Compared with the support leg crossing 20% leg length obstacle,the knee flexion angle and ankle plantar flexion angle were higher when the support leg crossing 30% leg length obstacle.The comparison results in the control group showed that compared with normal walking,the stride speed of the control group was lower when crossing 20% and 30% leg length obstacles,the swing time and the support time were higher when crossing 20% and 30% leg length obstacles;Compared with crossing 20% leg length obstacles,the swing time was higher when crossing 30% leg length obstacles.Compared with the swing leg crossing 20% leg length obstacle,the knee flexion angle was larger when the swing leg crossing 30% leg length obstacle;Compared with the support leg crossing 20% leg length obstacle,the knee flexion angle and ankle plantar flexion angle were higher when the support leg crossing 30% leg length obstacle.2.Kinetics:The results showed that compared with the control group,the peak values of hip extension and hip flexion moment and the first peak value of ankle plantar flexion in CLBP group decreased under three conditions(normal walking,crossing 20% and 30% leg length obstacles),and the peak values of knee extension moment increased under three conditions,but there was no significant difference.Compared with normal walking,the peak value of hip extension moment in CLBP group was higher when crossing 20% leg length obstacle.Compared with normal walking,the peak value of hip extension moment in the control group was higher when crossing 20% and 30% leg length obstacles,and the second peak value of ankle plantar flexion moment was lower when crossing 20% and 30% leg length obstacles.3.Physical stability:The results showed that compared with the control group,the mean value of the anteroposterior COM-COP(COM-COPap)seperation,the mediolateral center of mass(COMml)sway and the anteroposterior center of mass(COMap)sway of the CLBP group decreased under three conditions(normal walking,crossing 20% and 30% leg length obstacles);the mean value of the mediolateral COM-COP(COM-COPml)seperation increased when the CLBP group crossing 20% leg length height;but there was no significant difference.In the CLBP group,compared with the normal walking,COM-COPap seperation and COMml sway were larger when crossed 20% and 30% leg length obstacles.In the control group,compared with the normal walking,COM-COPap seperation and COMml sway were larger when crossed 20% and 30% leg length obstacles.Conclusions:The elderly people with chronic low back pain adopt a conservative walking strategy when crossing obstacles: the limited walking characteristics such as walking length,low walking speed,long swinging time,reduced hip,knee and ankle joint activity,and reduced moment,which directly lead to the decline of the physical stability of the elderly with chronic low back pain.When crossing the obstacle,COMap sway and COMml sway,COM-COPap seperation and COM-COPml seperation were increased in varying degrees of the elderly with chronic low back pain,which directly destroys their physical stability.Therefore,the elderly with chronic low back pain can improve their physical stability and prevent falls by improving the ability of lower limb movement,expanding the range of joint activity and improving the shaking distance of the center of mass.