RÉSUMÉ
BACKGROUND:Many studies have shown that total hip arthroplasty will improve low back pain in patients with hip-spine syndrome.However,there are few studies on the relationship between postoperative low back pain improvement and changes in spinal-pelvic sagittal parameters.This study aims to reveal their connections between the two. OBJECTIVE:To explore the relationship between the improvement of low back pain and changes in the spinal-pelvic sagittal parameters in patients with hip-spine syndrome after total hip arthroplasty. METHODS:A retrospective analysis was performed on the clinical and imaging data of 93 end-stage hip disease patients who underwent primary total hip arthroplasty and combined with low back pain and were admitted to Affiliated Hospital of Xuzhou Medical University from January 2019 to January 2022.Spinal-pelvic sagittal parameters were measured on lateral lumbar X-rays before surgery and 1 year at the last follow-up:pelvic incidence,pelvic tilt,sacral slope,lumbar lordosis,pelvic incidence-lumbar lordosis(difference between pelvic incident angle and lumbar lordosis angle).Visual analog scale score,Oswestry disability index,and hip Harris score were recorded before and 1 year after arthroplasty.The patients were divided into two groups according to whether the change in visual analog scale scores 1 year after surgery reached the minimal clinically important difference for low back pain treatment,including 45 cases in the low back pain unimproved group and 48 cases in the low back pain improved group.The preoperative general data of patients,differences in spinal-pelvic sagittal parameters,Oswestry Disability Index and hip Harris score before and after surgery were compared between the two groups. RESULTS AND CONCLUSION:(1)There was no significant difference in age,gender,surgical side,body mass index,and etiology between the two groups(P>0.05),and they were comparable.(2)There was no significant difference in visual analog scale scores before surgery(P>0.05).The visual analog scale scores of the low back pain improved group were lower than those of the low back pain unimproved group 1 year after surgery(P<0.01).(3)At 1 year after surgery,the lumbar lordosis of the low back pain unimproved group was significantly smaller than that before surgery,while the lumbar lordosis of the low back pain improved group was significantly smaller than that before surgery(P<0.01).At the same time,the pelvic incidence-lumbar lordosis mismatch in the low back pain unimproved group was greater than before surgery,while the pelvic incidence-lumbar lordosis mismatch in the low back pain improved group was smaller than before surgery,with significant differences between the two groups(P<0.01).There was no significant difference in the changes of other spinal-pelvic sagittal parameters between the two groups(P>0.05).(4)Preoperative lumbar Oswestry disability index and hip Harris score were not significantly different between the two groups(P>0.05).At 1 year after surgery,Oswestry disability index of the low back pain improved group was lower than that of the low back pain unimproved group and the hip Harris score was higher than that of the low back pain unimproved group(P<0.05).(5)The results showed that the improvement of low back pain was related to changes in spinal-pelvic sagittal parameters in patients with hip-spine syndrome after total hip arthroplasty,showing reduced lumbar lordosis and pelvic incidence-lumbar lordosis mismatch.Moreover,patients with improved low back pain after surgery had better functional scores,indicating that total hip arthroplasty improved spinal alignment and spinal-pelvic sagittal balance.For patients with hip-spine syndrome,a total hip arthroplasty performed before the onset of lumbar disease can have a favorable effect on the lumbar spine.