Influencing Factors Analysis Of The Method In Maintaining Equal Length Of Both Lower Limbs During Total Hip Arthroplasty

BackgroundTotal hip arthroplasty(total hip arthroplasty,THA)refers to the use of artificial prostheses to replace damaged hip joints that can not be used normally,which can treat a variety of end-stage hip diseases.Leg length difference(leg-length discrepancy,LLD)is the most common cause of patient dissatisfaction and malpractice litigation in total hip arthroplasty.How to reduce LLD by intraoperative measurement is a hot topic.The method of patella touching is put forward,which refers to standard lateral decubitus position with the heel aligned,knee flexion position with knee at 90° Angle,the hip flexed naturally,and the 10 mm of the superior patella is far away from that of the inferior patella to balance the equal length of both lower limbs.It is convenient,efficient and accurate in patients with hip osteoarthritis,when the scope of application is expanded,we find that the accuracy of the measurement method has decreased.ObjectiveThrough the analysis of the influencing factors of patella touching method to control the length of both lower limbs,to identify the risk factors and reduce the incidence of unequal length of both lower limbs after operation.MethodsPatients who underwent total hip arthroplasty in the Department of Orthopedics,the First Affiliated Hospital of Xinxiang Medical University from June 2019 to December 2020 were selected as the research subjects,and 97 patients who met the inclusion and exclusion criteria were selected.Basic information of patients was collected,including gender,age,height,weight,preoperative differences in the length and circumference of lower limbs and postoperative differences in the length of lower limbs,and indexes such as body mass index(BMI)were calculated.According to the statistical data,the length changes of lower limbs of patients who used touch patella method during total hip arthroplasty were analyzed,and the factors affecting the length changes of both lower limbs were analyzed by chi-square test,independent sample t-test and binary logistic regression.Results(1)In this study,the difference in the length of both lower limbs was 4.65 ±3.23 mm.There were 74 patients with equal length of both lower limbs,it accounted for 76.3% of the total study population,and 23 patients with unequal length,accounting for 23.7% of the total study.(2)According to the chi-square test and independent sample t-test analysis,gender,age and height had no statistical significance in controlling the equal length of lower limbs after THA control by patella touching method(P>0.05),while BMI,preoperative difference of lower limb length and circumference had statistical significance(P<0.05).(3)The results of binary logistic regression analysis showed that the preoperative difference of > 20 mm in the circumference of both lower limbs was a risk factor for LLD after patella touching.ConclusionsTouching patella method can effectively maintain the equal length of both lower limbs during THA,and gender,age,height and other factors will not affect its accuracy.Patients with preoperative > 20 mm difference in circumference of lower limbs are recommended to use intraoperative perspective method to verify again.