| Background:Total knee arthroplasty(TKA),one of the most commonly performed operation for osteoarthritis with knee joint deformity and persistent pain,is highly recognized by joint surgeons and patients.The proper intramedullary entry point in TKA is very important for the placement of prosthesis and the function of joint after operation.Objective:This study aim to improve the accuracy of entry point at the distal femur in TKA and provide basis for precise osteotomy,so as to obtain good postoperative lower limb alignment and reduce its potential complications,expand its clinical application to find a proper entry point.Methods:CT scanning was performed on 60 patients(100 knees)undergoing TKA for knee osteoarthritis(KOA)in the Joint Surgery Department of Qingdao West Coast Medical Center,Affiliated Hospital of Qingdao University.The entry point(point A)at the distal femur was identified by the three-dimensional reconstruction of Mimics Research 21.0.The three common insertion points are B(1cm superior to femoral insertion for posterior cruciate ligament),C(medial to femoral intercondylar notch)and D(intersection of the supracondylar line and Whiteside's line).The vertical distances of AB,AC and AD were measured.Site-selection measurement was carried out twice by one research and once by another research,then mean value was calculated.Results:In this study,the theoretical intramedullary entry point at the distal femur was close to the medial femoral condyle.The vertical distances of AB,AC and AD were(4.06±1.09)mm,(13.04±1.90)mm and(18.25±2.47)mm,respectively.The measurement results for vertical distances of AB,AC and AD obtained by the two researchers were compared.The result showed that there was not statistically different,indicating that the data were repeatable and reliable.In the two-sided test,the data were tested for normality and homogeneity of variance,both of which satisfied the conditions of normal distribution and homogeneity of variance.The results of one-way analysis of variance showed that there was no significant statistical difference in the results of two-sided test for male between groups and also no significant statistical difference in the results of two-sided test for female between AB and AD groups,but there was statistical significant difference between AC groups(p< 0.05).In the gender test,the data were tested by normality and homogeneity of variance,both of which satisfied the conditions of normal distribution,but did not meet the conditions of homogeneity of variance.The results of Welch's Anova showed that there was significant statistical difference in the results of two-sided test between different gender groups(p<0.05).In this paper,the femoral insertion for posterior cruciate ligament(PCL)was selected at the junction of the intercondylar fossa and the medial wall.The mean value of vertical distance from 1 cm superior to this site to point A was(4.06±1.09)mm.When trochlear point was selected as the femoral insertion,the distance was(3.43±0.83)mm.There was significant statistical difference between them(p< 0.05).It is shown that the trochlear point used as PCL femoral insertion is more accurate.Conclusion:Among the three commonly used intramedullary insertion points,the one 1 cm superior to the PCL femoral insertion is more accurate to be selected as the intramedullary entry point,which helps to obtain good postoperative lower limb alignment.In addition,the site 1 cm superior to the trochlear point used as PCL femoral insertion is more accurate to be selected as the intramedullary entry point. |
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