Objective To investigate the effect of stem length on aseptic loosening after knee prosthesis replacement for tumors of distal femur.Methods A total of 164 patients with tumors of distal femur who underwent knee prosthesis replacement in Sichuan friendship hospital from June 2015 to June 2021 were selected.According to the aseptic loosening of the prosthesis during the follow-up of 2 to 8 years,the patients were divided into two groups:non-loosening group and loosening group.There were 126 patients in the non-loosening group,71 males and 55 females,aged from 25 to 69 years old,with an average age of(47.69±5.48)years old.There were 38 patients in the loosening group,including 24 males and 14 females,aged from 27 to 70 years old,with an average age of(46.12±5.33)years old.The clinical data of the two groups were compared.Kaplan-Meier method was used to analyze the relationship between the length of the stem and the service life of the prosthesis.Random forest algorithm and multivariate Logistic regression were used to analyze the factors affecting postoperative aseptic loosening of the prosthesis.The sensitivity of the research results was analyzed by correlation E-value method.The dose-effect relationship between the length of prosthesis stalk and postoperative aseptic loosening was analyzed by restriction cubic spline.Establish a prediction model and evaluate its prediction efficiency.Results The results of Kaplan-Meier analysis showed that the length of prosthesis handle was related to the service life of prosthesis(P＜0.001).The increase of the distance between the lower limb force line and the center of the knee joint were the risk factors of postoperative aseptic loosening of the prosthesis(P＜0.05),the length of the prosthesis,the ratio of the diameter of the medullary stalk to the femur,mechanical lateral distal femoral angle(mLDFA)and the increase of postoperative hip knee ankle angle(HKAA)were protective factors(P＜0.05).Sensitivity analysis showed that E=2.015.In both male and female patients,there was no non-linear relationship between stem length and postoperative aseptic loosening(P＞0.05).When the model predicted that the probability of aseptic loosening of the prosthesis was 0.80,the Jordan index was the highest(77.77),the accuracy was 92.24％,the sensitivity was 85.63％,the specificity was 92.14％,and the area under the subject working characteristic(ROC)curve was 0.825(95％CI:0.766～0.884,P＜0.001).Conclusion The distance of lower limb force line from the center of knee joint,the length of prosthetic stem and the ratio of medullary stalk to femoral diameter are the influencing factors of aseptic loosening after knee prosthesis replacement in patients with distal femoral tumor.It is suggested that surgeons should choose longer prosthetic handle and thicker medullary handle to increase the fit of prosthetic medullary handle to the diameter of femur and medullary cavity diameter.Regular postoperative monitoring of the deviation of the lower limb force line is recommended,with prompt reconstruction of the lower limb force line when necessary.
关键词
假体柄长度/膝关节假体置换术/假体无菌性松动/股骨远端肿瘤
Key words
stem length of prosthesis/knee prosthesis replacement/aseptic loosening of prosthesis/tumor of distal femur
维普
万方数据