Study Of Factors Influencing Tibial Radiolucent Lines After Primary TKA For Knee Osteoarthritis

Objective:Knee osteoarthritis（OA）is the most common joint disease in the elderly,and total knee arthroplasty（TKA）is an extremely valuable therapeutic measure for patients with end stage OA.Tibial radiolucent lines are radiolucent intervals between the bone cement or the prosthesis and the adjacent tibia that occur after TKA.The occurrence of RLL after TKA has important long-term implications and is often considered to be an indicator or predictor of prosthetic loosening.The purpose of this study was to evaluate the relevant influences on the occurrence of tibial RLL after primary TKA.Methods:A retrospective nested case-control study was used with a cohort of433 patients with OA who underwent primary TKA at a single university-affiliated top three hospitals between July 2015 and June 2021 and included postoperative follow-up information.Morbidity and characteristics of RLL were calculated by improved partition of tibial RLL as diagnostic criteria.A total of 83 patients（87 knees）who developed RLL during follow-up were included as the case group,and 83non-RLL patients（85 knees）were matched from the cohort as the control group in a 1:1 ratio according to the same sex,date of surgery（±365days）,and follow-up period（± 14 days）.General clinical information including age,gender,height,weight,Body mass index（BMI）,obesity classification,smoking history,diabetes,hospital stays,and preoperative hemoglobin（Hb）were compared between the case and control group patients.The surgical and postoperative clinical data of the two groups were compared,including time of operation,anesthesia,whether tranexamic acid was used intraoperatively,postoperative Hb,whether blood was transfused postoperatively,whether continuous passive motion was performed postoperatively,and whether postoperative infection was present.The imaging data of the two groups were compared,including the cumulative tibial cement mantle thickness,preoperative knee varus angulation,modified Krackow classification of knee varus,and preoperative femoral mechanical-anatomical angle,and analyzed the factors influencing the occurrence of RLL after TKA.Statistically significant influencing factors were included in the receiver operating characteristic curve（ROC）analysis to assess relevant factors with predictive value for the occurrence of RLL after TKA.Results:A total of 104 of the 433 patients in the cohort were found to have tibial RLL at follow-up after TKA,with a median follow-up of 113（57.0-294.5）days,an overall incidence of 24.0%,and the mean time of onset was（219.5 ± 200.9）days.Thirty（28.8%）cases of RLL appeared within 3 months after TKA and 82（78.8%）cases of RLL appeared within1 year after TKA.In the case group of 83 patients（87 knees）in the tibial component AP view after TKA,the medial baseplate was complicated by RLL in 62（71.3%）cases and the lateral baseplate was complicated by RLL in 11（12.6%）cases,with a statistically significant difference in the location of morbidity（p < 0.001）.In the tibial component AP ＆ LAT view after TKA,the mean cumulative tibial cement mantle thickness was（12.61±4.08）mm in the case group,whereas the mean cumulative tibial cement mantle thickness was（15.71 ± 3.72）mm in the control group,with a statistically significant difference between the two groups（p <0.001）.There was no statistically significant difference in age,gender,height,weight,BMI,obesity classification,smoking history,diabetes,hospital stays,preoperative Hb,postoperative Hb,whether postoperative blood transfusion was given,time of operation,anesthesia,whether tranexamic acid was used intraoperatively,whether continuous passive training was performed postoperatively,whether postoperative infection was present,preoperative knee varus angulation,modified Krackow classification of knee varus,and preoperative femoral mechanical-anatomical angle between the two groups（p > 0.05）.Further ROC results showed that the area under the curve（AUC）for cumulative tibial cement mantle thickness was 0.728（95% CI,0.650-0.805）and that reduced cement thickness had significant predictive value for the development of tibial RLL after TKA.Conclusion:The overall incidence of tibial RLL after primary TKA in patients with OA was 24.0%.Tibial RLL appeared early after TKA,with most appearing within 1 year after surgery.Tibial RLL occurs most frequently around the medial baseplate,which may be closely related to the fact that the knee medial compartment is subjected to more weight bearing during neutral gait.The cumulative tibial cement mantle thickness is an independent risk factor associated with the development of RLL after primary TKA in patients with OA.Decreased tibial cement mantle thickness has a significant predictive value for the development of tibial RLL after TKA.