Comparison Of Clinical Outcomes And Kinematics After Bilateral TKA Using Posterior Substituting Versus Cruciate Retaining Implants

Part Ⅰ Comparison of clinical outcomes after bilateral total knee arthroplasties using posterior substituting versus cruciate retaining implantsObject:To compare the clinical outcome between bilateral knees after bilateral total knee arthroplasties(TKA)using posterior substituting implant in one knee versus cruciate retaining implant in the contralateral knee。Methods:A retrospective study was conducted to analysis the clinical outcome of patients who performed bilateral total knee arthroplasties in Changhai Hospital between June 2010 and June 2021.All patients underwent posterior substituted total knee arthroplasty(PS-TKA)in one knee and cruciate retaining total knee arthroplasty(CRTKA)in the contralateral knee.Patients were followed up in the outpatient room,the postoperative satisfaction level and complication rate were evaluated.The patients were assessed with the use of the Hospital for Special Surgery scale(HSS).Each patient completed the Western Ontario and Mc Master Universities Osteoarthritis score(WOMAC)questionnaires and Forgotten Joint Score(FJS)questionnaires by themself.Meanwhile,the non-weight-bearing and weight-bearing ranges of motion(ROM)of both knees were measured.The radiographic materials were collected,the preoperative hip-knee-ankle angle(HKA),anatomic valgus angulation(AVA),postoperative HKA and posterior tibial slope(PTS)were measured,osteolysis and aseptic loosening were evaluated at the same time.Result:20 patients included 4 men and 16 women were brought into the study,the average age was 71.75±7.04 years.10 patients used Vanguard PS and CR implants,while the other 10 patients used Legion PS and CR implants.No difference was found between the preoperative HKA and AVA of bilateral knees.However,the follow up time of PS-TKA knees was 74.14±27.90 months,which was significantly longer than CR-TKA knees(31.83±11.28 months)(P<0.001).No knee had osteolysis,suspicious aseptic loosening was found in the PS-TKA knee of one patient.After CR-TKA,3 patients reported mild knee pain.The postoperative satisfaction of PS-TKA and CR-TKA were 7.95±1.19 and7.85±1.18,respectively.No difference was found in postoperative satisfaction between bilateral knees(P=0.666).The HSS score,WOMAC score and FJS of PS-TKA knees were84.18±7.87,16.50(14.50-22.00)and 81.00(75.25-86.00),respectively.The HSS score,WOMAC score and FJS of CR-TKA knees were 86.71±5.76 、 18.00(14.00-21.75)and 82.50(74.88-85.00),respectively.No difference was found in HSS score,WOMAC score and FJS between bilateral knees(P>0.05).The non-weight-bearing ROM of PS-TKA knees and CR-TKA knees were101.35±8.38° and 99.77±6.20°,respectively.No difference was found in non-weight-bearing ROM between bilateral knees(P=0.271).The weight-bearing ROM of PS-TKA knees was higher than CR-TKA knees(108.1±8.33°versus 105.55±7.51°,P=0.045)Conclusion:Postoperative clinical outcomes of bilateral knees were similar after bilateral total knee arthroplasties using PS implant in one knee versus CR implant in the contralateral knee.No significant difference was found in implant survival rate,postoperative satisfaction and knee function scores between PS-TKA knees and CR-TKA knees.However,PS-TKA knees showed lower complication rate and higher weightbearing ROM compared to CR-TKA knees.Part Ⅱ In vivo kinematic study of bilateral total knee arthroplasties using posterior substituting versus cruciate retaining implants based on Opti-kneeObject:To investigate the changes of 6 degree of freedom(DOF)following bilateral TKA using PS implant versus CR implant when performed walking and deep knee bending.Methods:Patients who performed bilateral total knee arthroplasties in Changhai Hospital between June 2010 and June 2021 were included into this study.All patients underwent PS-TKA in one knee and CR-TKA in the contralateral knee.All implants were either Biomet Vanguard PS implants or Biomet Vanguard CR implants.The Opti-knee sports analysis system was applicated to explore changes of the 6 degree of freedom(DOF)following bilateral TKA.All patients walked by natural speed,5 gait cycles were recorded in 30 seconds.Then patients performed deep knee bending from full extension to 90°,5 times of deep knee bending were recorded again.Result:6 patients included 1 man and 5 women were brought into the study,the average age was 68.50±10.03 years.No difference was found between the preoperative HKA and AVA of bilateral knees(P>0.05).However,the follow up time of PS-TKA knees was 74.93±34.02 months,which was significantly longer than CR-TKA knees(29.07±11.33 months)(P < 0.001).In gait cycle,no difference was found in flexionextension,internal-external rotation,anterior-posterior translation,medial-lateral translation and distal-proximal translation between PS-TKA knees and CR-TKA knees.In the mid-swing term(80%-90% of the gait cycle),the PS-TKA knees showed smaller valgus than CR-TKA knees(P<0.05).In deep knee bending from full extension to 90° flexion,no difference was found in internal-external rotation,varus-valgus rotation,medial-lateral translation and distal-proximal translation between PS-TKA knees and CRTKA knees.However,PS-TKA knees showed greater femur posterior translation than CRTKA knees from 75° flexion to 90 °flexion.Conclusion : PS-TKA knees and CR-TKA knees had similar kinematic patterns when performed walking and deep knee bending.PS-TKA knees showed better femur roll back in deep knee bending.However,none of PS-TKA knees or CR-TKA knees restored physiological knee kinematics.