Objective To observe the posterior condylar offset (PCO) changes and anteroposterior femorotibial translation, to investigate the influence of them on the maximum knee range of flexion (ROF) in patients with posterior cruciatesacrificingself al ignment bearing total knee arthroplasty (TKA). Methods The cl inical data were analyzed retrospectively from 40 patients (40 knees) undergoing primary unilateral TC-PLUSTM SB posterior cruciate-sacrificing self al ignment andbearing TKA for osteoarthritis between January 2007 and June 2009. There were 18 males and 22 females with an average age of 70.6 years (range, 56-87 years). The disease duration was 5-14 years (mean, 9.1 years). The locations were the left side in 11 cases and the right side in 29 cases. Preoperative knee society score (KSS) and ROF were 48.0 ± 5.5 and (77.9 ± 9.0)°, respectively. The X-ray films were taken to measure PCO and anteroposterior femorotibial translation. Multi ple regression analysis was performed based on both the anteroposterior femorotibial translation and PCO changes as the independent variable, and maximum knee flexion as the dependent variable. Results All incisions healed by first intention. The patients were followed up 12-19 months (mean, 14.7 months). At last follow-up, there were significant differences in the KSS (91.9 ± 3.7, t=— 77.600, P=0.000), the ROF [(102.0 ± 9.3)°, t=— 23.105, P=0.000] when compared with preoperative values. Significant difference was observed in PCO (t=3.565, P=0.001) between before operation [(31.6 ± 5.5) mm] and at last follow-up [(30.6 ± 5.9) mm]. At ast follow-up, the anteroposterior femorotibial translation was (— 1.2 ± 2.1) mm (95%CI: — 1.9 mm to — 0.6 mm); femoral roll forward occurred in 27 cases (67.5%), no roll in 1 case (2.5%), and femoral roll back in 12 cases (30.0%). By multiple regression analysis (Stepwise method), the regression equation was establ ished (R=0.785, R2=0.617, F=61.128, P=0.000). Anteroposterior femorotibial translation could be introducted into the equation (t=7.818, P=0.000), but PCO changes were removed from the equation (t=1.471, P=0.150). Regression equation was y=25.587+2.349x. Conclusion Kinematics after TC-PLUSTM SB posterior cruciate-sacrificing self al ignment bearing TKA with posterior cruciate l igament-sacrificing show mostly roll forwardof the femur relative to the tibia, which have a negative effect on postoperative range of motion. There is no correlation between PCO changes and postoperative change in ROF in TC-PLUSTM SB posterior cruciate-sacrificing self al ignment bearing TKA.
ObjectiveTo investigate the efficiency of total knee arthroplasty (TKA) for varus osteoarthritic knees with tibial bone resection determined by lateral tibiofemoral joint 90° flexional gap measurement. MethodsBetween March and June 2013, 60 patients (60 knees) with varus osteoarthritic knees underwent TKA. All patients were randomly divided into traditional osteotomy group (control group, 30 cases) and lateral tibiofemoral joint 90° flexional gap measurement resection group (trial group, 30 cases). There was no significant difference in gender, age, affected side, body mass index and preoperative knee society score (KSS), range of motion (ROM) of the knee, anatomic tibiofemoral angle (ATFA), patellar tilt angle, posterior condylar offset (PCO), and joint line height between 2 groups (P>0.05). The bone resection thickness of the distal femoral lateral condyle, femoral posterior lateral condyle, and lateral tibial plateau were measured; and the X-ray films were taken to measure and compare ATFA, patellar tilt angle, PCO, and joint line height after TKA. The knee function recovery was evaluated with KSS score and ROM of the knee. ResultsThe bone resection thickness of the lateral tibial plateau and distal femoral lateral condyle in trial group was significantly smaller than that in control group (P<0.05); while the bone resection thickness of the femoral posterior lateral condyle was significantly bigger than that in control group (P<0.05). The 10 mm polyethylene insert was used in 19 cases of the trial group and in 8 cases of the control group, showing significant difference (Z=-4.040, P=0.003). All the patients were followed up 13-16 months (mean, 14.5 months). Radiography at 6 weeks after TKA indicated that the ATFA, patellar tilt angle, and joint line height had no significant difference between 2 groups (P>0.05); the PCO of trial group was significantly lower than that of control group (P<0.05). The KSS score and ROM of the knee at 12 months after operation were significantly improved when compared with preoperative ones in 2 groups (P<0.05), and trial group was significantly better than control group (P<0.05). ConclusionIt was an effective method to determine bone resection thickness using lateral tibiofemoral joint 90° flexional gap measurement in TKA for varus osteoarthritic knees, which can reduce the bone resection thickness of the tibial plateau and distal femoral lateral condyle and restore the joint line and PCO with better early recovery of the knee function.