Effects Of Posterior Condylar Offset And Posterior Tibial Slope Angle On Knee Function After PS-TKA

Objective:To explore the influencing factors of knee function after PS-TKA surgery.Methods:A retrospective study was conducted on patients who underwent PS-TKA(fixed platform prosthesis)in the second hospital of shanxi medical university for osteoarthritis of the knee from January 2015 to December 2018.Patients were measured with PCO(posterior condylar offset)and PSA(posterior tibial slope angle)pre and post operatively,and followed up to measure the postoperative maximum flexion Angle and HSS score.The patients were grouped according to the measured values of PCO and PSA,and the postoperative maximum flexion Angle and HSS score of each group were compared,and the corresponding correlation analysis was made.Results:216 patients,74 males and 142 females,finally met the inclusion criteria,with an average age of 68.62±4.15 years.PCO was 2.82±0.11 cm before surgery and 2.82±0.07 cm after surgery.PSA was 10.59°±3.95° before operation and 4.59°±2.78°after operation.Preoperative flexion Angle was 103.84°± 6.17°.Postoperative flexion Angle was 106.24 ° ± 5.26 °.Preoperative HSS score was 44.40 ± 5.95,and postoperative HSS score was 92.45±2.44.1.Relationship between Postoperative PCO and maximum flexion Angle or between Postoperative PCO and HSS score: Wilcoxon rank sum test was used to compare the maximum flexion Angle between PCO groups after surgery,and the results showed that there was no statistically significant difference between them(P values were 0.653 and0.171 respectively).There was also no significant correlation between postoperative PCO and postoperative maximum flexion Angle or between postoperative PCO and HSS score(P values were 0.074 and 0.120 respectively).2.Relationship between postoperative PSA and postoperative maximum flexion Angle or between postoperative PSA and postoperative HSS score: kruskal-wallis H test was used to compare each group,and the results showed statistically significant differences among the three groups(P < 0.001).The bonferroni method was used to conduct multiple comparisons,and the results showed that the postoperative PSA group c> PSA group b > PSA group a(All P values are less than 0.017).Kruskal-wallis H test was used to compare the HSS scores among the PSA groups after surgery,and the results showed that there was no statistically significant difference between the three groups(P=0.073).The correlation analysis between postoperative PSA and postoperative maximum flexion Angle showed a significant correlation(r=0.440,P<0.001).However,there was no significant correlation between postoperative PSA and postoperative HSS score(P=0.408).3.Preoperative linear correlation analysis of PCO and PSA showed a significant negative correlation between the two(r=-0.383,P<0.001),and no correlation between PCO and PSA after surgery(P=0.650).Conclusion:PCO had no significant effect on the maximum knee flexion Angle and HSS score after PS-TKA surgery.The increase of postoperative PSA can increase the maximum knee flexion Angle after PS-TKA,but has no significant effect on postoperative HSS score.Preoperative PCO was negatively correlated with Preoperative PSA and the restoration of the matching relationship between PCO and PSA during TKA surgery can help to obtain better soft tissue balance,which is of great significance for the knee function after TKA surgery.