The Relationship Between Postoperative Correction Rate Of Coronal Alignment And Knee Function Score After Total Knee Replacement:A Short Term Follow-up Study

Background:As a relatively mature surgical method,the number of total knee replacement is increasing annually.It has achieved satisfying results in treating end-stage knee joint diseases with the improvement of surgical technique and the concept of enhanced post-surgery recovery.The neutral alignment of lower extremity after total knee replacement is always the goal pursed by joint surgeons.Previous studies have shown that the neutral alignment is not only the golden standard for evaluating the success of the operation,but also closely related to the survival rate of the prosthesis and the postoperative joint function score.In recent years however,more and more scholars have found that the postoperative joint function and prosthesis survival rate have no statistical difference between their neutral alignment groups and control groups through the follow-up study.Therefore,the golden standard of neutral alignment after TKR is challenged.Objectives:We think it is too general to classify patients according to whether they are in neutral alignment.The method of grouping does not take into account the original state of the knee joint.Especially in the non-neutral alignment group,there are two types of inadequate correction and overcorrection.Therefore,according to the coronal alignment of lower limb after TKR,the patients were divided into 3 groups to be compared,namely insufficient correction group,neutral position of group and overcorrection group.Moreover,the relationship between alignment and joint function is also discussed based on the concept of correction degree.Methods:1.A retrospective analysis was conducted on the knee surgery patients operated by one physician of the Department of Orthopedics of Peking Union Medical College Hospital from March 2005 to November 2017.According to the coronal alignment of lower limb after TKR,the patients were divided into 3 groups through screening,namely insufficient correction group(A),neutral position of group(B)and overcorrection group(C).The specific method of grouping is listed below.2.The HSS score,improvement degree of HSS score and prosthesis survival rate in the three groups were compared to determine if there was statistical difference.Furthermore,the correlational analyses between MFTA and HSS score,TKR correction rate,TKR correction degree and postoperative HSS score,improvement degree of HSS score were conducted.The data were statistically analyzed by SPSS 22.0,including row*column chi square test,one-way ANOVA,repeated measurement ANOVA,K-W test,LSD-t test,Simple linear correlation analysis and so on.Results:1.A total of 259 patients(358 knees)who met the inclusion criteria,were divided into 3 groups:Group A(128 knees),group B(209 knees),and group C(21 knees).The postoperative prosthesis survival rate of three groups:group A(100%),group B(2 cases revision,99.04%),group C(100%),K-W test,X2=1.43,P=0.49,no statistical difference.In addition,one-way ANOVA showed that no statistical difference of postoperative HSS score was observed between the three groups:group A(88.27 + 5.06),group B(88 +7.66),group C(85.62+ 6.91).2.Correlation analysis:No correlation was found between MFTA and HSS score in 358 cases,the correlation coefficient was R=-0.095,p=0.072.The correlation coefficient between correction degrees and HSS score was R=0.105,p=0.047.The correlation coefficient between correction degree,and improvement degree of HSS score was R=0.072,p=0.177.The correlation coefficient between correction rate,and HSS score was R=0.054,p=0.311.The correlation coefficient between correction rate1 and improvement degree of HSS score was R=-0.066,p=0.215.The correlation coefficient between correction degree2 and HSS score was R=0.073,p=0.193.The correlation coefficient between correction degree2 and improvement degree of HSS score was R=0.052,p=0.355.The correlation coefficient between correction rate2 and HSS score was R=-0.109,p=0.053.The correlation coefficient between correction rate2 and improvement degree of HSS score was R=-0.033,p=0.565.No correlation was found between them.3.There were 174 knees with severe deformity before operation.The correlation coefficient between correction degree and postoperative HSS score was R=-0.005,p=0.946,and the correlation coefficient between correction degree and improvement degree of HSS score was R=-0.003,p=0.967.The correlation coefficient between correction rate and postoperative HSS score was R=0.111,p=0.146,and the correlation coefficient between correction rate and improvement degree of HSS score was R=0.010,p=0.900.No correlation was found.Conclusions:In our study,there was no statistically difference in knee function among the three groups,and no definite correlation was found between the postoperative correction rate of coronal alignment and knee function score.However,the knee function after TKR is related to a variety of factors,including the balance of ligaments and soft tissues,the fixation and rotation of the prosthesis and the rehabilitation of the patients after the surgery.It may also require a long-term follow-up study and an expansion of the sample size to clarify the relationship between alignment and knee function score,prosthesis survival rate after surgery.