Clinical And Imaging Study On Recurrent Patellar Dislocation Under The Guidance Of The "Jin-Gu" Theory Of Traditional Chinese Medicine

Background:Recurrent Patellar dislocation(RPD)is one of the common instability disorders in the knee,which will significantly reduce the sport activity of the patients,result in degeneration or even pain of the knee joint.Recently abnormal lower limbs rotation has been identified in patients with RPD and attract the attention of more researchers.Nevertheless,the study of abnormal lower limbs rotation in standing position of RPD patients is still unavailable and there is a lack of observation on the efficacy of distal femur derotational osteotomy(DFO)and a good Patient-reported outcomes(PROs)for the knee function evaluation in Chinese RPD patients.This study aims to under the guidance of "Jin-Gu" theory of traditional Chinese medicine,through imaging study to search the overall lower limbs abnormal rotation risk factors,verify the efficacy of DFO and validate a new PROs for patient knee function assessment.Objective:1、To identify the differences on the femur rotation between the supine and standing positions and investigate the differences of anatomical and functional femur rotation between recurrent patellar dislocation(RPD)patients and controls.2、To investigate the mid-term outcomes of distal derotational femur osteotomy(DFO)in RPD treatment.3、To cross-culturally translate and validate the Chinese versions of the Oxford Knee Score and the Activity and Participation Questionnaire(OKS&APQ)in mainland China.Methods:1、Thirty RPD patients and 27 controls were recruited.Anatomical femoral anteversion(AFA),functional femoral anteversion(FFA),femorotibial rotation(FTR)and distal femoral torsion(DFT)of all subjects were measured with the EOS imaging system.The differences of FFA between supine and standing position and of AFA,FTR and DFT between RPD and controls were analyzed.The predictor importance of each variable was observed after cluster analysis.2、Eight patients with RPD who underwent DFO from January 2018 to April 2020 were included.Postoperative follow-up was 10 to 24 months.Preoperative and postoperative AFA was measured and recorded using the EOS imaging system.Patellar Feller score and APQ score were recorded preoperatively,6 months after surgery,and 1 year after surgery or at the last follow-up.Patellar tracking and stability of the affected knee were evaluated at the last follow-up.3、The Chinese version of the OKS and APQ was completed by standard forwardbackward translation and adaption.The final version together with the Short Form-36(SF-36),EQ-5D and EQ visual analogue scale(EQ VAS)were assessed in 150 patients,and the OKS and APQ were repeated in thirty patients after a two-week interval.The psychometric properties of the OKS and APQ were evaluated for test-retest reliability using intraclass correlation coefficients(ICCs),internal consistency using Cronbach’s alpha,and construct validity using Spearman’s correlation analysis.Results:1、The EOS images were available in all subjects.The FFA was significantly smaller in standing position than supine position(p<.05).When comparing to the controls,RPD patients showed higher AFA,FTR and DFT(p<.05)while there was no significant difference in FFA(p>.05).The cluster model prompted that FTR and DFT had higher predictor importance compared with AFA.2、All patients were followed up from 10 to 24 months(15.9±5.8).Preoperative "J"sign of patella was 3+in 2 cases and 2+in 6 cases,of which the patella tracking of 5 patients was observed with arthroscope during the internal fixation material removal surgery.The average AFA of patients was 32.7±9.0° preoperatively and 18.0±3.3°postoperatively,which was significantly lower than preoperatively.Postoperatively,1 patient presented delayed union at the osteotomy site,and fracture union was followed up in partial weight-bearing state until 12 months after surgery.The average APQ score of patients was 17.5 ± 2.1 before surgery,10.6 ± 1.4 6 months after surgery,and 10.4±1.1 at the last follow-up.The average Feller score of patients before surgery was 17.5±2.1,10.6±1.4 6 months after surgery,and 10.4±1.1 at the last follow-up.APQ score and Feller score improved significantly after surgery.In the last follow-up,all the patients were negative in the "J" sign and in the patellar apprehension sign.3、All patients were able to understand and complete both the OKS and APQ without difficulty.The ICCs were 0.959 for the OKS,0.956 for the APQ for total scores and>0.7 for each item.Cronbach’s alpha was greater than 0.7,and the corrected itemtotal correlation was greater than 0.4 for each item of both questionnaires.The OKS and APQ showed better correlations with questions from the pain and function domains than with those from the mental status domains of the SF-36 and EQ-5D.No floor or ceiling effect was identified in either questionnaire.Conclusion:1、The FFA in the standing position is significantly less than that in the supine position.AFA may be inadequate and FFA should also be considered while planning the treatment for RPD.DFT and FTR should be taken into consideration when evaluating the abnormalities in femur rotation in RPD patients.2、DFO was a safe and reliable approach in RPD treatment,and the mid-term followup results showed that the patients knee function improved significantly after surgery.3、The Chinese versions of the OKS and APQ are easy to understand and complete and showed good reliability and validity.They can be used to assess patient-reported outcomes for people with knee diseases in mainland China.