MPFL Reconstruction In The Treatment Of Recurrent Patellofemoral Instability And Risk Factors For Failure

PART1 Study of Isolated MPFL Reconstruction in the Treatment of Recurrent Ratellofemoral InstabilityObjective: The purpose of this study is to clarify whether isolated MPFL reconstruction is sufficient to produce good clinical results only by solving the influencing factors of recurrent patellofemoral instability,so that we can avoid overtreatment.Methods: Retrospective analysis of patients who received simple MPFL reconstruction(both using tibia line anchor fixation)between January 2015 and January 2017 were included in 69 patients(78 knee cases)due to recurrent instability of the fissure),the average follow-up time was 2.5 years(range 1.6-3.1 years),of which 5 patients(6 cases of knee)were missed,so we analyzed 64 patients(72 knee)of the hospital,of which 30 were knees and 42 knee sons were in Beijing University International Hospital.All operations are performed by physicians above the deputy director level for simple MPFL reconstruction,which is managed and rehabilitated in accordance with standardized procedures.Preoperative/postoperative clinical evaluation of patients included Kujala scoring,fear testing,and tibia exorcism tests.Imaging data were obtained through knee positive plates,standard side plates,shaft slots,and knee CT/MRI to evaluate changes in the tilt angle of the tibia before and after treatment in patientsResults: The Kujala score increased from 66.7 ±7.8 before operation to 90.4 ±9.7after operation(P<0.001).The tilt angle of patella decreased from 20.6 ±2.5°to 11.3±1.6°(P<0.001).Postoperative fear test and patellar extrapolation test were negative in all patients.after isolated MPFL reconstruction,9 patients(9 knees)with patellofemoral instability needed surgical revision(12.5%).Conclusion: Isolated MPFL reconstruction is a safe and effective method for the treatment of recurrent patellofemoral instability in the current short-term follow-up(average 2.5 years).The success rate is high(87.5%).The knee joint function of the patients can be improved after operation.PART2 Analysis of Risk Factors for Failure of Isolated MPFL Reconstruction in the Treatment of Recurrent Patellofemoral InstabilityObjective: To analyze which risk factors affect the clinical outcome through failed cases,and to evaluate which risk factors for failure can help clinicians identify "high-risk" patients.This information will help to analyze the patients and their prognosis.If these high-risk patients are predicted to have a significant risk of recurrent instability or persistent symptoms after the first dislocation,then consider MPFL reconstruction in combination with other surgical procedures for these high-risk patients.Methods: According to the results of the last follow-up,the patients were divided into control group(n = 63)and revision group(n = 9).The imaging data were obtained from the knee joint anteroposterior film,standard lateral film,axial film and knee joint CT/MRI.According to the Dejour classification of trochlear dysplasia,the patellar height was evaluated by Caton index(CDI),and the tibial tubercle-trochlear groove(TT-TG)distance and patellar tilt angle were measured.Analysis of whether there is a difference between the two groups,there is a statistical analysis of the indicators of the difference in order to find out the failure factors of simple MPFL reconstruction in the treatment of recurrent patellofemoral instability.Results:1.The difference between the two groups in preoperative data was no significant,including age,side,sex,body mass index((BMI)),patellar tilt angle and tibial tubercle-trochlear groove distance(TT-TG).2.The Kujala score of the control group increased from 68.6±9.3 to 91.3±6.7(P<0.001),and the Kujala score of the revision group increased from 64.8±7.8 to 89.6 ±5.4(P <0.001).There was no significant difference in Kujala score between the two groups.The proportion of pulley dysplasia(especially type D)and the severity of patella alta in the revision group were higher than those in the control group,and the difference was statistically significant.3.Univariate and multivariate analysis of the revision group showed that there were two risk factors for the failure of simple MPFL reconstruction: severe trochlear dysplasia(OR,3.08;95% CI,1.38-8.72;P = 0.03)and patella alta(OR,1.86;95% CI,1.25-7.56;P = 0.01).Conclusion:1.Severe trochlear dysplasia(especially type D pulley)and patella alta are failure risk factors for revision after simple MPFL reconstruction.2.The increase of TT-TG distance alone(? 20 mm)will not lead to the failure of simple MPFL reconstruction,but will increase the risk of postoperative revision in patients with pulley dysplasia,especially in patients with severe cochlear dysplasia.3.No correlation was found between patella alta and trochlear dysplasia.