Clinical Study Of The Medial Patellofemoral Ligament Combined With Medial Patellotibial Ligament Reconstruction In The Treatment Of "J" Sign Positive Recurrent Patellofemoral Dislocation

OBJECTIVES:(1)To evaluate the short-term outcome of medial patellofemoral ligament(MPFL)combined with medial patellotibial ligament(MPTL)reconstruction for recurrent patellar dislocation with a positive "J" sign,and to provide a new and more optimal treatment option for reducing the risk of redislocation after surgery.(2)Assess the risk factors associated with the "J" sign and investigate the causes of the "J" sign.METHODS: A total of 32 patients were divided into a high grade study group of 2 or more degrees and a low grade control group of 1 degree according to the "J" sign classification.13 patients were in the study group and 19 in the control group.The study group performed total arthroscopic reconstruction of the medial patellofemoral ligament combined with the medial patellotibial ligament,while the control group performed total arthroscopic reconstruction of the medial patellofemoral ligament,and both groups performed lateral collateral ligament release.Patients were assessed preoperatively for knee function and followed up at 3 months,6 months and 9 months postoperatively to record and compare the differences between the two groups in Kujala,International Knee Documentation Committee(IKDC)subjective knee scores,Lysholm objective knee function scores,comparison of Tegner scores preoperatively and at last follow-up and patellar redislocation rates in each group;radiological assessment of differences between the two groups in femoral anteversion angle(FAA),TTTG distance,TTRA distance,degree of trochlear dysplasia,patellar height,patellar lateral tilt and patellar bisect offset index.RESULTS: In terms of general information,the study group had a lower overall BMI compared to the control group(p < 0.05).In terms of overall knee function,the Lysholm,Kujala and IKDC scores at 9 months postoperatively were significantly higher in both the study and control groups compared to the preoperative scores(P < 0.05);the Lysholm and Kujala scores were lower in the study group compared to the control group at 3 and 6 months postoperatively(P < 0.05);there was one case of patellar redislocation in each of the study and control groups postoperatively.The patellar redislocation rate was 7.1% and 5.6% in the study and control groups,respectively.At9 months after surgery,there was no significant difference in the Tegner score between the two groups,and the return to sport rate was 84.6% in the study group and 84.2% in the another group.There was a statistically significant improvement in the Tegner score at 9 months postoperatively in both the study and control groups compared to the preoperative score(P < 0.05);there was a statistically significant improvement in the Tegner score at 9 months postoperatively in the study group compared to the pre-injury score(P < 0.05).On radiological assessment,the femoral anteversion angle was significantly greater than normal in both the study and control groups,more so in the study group compared to the control group,with a statistical difference(P < 0.05);no significant increase in TTTG distance and TTRA distance was found in either the study or control groups,and there were no intergroup differences;femoral trochlear dysplasia was predominantly type B in both the study and control groups(8/13: 15/ 19);the preoperative Caton index and Insall index were not significantly higher than normal in the control group,with a significant difference(P < 0.05),while the study group was at the threshold of patella alta;the preoperative patellar lateral tilt angle and patellar bisect offset index were significantly higher than normal in both groups,with a significant difference(P < 0.05),and there was no significant difference between the two groups.Postoperatively,patellar height,patellar lateral tilt angle and patellar bisect offset index all returned to normal(P < 0.05),with no significant difference between the two groups.CONCLUSION: Medial patellofemoral ligament combined with patellotibial ligament reconstruction is an effective treatment for high grade “J” sign positive recurrent patellar dislocations and can significantly improve knee function.It is possible to consider combined ligament reconstruction in patients with recurrent patellar dislocations of high grade "J" sign.Risk factors for the "J" sign include femoral anteversion,patellar lateral tilt and patellar bisect offset index,with a higher femoral anteversion angle tending to indicate a higher grade of "J" sign.