Long-term Postoperative Evaluation Of TMJ Disc Anchorage A Study On Clinic And MRI And Posterior Disc Displacement Animal Model Study

PURPOSE: The purpose of this study was to make long-term efficacy evaluation for the cases with temporomandibular joint(TMJ)anterior disc displacement(ADD)who have undergone TMJ disc anchorage for more than 2 years,and to analyze the influence of different disc position,the length of disc,the height of condyle and the age on the efficacy of operation.METHODS: From January 2014 to December 2015,a total of 37patients(51 joints)were included in the study.The long-term clinical effect of the operation was evaluated by clinical examination and clinical efficacy questionnaire survey;the relationship between the disc and condyle was qualitatively evaluated by MRI and the length of the disc and the height of the condyle were quantitatively measured by MRI.A rabbit model of posterior disc displacement of TMJ was established to analyse the effect of operation on condylar cartilage.RESULTS: The mean age of patients was 23.84±11.83 years and the mean follow-up time was 41.3 months.The average maximum mouth opening improved by 12.26±3.92 mm compared with preoperative examination and the mean value of Visual analog scale(VAS)decreased by 1.41±1.83.There were significant differences in both results(p<0.05).The efficiency of clinical evaluation was 94.12% and the satisfaction rate of patients' self-evaluation was 100%.The MRI results showed that the total effective rate was 96.08%.In normal-repositioning group the effective rate was 91.7% while in over-repositioning group the effective rate was97.4%.On the immediate post-operation MRI,the disc length increased by3.60±1.66 mm compared with that before operation,and there was significant differences(P < 0.05);During the follow-up period,the disc length increased by 0.47±2.26 mm,and there was no significant differences(P > 0.05);During the follow-up period,the disc length decreased by 1.45± 1.85 mm in the normal-repositioning group,but increased by 1.06 ±2.05 mm in the over-repositioning group,there was significant difference between the two groups(P < 0.05).During the follow-up period,the height of the condyle increased by 1.79±1.95 mm,with a significant statistical difference(P < 0.05),and the younger the patients were,the more obvious the height of the condylar increased;During the follow-up period,the height of the condyle increased by 0.73±2.01 mm in the normalrepositioning group and 2.09±1.85 mm in the over-repositioning group,with no significant statistical difference between the two groups(P >0.05).A rabbit model of posterior disc displacement of TMJ was established,and the success rate was 88.89%.Conclusion:1.The clinical symptoms and joint functiuon of the patients were improved significantly after anchorage surgery;2.MRI confirmed the TMJ disc anchorage has a long-term stablity;3.When disc was over-repositioned,the disc-condyle position was more stable,and the disc length was significantly increased;4.A rabbit model of posterior disc displacement of TMJ was established,which may play an important role on further study of the impact of surgery on condylar cartilage osteogenesis.