The Role Of TT-RA And TT-TG Measured By MRI In The Diagnosis And Treatment Of Patellar Dislocation

Research purpose: To explore the diagnosis and treatment significance of TT-TG and TT-RA on MRI for patellar dislocation.CT-measured TT-TG has been widely used as the gold standard to guide TTO surgery,but it does not perform well in patients with patellar trochlear dysplasia.TT-RA was proposed for this situation,and its diagnostic ability was preliminarily tested on CT and a guide value for surgery was obtained.The authors reported that CT-measured TT-RA was superior to TT-TG in terms of data stability and diagnostic ability.The value of MRI in evaluating the degree of acute injury of patellar dislocation and evaluating the condition of cartilage and soft tissue cannot be replaced by other examinations.TT-TG has also been reported to perform very well on MRI,although not interchangeable with measurements on CT.In MRI,the center of the insertion of the patellar tendon can be selected on the tibial side as a reference,rather than the tibial tubercle,which is more in line with the axis of force.Based on this research background,if it can be proved that TT-RA on MRI has a stable diagnostic ability and is superior to TT-TG,a more scientific critical value for guiding surgery can be calculated.In this way,CT examinations with radioactivity can be avoided,and more accurate diagnosis and surgical indications can be provided.Research methods: The MRI images of 32 healthy knee joints and 47 knee joints diagnosed with patellar dislocation in our hospital in the past 5 years were collected.The difference between TT-TG and TT-RA on MRI between the case group and the control group were analyzed.The ROC curve was drawn to explore the ability of two indicators to diagnose patellar dislocation and predict recurrence separately,and to get the critical value of diagnosis.The intra-group correlation coefficient（ICC）was used to analyze the reliability of two indicators in different pulley dysplasia types（Dejour type）Research results: 1.The values of TT-TG and TT-RA in the case group were significantly higher than those in the control group.2.The area under the ROC curve of TT-RA for diagnosing patellar dislocation was 0.752.When the critical value was 16.58 mm,the sensitivity was 72.3% and the specificity was 75.0%.The area under the curve for predicting the recurrence of patellar dislocation was 0.778,and when the critical value was 23.43 mm,the sensitivity was 66.7% and the specificity was 96.9%.The area under the ROC curve of TT-TG for diagnosing patellar dislocation was 0.768.When the critical value was 15.02 mm,the sensitivity was 57.4% and the specificity was 87.5%.The area under the curve for predicting the recurrence of patellar dislocation was 0.733.When the critical value was 19.05 mm,the sensitivity was 60.0% and the specificity was 93.7%.3.TT-RA showed stable performance in all types of trochlear dysplasia,while TT-TG showed poor performance in C type（ICC=0.742）.Research conclusion: 1.MRI measurement of TT-TG and TT-RA has definite diagnostic significance in diagnosing patellar dislocation and predicting recurrence.2.When the TT-RA measured by MRI is greater than 23.43 mm and the TT-TG is greater than 19.05 mm,surgical treatment of patellar dislocation can be considered.3.TT-RA can not completely replace TT-TG,but TT-RA has a more stable ICC value in various types of trochlear dysplasia.TT-RA can assist TT-TG in the diagnosis of severe trochlear dysplasia.