| Objective:To study retrospectively the indirect signs of knee joint magnetic resonance imaging(MRI)and the characteristics of anterior cruciate ligament(ACL)injury with anterior tibial advancement(ATT),to assess the diagnostic value of ATT in gradeⅢ damage(complete rupture)to the ACL.Method:123 cases of knee joint with MR I examination before operation were selected.The patients’ACL status was observed by arthroscopy.According to the different status of ACL,123 cases were classified into the standard,there are three groups:ACL Normal Group,ACL Incomplete Fracture Group,ACL Complete Fracture Group.The ATT distances were measured on MRI data collected by two orthopaedic surgeons and the positive rate of ATT among the different groups was calculated.The t2-weighted sagittal MRI images of the knee were taken at the level of the lateral platform(just exposing the fibular head).Draw a parallel line on the lateral tibial plateau,then draw a circle with reference to the lateral femoral condyle,then draw a tangent a behind the circle so that the tangent a is perpendicular to the parallel line of the lateral tibial plateau,the ATT length was indicated by measuring the distance of the AB line through the final cortex of the lateral tibial plateau as another vertical line B.The positive rate of ATT and the distance of ATT between the three groups were statistically analyzed.The difference of ATT distance between the ACL complete rupture group and the other two groups was compared,the mean ATT distance of each group can be used to characterize the ACL with different damage levels.Because the ACL states collected in this study did not come from the same surgeon,the error of the ACL microscopic diagnosis of incomplete injury was greater than that of complete fracture,therefore,only the mean ATT distance of the complete fracture group was described and used as the primary diagnostic criteria for the diagnosis of gradeⅢ damage of ACL.Basic data on patients including sex,age,and whether or not they had associated meniscal injury were collected and analyzed for interference with the objectives of the study.Variance analysis was used to analyze the differences among the three groups,and MedCalc and SPSS25.0 were used to process all patients’ data.Results:Bland-altman figure shows that there was good agreement between the two orthopedic surgeons in the measurement of ATT distance(p>0.05).There was no significant difference in the positive rate of ATT sign between patients of different sex,age and with or without meniscal injury(p>0.05),there was no significant difference in the length of ATT between sexes and with or without meniscal injury(p>0.05).In all patients with positive ATT,there was no significant correlation between age and ATT length(r=0.193,P>0.05).In 123 cases,the length of ATT in patients with grade Ⅲ injury(ACL complete rupture)was significantly longer than that in patients with normal ACL or incomplete ACL rupture(p<0.001),the positive rate of ATT was higher than that of ACL normal group and incomplete rupture group(p<0.05).The average length of ATT in the ACL complete fracture group was 6.45 mm,and that in the ACL incomplete fracture group was 4.25 mm.Conclusion:Indirect sign ATT of MRI can provide a reference for clinical doctors to evaluate the grade Ⅲ injury of ACL and assess whether ACL is completely broken by measuring the length of ATT,the ACL is more likely to be completely fractured when the ATT distance is greater than 6.45 mm. |
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