| Objective: 1.To investigate the correlation between the four imaging signs of Acetabular Retroversion(AR)and their value in the diagnosis of AR,2.To investigate the reasons for the high false positive rate of Cross over sign(COS)in the diagnosis of AR and its relationship with the pincer-type deformity(Pincer type)in Femoral acetabular impingement syndrome(FAI).Methods: In this prospective study,clinical data were collected from January 2021 to December 2022 from patients attending the outpatient clinic of Qingdao University Hospital with hip pain as the main complaint.All patients had standard pelvic radiograph and CT of the hip joint,and imaging measurements were performed using Micro Dicom software.The presence of AR was determined according to the CT results(the diagnostic criteria were: firstly,the longest femoral head diameter was determined in the coronal position,and the measurement of the acetabular anterior tilt angle was performed in the horizontal position after flipping,and the line connecting the anterior and posterior edges of the acetabulum was made while passing through the posterior edge of the acetabulum to make a vertical line passing through the horizontal straight line,and AR was determined by the acetabular anterior tilt angle 40° was used as the diagnostic criterion for Pincer deformity.The number of positive cases of COS,Posterior wall sign(PWS),Prominence of the ischial spine sign(PRISS),and Elephant’s ear sign(EES)were counted in all patients.The diagnostic efficacy indicators of the four signs were calculated:sensitivity(Sen),specificity(Spe),positive likelihood ratio(+LR=Sen/1-Spe)and positive predictive value(PPV).Logistic regression was applied to analyze the relationship between the four imaging signs and AR and Pincer’s malformation.Results: Clinical data were collected from a total of 1250 patients.A total of 335 patients,149(44.5%)males and 186(55.5%)females;age 42.48±11.65(18-65)years,were included in the study after screening according to the nadir criteria.The mean age of patients in the AR group was 39.54±12.49 years(interval),33(41.2%)were male and 47(58.8%)were female;23(28.8%)were left-sided,25(31.2%)were right-sided,and 32(40.5%)were bilateral.The mean age of patients in the Non-AR group was 43.41±11.24years(interval),116(45.5%)were male;139(54.5%)were female,89(34.9%)were leftsided,96(37.6%)were right-sided,and 70(27.5%)were bilateral;the results of statistical analysis showed that there was no statistical difference in age,gender,and side between the two groups.The results of statistical analysis showed no statistically significant differences in age,gender and side between the two groups(P > 0.05).In terms of imaging angles and signs between the AR and Non-AR groups,statistical analysis showed that the difference between the CE angle of 35.86±6.89° in the AR group and 38.09±7.19°in the Non-AR group was not statistically significant(P>0.05);the Tonnis angle of9.64±2.34° in the AR group and 9.44±2.01° in the Non-AR group was statistically significant.±The positive rate of COS in the AR group was 80.0%,PWS was 85.0%,PRISS was 93.7%,and EES was 96.3%;the positive rate of COS in the Non-AR group was 22.4%,PWS was 4.7%,PRISS was 7.5%,and EES was 7.5%.The positive rates of COS,PWS,PRISS and EES in the AR and Non-AR groups were statistically analyzed and the differences were statistically significant(P < 0.05).The diagnostic indexes of the four major signs were also calculated: sensitivity(Sen),specificity(Spe),and positive likelihood ratio(+LR=Sen/1-Spe),and the results showed that Sen was 80.0% and Spe was 77.6% for COS,85.0% and Spe was 4.7% for PWS,93.7% and Spe was 7.5% for PRISS,and Sen of 96.3% and Spe of 9.0% for EES,+LR of 3.6 for COS,+LR of 18.1 for PWS,+LR of 12.5 for PRISS,and +LR of 10.7 for EES,with significant reliability in diagnosing AR.For the analysis of the PPV of the four signs,the PPV when three of the four imaging signs were positive at the same time in AR patients: 1,the PPV for the diagnosis of AR was 90.9% when PWS,PRISS,and EES were positive at the same time,2,the PPV when COS,PRISS,and EES were positive at the same time was 77.8%,and 3,the PPV was 43.8%.The PPV was 53.8% when two of the four signs were positive at the same time: 1.53.8% when PRISS and any other sign were positive,2.50.0% when PWS and any other sign were positive,3.36.4% when EES and any other sign were positive,and 4.23.1% when COS and any other sign were positive.Regression analysis with AR as the dependent variable showed that there was a positive relationship between positive PWS,PRISS and EES and positive AR;positive COS had no effect on positive AR.The OR values of COS,PWS,PRISS and EES were >1,which were risk factors for the development of AR.The regression analysis with Pincer deformity as the dependent variable showed that COS had a positive effect on the occurrence of Pincer deformity;the size of CE angle had a positive effect on the occurrence of Pincer deformity;the size of Tonnis angle did not have an effect on the occurrence of Pincer deformity.Among them,OR values of COS,CE angle and Tonnis angle >1 were risk factors for the development of Pincer deformity.All patients with both AR and Pincer deformity were excluded,at which point a logistic regression analysis was performed with AR as the dependent variable and COS as the independent variable,showing a significant increase in the effect of COS on the presence or absence of AR(p < 0.001).Conclusion: The diagnostic efficacy indexes of the four imaging signs COS,PWS,PRISS,and EES were all good indicators of AR,and were effective imaging signs for diagnosing AR in radiographs.Among the diagnostic efficacy when multiple signs were positive at the same time,the PPV for diagnosing AR was the highest when three signs were positive at the same time,PRISS,PWS,and EES.The statistical significance of COS in diagnosing AR in patients with AR with Pincer malformation in FAI was not significant,and the statistical significance of COS in diagnosing AR was significantly higher after excluding this group of patients with AR with Pincer malformation,so COS was susceptible to the influence of Pincer malformation in diagnosing AR;the diagnosis of AR by imaging signs or AR with Pincer malformation in FAI When diagnosing patients with AR or AR with Pincer deformity in FAI by imaging signs,COS could not easily diagnose whether the patients with FAI also had AR,while the diagnostic efficacy of PWS,PRISS,and EES were not affected,so it had a higher reference value for indicating whether the patients also had AR,and the clear diagnosis of whether the patients with FAI had AR was important for guiding the subsequent surgical treatment of such patients. |
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