The Application Of Modified Tonnis Angle In The Imaging Diagnosis Of Acetabular Dysplasia In Adult

Adults with acetabular dysplasia usually have a shallow or deformed acetabulum, occasionally with luxation or subluxation of the hip. Acetabular dysplasia is the most common type of congenital hip disease in adult. The disease in adult had been undiagnosed until the onset of symptoms during the second or third decade of a patient’s life. Dysfunction, moderate pain during exertion, and a mild limp were the initial symptoms. Patients with persistent acetabular dysplasia and subluxation are at high risk of osteoarthritis (OA). Between20%and50%of adults develop arthritis because of subluxation or dysplasia of the hip. The lack of early diagnosis and treatment for acetabular dysplasia can lead to OA in adults. At present, the imaging diagnosis of acetabular dysplasia typically depends on radiographic evaluation. Certain parameters, such as the center-edge (CE) and Tonnis angles, are the most commonly used measurements of acetabular dysplasia. As an improvement of the Tonnis angle, a new angle preliminarily named the Modified Tonnis angle was created The study was divided three chapters:CHAPTER I:Feasibility study of modified Tonnis angle in the imaging diagnosis of acetabular dysplasia in adult, CHAPTER II: The evaluation of the diagnostic criteria of CE angle, Tonnis angle and Modified Tonnis angle in the diagnosis of acetabular dysplasia, and CHAPTER III: Reproducibility of the measurement of CE angle, Tonnis angle and Modified Tonnis angle in adults. Objective:This study is to evaluate the limitations of Tonnis angle as one of the most commonly used parameters in the diagnosis of acetabular dysplasia, and to explore the feasibility of the modified Tonnis angle in the diagnosis of acetabular dysplasia.Methods:Conventional anterior-posterior pelvic radiographs of patients were extracted from the picture-archiving communication system in The Second Hospital of Shandong University, we assessed all anterior-posterior pelvic radiographs according to the criteria of Siebenrock et al. A total of224patients (120females and104males) with448hips, aged from15to83years (median45.0years), were selected. CE angle, Tonnis angle, center-medial-edge (CME) angle and modified Tonnis angle were measured, center-medial-edge (CME) angle was designed to evaluate the relative position of the medial edge of the acetabular sourcil. As an improvement of the Tonnis angle, a new angle preliminarily named the modified Tonnis angle was created. In addition, the degree of clarity of the medial edge of acetabular sourcil on radiograph was evaluated, and all hips were divided into two groups, the clear-edge group and the blurred-edge group. The. hips belonging to the blurred-edge group could not be used to measure Tonnis angle. All measurements were performed digitally using the tool of the picture-archiving communication system. All statistical analyses were performed using SPSS18.0for Windows (StatSoft Inc., USA). Associations between any two of the CE angle, the Tonnis angle and the modified Tonnis angle were evaluated using Pearson’s coefficient of correlation (r). Association between CME angle and CE angle was also evaluated. Differences were considered significant when P<0.01.Results:Among the448acetabular sourcils,142had blurred medial edge (31.7%). The measurement of CE angel (448hips, mean=33.03°,95%CI:32.42°-33.64°, standard deviation=6.63), CME angle (306hips, mean=37.94°,95%CI:37.22°-38.66°, standard deviation=6.41), Tonnis angle(306hips, mean=5.83°,95%CI:5.19°-6.47°, standard deviation=5.69) and,modified Tonnis angle(448hips, mean=2.67°,95%CI:2.24°-3.10°, standard deviation=4.62,95%PI:-6.39°-11.73°) were made. The mean value of CME angle was37.94°with a range from21.76°to63.99°. The95%prediction interval of the modified Tonnis angle was estimated to be-6.39°to11.73°. The correlation coefficients were-0.838between CE angle and Tonnis angle,0.889between Tonnis angle and modified Tonnis angle, and-0.905between CE angle and modified Tonnis angle. The correlation between CE angle and modified Tonnis angle was the strongest. According to the scatter plot, there was no association between CE angle and CME angle.Conclusion:the measurement of Tonnis angle sometimes became impossible on account of blurred medial edge of sourcil, and could be more or less influenced by the relative position of the sourcil’s medial edge, which could be considered as limitations of the Tonnis angle in the diagnosis of acetabular dysplasia. This study demonstrated that the modified Tonnis angle was a feasible and available parameter for radiographic evaluation of the acetabular dysplasia,and could substitute for Tonnis angle without joint space narrowing and subluxation of the hip, especially when Tonnis angle cannot be measured due to blurred medial edge of acetabular sourcil on pelvic radiograph. Objective:This study is to evaluate the diagnostic criteria of CE angle,Tonnis angle and Modified Tonnis angle in the diagnosis of acetabular dysplasia, and to find the most appropriate of diagnostic criteria.Methods:Conventional anterior-posterior pelvic radiographs of patients were extracted from the picture-archiving communication system in The Second Hospital of Shandong University. We assessed all anterior-posterior pelvic radiographs according to the criteria of Siebenrock et al. A total of224patients (120females and104males) with448hips, aged from15to83years (median45.0years), were selected. CE angle, Tonnis angle, and modified Tonnis angle were measured. Associations between any two of the CE angle, the Tonnis angle and the modified Tonnis angle were evaluated using Pearson’s coefficient of correlation (r). The diagnostic criteria for acetabular dysplasia were selected:CE angle value less than20°, CE angle value less than25°, Tonnis angle value greater than10°, Tonnis angle value greater than13°, Modified Tonnis angle value greater than10°, Modified Tonnis angle value greater than12°and Modified Tonnis angle value greater than8.5°. The positive rates of all diagnostic criteria were computed. McNemar’s test were used to evaluate the statistical difference of the positive rates of all diagnostic criteria. All measurements were performed digitally using the tool of the picture-archiving communication system. All statistical analyses were performed using SPSS18.0for Windows (StatSoft Inc., USA). Differences were considered significant when P<0.01.Results:The CE angle and Modified Tonnis angle were measured at all the448acetabular sourcils, and306hips were used to measure the Tonnis angle. The correlation coefficients were-0.838between CE angle and Tonnis angle,0.889between Tonnis angle and modified Tonnis angle, and-0.905between CE angle and modified Tonnis angle. The correlation between CE angle and modified Tonnis angle was the strongest. The diagnostic positive rates were2.46%(CE angle value less than20°),10.94%(CE angle value less than25°),23.53%(Tonnis angle value greater than10°),9.80%(Tonnis angle value greater than13°),5.58%(Modified Tonnis angle value greater than10°),1.79%(Modified Tonnis angle value greater than12°) and9.38%(Modified Tonnis angle value greater than8.5°). According to results of McNemar’s test, there were no statistically significant difference (P<0.05) in diagnostic positive rates between CE angle value less than25°, Tonnis angle value greater than13°and Modified Tonnis angle value greater than8.5°.Conclusion:Among all the diagnostic criteria, CE angle value less than25°, Tonnis angle value greater than13°and Modified Tonnis angle value greater than8.5°were the most appropriate of diagnostic criteria. Objective:To evaluate the interobserver and intraobserver reproducibility of CE angle, Tonnis angle, Modified Tonnis angle measurement in adults.Methods:Conventional anterior-posterior pelvic radiographs of patients were extracted from the picture-archiving communication system in The Second Hospital of Shandong University. We assessed all anterior-posterior pelvic radiographs according to the criteria of Siebenrock et al. A total of224patients (120females and104males) with448hips, aged from15to83years (median45.0years), were selected. CE angle, Tonnis angle, and Modified Tonnis angle were measured. All measurements were performed by two experienced observers, who worked independently of each other and were blind to the other measurement results. These measurements were performed twice at an interval of1month. No marks were made on the radiographs during the initial measurements. All measurements were performed digitally using the tool of the picture-archiving communication system. Inter-and intraobserver reproducibilities of radiographic parameter measurements were evaluated based on the intraclass correlation coefficients (ICCs). All statistical analyses were performed using SPSS18.0for Windows (SPSS Inc., USA). Differences were considered significant when P<0.01.Results:The CE angle and Modified Tonnis angle were measured at all the448acetabular sourcils, and306hips were used to measure the Tonnis angle. ICCs indicated very good intraobserver reproducibility of radiographic parameter measurement, with values of0.86to0.89for one observer and0.87to0.91for the other observer. ICCs also indicated very good interobserver reproducibility for CE angle, Tonnis angle and Modified Tonnis angle, with values of0.83for CE angle,0.80for Tonnis angle and0.86for Modified Tonnis angle.Conclusion:In this study, reproducibility of the CE angle, Tonnis angle and Modified Tonnis angle was good according to the intraclass correlation coefficients (ICCs).