Radiology Measurement Of Distal Clavicle Tilt Angle

Object: Propose a method for measuring the inclination angle of distal clavicle on anteroposterior x-ray.Prove the hypothesis that the inclination of the distal clavicle is related to the acromioclavicular joint dislocation and analyse the clinical application value of it.Materials and methods: In the experimental group,41 patients with acromioclavicular dislocation,33 males and 8 females,aged 43.5±10.8(23-63)years,were selected.In the control group,100 normal population,50 male and 50 female were selected,and the age was 52.2-15.7(14-84)years.Measurement of mechanical tilt angle and anatomical tilt angle of distal clavicle on AP view of shoulder X-ray of dislocated side in experimental group and normal shoulder in control group,make acromioclavicular joint morphological grouping.Test the difference and correlation of two kinds of angle measurement in 141 samples,correlation between age and distal clavicle tilt angle and differences among different morphological groups.Test the differences of distal clavicle angle in gender and compared the differences of patients and normal population.Result: In 141 samples,the angle values of two different measurement methods were significantly different and also correlate with each other significantly.No correlation was found between angle values and age.In the three different morphological group,oblique type showed smaller angle values than other type significantly but no difference between flat type and curved type.The mechanical and anatomical angles of normal males were 68.1 °±12.9 °and 75.9 °±11.1 °respectively,lower than 76.8 °±9.3 °and83.1 °±7.9 °significantly of normal women.The mechanical angle and the anatomical angle of the male patient were 65.0°±9.5°and 71.3°±9.2°,and were significantly lower than 75.6°±15.8°and 82.4°±20.1°for female patients.In male,there was a significant anatomical angle value difference between patientsand normal males.But no difference was revealed in female patient and normal females.Conclusion: Two different measurement of inclination is not affected by age but lower value in oblique type when compared with flat and curved type.The significant difference of angle value in gender,and between patient and normal were authenticated by statistics analyse.There is a relationship between the tilt angle of the distal clavicle and the occurrence of acromioclavicular joint dislocation and a trend that the smaller the inclination angle of the distal clavicle is,the more likely it is to occur acromioclavicular joint dislocation in trauma is revealed.Distal clavicle tilt angle can be a diagnostic reference indicator to avoid missed diagnosis,also as a potential surgical guidelines and has a great potential for clinical application.