Radiometric characteristics of the acromioclavicular joint with respect to clinical relevance, age and gender [Radiometrische Charakteristika des Akromioklavikulargelenks im Hinblick auf klinische Relevanz, Alter und Geschlecht]

Introduction: The objective of the examination was to quantify the acromioclavicular joint (ACJ) angles in the light of different X-ray projection methods in correlation to age and gender, to ACJ gap width and to acromiohumeral distance (AHD) under clinical aspects. Materials and methods: The cohort consisted of 300 patients (114 female and 186 male, average age 61 years) and ACJ angles as well as the ACJ gap width and AHD were determined on standardized radiological projection methods. Results: The ACJ angle amounted to an average of 20. 36° (± 9. 8°) in the Zanca view. With increasing age the mean angle showed a decrease to an average of 17. 00° (± 11. 5°) in the group of patients aged 81-90 years. The ratio between the ACJ angle and gap width showed a significant decrease of gap width at shallow ACJ angles and the AHD decreased with increasing age without correlation to the ACJ angle. Conclusions: The findings showed a projection-related shallower ACJ angle in conventional a. p. projection compared to the Zanca view independent of gender and 50 % of the cohort showed an ACJ angle of more than 20°. This is of relevance for both injections and ACJ resections. © 2012 Springer-Verlag Berlin Heidelberg.