Abstract
BackgroundThe primary goal of this study was to analyse the anatomic configuration of the acromio-clavicular joint in a healthy population to be able to develop a classification in a second step. On the basis of the primary findings a secondary goal was to find potential clinical indications in refer to AC-joint dislocation and lateral clavicle fractures.MethodsThe upper thoracic aperture including both shoulder joints as well as both sterno-clavicular joints was retrospectively reformatted in a bone kernel in axial orientation with 0.6 mm slice thickness out of existing multiple trauma or post mortem computed tomography (CT) scans. The DICOM data was converted into the STL file format using a three dimensional (3D) reconstruction software (Smartbrush, Brainlab, Feldkirchen, Germany). The data analysis was performed using a 3D—Computer Aided Detection (CAD) Software (BioCAD, Technical University Munich, Germany). For the analysis, the angle between the cranial surface of the acromion and the tangent to its articular surface was evaluated. Accordingly, the angle between the cranial surface of the clavicle and the tangent to its articular surface was assessed.ResultsOverall CT-datasets of 80 healthy patients (40 males, 40 females, mean age 45 ± 8 years) were enrolled and evaluated regarding the configuration of the AC-joint. In this context, three statistically significant (p < 0.001) different configurations of the AC-joint in terms of overhanging acromion, neutral type, overhanging clavicle were identified. The “overhanging acromion” type of AC-joint configuration turned out to be the most common type (46.2%) followed by the “neutral type” (38.4%) and finally the “overhanging clavicle type” (15.4%).ConclusionsWe assume that the shown differences of the AC joint congruency might play an important role in the development of different shoulder injuries resulting from the similar trauma mechanism. However, the proof of these assumptions will be the focus of future studies.
Highlights
The primary goal of this study was to analyse the anatomic configuration of the acromio-clavicular joint in a healthy population to be able to develop a classification in a second step
From the anatomical point of view the acromion articulates with the lateral clavicle via the medial facet with its orientation posteriorly and laterally whereas the acromial articular surface is oriented medially and anteriorly [5]
Knowing about the numerous studies of the anatomy of the AC region [1, 2, 5, 8,9,10], the aim of our study was to evaluate the configuration of the AC joint on the basis of computed tomography (CT) Data sets of a young population without pre-existing joint pathologies
Summary
The primary goal of this study was to analyse the anatomic configuration of the acromio-clavicular joint in a healthy population to be able to develop a classification in a second step. The clavicle is known for its double curved configuration. The average size of the AC joint surface was Crönlein et al Eur J Med Res (2018) 23:50 described as 9 mm in vertical by 19 mm in antero-posterior orientation [6, 7]. The current literature provides sufficient information regarding the rather complex anatomy of the double curved clavicle as it is described that on average of 40 mm medial of the AC joint the clavicle presents an anterior sweep with an increased thickness of the superior cortical bone ranging between 1 and 4.5 mm [2, 8, 9]
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