Variations in normal sternoclavicular joints; a retrospective study to quantify SCJ asymmetry

Abstract

Objective: A wide degree of normal anatomical variation can occur at the sternoclavicular joint (SCJ). On occasion, this has led to concern for a pathological process, potentially resulting in a costly work-up, unnecessary patient worry and invasive diagnostic procedures such as biopsy. The purpose of this study was to determine the normal range of anatomical variation at sternoclavicular joints.

Materials and methods: One hundred four consecutive patients with chest CT done at our institution were selected. Patients with clear SCJ pathology, chest wall abnormality, CT slice thickness greater than 5 mm and sternotomy wires, were excluded. Chart review was done and showed no SCJ symptoms/signs. We measured the SCJ space, maximum clavicular head diameter within the joint and the distance from manubrium to the anterior margin of the clavicular head.

Results: Left and right SCJ space ranged from 0.2 to 1.37 cm. The difference (delta or asymmetry) between left SCJ space and right SCJ space ranged from 0 (symmetrical) to 0.57 cm in 104 cases. Left and right clavicular head diameter ranged from 1.2 to 3.7 cm with left/right asymmetry (delta) ranging from 0 (symmetrical) to 1 cm. Manubrium to anterior margin of clavicular head ranged from 0.1 to 2.13 cm with delta ranging from 0 to 0.8 cm. Thirty-three patients demonstrated gas in the joint, five had poor articulation and four had calcification in the joint.

Conclusion: Greater than 10% of patients show substantial asymmetry in the sternoclavicular joints, which may be misinterpreted as pathological. Gas in the joint is a common phenomenon therefore should not be an indication for further work-up in asymptomatic patients and likely excludes the presence of effusion.