Purpose: The aim of the study is to evaluate the difference in shape of the upper part and lower part of the Scapulothoracic Gliding Surface (STGS).
Methods: 3D-CT images of the thoracic cage of 50 patients were created in MIMICS ®. Three anatomical landmarks (insertion m. serratus anterior on 5th rib; transverse process of 2th and 7th vertebra) were used as an anteroposterior cutting plane to define the STGS. The upper part of the STG was defined as rib 2-5 and the lower part as 5-8. Next, in MATLAB ®, a script was used to create the sphere with best fit for upper and lower parts of STGS. The Root-Square-Mean Error (RSME) (mm) between two closest points on the fitted sphere and the STGS of both parts were calculated to determine the goodness-of-fit.
Results: The RSME was found to be significantly lower for the area ribs 2-5 (mean 7.85 mm, SD 1.86) compared the area of ribs 5-8 (mean 10.08 mm, SD 1.90).
Conclusion: The STGS of the upper thoracic wall (2-5) is more spherical shaped than the STGS of the lower thoracic wall (rib 5-8).
Keywords: Anatomy; Ellipsoid; Motion; Scapula; Thorax.