Septal Aperture of the Humerus: A Morpho-anatomical Variation with Clinical Significance

Introduction: In the distal end of the humerus, between the coronoid and olecranon fossae, there is a bony plate with different thicknesses and transparency. There may be an opening that represents an anatomical variation with significant implications for surgical and radiological practice. Aim: The aim of this study was to examine the incidence, morphological characteristics, and morphometric relationships of the septal aperture (SA)/transparent septum (TS) to the adjacent structures and present their clinical implication. Materials and Methods: The study included 80 humeri. Morphometric measurements (dimensions and position of the aperture) were performed in the ImageJ (version 150i) program. The presence and number of SAs were detected by inspection. Humeri without aperture were exposed to a beam of light to determine the degree of septum transparency. Results: The SA was found on 12 humeri (15%), and 25 humeri had a TS (31.25%). The most common shape was circular (50%), and oval and irregular types were also observed. A cribriform shape (17%) was detected in the group of transparent septa. The vertical and horizontal diameters were 4.06 mm and 6.59 mm, and the area was 26.12 mm 2 . The SA is located 28.10 mm from the lateral and 24.81 mm from the medial epicondyle. No statistically significant difference was observed between the left and right humeri. Conclusion: This research provides important insights for surgical treatment of the lower segment of the humerus and in radiology to distinguish it from osteolytic and cystic lesions.