Anatomical characterization of sternoclavicular joint and correlation of arthroscopic portals and structures at risk:...

The sternoclavicular joint (SCJ) is a synovial saddle joint and the only articulation between the axial skeleton and the upper limb. Although SCJ pathology is rare, it may include degenerative, autoimmune, infectious, tumoral, or traumatic conditions. Arthroscopic approaches to this region carry a risk of damaging vital mediastinal structures. This study aims to anatomically characterize the SCJ and surrounding neurovascular structures, emphasizing the posterior capsule as a critical safety barrier during arthroscopy.

Ten cadaveric specimens were bilaterally dissected. Arthroscopic portals were first marked and used to identify the posterior capsule. Open dissections were performed to measure the distances between the portals and nearby mediastinal structures using digital calipers. Data were recorded in Excel 2024 (Microsoft Corp., Redmond, WA, USA) and REDCap (Vanderbilt University, Nashville, TN, USA) and analyzed with SPSS version 28 (IBM Corp., Armonk, NY, USA).

The posterior capsule consistently acted as a protective boundary between the joint and mediastinal structures. The average distances from the superomedial (SM) and inferolateral (IL) portals to the posterior capsule were 26.3 mm and 26.5 mm, respectively. From the posterior capsule, the average distances to key mediastinal structures were: common carotid artery: 42.5 mm (SM), 44.1 mm (IL), brachiocephalic trunk: 40.5 mm (SM), 43.5 mm (IL), innominate vein: 37.8 mm (SM), 39.7 mm (IL), and vagus nerve: 45.4 mm (SM), 46.5 mm (IL).

The posterior capsule provides a reliable anatomical safety margin between the SCJ and vital mediastinal structures. During SCJ arthroscopy, referencing the anterior sternoclavicular ligament and maintaining a minimum 5.1 cm safety margin posteriorly can minimize the risk of catastrophic injury. These findings support safer surgical planning and highlight the importance of precise portal placement.