Purpose: Arthroscopic approaches have been less preferred than open techniques for treating suprascapular nerve entrapment, possibly because current arthroscopic portals are based on distances to reference points, resulting in discrepancies from differing shoulder sizes. This study reports a portal placement based on proportions rather than absolute length.
Methods: Open dissection (12 left shoulders) and arthroscopy (12 contralateral shoulders) of the suprascapular notch were performed. In left shoulders, the posterolateral prominence of the acromion, the T1 spinous process, and the suprascapular notch were marked (K-wires). Distances from the posterolateral prominence of the acromion to the suprascapular notch and to the T1 spinous process were measured, and the proportion of those distances (distance to the suprascapular notch/distance to the T1 spinous process) was calculated to indicate the portal's location. In right shoulders, arthroscopy anatomically assessed that proportion's reliability.
Results: Median distances from the posterolateral prominence of the acromion to the T1 spinous process and to the suprascapular notch were 175.7 mm (average 180.4, SD 11.8 mm) and 72.3 mm (average 73.9, SD 4.9), respectively. The medians of the proportions of the defined distances were 40.9 % (range 40-42 %) and 41 % (range 39.3-42.1 %), respectively.
Conclusion: Locating the portal at the lateral, 41 % of the distance between the posterolateral prominence of the acromion and the T1 spinous process was accurate and reproducible for suprascapular notch visualization. Clinically, this portal seems to eliminate perioperative morbidity by reducing excessive soft-tissue dissection with a shorter arthroscopic route and avoiding the ligamentous damage.