Arthroscopic decompression at the suprascapular notch: a radiographic and anatomic roadmap.

Background: Arthroscopic decompression of the suprascapular nerve (SSN) at the suprascapular notch is a technically demanding procedure. Additional preoperative and intraoperative information may assist surgeons. The purpose of this study was to (1) identify which imaging modality most accurately represents the anatomic distance to the notch and (2) quantify the mean intraoperative distances from routine arthroscopic portals to the notch.

Methods: Ten matched pairs of fresh cadaveric shoulders were imaged by roentgenogram, computed tomography (CT), magnetic resonance imaging, and 3-dimensional (3D) CT, followed by arthroscopic SSN decompression at the notch and anatomic dissection. Measurements obtained included the distances from the anterolateral, posterior, and SSN portal sites to the notch in addition to the distance from the anterolateral acromion to the notch. Statistical analysis with Spearman correlation coefficients and Bland-Altman plots were used to determine the correlation and agreement between measurements.

Results: The preoperative imaging modality with the highest correlation to anatomic distances from the anterolateral acromion to the notch was 3D CT (Rs = 0.90, P < .0001). The mean intraoperative distances to the notch from the anterolateral, posterior, and SSN arthroscopic portals were 89 mm, 88 mm, and 49 mm, respectively. The mean anatomic distance from the anterolateral acromion to the notch was 64 mm.

Conclusions: Preoperative imaging with 3D CT may assist surgeons in performing arthroscopic SSN decompression. Understanding of the mean distances from the portal sites to the suprascapular notch and being cautious of arthroscopic instruments placed beyond 9 cm from laterally based portals may result in safer intraoperative medial dissection.