The Safety of a Far Medial Arthroscopic Portal for Anatomic Glenoid Reconstruction: A Cadaveric Study

Background: An arthroscopic technique for anatomic glenoid reconstruction has been proposed for the treatment of glenohumeral bone loss in patients with recurrent shoulder instability. This technique is proposed as an alternative to open techniques as well as to the technically challenging arthroscopic Latarjet procedure. In arthroscopic anatomic glenoid reconstruction, a distal tibial allograft is inserted through a novel far medial portal, superior to the subscapularis tendon and lateral to the conjoint tendon. Purpose: To evaluate the safety of the far medial arthroscopic portal for anatomic glenoid reconstruction in a cadaveric study. Study Design: Descriptive laboratory study. Methods: Ten cadaveric shoulder specimens were dissected after inside-out medial arthroscopic portal insertion in the lateral decubitus position for arthroscopic anatomic glenoid reconstruction. A single observer performed 3 measurements on each specimen with a digital caliper (to the nearest 0.1 mm) from the medial portal to neurovascular structures, and the mean (SD) and the range were calculated. The anthropometric data of the cadaveric specimens were also collected. Results: The mean distances between the far medial arthroscopic portal and sensitive anatomic structures were as follows: 50.79 13.69 mm from the musculocutaneous nerve, 46.28 +/- 9.64 mm from the axillary nerve, 6.71 +/- 8.52 mm from the cephalic vein, and 48.52 +/- 7.22 mm from the subclavian artery and vein. The mean size of the medial arthroscopic portal was 25.60 mm. In all cases, the subscapularis muscle was intact. Conclusion: The far medial arthroscopic portal for anatomic glenoid reconstruction without a subscapularis split presents a minimal risk to most neurovascular structures during bony reconstruction of the glenoid surface in patients with anterior shoulder instability. The only anatomic structure at risk is the cephalic vein, while the axillary and musculocutaneous nerves are at a safe distance away from the portal, based on previous shoulder arthroscopic portal safety studies in the literature. Clinical Relevance: Arthroscopic anatomic glenoid reconstruction using a distal tibial allograft is increasing in popularity for the treatment of anterior shoulder instability with significant bone loss. Being a relatively new technique, the safety of it has yet to be established. This study aimed to demonstrate the safety of a new portal used for arthroscopic anatomic glenoid reconstruction.