Scapulothoracic anatomy for the arthroscopist

Because endoscopic management has recently been introduced as treatment for painful subscapular snapping, we designed a cadaveric study to identify the boundaries of the scapulothoracic spaces and the relationship of important neurovascular structures to safe portal sites for arthroscopic surgery. We studied eight fresh, unembalmed cadaveric shoulders by anatomic dissection alone and eight fresh, unembalmed cadaveric shoulders by dissection after arthroscopy. We noted the following findings: (1) the scapulothoracic articulation has two triangular spaces, the serratus anterior space and the subscapularis space, that are divided obliquely by the serratus anterior muscle; (2) the boundaries of the larger serratus anterior space include the chest wall anteriorly, the serratus anterior muscle posteriorly, and the rhomboids medially; (3) the boundaries of the subscapularis space are the serratus anterior muscle anteriorly, the subscapularis muscle posteriorly, and the axilla laterally; and (4) a well-defined bursa occupies the serratus anterior space. Based on these findings, we recommend that portals for arthroscopic surgery should be inferior to the spine of the scapula and three to four fingerbreadths from the vertebral border of the scapula (1) to avoid the neurovascular structures at the superomedial angle of the scapula, (2) to avoid the dorsosacpular nerve and artery, and (3) to prevent perpendicular orientation of the arthroscope to the lateral chest wall.