Anatomy of the supraclavicular fossa portal in shoulder arthroscopy.

Because of the need for a third portal for operative procedures during glenohumeral joint arthroscopy, we studied the anatomy of the supraclavicular fossa portal with the humerus in various degrees of abduction and the trochar placed at various angles. Our purpose was to establish a "safe zone" of introduction that would avoid damage to the tendinou portion of the rotator cuff. Eight shoulder specimens were studied. Sharp- and blunt-tipped 4-mm trocars were used to enter the joint. The trapezius was penetrated at all angles of humeral abduction and trocar angulation. The trocar penetrated the tendinous portion of the rotator cuff in all specimens at 90 degrees of abduction, seven of eight specimens at 70 degrees, six of eight specimens at 60 degrees, and three of eight specimens at 45 degrees of abduction. No penetration of the musculotendinous portion occurred when the arm was in 30 degrees of abduction or at the side. When it is necessary to use the supraclavicular portal, traction should be released and the humerus should be brought down to at least 45 degrees. The trocar should be introduced laterally at 30 degrees and angled slightly posteriorly to avoid the tendinous portion of the rotator cuff.