HYPOTHESIS: The present study aimed to evaluate the variability of the posterolateral corner of the acromion (PCA) position in relation to the glenohumeral joint, in a craniocaudal direction, to assess whether the universal use of a certain distance from that point will always lead to a consistent placement of the posterior arthroscopic portal of the shoulder.METHODS: The study used 140 dried scapulae (36 women and 34 men). Measurements included the glenoid height and the perpendicular distance between the PCA and the most superior point of the glenoid. The percentage of coverage of the glenoid by the acromion was defined as the ratio between the 2 measurements. The Student t test was used to examine for significant differences between the sexes and the Student paired t test between sides (P < .05).RESULTS: The average glenoid height was 3.37 ± 0.29 cm (range, 2.69-4.00 cm). The perpendicular distance between the PCA and the most superior point of the glenoid was 0.82 ± 0.69 cm (range, -0.35 to 2.27 cm). The percentage of coverage of the glenoid by the acromion was 24% ± 20% (range, -10% to 64%).CONCLUSIONS: The position of the PCA in relation to the glenohumeral joint is quite variable. Therefore, the use of a universal distance from the PCA will not always lead to a consistent placement of the posterior arthroscopic portal of the shoulder. Future research is needed in this area to develop techniques to individualize placement of the posterior portal.