Which angle of shoulder abduction is considered the least stable for the glenohumeral joint?

The angle of shoulder abduction that is considered the least stable for the glenohumeral joint is 30°. At this position, the shoulder joint is in a mid-range position where the rotator cuff muscles are less effective in providing stability. The anatomical structure of the shoulder allows for greater mobility due to its ball-and-socket design, but this also makes it susceptible to instability at certain angles.

At 30° of abduction, the glenoid cavity is not optimally positioned to support the head of the humerus. This engagement can lead to compromised dynamic stability, making it more prone to dislocations or other injuries if not properly supported. Additionally, at an angle of 90°, while the joint is often described as being above the plane of the scapula, dynamic stabilization is generally better supported due to increased engagement of stabilizing muscles and ligaments.

Understanding these dynamics is crucial for corrective exercise approaches, as assessing and improving shoulder stability at this angle can prevent injuries and improve overall function.