College of Massage Therapists of British Columbia (CMTBC) Practice Exam

With a positive Sulcus Sign, what type of glenohumeral instability is typically suspected?

1. Anterior GH instability

2. Posterior GH instability

3. Inferior GH instability

4. Multidirectional instability

The correct answer is: Inferior GH instability

A positive Sulcus Sign indicates that there is a noticeable depression or "sulcus" below the acromion when the arm is pulled downwards, suggesting that the head of the humerus is able to be displaced inferiorly relative to the glenoid. This sign is indicative of inferior glenohumeral instability, as the humeral head moves away from the glenoid cavity, leading to the creation of a prominent sulcus. Inferior glenohumeral instability typically involves an excessive amount of movement or displacement of the humeral head in an inferior direction, which can be particularly apparent when the arm is held in a certain position. This is commonly seen in individuals who have experienced chronic shoulder instability. While anterior and posterior instabilities also play a role in shoulder injuries, the Sulcus Sign specifically points to inferior instability. Moreover, multidirectional instability could potentially lead to a similar finding; however, the presence of a positive Sulcus Sign primarily suggests inferior instability. Hence, while multidirectional instability may display symptoms of both anterior and inferior displacement, it is the sign of the sulcus that distinctly indicates inferior glenohumeral instability. Thus, the identification of this sign is crucial for diagnosis and appropriate management of shoulder instability.