What is the defining feature of primary adhesive capsulitis?

• A. Sudden onset with a history of trauma
• B. Insidious onset with no identifiable cause
• C. Association with sports injuries
• D. Severe pain with active movement

Answer: (B)

The defining feature of primary adhesive capsulitis, commonly known as frozen shoulder, is indeed an insidious onset with no identifiable cause. This condition typically develops gradually and without any obvious precipitating event, which differentiates it from other shoulder issues that may arise from trauma or sports injuries.

Primary adhesive capsulitis is characterized by a progressive loss of shoulder range of motion and the stiffness that accompanies it. This loss of motion occurs in a specific pattern and is not directly tied to a particular injury, making the insidious nature of its onset a critical element in its diagnosis.

While some cases may be associated with certain predisposing factors—such as diabetes or thyroid disease—these do not constitute identifiable causes that can explain the onset of symptoms. Thus, the absence of a clear trigger for the condition is a hallmark feature that helps clinicians distinguish primary adhesive capsulitis from other shoulder pathologies that present with more acute characteristics or identifiable origins.