A 28-year-old basketball player presents to the emergency department after falling during a game and landing on an outstretched arm. The nurse is conducting an initial assessment for a suspected shoulder dislocation. Which assessment finding would be most indicative of an anterior shoulder dislocation?

Anterior shoulder dislocation typically presents with loss of the normal rounded shoulder contour and a visible depression below the acromion due to anterior displacement of the humeral head. Other findings like pain and limited motion are common but less specific.

Clinical Reasoning: Recognizing Anterior Shoulder Dislocation

The correct answer is 3, loss of the normal rounded shoulder contour with a visible depression below the acromion process. This finding describes the classic "sulcus sign" or flattening of the deltoid prominence, which is the hallmark physical presentation of an anterior shoulder dislocation. In this injury, the humeral head is displaced anteriorly and inferiorly out of the glenoid fossa, leaving a visible and palpable void beneath the acromion where the humeral head should normally sit ^[1].

When a patient falls on an outstretched arm, the mechanism forces the humeral head anteriorly and inferiorly, stretching or tearing the anterior capsule and labrum. This anterior displacement explains why the arm is typically held in slight abduction and external rotation, not internal rotation. The visible loss of the deltoid contour is a direct result of the humeral head no longer supporting the overlying soft tissue, creating a sharp, squared-off appearance of the shoulder. This assessment finding is so characteristic that it is considered a key diagnostic clue during the initial physical examination for traumatic anterior shoulder instability (TASI) ^[1].

Why the Other Options Are Incorrect

Option 1: "The affected shoulder appears higher than the unaffected shoulder with the arm held in internal rotation." This description is inconsistent with an anterior dislocation. In an anterior dislocation, the humeral head moves inferiorly and medially, often making the affected shoulder appear lower or flattened, not higher. Furthermore, the arm is typically held in slight abduction and external rotation due to the position of the displaced humeral head and associated muscle spasm, not internal rotation. A shoulder appearing higher with internal rotation might suggest a posterior dislocation or an acromioclavicular joint injury.

Option 2: "The patient can easily move the arm through full range of motion despite reporting pain." This is not consistent with a shoulder dislocation. A dislocation is a mechanical block to joint movement. The displaced humeral head physically prevents normal range of motion, and any attempt at movement typically causes severe pain and muscle guarding. The patient will actively resist both active and passive motion. Full range of motion despite pain would be more suggestive of a soft tissue injury like a rotator cuff strain or contusion, not a dislocation.

Option 4: "The arm is positioned in external rotation and abduction with minimal pain reported." While the position of external rotation and slight abduction is correct for an anterior dislocation, the description of "minimal pain" is clinically inaccurate. An acute traumatic shoulder dislocation is intensely painful due to capsular stretching, ligamentous injury, and severe muscle spasm. The patient typically presents in significant distress, supporting the affected arm with the contralateral hand. The physical examination for TASI must be performed gently, as the patient will be guarding and highly sensitive to movement ^[1].