What is the drop arm sign mainly used to detect?

Appeared in: PGICH Noida NO-2025

Explanation

The drop arm test is a specific physical examination maneuver to assess the integrity of the rotator cuff muscles of the shoulder.
It primarily tests for a full-thickness tear in the supraspinatus tendon, one of the four rotator cuff muscles.
The test is considered positive if the patient, after having their arm passively abducted to 90 degrees, cannot lower it slowly and smoothly, causing the arm to 'drop'.
This inability to control the arm's descent indicates a loss of muscle function due to a significant tear.

Option A: Golfer's elbow, or medial epicondylitis, is an inflammation of the tendons on the inner side of the elbow, not the shoulder.
Option B: Tennis elbow, or lateral epicondylitis, is an inflammation of the tendons on the outer side of the elbow.
Option D: Hip dislocation is a severe injury involving the femur and the pelvis. It is anatomically distant and functionally unrelated to the shoulder joint where the drop arm sign is elicited.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physical assessment of the shoulder: Drop arm test as background academic context rather than a clinical decision trigger.
Nurses performing musculoskeletal assessments use specific tests like the drop arm sign to screen for injuries and determine the need for further evaluation by a physician or specialist.
Early and accurate identification of a rotator cuff tear can lead to timely intervention (e.g., physical therapy, imaging, or surgery), which can prevent long-term disability, chronic pain, and muscle atrophy.
What if? If the patient can lower the arm slowly but experiences significant pain between 60 and 120 degrees of abduction (a 'painful arc'), it might suggest rotator cuff tendinitis or impingement syndrome rather than a full-thickness tear.

How to Approach the Question

First, identify the key term in the question, which is 'drop arm sign'. This is a specific clinical test.
Recall or deduce the anatomical location associated with this sign. The name 'arm' points to the upper extremity, specifically the shoulder's range of motion.
Evaluate the given options based on this anatomical context.
Eliminate options related to different joints: 'Golfer's elbow' and 'Tennis elbow' relate to the elbow, and 'Hip dislocation' relates to the hip.
This process of elimination leaves 'Rotator cuff tear', a known pathology of the shoulder, as the most plausible answer.
Confirm the direct association: the drop arm sign is a classic test for a tear in the rotator cuff muscles.

Concept Tested & Keywords

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E6 Medicine Macleod Clinical Examination 15e p. 311-313

E6 Medicine Harrison 22e Part 2 p. 848-850

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