The patient is seated with his or her back to the examiner.
The affected arm is held at 90 degrees of elevation in the scapular plane and at almost full external rotation with the elbow flexed at 90 degrees.
The patient is asked to maintain this position actively as the examiner releases the wrist while supporting the elbow, which is mainly a function of the infraspinatus.
What does a positive Drop Arm Test mean?
Weakness in maintaining the position of the arm , with or without pain, or sudden dropping of the arm suggests a rotator cuff lesion, most often this is due to a defect in the supraspinatus muscle.
Sensitivity & Specificity
A literature review 1 in MEDLINE was performed for physical examination tests/maneuvers of the rotator cuff tears, and found that drop arm test has the following accuracy:
Sensitivity: 73 %
Specificity: 98 %
A positive drop arm test may also have neurologic causes, such as damage to the subscapular nerve, so the patient must be thoroughly examined from a neurologic standpoint.
In lesions of the supraspinatus muscle as a result of chronic degenerative processes, the drop arm test may be falsely negative due to muscular compensation, especially by the deltoid muscle.
Supraspinatus muscle originates from Superior scapula and inserts onto Greater tuberosity of the humerus.
Its action includes Abducting and externally rotating arm, providing stability to the shoulder joint.
It’s innervated by the Suprascapular nerve.
Nitin B. Jain, MD, MSPH, Reginald Wilcox, PT, Jeffrey N. Katz, MD, MS, and Laurence D. Higgins, MD: Clinical Examination of the Rotator Cuff. PM R. Author manuscript; available in PMC 2014 Jan 1. PMID: 23332909.
Miller CA, Forrester GA, Lewis JS: The validity of the lag signs in diagnosing full-thickness tears of the rotator cuff: a preliminary investigation. Arch Phys Med Rehabil. 2008 Jun; 89(6):1162-8. PMID: 18503815.
Park HB, Yokota A, Gill HS, El Rassi G, McFarland EG: Diagnostic accuracy of clinical tests for the different degrees of subacromial impingement syndrome. J Bone Joint Surg Am. 2005 Jul; 87(7):1446-55. PMID: 15995110.
Yuen CK, Mok KL, Kan PG: The validity of 9 physical tests for full-thickness rotator cuff tears after primary anterior shoulder dislocation in ED patients. The American journal of emergency medicine. 2012 Feb 29. PMID: 22386341.
Murrell GA, Walton JR. Diagnosis of rotator cuff tears. Lancet. 2001 Mar 10;357(9258):769–770. PMID: 11253973.