What is Internal Rotation Lag Sign?
Internal Rotation Lag Sign is used to check for the integrity of the subscapularis tendon of the rotator cuff of the shoulder.
How it’s Performed?
The patient is sitting or standing with his or her back to the examiner. The affected arm is held by the examiner in almost maximal internal rotation. The elbow is flexed to 90 degrees, and the shoulder is held at 20 degrees of elevation and 20 degrees of extension. The dorsum of the hand is passively lifted away from the lumbar region until almost full internal rotation is reached. The patient is asked to maintain this position actively as the examiner releases the wrist while maintaining support at the elbow.
Arm in submaximal internal rotation Recoil of the arm when there is a tear of the subscapularis muscle Internal rotation lag sign What does a positive Internal Rotation Lag Sign mean?
If there is a tear of the subscapularis tendon, the patient is unable to actively hold the submaximally internally rotated position. The arm recoils against the back. Sensitivity & Specificity
A study by Hertel et al.
reported high sensitivity and specificity with this test: 1
Sensitivity: 97 % Specificity: 96 %
Another study by Caroline A Miller
found that the specificities of the 2 drop sign and internal rotation lag sign were 77% and 84%, respectively, and a sensitivity of 73% and 100%, respectively. Related Anatomy
Subscapularis Muscle originates from Ventral scapula. It inserts on Humerus (lesser tuberosity). Its action include Internally rotates the arm and provided anterior stability to the shoulder joint. It innervates from upper and lower subscapular nerves.
Subscapularis Tendon Anatomy Reference
Hertel R, Ballmer FT, Lombert SM, et al: Lag signs in the diagnosis of rotator cuff rupture. J Elbow Shoulder Surg Am 5:307–313, 1996. PMID: . 8872929 Caroline A Miller, Gail A Forrester, Jeremy S Lewis: The validity of the lag signs in diagnosing full-thickness tears of the rotator cuff: a preliminary investigation. Arch Phys Med Rehabil. 2008 Jun. PMID: 18503815. Clinical Tests for the Musculoskeletal System 3rd Edition. Dutton’s Orthopaedic Examination, Evaluation, And Intervention 3rd Edition.
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