An Extremely Specific Sign of an Anterior Shoulder Dislocation

A 17-year-old female presented to the ED with the complaint of right shoulder pain. She was walking in a crowded video arcade when she accidentally bumped her right shoulder against the edge of a door and then fell with her arm outstretched. She described a “popping-like” sensation in her shoulder. She had no other associated injuries and complained only of isolated shoulder pain. Her past medical history was insignificant. She denied any prior surgeries and was not taking any medications.

At the time of her presentation, she rated her shoulder pain as a “13” on a scale of 0 to 10. Her right shoulder appeared to be very tender to the touch. There was no bruising or swelling, and no apparent asymmetry was noted between her shoulders.  No evident sulcus sign was appreciated.  She denied any loss of sensation, numbness or tingling of her arm and shoulder, and she was neurovascularly intact. She did have limited range of motion of the shoulder secondary to extreme pain, and was only able to abduct her shoulder to 35 to 45 degrees. Suspecting a shoulder dislocation, an AP, AP internal rotation, and scapular Y views of the right shoulder were obtained. The Figure shows the AP view.

Both the glenohumeral and acromioclavicular joints were intact and showed no displacement on the radiographs. However, an irregular contour of the posteriolateral humeral head was evident with a mild cortical depression. These findings were consistent with a Hill-Sachs lesion.

A Hill-Sachs deformity is a compression injury to the posterolateral aspect of the humeral head created by the glenoid rim during dislocation.¹ When driven from the glenohumeral cavity during dislocation, the relatively soft head of the humerus hits against the anterior edge of the glenoid. The result is a flattening of the posterolateral aspect of the humeral head.
 
The Hill-Sachs lesion occurs in 35% to 40% of anterior dislocations and in up to 80 % of recurrent dislocations.² It is usually best seen on an AP view of the shoulder in internal rotation.¹  Most anterior shoulder dislocations present with swelling and deformity, with loss of the usual rounded contour of the shoulder.³

The presence of a Hill-Sachs lesion is an extremely specific sign of an anterior shoulder dislocation and can be used as an indicator that a dislocation has occurred even if the joint has regained its normal arrangement.

Because our patient was noted to have a Hill-Sachs deformity and her physical exam was clinically consistent with a shoulder dislocation, we proceeded to reduce her shoulder using the external rotation technique.  On reduction, she had a vast improvement in her range of motion of her right arm and shoulder, as well as decreased pain.  Her neurovascular examination after reduction was normal.  She was discharged home in a shoulder sling and acetaminophen with codeine for pain.  She was also instructed to limit her activity and to follow up with orthopedics in 1 week.

References:
1. Srinivasan S. Shoulder Trauma. In Fleisher GR, et al, eds. Fleischer and Ludwig’s 5-Minute Pediatric Emergency Medicine Consult. Philadelphia; Lippincott Williams & Wilkins; 2012: 976.
2. Wheeless CR , Clifford R. Hills-Sachs Lesion [online chapter].  Wheeless’ Textbook of Orthopaedics. 2012. Available at: www.wheelessonline.com/ortho/hill_sachs_lesion.com. Accessed July 20, 2012.
3. Tseng GY. Shoulder Dislocation Imaging.  2011. http://emedicine.medscape.com/article/395520-overview. Accessed July 18, 2012.
4. Fleisher GR. Textbook of Pediatric Emergency Medicine. 5th edition. Philadelphia; Lippincott Williams & Wilkins; 2005:1536.