Annie M. Wang MD, Presenter: Nothing to Disclose

James S. Babb PhD, Abstract Co-Author: Nothing to Disclose

Soterios Gyftopoulos MD, Abstract Co-Author: Nothing to Disclose

To see if there is an association between engagement on physical examination and the location of the Hill- Sachs lesion [HSL] as assessed by the modified biceps angle.

62 consecutive patients with a history of anterior shoulder dislocation, who underwent pre-operative MRI and arthroscopy at our institution, and tested for engagement on physical examination [PE] were collected over an 18 month period. The test for engagement was performed at the beginning of the arthroscopy under anesthesia by one of four fellowship-trained shoulder/sports medicine orthopaedic surgeons. Two blinded musculoskeletal radiologists reviewed the MR studies of these patients, noted the presence of a HSL and documented the location of the HSL with the modified biceps angle, which consisted of the angle between the center of the biceps groove and medial margin of the HSL. The angle accounts for the medial extent of the HSL, the portion of the lesion that would first engage onto the glenoid during abduction and external rotation. Statistical analysis included Mann-Whitney test and ROC curve.

There were 58 males/4 females with mean age of 30 (range 18-59). 20 patients demonstrated engagement on PE, while 42 did not. All 62 patients had a Hill-Sachs lesion on MRI and arthroscopy. The mean modified biceps angle for the engaging group was 151.5+13.9o, and 142.4+17.3o for the non-engaging group. According to a Mann-Whitney test, the modified biceps angle was statistically significantly higher among patients who had engagement compared to those who did not (p=0.027). Overall, diagnostic accuracy was highest for a modified biceps angle > 149o,which resulted in a sensitivity of 70%/specificity of 67%. According to a receiver operating characteristic (ROC) curve to assess the utility of the modified biceps angle as a test criterion for the detection of patients who had engagement, the area under the curve (AUC) measured 0.67, which was statistically significant (p=0.017) when compared to the AUC associated with random guessing.

The modified biceps angle, as measured on MRI, was significantly higher in patients who demonstrated engagement on physical examination than in those who did not have engagement.

This supports the theory that the location of the Hill-Sachs lesion may play a role in engagement, and may be the Hill-Sachs’ most important characteristic when determining its significance.

Wang, A, Babb, J, Gyftopoulos, S, Hill-Sachs Lesion Location: Does It Play a Role in Engagement?.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003872.html