Bear-hug test performed in shoulder flexion may be used to indicate scapularis pathology

The bear-hug test done at 45· showed greater peak muscle activity in the upper vs. lower scapularis.

Simon Chao

LAS VEGAS — Although there are many tests to evaluate the subscapularis, a recently presented investigation found the bear-hug test to be a valuable diagnostic tool for evaluating the muscle.

“We found that the bear-hug test, performed at 90°, isolated the lower subscapularis muscle significantly more than all of the other tests,” Simon Chao, MD, said during his presentation at the American Academy of Orthopaedic Surgeons annual meeting. “Also, the bear-hug at 45° shows greater activity of the upper subscapularis vs. the lower subscapularis, more than the belly-press test. Thus, the bear-hug test performed at 45° may be used as a clinical indicator of upper versus lower subscapularis pathology.”

Three types of tests

In an IRB-approved study, Chao and his colleagues assessed the electromyographic (EMG) activity of the shoulder internal rotators in the dominant arms of 21 men using the following tests:

• the lift-off test;
• the belly-press test;
• the bear-hug test at 0°;
• the bear-hug test at 45° of shoulder flexion; and
• the bear-hug test at 90° of shoulder flexion.

The investigators also compared the EMG activity in the lower and upper subscapularis among the tests and assessed the upper and lower subscapularis activity in relation to the pectoralis major and latissimus dorsi.

To assess the EMG activity, they placed intramuscular fine-wire electrodes in the upper and lower subscapularis and positioned surface electrodes over the latissimus dorsi and pectoralis major. They confirmed the correct placement of the electrodes by monitoring activity during isolated muscle testing, Chao said.

Bear-hug test being performed at 45°. Image: Chao S

The study participants had an average age of nearly 23 years old and no history of previous shoulder injury or surgery, according to the study abstract.

When the bear-hug test was performed at 0·, the investigators discovered that the latissimus dorsi showed significantly less peak EMG activity than all of the other muscles tested.

“The upper and lower subscapularis showed similar activity,” Chao said.

The bear-hug test performed at 45° of shoulder flexion showed significantly greater peak EMG activity in the upper and lower subscapularis compared to that in the pectoralis major and latissimus dorsi. Chao also noted that the activity in the upper subscapularis was greater than that in the lower subscapularis, but the difference was not statistically significant.

“At 90°, the lower subscapularis activity was significantly greater than all other muscles,” Chao said. He added, “With the belly press, the upper and lower subscapularis activity was significantly greater than all other muscles. During the performance of the lift-off test, the pectoralis major was significantly less active.”

Sound research

Felix H. Savoie III, MD, a co-moderator of the session, said that the research conducted by the group was sound. “The authors are attempting to find out if the test is an accurate clinical exam for the subscapularis,” Savoie told Orthopedics Today. “They have found the activity to be a little different than previously thought, which may well change the way we perform this test and make it more accurate.”

For more information:

• Simon Chao, MD, can be reached at the department of orthopedic surgery, 6th Floor, Outpatient Building, Temple University Hospital, 3401 N. Broad St., Philadelphia, PA 19140; 215-707-2111; e-mail: schao@temple.edu. He has no direct financial interest in any products or companies mentioned in this article.
• Felix H. Savoie III, MD, can be reached at Tulane University School of Medicine, 1430 Tulane Ave., Room 2070, department of orthopedics, New Orleans, LA 70112-2699; 504-988-5770; e-mail: BuSavoie@aol.com. He belongs to the speakers bureau for Mitek.

Reference:

• Chao S, Yucha D, Kelly JD. An electromyographic assessment of the bear-hug. An exam for the evaluation of the subscapularis. Paper #458. Presented at the American Academy of Orthopaedic Surgeons 76th Annual Meeting. Feb. 25-27, 2009. Las Vegas.