Shoulder Stability Testing Using the Lateral Decubitus Position
James P. Tasto, MD
Department Editor: William O. Roberts, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 12 - DECEMBER 2021
Examination of the patient who has a painful shoulder presents a challenge, and one of the more difficult parts of the exam is evaluating instability. Many tests and maneuvers have been recorded in the literature, but they are often difficult to use effectively. The examiner must have an appreciation of what constitutes normal and abnormal humeral translation, the patient must be relaxed, and pain must not interfere with the exam. Instability may be unidirectional or multidirectional, subtle or gross, and it is often difficult to quantify with the standard tests.
A position that can help make shoulder stability testing easier and more productive is the lateral decubitus position. The patient lies on his or her side, with the normal shoulder on the table. In my experience, patients are uniformly more relaxed, comfortable, and cooperative in this position than in the supine position. The position permits stabilization of the scapula against the examiner's body and better relaxation of the glenohumeral musculature.
The position also, in my experience, permits far more translation and more accurate grading of instability. It is particularly effective in the patient who has pain and is apprehensive. Most standard tests can be performed in this position, including the apprehension and relocation tests.
Since the advent of arthroscopy, many orthopedic surgeons have used the lateral decubitus position when doing arthroscopic procedures on the shoulder. In preparing to do a surgical procedure, surgeons customarily reexamine patients in this position after they are anesthetized. After years of using the technique, many surgeons adopted it for their examination protocol in the office.
How to Proceed
At our clinic, standard tests are usually performed with the patient supine before the lateral decubitus position is used. These tests in the supine position include the apprehension and relocation tests, a load-and-shift test with the arm in the plane of the scapula, and a test for posterior instability (with the arm forward elevated 90° and subjected to a posterior force). The tests should be done on both shoulders for comparison purposes.
After these maneuvers in the supine position, the patient rolls onto his or her unaffected side, with hips and knees flexed, and rests his or her back against the examiner. The patient's elbow is bent and draped over one of the examiner's arms (figure 1a). To perform load-and-shift testing, the examiner then places his or her other hand over the humeral head and moves the humeral head in anterior-posterior and inferior directions while applying an axial load to the abducted arm (figure 1b). Axial loading is provided by the weight of the arm plus gentle downward pressure.
If the patient begins to resist the examination, it is easy to help him or her relax by gently rotating the arm. As in the supine position, the affected and unaffected shoulders should be tested and the results compared.
Testing should include placing the arm in the positions that typically provoke subluxation or dislocation if instability is present. For anterior and inferior instability, this is usually 90° of abduction and maximum external rotation. For posterior dislocations, the arm is usually forward-elevated 90° and internally rotated, and a posterior-directed force is applied.
During the various attempts to translocate the humeral head into a pathologic position, the examiner may appreciate a click, which may reveal a SLAP (superior labral anterior-posterior) lesion or Bankart lesion. The humeral head can then be felt to ride up to the glenoid rim or over the rim in cases of significant instability. Discreet popping and occasional catching may reveal that the patient has subtle labral tears as well.
In my experience, most standard shoulder stability tests are more effective in the lateral decubitus position. The exception is the relocation test, which seems more reliable with the patient supine.
Subtle and overt shoulder instability continues to provide a diagnostic challenge. With repetition and practice, this technique will enhance your ability to diagnose and classify it.
Dr Tasto is an associate clinical professor of orthopedic surgery at the University of California, San Diego; medical director of the San Diego Sports Medicine and Orthopedic Center; and president-elect of the Arthroscopy Association of North America. Dr Roberts is a family physician at MinnHealth SportsCare in White Bear Lake, Minnesota, and medical director of the Twin Cities Marathon. He is a fellow of the American College of Sports Medicine, a charter member of the American Medical Society for Sports Medicine, and an editorial board member of The Physician and Sportsmedicine.
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