Apprehension-based Training Compared With Standard Physical Therapy for Military Personnel Following Anterior Shoulder Dislocation - a Randomized Clinical Trial

Patient's ability to resume their preinjury military and overall level of function will be assessed separately through a telephone interview 3 months after the end of their assigned intervention. This outcome will be rated dichotomously: "Yes" (have resumed my preinjury military/overall level of function), or "No" (have not been able to resume my preinjury military/overall level of function).

The Western Ontario Shoulder Instability Index is a self-reported measure of shoulder instability related quality of life. This questionnaire includes 21 items regarding symptoms, activity limitations, quality of life and emotions. Each item is scored on a 100mm visual analogue scale resulting in a total score of 0 - 2100 which can be converted to a percentage with greater scores indicating greater disability.

Recurrent events of instability, either in the form of a frank dislocation or a sensation of instability (subluxation) will be assessed through a telephone interview.

Dynamic stability will be assessed with the supine moving apprehension test. This is a functional performance test in which the patient is asked to repeatedly move the shoulder into 135- and 180-degrees of abduction from a supine position while holding a dumbbell (2-3 kg). The number of repetitions over one minute comprises the score of the test.

A patient reported single numeric assessment of shoulder function as a percent of a normal shoulder: "What is the overall percent value of your shoulder if a completely normal shoulder represents 100%?"

A self-reported 17-item fear of movement and reinjury measure. Each item is scored on a 4-point Likert scale for a total score between 17-68.

The sensation of apprehension will be assessed through the anterior apprehension test performed in 4 stages: 1.) shoulder abduction to 90 degrees; 2.) external rotation; 3.) horizontal abduction; 4.) Shoulder abduction beyond 90 degrees. Elicitation of apprehension (verbal, fascial expression, or muscle guarding) will be rated according to the stage at which it occurs (1-4). The test will be rated negative (5) if apprehension is not elicited at any stage.

Shoulder internal and external rotator muscle strength will be assessed using a hand-held dynamometer in a supine-lying position with the shoulder abducted 90 degrees, neutral rotation, and the elbow bent 90 degrees. The examiner will position a hand-held dynamometer over the distal anterior (internal rotator strength) or posterior (external rotator strength) aspect of the forearm and resist a maximal voluntary effort by the patient. two repetitions will be performed for each strength test with the highest value used for data analysis.

From a kneeling position with the hands gripping a barbell loaded with a 5kg plate on each side, the patient will roll forward to the greatest distance possible and return to the starting position. The test will be performed in a narrow (shoulder width) and wide (2x shoulder width) hand grip. Up to 5 repetitions will be allowed to achieve maximum distance in each grip condition.

Heart rate variability (HRV) during apprehension provocative and non-apprehension provocative shoulder movements will be measured using a Polar H10 chest strap. Heart rate variability will serve a physiological marker for autonomic nervous system response to movement provoked stress in the context of anterior shoulder dislocation.