Research Review by Dr. Shawn Thistle©
Authors’ Affiliations: Physical Therapy faculty, Arcadia University, PA.
Shoulder pain is a common condition, particularly in overhead athletes and people involved in physically demanding occupations. Clinically, patients often present with “functional” impingement symptoms in the anterior or lateral aspect of the shoulder that are provoked by specific arm/shoulder girdle motions (i.e. secondary glenohumeral impingement). This typically occurs in the absence of any overt trauma or easily defined anatomical injury. These patients can be challenging to assess, but recent insight and research into shoulder function and mechanics has enhanced our ability to manage this condition.
It is now commonly accepted that shoulder girdle mechanics (particularly involving the scapula) are paramount in the development of secondary shoulder impingement. Several etiologies have been proposed attempting to explain this, each with varying degrees of supporting evidence – altered motor performance of the rotator cuff, lack of flexibility of soft tissue structures (including the joint capsule), glenohumeral joint laxity, structural abnormalities of the rib cage or scapula, postural changes, and scapular motion deficiencies (often termed scapular dyskinesis).
To date, studies assessing 3-dimensional scapular motion relating to shoulder pain have produced mixed and inconsistent results. Further, differences noted in these studies between symptomatic and asymptomatic people are normally small, calling into question their significance. Taken together, this may indicate that scapular mechanics are an individual factor, which may vary from person to person in terms of how clinical symptoms are influenced. However, this does not mean that assessing scapular mechanics cannot have clinical value.
This study attempted to address this issue by evaluating the Scapular Reposition Test (SRT). The premise of this test, and two others previously evaluated (1,2), is to first assess provocative orthopedic tests of the shoulder with natural scapular position, then repeating the tests with the examiner or patient manually positioning the scapula. In theory, proper scapular positioning should allow smoother movement of the glenohumeral joint and reduce secondary impingement symptoms.
This study utilized a convenience sample of 142 college athletes (111 males, 31 females, average age 20.8) involved in sports requiring repetitive overhead movements (baseball, volleyball, swimming, and water polo). In order to participate in the study, subjects could not have a BMI over 30, or have a recent history of a rotator cuff tear, shoulder dislocation, or traumatic shoulder injury.
Each subject underwent a standardized physical examination including three commonly used shoulder impingement tests – Jobe, Hawkins-Kennedy, and Neer – all performed as originally described with the scapula in its natural position. In general, these three tests have been shown to have adequate sensitivity, but low specificity, making them acceptable for screening purposes but not appropriate for determining a specific diagnosis. Isometric shoulder abduction strength was also assessed in Jobe’s test position (arm elevated to 90° in the scapular plane with the thumb turned downwards).
These orthopedic and isometric strength tests were then repeated using the Scapular Repositioning Test which was performed as follows:
- the examiner grasped the patient’s scapula from behind with the fingers overlying the acromioclavicular joint anteriorly, and the palm and thenar eminence on the spine of the scapula posteriorly
- the examiner’s forearm was obliquely angled toward the inferior angle of the scapula for additional support (NOTE: examiner’s left hand used for patient’s right shoulder and vice versa)
- the examiner’s hand/forearm was used to apply a “moderate” force to encourage posterior scapular tilting and external rotation (inferior angle/medial border moved anteriorly toward thorax), and approximate the scapula to the middle of the thorax
- end range retraction was avoided (unlike in Kibler’s paper referenced below)
Subjects were asked to rate their level of pain before and after each test using a verbal Numeric Rating Scale (0-10). A significant difference was set as a minimum 1-point difference on the VNRS.
Pertinent results of this study include:
- at least one positive impingement test was noted for 69% of subjects, while 30% had 2 positive tests
- 31% of subjects were negative on all 3 impingement tests
- for those with at least 1 positive test, the average report of pain level on VNRS was 2.8 ± 1.5
- for those with at least 1 positive test, 47% (46/98) had a reduction in pain when repeating the test with the SRT – only 24/46 reduced by 2 points however, with the remaining 22/46 experiencing the minimum 1-point reduction (remember, initial pain levels were not very high)
- SRT produced a significant increase in isometric torque in those with impingement symptoms (p = 0.001) and those without (p = 0.012) – this suggests that the presence of impingement did not influence the strength changes with the SRT, even though the SRT did increase strength in general
Conclusions & Practical Application:
In patients with secondary impingement symptoms, the prudent clinician should attempt to change clinical symptoms and response to provocative movements by attempting to position or stabilize the scapula. Should the patient’s symptoms reduce, attempts should be made to “normalize” scapular motion with exercise, soft tissue therapy, mobilization/manipulation etc. Here, the literature must catch up before it can guide us more comprehensively.
- Kibler, Sciascia A & Dome D. Evaluation of apparent and absolute supraspinatus strength in patients with shoulder injury using the Scapular Retraction Test. Am J Sports Med 2006; 34: 1643-1647.
- Rabin A et al. The intertester reliability of the Scapular Assistance Test. J Orthop Sports Phys Ther 2006; 36: 653-660.