Effects of scapular dyskinesis and scapular assistance test on subacromial space during static arm elevation.
Seitz AL, McClure PW, Lynch SS, Ketchum JM, Michener LA. J Shoulder Elbow Surg. 2011 Mar 26. [Epub ahead of print]
Scapular dyskinesis has been defined as an alteration in the motion and position of the scapula during arm elevation. It has been observed in patients with shoulders injuries including impingement syndrome and rotator cuff tears. The commonly observed altered scapular motions are decreased upward rotation, posterior tilt, and increased external rotation. These altered motions have been suggested to cumulatively decrease the subacromial space and cause compression of the supraspinatus tendon. The scapular assistance test (SAT) is a new clinical test that is designed to identify if there is scapular involvement associated with impingement syndrome. The SAT involves the clinician passively assisting scapular upward rotation and posterior tilt during arm elevation. A positive test is if the corrective action ameliorates the patient’s symptoms. However, it has not been determined if the SAT actually increases these motions and the subacromial space during arm elevation. This study divided 40 asymptomatic participants into two groups (20 obvious dyskinesis and 20 normal motion). Scapular motion was measured using a magnetic tracking system and the subacromial space was measured with a diagnostic ultrasound at rest, 45°, and 90° of arm elevation. All subjects were evaluated both with and without the SAT. The results indicate that there were no differences between groups for scapular kinematics or subacromial space. The SAT was found to increase upward rotation, posterior tilting, and subacromial space in both groups. The dyskinesis group had more upward rotation during the SAT compared to the normal motion group.
This study evaluated the effectiveness of a new clinical test used to determine the amount of scapular involvement in subacromial impingement. It also examined scapular kinematics and subacromial space between a group with dyskinesis compared to normal controls. These results indicate that the SAT is effective at increasing the subacromial space by increasing scapular upward rotation and posterior tilting. On average the subacromial space was only increased by 1.8 mm and it is difficult to determine if this is clinically significant due to the measurement error being 1.1 mm. It also found that subjects with dyskinesis do not have any alterations in the measured scapular kinematics or subacromial space. This is in disagreement with other studies and suggests that these variables may not be altered even when obvious dyskinesis is present. Unlike other studies subjects did not present with shoulder pain or symptoms so the role of pain may need to be further investigated to determine if alterations are only associated in symptomatic patients. Clinically, this suggests that the SAT will increase scapular upward rotation and posterior tilting, although it is still unclear if the amount of subacromial space is a cause of shoulder injury or a consequence. Personally I have great success with the SAT to determine if patients suffering from impingement syndrome will benefit from scapular rehabilitation. What are your experiences?
Written by: Stephen Thomas
Reviewed by: Jeffrey Driban
Nice post. It's nice to see that SAT is doing what it is hypothesized to do (increase certain scapular movements and the subacromial space). Have other studies examined the reliability of this test or the sensitivity/specificity of the test? Those items would probably be the remaining key pieces of information to determine if the SAT is ready for widespread adoption in the sports medicine community. Thanks!
Good point. This study did report the reliability of bot the scapular kinematics and the subacromial space measurement. However, reliability values of the SAT were not reported. They did discuss that the SAT was performed in the static positions of rest, 45, and 90 degrees of arm elevation and not dynamically like the test is normally performed due to reductions in reliability. Since it is a manual technique I am sure there is some variability and would require training to be highly reliable.
JOSPT Sept 2006 (vol36, #9)found the Mod SAT as possessing acceptable interrater reliability for clinical use.
The findings of this study tie in nicely with those findings with making the SAT an important part of the examination.
I always would struggle between findings with the SAT, the Scapular Retraction Test (stab scap in retraction and MMT; assessing pain/strength) and the The Scapular Repostion Test (emph post tilt/ER and MMT, looking at pain/strength), as far as a consistent finding.
I am going from memory on these tests so I am pretty sure of the specifics.
The SAT seemed like the better of the tests bc it involved active movement and an immedeate response/change in sx. I have focused mainly on using it exclusively over the years.
Are there other tests the have supportive data like the SAT??