Monday, May 16, 2016

How do rotator cuff tears influence shoulder motion?

These authors studied 14 patients with rotator cuff tears and 14 healthy individuals with 35 reflective markers on the trunk and upper limb tracked by an optoelectronic system to measure the scapulohumeral rhythm (the ratio of glenohumeral to scapulothoracic motion in arm elevation) while the subjects carried out 5 comfortable scapular plane maximal arm elevations. They found a value of 3.9 for healthy controls.

Patients were separated by maximal arm elevation of 85° (category A) and 40° (category B). 

The mean scapulohumeral rhythm ratio during arm elevation was 2.8 for patients in category A; these patients  had a relatively consistent pattern as shown below with much lower values than controls (that is relatively less glenohumeral movement and relatively more scapulothoracic motion).  

The patients with only 40 degrees of active motion (Group B) had widely varying patterns of motion as shown below

The authors concluded that patients who reached at least 85° compensated for the loss of glenohumeral motion by increased scapulothoracic contribution.  
In contrast, patients who had less active range of motion had less contribution from scapulothoracic motion.

Comment: This study demonstrates that some patients with cuff deficiency can compensate by increasing the scapulothoracic contribution to active motion. There were only seven patients in each group and we are not presented with the cuff tear sizes in the two groups.

In our management of individuals with chronic cuff tears we encourage them to try a simple exercise program that encourages use of both the glenohumeral and scapulothoracic musculature (shown below)
It is interesting that some patients sent to us for consideration of reverse total shoulders because of apparent pseudoparalysis are able to regain substantial function with this simple exercise.


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