Saturday, November 19, 2011

Critical rotator cuff tear stage? - recent JBJS article

There are many cadaver studies on the rotator cuff. The Journal of Bone and Joint Surgery recently published another, Does a Critical Rotator Cuff Tear Stage Exist?: A Biomechanical Study of Rotator Cuff Tear Progression in Human Cadaver Shoulders. From their study of eight cadavers the authors concluded that "Tear of the entire supraspinatus tendon was the critical stage for increasing rotational range of shoulder motion and for decreased abduction capability and that further tear progression to the infraspinatus muscle was the critical stage for significant changes in humeral head kinematics. " The authors propose that the clinical relevance of this study is that early detection and proper management may prevent abnormal biomechanics and improve outcomes.

While this is an elegant biomechanical cadaveric study, the clinical realities are more complex. It is a frequent clinical observation that individuals with full thickness tears of the supraspinatus can be asymptomatic, while small tears may motivate the patient to surgical repair. Acute tears in young individuals tend to be reparable while chronic tears in older individuals may not be. Results with the smooth and move procedure (in which poor quality tendon is not 'repaired') show that an intact supraspinatus is not required to initiate abduction. The concept of the cuff muscles as 'head depressors' is being re-examined in light of the fact that their line of action exerts more compression of the humeral head into the glenoid concavity that 'depression' of the head.

Thus it is difficult to establish a clinically useful definition of a 'critical rotator cuff tear stage'. As an example, the woman shown in the movie below had no supraspinatus or infraspinatus; her shoulder function was restored by a simple deltoid strengthening program.

video
In our office we see far too many individuals who have had 'rotator cuff repairs' only to have the repair fail, often because their tendons were of insufficient quantity or quality for a robust repair. The 'critical' elements in managing individuals with cuff disease are good assessment of the patient and sound shared clinical decision making with informed consideration of the options.

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