Sonography of the coracohumeral interval: a potential technique for diagnosing coracoid impingement

Tracy MR, Trella TA, Nazarian LN, Tuohy CJ, Williams GR. J Ultrasound Med. 2010 Mar;29(3):337-41.


At the shoulder the term “impingement” has become very well known even outside the sports medicine field.  Although it is mainly referring to sub-acromial impingement, there have been several other forms of impingement introduced.  Within sub-acromial impingement you could be even more specific and classify it as primary or secondary.  Internal impingement has also gained popularity among overhead athletes and baseball players specifically.  However, one form of impingement “sub-coracoid” commonly goes unrecognized and therefore misdiagnosed.  Sub-coracoid impingement is when the subscapularis tendon (mainly the upper portion) is impinged between the coracoid process and the lesser tuberosity.  This commonly occurs in a position of forward flexion, horizontal adduction, and internal rotation.  Basically the position the shoulder is in during the follow-through phase of overhead throwing.  The pain is typically within the anterior shoulder causing it to be misdiagnosed as sub-acromial impingement, biceps tendonitis, or anterior instability.  This study describes a new way of diagnosing this injury with use of diagnostic ultrasound.  It was hypothesized that a patients with sub-coracoid impingement will have a decrease in the coracohumeral interval (distance from the coracoid process to the lesser tuberosity with the shoulder horizontally adducted) compared to normal shoulders.  They tested 27 subjects (19 asymptomatic volunteers and 8 with a clinical diagnosis of sub-coracoid impingement).  They found that the patients with sub-coracoid impingement had a decreased coracohumeral interval compared to asymptomatic controls. 


This study although simple and straightforward describes a very easy assessment for an otherwise difficult injury to diagnosis clinically.  Sub-coracoid impingement is an injury that gets misdiagnosed more often then we think.  The more clinicians are aware of this injury the better we can treat and prevent this injury from progressing into an upper subscapularis tendon tear.  Currently additional research is required to indentify the role of scapular dyskinesis and alterations in the coracoid process morphology in the development of sub-coracoid impingement.  I also know what everyone is thinking “Yeah that sounds great BUT we don’t have diagnostic ultrasounds in the athletic training room.”  Well currently this is true but I think that will be changing in the near future.  Diagnostic ultrasounds have become extremely advanced, portable, and therefore popular with the advances in computer technology.  It has been moving into NFL athletic training rooms and progressing to MLB as well.  As the popularity of these devices increases, the price will likely decrease; which will allow the transition into athletic training rooms across the country. 


Written by: Stephen Thomas

Reviewed by: Jeffrey Driban