This past week I had a patient that presented with left upper quarter pain following a traction injury to her left arm as her dog yanked her arm forward. The pain was located over her left clavicular region and anterior to left scapula. My examination revealed hypomobility over her left ribs 2-3 and left sternoclavicular (SC) joint as her primary restrictions (both of which reproduced her pain when assessed). She has made excellent progress just in the treatment from the first day with joint mobilizations of the SC joint and and ribs. With reflecting upon this patient, I thought it would be great to review some of the anatomy and arthrokinematics for the SC joint.
Anatomy of Sternoclavicular Joint
The SC joint is made up of the medial end of the clavicle, the manubrium and an articular disc in-between. It is important to understand that the sternoclavicular joint is a saddle joint. It gets its name from the shape as it has a concave surface in one direction and convex in another, like a saddle. The medial aspect of the clavicle is concave anterior-to-posterior and convex superior-to-inferior. The manubrium has the reciprocal joint surface. The result is that with protraction/retraction, the sternum rolls and glides anteriorly and posteriorly, respectively speaking, and with elevation and depression, the clavicle rolls and slides opposite (roll superiorly and slide inferiorly with elevation; opposite for depression). Additionally, there is some posterior rotation of the clavicle that occurs with elevation and anterior rotation with extension.
When it comes to assessing and treating joint restrictions in the SC joint, I try to keep it simple. Assess the mobility in each direction and mobilize into the restriction. It's possible you'll note some hypermobility in a certain direction (you don't want to increase mobility there). Often, you will note that the restricted aspect of the joint may correlate with physiological motion deficits in the shoulder; however, that is not a rule of presentation. To make matters simpler, stick with finding the restricted direction and mobilizing it. For more information on the anatomy and biomechanics of the SC joint, check out the videos below!
-Dr. Chris Fox, PT, DPT, OCS
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