Acromioclavicular joint injuries revisited: Pathoanatomy, pathomechanics, and clinical presentation.

Multiple papers have described aspects of treatment of acromioclavicular (AC) joint injuries. Most have emphasized aspects of surgical treatment, and some papers have addressed non-operative treatment. Few papers have highlighted the specific pathoanatomy of an AC joint injury or have described methods of evaluating the 3-dimensional pathomechanics resulting from the pathoanatomical injury. This paper is based on 3 observations: (1) AC joint injuries exist and present on a spectrum of pathoanatomy; (2) The effect of the pathoanatomy on normal AC joint mechanics to produce pathomechanics is dependent on the extent of the pathoanatomy; and (3) Treatment protocols should be developed to address the specific pathoanatomy to optimize the mechanics. A comprehensive clinical approach emphasizing the evaluation of the extent of the anatomic injury and understanding its mechanical consequences regarding shoulder and arm function is a key in the development of guidelines for developing operative or non-operative treatment protocols and for establishing outcomes of the treatment protocols.