Anatomy and Function
The scapula is a thin, flat bone oriented obliquely to the posterior thorax in both the coronal and sagittal planes. The structure of the scapula is unique with two osseous projections, the coracoid and acromion, and the glenoid articular surface. Additional overlying structures such as the rib cage, clavicle, and humerus make radiographic projections and their interpretation complicated.[5,6]
There is new evidence to support the notion that the scapula acts as a dynamic stabilizer of the humerus and shoulder complex. The scapula's glenoid surface has been likened to a seal balancing a ball on its nose, acting as a dynamic stabilizer in combination with the 18 muscles that originate from, insert on, or cross the scapula and glenohumeral joint.[4,7] The scapula is the base on which the arm rests in both static and dynamic positions, and malunion after fracture creates a mechanical disadvantage for upper extremity function and may cause symptoms such as pain, weakness, and loss of function. Cole et al. have reported a series of patients who underwent osteotomy for malunited scapular fractures and found good results after correction.
The superior shoulder suspensory complex (SSSC) is the ring of soft tissues and bone that comprise the acromion, acromioclavicular joint, distal clavicle, coracoclavicular ligament, coracoid process, and the glenoid. Disruption of one aspect of the SSSC is relatively benign regarding functional changes but disruption of both can result in instability and functional deficits. It is debatable whether one, both, or neither disruption requires fixation, and currently no evidence exists to support fixation of a double disruption based solely on the fact it is disrupted in two locations.
Curr Orthop Pract. 2015;26(2):99-104. © 2015 Lippincott Williams & Wilkins