The term floating shoulder was used in 1992 by Herscovici et al to describe their series of ipsilateral fractures of the clavicle and scapular neck.  Although some have questioned the accuracy of this definition, the term floating shoulder, in contemporary use, usually refers to ipsilateral fractures of the clavicle and scapular neck but can also apply to any combined injury to the superior shoulder suspensory complex (SSSC). 
Floating shoulder injuries are rare. They result from high-energy trauma and have a high incidence of associated injuries, which likely contribute to their underdiagnosis and undertreatment. Understanding the pathologic anatomy and instituting appropriate treatment are important for minimizing the sometimes-significant morbidity from this injury. [3, 4, 5, 6]
Although this unstable injury tends to have a better outcome in patients in whom the clavicle fracture is surgically stabilized (particularly more distal clavicle fractures), the injury should be assessed in the context of the whole patient. Consideration of the age, demands, associated injuries, and the severity and displacement of the fracture may make nonoperative treatment preferable, with an expectation of a good result. 
The upper extremity is suspended primarily from the axial skeleton by a bony and ligamentous ring (ie, the SSSC).  The ring consists of the middle and distal clavicle, coracoclavicular and acromioclavicular ligaments, acromion, coracoid process, and glenoid. Of these, the clavicle is the primary support to the axial skeleton. The musculotendinous attachments from the spine, sternum, ribs, and medial clavicle to the scapula, distal clavicle, and proximal humerus provide the secondary support.
A double disruption of the SSSC ring results in an unstable construct and is the most accurate description of a floating shoulder.  The most common double disruption of this ring is the combined fracture of the clavicle and scapular neck, and the terms are usually equated. However, the term floating shoulder can apply to any combined injury to the SSSC.
The deforming forces acting on this unstable construct include the weight of the arm and the force of the muscles acting on the proximal humerus, both of which pull the glenoid fragment distally and anteromedially.
Ipsilateral fractures of the clavicle and scapular neck typically occur after high-energy trauma, such as the following:
Motor vehicle accidents
Falls from a height
With the exception of those occurring from gunshot wounds, most such fractures are closed injuries.
Ipsilateral fractures of the clavicle and scapular neck are exceedingly rare, constituting approximately 0.1% of all fractures. 
Displaced ipsilateral fractures of the clavicle and scapular neck are rare. These patients often have significant associated injuries because of the severity of the initial trauma. Initial treatment of these patients involves assessment and stabilization of the often life-threatening associated injuries.
The prognosis for injuries treated nonsurgically often depends on the predicted rotator cuff dysfunction. Excessive glenoid displacement from combined injuries will alter the normal lever arm of the rotator cuff and the surrounding musculature.  In patients who do not have contraindications for surgical treatment, the best outcomes are achieved most predictably with reduction and stabilization of at least one part of the SSSC.