Floating Shoulder - Anatomy, Clinical Presentation, Diagnosis, and Treatment

What Is a Floating Shoulder?

It is a fracture involving the clavicle and scapula associated with the superior shoulder suspensory complex. The fracture occurs due to high-impact trauma and involves injuries to the associated structures. A floating shoulder is better understood by studying the fractures of the scapula.

What Is the Anatomy of the Floating Shoulder?

A Floating shoulder anatomically comprises three components:

• Superior shoulder suspensory complex.

• The clavicle.

• The scapula.

1. Superior Shoulder Suspensory Complex (SSSC): The superior shoulder suspensory complex is soft tissue or a bony ring attached to the body's trunk by the inferior and superior bony struts (struts are structures possessing a design to resist pressure along the direction of their length). This ring is formed by:

• Glenoid process.
• Acromioclavicular process.
• Coracoid process.
• Coracoclavicular ligament.
• Acromion process.
• The distal part of the clavicle.

This SSS complex is subdivided into three units:

• The clavicle, acromioclavicular joint with acromion struts.
• The three process junction of the scapular body.
• The clavicular - coracoclavicular ligament-coracoid.

The superior shoulder suspensory complex is significant because of its biomechanical nature, as it acts as articular cartilage to which the clavicle, scapula, and other soft tissues articulate. It is also said that the scapula is hung from the clavicle through the SSSC.

2. The Clavicle: The clavicle is an 'S'-shaped bone present horizontally to the sternum. The clavicle is the only bone in the trunk connecting the scapula to the upper arm through the axial complex. The clavicle is one of the bones in the body which are more commonly prone to fracture.

3. The Scapula: The scapula is a triangular-shaped flat bony structure located at the back side of the rib cage. It is also called the shoulder blade. The scapula forms the posterior portion of the Shoulder. The scapula has 17 muscles attached, making it less prone to fracture. The fractures of the scapula are:

• Fracture of the surgical neck of the scapula.

• Fracture of the anatomical neck of the scapula.

• Fracture of the scapular neck of the scapula.

The fracture of the surgical neck is the most typical fracture of all. The neck and body fracture is called a double disruption fracture of the SSSC. A Floating shoulder is a type of double disruption fracture of the scapula showing a typical pattern involving the ipsilateral (same side) part of the scapular neck and the distal third of the clavicle.

How Is It Observed Clinically?

A floating Shoulder is an unstable shoulder showing distal displacement with internal rotation. The patient shows the following symptoms:

• Very high and non-specific shoulder pain.

• Tenderness when palpated.

• Shoulder displacement.

• Significant swelling of the soft tissue.

• Restricted movement of the arm or Shoulder.

• Surface abrasions or wounds.

• Chest pain.

• Shortness of breath.

• Nerve or vessel damage can also occur due to the rupture of nerves or blood vessels.

How Does a Floating Shoulder Occur?

Floating Shoulder is a rarely occurring fracture with an incidence rate of less than five percent. A floating shoulder is more commonly seen to occur in males than in females between the ages of 25 to 50. The cause of the injury is primarily due to high-intensity trauma or motor vehicle accidents. Another reason is a fall with outstretched arms during a seizure or electric shock.

What Are the Injuries Associated With a Floating Shoulder?

There are injuries associated with the floating shoulder because of its position in the associated structures. Such associated systemic injuries are:

• Pneumothorax or hemothorax (a clinical condition where the lungs are filled with blood or fluid).

• Head injury.

• Rib fractures.

• Upper vascular injury.

• Damage to the brachial plexus (brachial plexus is a comprehensive network of nerves sending signals from the spinal cord to the shoulder, arms, and hands).

What Are the Methods Used for Diagnosing a Floating Shoulder?

Because a floating shoulder is a very complex injury, there is a greater index for suspicion of the fracture and a need for confirming it. Hence the methods used for diagnosing a floating shoulder are:

1. Computed Tomography (CT): The CT scans are three-dimensional images that are taken to assess the fracture in all directions, making it easier to locate the fracture line and plan the treatment access.

2. Radiographs (X-RAY): Radiographs of the shoulder and chest are taken to evaluate the displacement of the shoulder and the time required for healing and compare the side of displacement with the healthier side.

3. Magnetic Resonance Imaging (MRI): Magnetic resonance imaging or MRI is used to obtain soft tissue images that help evaluate injuries to SSSC and associated ligaments.

How Is a Floating Shoulder Treated?

As a floating shoulder is a rare fracture, the guidelines for treating this condition are not very indicative. The treatment usually depends on the state and severity of the patient. There are two factors used for determining the severity of a floating Shoulder:

1. The monopolar angle (GPA): The GPA is an angle formed between two lines, each of which runs from the inferior and superior points of the glenoid fossa.

2. The severity of shoulder displacement.

A Floating shoulder is treated by both conservative and surgical management.

1. Conservative Management: In cases showing minimal displacement of the neck of the scapula, conservative management is sufficient. Conservative management is done by immobilization using an arm sling for two to three weeks with medication for pain and healing.

2. Surgical Management: In cases with severe displacement or a very abnormal GPA angle, surgical management is done by reducing the displaced scapular neck and internal fixation of the mandible using plates and screws. It is done to restore the dislocation and degree of displacement. However, it is essential to resolve the problem and restore the normal anatomy of the scapula along with the replacement of functions of the shoulder.

What Are the Complications After Treating the Fracture?

The complications that may occur after surgically managing a floating shoulder is

• Infection.

• Delayed healing.

• Functional retardation.

• Arthritis (Inflammation of the bony joints).

• Shoulder joint instability.

Although these are the commonly occurring complications of any fracture joint, the surgical management of a floating shoulder has a better prognosis, and these postoperative complications are seldom seen.

What Are the Guidelines Indicating the Severity of Displacement?

The significant displacement of the shoulder is around 10 to 15 mm (millimeters), where Vidovic et al. stated the indication for surgery when the scapular neck displacement is greater than 10 mm with a resting period of eight weeks.

Conclusion

Although a floating shoulder is a very rare type of fracture with fewer treatment guidelines, it is a type of fracture that shows an excellent prognosis without compromising functional activities when appropriately fixed and given time to heal. Managing a floating shoulder with a proper diagnosis and the right approach is essential for an excellent prognosis.