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Proximal fractures of the humerus

Doctor Attia
3d CT shows comminuted Proximal fracture of the humerus 
X ray AP view shows proximal fracture of the humerus 
X ray AP view of the same case shows union of the fracture.
X ray AP view with abduction up-to 60 degrees of the shoulder of the same patient shows union of the fracture.

Review of literature of Proximal fractures of the humerus 
Incidence 
Proximal fractures of the humerus are the 7th most frequent fracture in adults. It is also the 3rd in patients in older populations following wrist and femoral neck fractures. They represent 5% of all fractures. It occurs mainly in osteoporotic patients. There is a bimodal distribution with also a peak amongst the young.

The majority of elderly patients of proximal fractures of the humerus are women, due to the greater incidence of osteoporosis. The majority of these occur at home due to a fall.

Anatomy

The proximal humerus includes 4 parts: the articular surface of the head, greater tuberosity, lesser tuberosity, and the humeral shaft. The surgical neck of the humerus is a constriction below the greater tuberosity and lesser tuberosity, and above the deltoid tuberosity. 

The surgical neck is much more frequently fractured than the anatomical neck of the humerus. 

The shaft joins the proximal segment at the surgical neck. 

The anatomical neck of humerus is best marked in the lower half of its circumference. In the upper half it is represented by a groove separating the head of the humerus from 2 tuberosities, the greater tuberosity and the lesser tuberosity. The anatomical neck represents the fused epiphyseal plate. 

Neurovascular structures at risk

Several neurovascular structures are at risk of injury in proximal fractures of the humerus.  The axillary nerve is the most commonly injured nerve. Arterial injury may occur in comminuted surgical neck fractures and subcoracoid dislocation of the humerus head. The main blood supply to the humeral head is the posterior humeral circumflex artery. The anterior humeral circumflex artery has extensive arterial branching and anastomotic networks.

Deforming forces 

 The deforming forces of proximal fractures of the humerus include:

  • pectoralis major: adducts the humeral shaft
  • supraspinatus, infraspinatus, teres minor: displace and externally rotate the greater tuberosity
  • subscapularis: internally rotates the lesser tuberosity and exerts anteromedially directed force. 
  • Deltoid: pulls superiority on the metaphysis

History

Many older patients present following a fall on out stretched hand. Younger patients usually present following a high energy trauma incident, e.g. a motor accident. Patients may present following a seizure, electrical shock or following direct trauma.

Symptoms and signs 

Proximal fractures of the humerus can cause pain, swelling, and bruising of the upper arm. Other symptoms may include: Limited shoulder motion, numbness and upper arm deformity.

The most common mechanism for proximal fractures of the humerus usually result from a fall on an outstretched hand. Indirect forces transmitted through the proximal humerus and shoulder are the cause of most fractures. In younger patients, high energy trauma is a much more frequent cause. These forces may be compressive, tension, torsion or bending.

X rays are usually sufficient to characterize proximal humeral fractures, and so to determine management. CT can be useful if adequate views cannot be done, if there are unusual fractures or if associated fractures are present (such as glenoid, coracoid or acromion).

Appropriate classification of the fracture depends on the number of displaced fragments that are determined by X rays or CT. The two commonly used classifications are Neer and AO classification.

Proximal fractures of the humerus description should include:

- location of fracture lines, displacement or impaction and angulation of each part (>1 cm and >45 degrees respectively is particularly important in the Neer Classification, presence of involvement of the articular surface.

- The descriptions required to classify the fracture should be included.

Associated injuries

- Shoulder and acromioclavicular dislocations.  Scapular, clavicular, and distal radial fractures. 

Associated osteoporosis 

Proximal fractures of the humerus most commonly occur in patients over 65 years of age. Low-energy fall results in Proximal fractures of the humerus. It is considered a fragility fracture. Patients have these injuries should be considered to already be on the osteoporotic spectrum. 

The three most common osteoporotic fractures include: vertebral compression fractures, distal radius fractures and proximal fractures of the humerus.

Management depends on the type of fracture and more importantly on the functional status of the patient. For example, the daily activities of someone who lives alone may not be done without the use of a single arm.

Undisplaced Proximal fractures of the humerus are treated conservatively. Displaced fractures are treated surgically with closed or open reduction and internal fixation (with intramedullary nails, plates and screws or K wires). Three and four-part fractures are treated usually with hemi-arthroplasty due to the high risk of malunion and avascular necrosis.

Prognosis 

The prognosis is usually good. The majority of fractures heal well with little functional loss. Poor prognosis is associated with a variety of factors that include:

  • displaced fractures
  • old age
  • type C fractures (AO classification)
  • three and four-part fractures (Neer classification)

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