Proximal humerus fractures

Proximal humerus fractures have been reported to account for about 5% of all fractures. These injuries usually occur in older patients who have osteoporotic, fragile bone. The fracture usually occurs from a ground-level fall. A much higher level of trauma would typically be required for a younger person to sustain the same type of fracture. Studies from Sweden and Denmark indicate a steady and significant increase of proximal humeral fractures. Longer life span and osteoporosis were credited for this trend. The incidence of these fractures will continue to increase as the population base ages.

When treating a patient with a proximal humerus fracture, the physician must consider many factors. The type of fracture, patient ability to participate in rehabilitation, general health and age of the patient, and time from injury to treatment are important factors that affect treatment results. Additionally, surgical reconstruction of the proximal humerus may be technically difficult.

Proximal humerus fractures are usually classified by the Neer classification system (Figure 1). The majority of fractures (about 85%) are nondisplaced, and nonoperative treatment with a sling and early range-of-motion (ROM) exercises is usually successful. Gentle ROM exercises may begin after 7-10 days if the fracture is stable. When fracture displacement occurs, operative intervention is selected.

Figure 1. In the Neer classification* of proximal humerus fractures, the proximal humerus is made up of four parts:

  1. humeral head (articular surface)
  2. greater tubercle
  3. lesser tubercle
  4. diaphysis (shaft)

These four parts are separated by epiphyseal lines (bone growth plates) during the early developmental years. When the proximal humerus is broken, the fracture line predictably occurs along one or more of these planes.

Displacement of a fracture fragment by 1 cm, or angulation between fracture fragments of 45° or greater, is what defines a fragment as being a "separate" part. Hence, a proximal humerus fractures may be called 2-part, 3-part, or 4-part according to the Neer classification system, depending upon the amount of displacement and angulation seen on x-ray.

*Neer CS 2nd: Displaced proximal humeral fractures. I. Classification and evaluation. J Bone Joint Surg Am 1970 Sep; 52(6): 1077-89

Surgery may be recommended if one or more of the fracture fragments is displaced or angulated. Displacement of a fracture fragment by 1 cm, or angulation between fracture fragments of 45° or greater, is what defines a fragment as being a "separate" part (Figure 2A). More recent literature suggests that the greater tuberosity should be reduced if it is displaced 5 mm or more. However, other factors such as bone quality, fracture orientation, and soft tissue injuries, the age and health status of the patient, and the surgeon's level of compfort in treating these injuries all have a tremendous effect on specific treatment indications.

In general, 2- and 3-part fractures are treated with open reduction and internal fixation (a plate with screws is the choice of many surgeons currently). Four-part fractures in the younger, active patient also can be treated successfully with open reduction and internal fixation. However, in the elderly and in the patient with osteoporosis, a hemiarthroplasty is the treatment of choice (Figure 3).

Figure 2. A. 1. The humeral head, greater tubercle, and lesser tubercle count as one part in this 2-part fracture. Note that there is a crack in the bone between the greater tubercle and the humeral head (yellow asterisk), but because the displacement is less than 1 cm and the angulation is less than 45°, the greater tubercle itself does not count as a separate part. 2. The diaphysis (shaft) of the humerus is makes up the second part. B. Treatment of a two-part proximal humerus fracture with a locking plate. The red asterisk serves to point to the subluxation (partial dislocation) of the shoulder that is a result of an axillary nerve palsy. Nerve injuries are commonly associated with proximal humerus fractures. Fortunately, most will recover within a month or two.

The incidence of neurologic injuries associated with proximal humerus fractures is high (59% for nondisplaced fractures, but as high as 82% if the fracture was displaced, according to Visser et al.). The axillary nerve is the most commonly injured nerve . Loss of skin sensation over the lateral deltoid muscle should alert the examiner to possible axillary nerve injury (Figure 2B). Lack of deltoid muscle contraction is another clue that the nerve may be damaged. The suprascapular, radial, and musculocutaneous nerves also are at risk. Fortunately, nerve recovery is the norm, and only a small percentage of fractures result in permanent nerve damage.

Stiffness is the leading complication following non-operative or surgical treatment of a proximal humerus fracture. Physical therapy may be initiated after a few weeks to preserve range of motion. However, strengthening and aggressive range of motion exercises must not be performed until the bone has healed.

Figure 3. A. A 4-part, valgus impacted humerus fracture. 1. The humeral head. 2. The greater tubercle. 3. The lesser tubercle. 4. The diaphysis (shaft). When the humeral head is impacted in a valgus position the blood supply is usually preserved, so it is possible to treat the injury with a plate and screws rather than with a shoulder replacement. B. In this patient other factors were considered, and the patient elected to be treated with a fracture prosthesis.

 
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