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Proximal Humerus (shoulder) fractures

Description

Proximal humerus fractures are common orthopaedic injuries that usually occur as a result from a direct blow to the shoulder, either in a fall or as the result of a high-energy trauma. They usually can be treated conservatively with immobilization but more complex fracture patterns often require operative treatment.

Structure and function

The humerus is the largest bone in the upper extremity. Proximally, it articulates with the scapula at the glenohumeral joint. The Neer classification divides the proximal humerus into four sections including the anatomical and surgical necks as well as the greater and lesser tuberosities (GT and LT, respectively). These anatomical landmarks are clinically important both for understanding the deforming forces acting on the shoulder and for classification of the injury, which serves as a base for surgical indication.

The GT serves as the site of attachment of the supraspinatus, infraspinatus and teres minor rotator cuff muscles. The subscapularis courses from the underside of the scapula to the anteromedial aspect of the humerus to insert on the LT. Other muscular insertions include the pectoralis major, biceps brachialis, triceps, and latissimus dorsi.

The deforming muscular forces include superior and posterior displacement of the GT by the supraspinatus and external rotators, medial displacement of the LT by the subscapularis, medial displacement of the humeral shaft by pectoralis major, and abduction of proximal bone fragments by the deltoid.

The axillary artery provides the blood supply to the proximal humerus. The anterior and posterior humeral circumflex arteries branch off the axillary artery distal to the anatomic neck and then course back proximal to supply the humeral head. The blood supply to the humeral head is susceptible to interruption in anatomical neck fractures and may result in osteonecrosis. Distally branches of the brachial and axillary arteries supply the humeral shaft.

The axillary nerve runs just anterior and inferior to the glenohumeral joint. Indirect injury may occur via traction. Direct injury most commonly is due to anterior dislocation. 

Epidemiology

Proximal humerus fractures are estimated to make up 5% of all fractures, making them the 3rd most common adult fracture type. They most commonly occur in the elderly and exhibit a female to male predominance of 2-4:1. Other risk factors include osteoporosis, advanced age and a history of falls.

Clinical presentation

The mechanism of injury typically varies based on age. For elderly patients, the history usually involves a fall on an outstretched hand from a standing height. Younger patients often present following a high-energy trauma with a direct blow to the shoulder. Less commonly, proximal humerus fractures may occur as the result of a violent muscle contraction (i.e. during a seizure or following an electrical shock).

Initial complaints include pain and immobility of the affected upper extremity. Patients may report paresthesias and/or diminished sensation distal to the injury. Complaints of weakness may be secondary to pain inhibition or nerve injury. Patients will often present with the affected upper extremity held closely to the chest by the contralateral hand. Evaluation of the affected limb reveals swelling (within hours) and ecchymoses (within days). Comminution and displacement of the fracture fragments may be appreciated on gross inspection and palpation.

Important elements of the history including the mechanism of injury. In the case of a fall, for instance, a syncopal event or history suggestive of a seizure would warrant further workup. For trauma patients, comorbid injuries are common and are often missed. Make sure to rule out life threatening complications including pneumothorax and hemothorax. When time permits, make sure to assess the remainder of the musculoskeletal system for occult bony, neurologic and vascular injury.

Red flags

Proximal humerus fractures with open wounds, neurologic and/or vascular injury require special attention (ie immediate orthopaedic referral) as they may alter management. Primarily for trauma victims, make sure to assess the integrity of the overlying skin to ensure adequate perfusion and no commincating wounds. Neurovascular examination is critical during secondary assessment of the patient. The most commonly injured nerves are the axillary and suprascapular nerves. The axillary nerve can be tested via sensation over the deltoid muscle and isometric deltoid motor function while injury to the suprascapular nerve will result in weakness in initiating abduction and external rotation of the shoulder. Assessment of vascular status is difficult in the upper extremity. Peripheral pulses may remain palpable due to collateral circulation. If vascular injury is suspected due to mechanism or signs of expanding hematoma, order an angiogram and consult vascular surgery. Of note, do not attempt closed reduction prior to orthopaedic consultation due to the risk of iatrogenic neurovascular injury.

Differential diagnosis

As with any orthopaedic injury, assessment begins with examination of the neurological and vascular status of the affected limb. Assess the entire limb for occult fractures. Concurrent fractures are especially found in high-energy injury mechanisms. Injuries most commonly associated with proximal humerus fractures include axillary, suprascapular, or brachial plexus nerve injury, axillary artery damage, pneumothorax, and hemothorax. Up to two-thirds of patients may also have damage to their rotator cuff.

Objective evidence

Radiographic evaluation involves standard shoulder series plain films including AP, transcapular (Y) and axillary views. The axillary view provides the best assessment of angulation and displacement of the fracture. If a standard axillary is difficult to obtain due to the patient’s discomfort, a Velpeau axillary (patient leans backwards 45 degrees and film is shot caudally) can be performed allowing the patient to remain in a sling. It is important to assess other areas at risk of concurrent injury. Maintain a low threshold to image the elbow, wrist, etc. as indicated by the clinical scenario and presentation.

CT is usually not necessary but may be indicated for preoperative planning in the case of planned operative management. Additional indications include fracture dislocations, humeral head--splitting fractures and comminuted fractures. MRI is not typically useful but may help identify and characterize any associated rotator cuff pathology. Routine preoperative laboratory studies include a CBC, BMP, coagulation studies, and type and cross. EMG and

The Neer classification system is based on involvement of the major components of the proximal humerus listed previously. Displacement is defined as a >1cm fracture displacement and/or greater than 45 degrees of angulation. A one part fracture has no displaced fragments. Two part fractures have one displaced fragment (anatomic neck, surgical neck, GT, LT). Three part fractures are defined by two displaced fragments with an intact glenohumeral joint articulation. Four part fractures have three or more displaced segments with loss of glenoid articulation.

Risk factors and prevention

Risk reduction involves maintenance of adequate bone mineral density (BMD) and decreasing the risk of falls. In osteopenic or osteoporotic patients, pharmacological therapy including calcium and vitamin D supplementation as well as bisphosphonates and other drug treatments have been shown to be effective in reducing the risk of fractures. For patients with comorbidities who place them at risk of falling (e.g. stroke) occupational therapy can be a useful resource to help minimize risks in daily life and provide supportive devices as needed.

Treatment options

In general, management of proximal humerus fractures depends on the patient’s age, fracture type, level of displacement, bone quality, hand-dominance, lifestyle, and medical comorbidities.

Approximately 80-85% of proximal humerus fractures are nondisplaced or minimally displaced. Such one-part fractures are treated nonoperatively. Treatment involves sling immobilization of the affected arm, early passive range of motion (ROM) exercise at 1-2 weeks from injury, and active ROM exercises at 6 weeks. This approach has been validated by large observational trials, which have reported a 0% rate of nonunion and only minimal loss of ROM. Rehabilitation is ongoing for months after injury with the goal of progressing from passive activities to full active ROM in all planes of movement.

Despite clear evidence demonstrating the benefit of operative management over conservative therapy, two-part fractures are usually treated operatively. The approach varies by location of the fracture. Anatomic neck fractures are treated either with open reduction and internal fixation (ORIF) or prosthesis. Surgical neck fractures can be treated with closed reduction percutaneous pinning or ORIF. Greater tuberosity fractures usually require ORIF with rotator cuff repair as needed. Lesser tuberosity fractures may be closed reduced unless the displaced fragment prevents successful reduction, which would then require ORIF. In all circumstances ORIF may involve the use of screws, locking plates and/or intramedullary rodding.

Three-part fractures in younger patients are almost always open reduced, while older patients may do better with a hemiarthroplasty. The approach to four-part fractures varies according to the specific fracture pattern since certain types have a very high rate of osteonecrosis, which limits the usefulness of ORIF. The choice of hemiarthroplasty verus total arthroplasty depends on the injury pattern and the quality of the glenoid surface. 

Outcomes

In general full functional recovery is expected following appropriately treated proximal humerus fractures. The vast majority of patients do not have a complicated course or irreparable neurovascular injury. More than 80% are treated conservatively and can expect to return to full functional status within 6 months from the time of injury. More complicated injuries requiring operative management may take as long as 1 year for recovery. The risk is highest for complications in patients with multiple-part fracture types and those with medical comorbidities that disrupt bone healing.

Complications of proximal humeral fracture include vascular and neural injury, loss of joint ROM, osteonecrosis, nonunion, and malunion. Vascular injury is rare (5%) however the most commonly injured vessel is the axillary artery, which can contribute to avascular necrosis (AVN) of the humeral head as well as poor healing outcomes. Up to 75% of patients with four-part fractures develop AVN, which contributes to management decision.  Rates of brachial plexus injury are likewise low (6%). The axillary nerve is prone to neuropraxia or laceration with an anterior fracture-dislocation. About half of patients will experience axillary or suprascapular nerve damage. In the case of neuropraxia, recovery should be complete within 2-3 months after injury. Axillary nerve damage may further complicate functional recovery due to loss of deltoid muscle tone and resulting migration of the humeral head. While rare, there is a risk of intrathoracic dislocation with resulting pneumothorax or hemothorax. Risk factors for nonunion include severe fracture displacement, poor bone quality, infection, poor health, and inadequate fixation. Malunion is usually the result of a inadeqate closed reduction or ORIF.

Rehabilitation is a key component to regaining glenohumeral ROM. For conservatively managed patients who participate in rehab, most will gain back 85-90% of motion. Mobility may be compromised by damage sustained to the rotator cuff at the time of injury. Up to three-quarters of patients may have rotator cuff injury and should be evaluated as they recover to prevent any loss of ROM caused by a missed injury.

Holistic medicine

Proximal humerus fractures can have a significantly detrimental effect on patient’s quality of life. Injury to the dominant side further enhances disability. Shoulder injuries have a tendency to disrupt sleep, leading to effects secondary to chronic sleep deprivation/disruption.

Poor bone quality in the form of osteopenia or osteoporosis is a major risk factor for complications following proximal humerus fracture. Thus, patients need to be screened for their risk of low bone density and treated prophylactically if indicated to reduce their risk of fracture.

Miscellany

  • The most common neurologic sequelae of a proximal humerus fracture is axillary nerve injury. Second is suprascapular nerve injury.* The blood supply to the proximal humerus is tenuous. Disruption of blood flow is common in complicated fracture patterns and often results in avascular necrosis leading to poorer outcomes.
  • The anterolateral branch of the anterior circumflex artery (arcuate artery) is the dominant blood supply to the proximal humerus. It supplies the majority of the humeral head, lesser tuberosity, and greater tuberosity. The posterior circumflex artery primarily supplies posterior portions of the greater tuberosity and humeral head.

Key terms

  • Greater tuberosity
  • Lesser tuberosity
  • Surgical neck
  • Anatomic neck
  • Anterior & posterior circumflex arteries
  • Axillary nerve
  • Suprascapular nerve
  • Brachial plexus
  • Avascular necrosis
  • Neuropraxia
  • Closed reduction
  • ORIF
  • Hemiarthroplasty
  • Total shoulder arthroplasty

Skills

  • Neurologic examination of the upper extremities including relevant dermatomes, appropriate muscle groups for testing main nerve branches (radial, median, ulnar, anterior interosseus, posterior interosseus)
  • Assessment of vascular status to the affected limb via clinical signs and when to seek vascular referral due to supposed vascular injury.  



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Resources for Proximal Humerus (shoulder) fractures and related topics on OrthopaedicsOne.

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