PROXIMAL HUMERUS

FRACTURES

EPIDEMIOLOGY

Proximal humerus fractures comprise 4% to 5% of all fractures and represent the most common humerus fracture (45%).

The incidence is 300,000 per year (more common than hip fracture).

Most (85%) are nondisplaced.

Older individuals have a higher incidence secondary to osteoporosis.

• Proximal humerus fracture in an older individual after a simple fall is considered a fragility fracture.

The 2:1 female-to-male ratio is also related to osteoporosis.

ANATOMY

The shoulder has the greatest range of motion of any joint in the body, secondary to the shallow glenoid fossa that is only 25% the size of the humeral head. The major contributor to stability is not bone, but the soft tissue envelope composed of muscle, capsule, and ligaments.

The proximal humerus is retroverted 35 to 40 degrees relative to the epicondylar axis.

The four osseous segments (Neer) (Fig. 15.1) are the:

1. Humeral head

2. Lesser tuberosity

3. Greater tuberosity

4. Humeral shaft

The deforming muscular forces on the proximal humerus include (Fig. 15.1):

1. The supraspinatus and external rotators displace the greater tuberosity superior and posterior.

2. The subscapularis displaces the lesser tuberosity medially.

3. The pectoralis major displaces the humeral shaft medially.

4. The deltoid abducts the proximal fragment.

Neurovascular supply:

1. The major blood supply is from the anterior and posterior humeral circumflex arteries.

2. The arcuate artery is a continuation of the ascending branch of the anterior humeral circumflex. It enters the bicipital groove and supplies most of the humeral head. Small contributions to the humeral head blood supply arise from the posterior humeral circumflex, reaching the humeral head via tendo-osseous anastomoses through the rotator cuff. Fractures of the anatomic neck are uncommon, but they tend to have a poorer prognosis because of the precarious vascular supply to the humeral head.

3. The axillary nerve courses just anteroinferior to the glenohumeral joint, traversing the quadrangular space. It is at particular risk for traction injury owing to its relative rigid fixation at the posterior cord and deltoid as well as its proximity to the inferior capsule where it is susceptible to injury during anterior dislocation and anterior fracture-dislocation.

MECHANISM OF INJURY

The most common mechanism is a fall onto an outstretched upper extremity from a standing height, typically in an older woman.

Younger patients typically sustain a proximal humeral fracture following high-energy trauma, such as a motor vehicle accident. These usually represent more severe fractures and dislocations, with significant associated soft tissue disruption and multiple injuries.

Less common mechanisms include:

1. Excessive shoulder abduction in an individual with osteoporosis, in which the greater tuberosity prevents further rotation

2. Direct trauma, usually associated with greater tuberosity fractures

3. Electrical shock or seizure

4. Pathologic processes: malignant or benign processes in the proximal humerus

CLINICAL EVALUATION

Patients typically present with the arm held closely to the chest by the contralateral hand, with shoulder pain, swelling, tenderness, painful range of motion, and variable crepitus.

Ecchymosis about the proximal humerus may not be apparent immediately after injury. Chest wall and flank ecchymosis may be present and should be differentiated from thoracic injury.

A careful neurovascular examination is essential, with particular attention to axillary nerve function. This may be assessed by the presence of sensation on the lateral aspect of the proximal arm overlying the deltoid. Motor testing is usually not possible at this stage secondary to pain. Inferior translation of the distal fragment may result from deltoid atony and is not a true glenohumeral dislocation; this usually resolves by 4 weeks after fracture, but if it persists, it may represent a true axillary nerve injury.

RADIOGRAPHIC EVALUATION

A shoulder series, consisting of an anteroposterior and lateral (“Y”) views in the scapular plane as well as an axillary, is standard.

The axillary is the best view for evaluation of glenoid articular fractures and reduction of the glenohumeral articulation, but it may be difficult to obtain because of pain. This view does not accurately predict fracture angulation in the trauma setting.

Velpeau axillary: If a standard axillary cannot be obtained because of pain or fear of fracture displacement, the patient may be left in the sling and leaned obliquely backward 45 degrees over the cassette. The beam is directed caudally, orthogonal to the cassette, resulting in an axillary view with magnification (Fig. 15.2).

Computed tomography is helpful in evaluating articular involvement, degree of fracture displacement, impression fractures, and glenoid rim fractures. It is also helpful when an axillary view is not obtainable.

Magnetic resonance imaging is generally not indicated for fracture management, but it may be used to assess rotator cuff integrity.

CLASSIFICATION

Neer (Fig. 15.3)

Defines four parts: These are the greater and lesser tuberosities, humeral shaft, and humeral head.

A part is defined as displaced if there is >1 cm of fracture displacement or >45 degrees of angulation.

Fracture types include:

• One-part fractures: No displaced fragments regardless of number of fracture lines

• Two-part fractures (any of the following):

  • Anatomic neck

  • Surgical neck

  • Greater tuberosity

  • Lesser tuberosity

• Three-part fractures:

  • Surgical neck with greater tuberosity

  • Surgical neck with lesser tuberosity

• Four-part fractures

• Fracture-dislocation

• Articular surface fracture

  Orthopaedic Trauma Association Classification of Proximal Humerus Fractures

  See Fracture and Dislocation Compendium at http://ota.org/compendium/index.htm.

  TREATMENT

Minimally displaced fractures (one-part fracture)

• Sling immobilization or swathe for comfort.

• Early shoulder motion at 7 to 10 days consisting of pendulum exercises and passive range-of-motion exercises may be instituted.

• Early radiographic follow-up to detect loss of fracture reduction may be instituted.

• Active range-of-motion exercises are started 6 weeks postinjury.

• Resistive exercises are started anywhere from 6 to 12 weeks.

• Return to near full range of motion and function is the expected outcome by 1 year.

Two-part fractures

• Anatomic neck fractures: These are rare and difficult to treat by closed reduction. They require open reduction and internal fixation (ORIF) (younger patients) or prosthetic replacement (older individuals) and have been historically associated with a higher incidence of osteonecrosis.

• Surgical neck fractures

  • Nonoperative treatment is rarely indicated except for angulated/displaced surgical neck fractures, which are stable (move as a unit) in lower demand individuals, severely debilitated patients, and those who cannot tolerate surgery.

  • Closed reduction and percutaneously inserted terminally threaded pins or cannulated screws may be considered in younger individuals with good-quality bone. Problems associated with multiple pin fixation include nerve injury (axillary), pin loosening, pin migration, and inability to move the arm.

  • ORIF is the treatment of choice for most displaced surgical neck fractures of the proximal humerus and can involve placement of plate and screws or an intramedullary device. Most current proximal humerus plates use a locked screw construct for the metaphyseal component secondary to improved fixation of locked screws in osteopenic cancellous bone.

  • Prosthetic replacement may be considered for patients with extreme osteopenia and involves use of hemiarthroplasty, total shoulder, or reverse shoulder prosthesis.

• Greater tuberosity fractures: ORIF with or without rotator cuff repair is indicated for greater

  tuberosity fractures which are displaced >5 to 10 mm (5 mm for superior translation); otherwise, they may develop nonunion and subacromial impingement. A greater tuberosity fracture associated with anterior dislocation may reduce on reduction of the glenohumeral joint and be treated nonoperatively.

• Lesser tuberosity fractures: They may be treated closed unless displaced fragment blocks internal rotation; one must rule out associated posterior dislocation.

Three-part fractures

• These are usually unstable due to opposing muscle forces; as a result, closed reduction and maintenance of reduction are often difficult.

• Displaced fractures require operative treatment, except in severely debilitated patients or those

  who cannot tolerate surgery.

• Younger individuals should have an attempt at ORIF using plate and screws; preservation of the vascular supply is of paramount importance with minimization of soft tissue devascularization.

• Locking plate technology has expanded the indications for ORIF after three-part fracture in older

  individuals, secondary to improved screw fixation in osteopenic bone. However, one should be prepared to perform prosthetic replacement (hemiarthroplasty, total shoulder, or reverse shoulder prosthesis) in older individuals if necessary. There has been increased use of reverse shoulder prostheses as a prosthetic replacement after proximal humerus fractures in the elderly because of difficulty with tuberosity attachment and healing with conventional hemiarthroplasty.

Four-part fractures

• Incidence of osteonecrosis ranges from 4% to 35%.

• ORIF may be attempted in patients with good-quality bone if the humeral head is located within the glenoid fossa and there appears to be soft tissue continuity. Fixation is best achieved with locking plate and screw fixation, suture, and/or wire fixation.

• Primary prosthetic replacement of the humeral head (hemiarthroplasty, total shoulder, or reverse shoulder prosthesis) is indicated in the elderly.

  • Hemiarthroplasty is associated with predictable pain relief, but unpredictable results from the

    standpoint of function.

• Four-part valgus-impacted proximal humerus fractures represent variants that are associated with lower rate of osteonecrosis and have excellent results with ORIF (Fig. 15.4).

   

   

   

Fracture-dislocations

• Two-part fracture-dislocations: These may be treated closed after shoulder reduction unless the fracture fragments remain displaced.

• Three- and four-part fracture-dislocations: ORIF is used in younger individuals and

  prosthetic replacement in the elderly dependingpon the length of dislocation. The brachial plexus and axillary artery are in proximity to the humeral head fragment with anterior fracture-dislocations.

• Recurrent dislocation is rare following fracture union.

• Prosthetic replacement for anatomic neck fracture-dislocation is recommended because of the high incidence of osteonecrosis.

• These injuries may be associated with increased incidence of myositis ossificans with repeated

  attempts at closed reduction.

Articular surface fractures (Hill-Sachs, reverse Hill-Sachs)

• These are most often associated with posterior dislocations.

• Patients with >40% of humeral head involvement may require prosthetic replacement; ORIF

  should initially be considered in patients <40 years of age, if possible.

  Surgical Considerations

Patient positioning

• Supine or beach chair position. The supine position is easier to set up and bring in fluoroscopy. The beach chair position allows the weight of the arm to facilitate fracture reduction. In addition, prosthetic replacement is usually performed in a beach chair position.

Radiographic positioning

• Image intensification can come from the opposite side of the table, the head or foot of the table.

Surgical approach

• Deltopectoral versus deltoid split. The deltopectoral approach is the workhorse of the shoulder and allows for an extensile approach to the proximal humerus. ORIF or arthroplasty is well performed through this approach (Fig. 15.4). The deltoid split allows for easier plate placement on the greater tuberosity and requires fewer assistants to retract the deltoid muscle.

  COMPLICATIONS

Vascular injury: This is infrequent (5% to 6%); the axillary artery is the most common site (proximal to anterior circumflex artery). The incidence is increased in older individuals with atherosclerosis because of the loss of vessel wall elasticity. There is a rich collateral circulation about the shoulder which could mask vascular injury.

Neural injury

• Brachial plexus injury: This is infrequent (6%).

• Axillary nerve injury: This is particularly vulnerable with anterior fracture-dislocation because the nerve courses on the inferior capsule and is prone to traction injury or laceration. Complete axillary nerve injuries that do not improve within 2 to 3 months may require electromyographic evaluation and exploration.

Chest injury: Intrathoracic dislocation may occur with surgical neck fracture-dislocations; pneumothorax and hemothorax must be ruled out in the appropriate clinical setting.

Myositis ossificans: This is uncommon and is associated with chronic unreduced fracture-dislocations and repeated attempts at closed reduction. It may also be related to timing of surgery and deltoid split approaches (Fig. 15.5).

Shoulder stiffness: It may be minimized with an aggressive, supervised physical therapy regimen and may require open lysis of adhesions for recalcitrant cases.

Osteonecrosis: This may complicate 3% to 14% of three-part proximal humeral fractures, 4% to 34% of four-part fractures, and a high rate of anatomic neck fractures.

Nonunion: This occurs particularly in displaced two-part surgical neck fractures with soft tissue interposition. Other causes include excessive traction, severe fracture displacement, systemic disease, poor bone quality, inadequate fixation, and infection. It may be addressed with ORIF with or without bone graft or prosthetic replacement.

Malunion: This occurs after inadequate closed reduction or failed ORIF and may result in impingement of the greater tuberosity on the acromion, with subsequent restriction of shoulder motion. It is important to restore medial cortical support by either anatomic fracture reduction, use of oblique inferomedial locking screws, or an allograft strut to prevent varus collapse.