Humerus fractures are common injuries most often caused by falls and motor vehicle accidents.
Fracture of the humeral shaft is commonly due to fall and high-energy impact injury. Fracture after low-energy trauma must prompt further investigation, focusing on the possibility of malignancy or severe osteoporosis. Presence of wound, which denotes presence of open fracture, must prompt urgent attention. Nerve injury particularly of radial nerve, must be ruled out before any management is initiated .
Fracture of the proximal humerus often presents with swelling, pain, and bruising of the affected arm, with symptoms at its peak in the first two weeks post-injury. Due to shoulder
musculature, swelling can be more pronounced only at the anteroinferior side of the affected arm . Signs of distal ischemia may be absent due to extensive collateral vasculature in the shoulder, but very severe swelling may indicate vascular injury. Large or expanding hematoma, pulsatile external bleeding, unexplained hypotension, and nerve injury should increase suspicion of vascular involvement of proximal humeral fracture , hence careful examination must be conducted even in the absence of peripheral ischemia. Nerve injury, most commonly in the brachial plexus and axillary nerve, must also be ruled out during assessment .
For the humeral shaft fracture, two radiographs 90 degrees to each other (anteroposterior and lateral) and including the shoulder and elbow joints must be taken . Same radiographs must be used also in distal humeral fractures, although splints and plasters may obstruct the view, hence warranting gentle traction prior to taking the radiographs . Standard trauma series radiographs for suspecting proximal humerus fracture consist of anteroposterior, lateral, and axillary views. Axillary view may be uncomfortable for patient since the arm needs to be removed from the sling while taking the radiograph, hence Velpeau or modified axillary view can be alternatives. Glenoid, coracoid, and acromion may block the view of fracture in anteroposterior view taken in standard anatomic planes. Better view can be obtained by taking the radiograph on the glenoid plane by tilting
the X-ray beam 30 degrees medial to the normal plane .
CT scan, especially those with three-dimensional imaging, is increasingly used to further assess the complex anatomy of proximal humerus fracture and articular surface injury which is impossible to see in conventional radiographs . It is also used to assess vascular injury in humeral shaft fracture, along with angiogram. However, it is not usually done in assessing distal fractures, except in cases wherein a less invasive approach for open reduction and internal fixation is contemplated, or in elderly patients to whom an ORIF or direct arthroplasty management is decided.
MRI is not frequently used in assessing fracture since it is inferior to CT in providing details on bone architecture . In low resource setting, ultrasound can be used as an alternative to CT scan. Advanced ultrasound is now used also to rule out lacerated or entrapped radial nerve in humeral shaft fracture .
Humeral shaft fracture
Humeral shaft fracture is usually managed nonoperatively. The wide range of motion of the shoulder which easily accommodates angulatory, axial, and rotational malunion, as well as minimizing the functional limitation, makes nonoperative management enough for humeral shaft fracture, despite not achieving anatomic reduction. The shaft also does not bear weight, enveloped with a number of muscles, has rich supply of blood, and easily splinted. Functional bracing, presently a prefrabricated device with plastic support remains the gold standard in treating humeral shaft fracture and has a high rate of union. Initial deformities are corrected by gravity, time, and brace .
Indications for surgical management of humeral shaft fracture can be divided into three groups: fracture indication, associated injuries, and patient indications. Fracture indications include shortening of the arm of more than 3 cm., rotation of greater than 30 degrees, angulation of greater than 20 degrees, segmental fracture, pathologic primary cause, and shoulder or elbow joint involvement. Associated injuries such as open wound, vascular or brachial plexus injury, ipsilateral forearm, elbow, or shoulder fractures, bilateral humeral fractures, burn, and high velocity gun-shot injury also warrants operative management. Patient factors include multiple injuries, Glasgow Coma Scale greater than 8, chest trauma, poor tolerance, and morbid obesity are also indications .
Plate osteosynthesis is the gold standard in fixation of humeral shaft fractures, especially those with proximal and distal extension and those with open fractures. Most commonly used plate is a broad, 4.5mm, limited-contact dynamic compression plate. Bridge plating technique is required in comminuted fracture. For patients with poor bone quality, longer plate is required to improve stability. For plate fixation, two approaches are generally used: the anterolateral (or brachialis-splitting) approach for fractures in the middle or proximal third of the shaft, and the posterior (triceps-splitting or modified posterior) approach for fractures in the midshaft or distal third of the humeral shaft .
Fracture of proximal humerus
Most of the fracture of the proximal humerus can be treated nonoperatively also . The range of motion of the shoulder joint accommodates the moderate angular deformity without significant functional loss. 45 degrees of angulation and less than 1 cm of displacement is an acceptable deformity, but these criteria are not absolute since it still depends on the acceptability for the patient.
Fracture displacement, as an indicator of stability, is an indication for surgical management. The goal is to restore the injured proximal humerus anatomy by stable fixation to gain functional movement as early as possible . For 1 cm of displacement between the head and shaft fragment, or 5 mm of displacement of tuberosity fragment, transosseous suture fixation is used  in which a non-absorbable suture is used to capture rotator cuff tissue anteriorly, laterally, and posteriorly to the fragment. For cases with high risk of osteonecrosis requiring less exposure of the bones, close reduction by percutaneous fixation can be done. A difficult procedure, it is done by inserting terminally threaded Schantz
pins and bicortical pins from the greater tuberosity to the medial humeral shaft. This option however requires compliance of the patient. For better preservation of tissues, intramedullary nailing can be done .
Open reduction and internal fixation by locked plates is more preferred than using conventional plates due to difficulty in securing the screws due to poor bone quality in the region. It is indicated in fractures with metaphyseal comminution . For fractures with more than 40% articular involvement, hemiarthoplasty is indicated . This is also a difficult procedure, and the presence of infection is a contraindication for this option .
Fracture of distal humerus
Nonoperative management is reserved to patients with undisplaced fracture, inability to tolerate anesthesia, and dementia . Pain control is challenging especially on the first week postsurgery, and most of the time requires hospitalization . Satisfactory outcome can be achieved if the three complications – nonunion, symptomatic malunion and osteonecrosis – are avoided .
However, operative management is still preferred generaly to fractures of distal humerus due to high rate of nonunion in the nonoperative management . Operative treatment goal is to restore the joint surface with internal fixation that allows early motion . There are lots of approaches in operative management of distal humerus fracture. Regardless of the management employed, the ulnar nerve must be isolated, mobilized and protected throughout the procedure . Posterior approach with olecranon osteotomy was formerly used frequently  since it provides better visualization of the articular surface , but there are concerns on healing and symptomatic implants . More commonly used nowadays are the tricepsreflecting, triceps-reflecting anconeus pedicle, and triceps-splitting approaches which has fewer complications . Using plate fixation resulted to better surgical outcomes in the past few years. The principle for this option is anatomic articular reduction and rigid fixation by two plates . Orientation or postion of the plates, whether parallel or perpendicular, is still debatable. Some studies show nonunion in perpendicular plate fixation, while other studies show no significant difference between the two in terms of outcome . Locking plates can also be used with excellent result, but the plates are usually expensive, and the indications for its use are still unclear .
The radial head and the coronoid process are important stabilizers of the elbow, hence salvaging them should be done if possible . Injury to brachial artery, although rare, should be ruled out as early as possible, and if present, it should be reconstructed immediately using a saphenous vein graft. Compartment syndrome is also a complication post-surgery, hence patients should be closely monitored for swelling on the surgical site. Injury of median, ulnar, or anterior interosseous nerves results to simple neuropraxia most of the time, but further investigation, specifically exploration, must be done if normal function does not return after 3 months post-injury .
Due to the surrounding musculature and soft tissue, the prognosis of humeral shaft fracture is better compared to the injury in the distal part. Most of the humeral shaft fracture can be managed nonoperatively . It is actually the easiest to manage among the fractures of the long bones.
Functional bracing, the “gold standard” in nonoperative management of facture of humeral shaft, reportedly has 96% to 100% union rate. In addition, the range of motion of the elbows and shoulder, and the tolerance to small shortening of the humerus makes the humeral shaft fracture tolerable and only cause minimal functional deficit . Usual nerve injury is radial nerve neuropraxia, and is bruised or stretched only most of the time, hence function can be expected to return to normal .
Distal fracture, which often involves comminution of involved bones, on the other hand often results to abnormal elbow, though improvement has been seen recently due to improved technology in the management such as implant technology, surgical approaches, and rehabilitation protocols. Joint function is always compromised due to pain, stiffness, and weakness. Unlike the fracture of humeral shaft, it is often managed operatively .
In the US, regardless of the anatomic site, the most common cause of fracture of the humerus in the adults especially in the elderly people is fall , which accounts for 88% of all cases in emergency department setting. This is followed by motor vehicle accidents, the more common cause of fracture in the younger adults, at 8%, and impact injury at 5% . In children, fractures are often due to environmental causes and hence preventable. For instance, playing with the monkey bars is the most common cause of supracondylar fracture among pediatric patients less than 15 years old .
The type of fracture also reflects the mechanism of injury. For example, rotational injuries such as forceful wrenching of arms behind the back may cause spiral fracture. Most of the fractures of proximal humerus are usually physeal. In children, severe fracture usually gives suspicion of physical abuse .
Fracture of the humerus which occurred at minimal trauma should raise a flag on possible primary cause such as severe osteoporosis and malignancy, whether metastasis or a primary one like myeloma, warranting more in-depth history taking .
Risk factors for having fracture of the humerus are low bone density, history of fracture, inactive lifestyle, and low body mass index, history of fall, frequent walking, poor vision and diabetes mellitus . It was also found that depression, left-handedness, epilepsy, seizure medication use, and use of hearing aids increases the chances of having proximal humerus fracture . Women and the elderly are also at higher risk of having fracture of the arm, as well as the Caucasians compared to the Blacks .
Fracture of the humeral shaft is relatively common. The incidence is at 3 to 5% of the total cases of fracture . In the US, humeral fracture has an annual incidence rate of 122 per 100,000 people, less than the reported rate in other developing countries such as Japan and Europe . The most common site is the proximal part, accounting for 50% of the total cases of humerus fracture. Fracture of the distal humerus is rare and commonly occurs in children . Fractures involving two sites of the humerus occur only at less than 1% of the time .
There is a bimodal age distribution on the incidence of humeral shaft fracture, with a peak at age bracket 21-30 years old, mostly male, and at age 60-80 years old, mostly female. Peak in the younger age group is usually attributed to high-impact trauma , while in the second but larger peak, the most common cause is simple fall . Larger number of proximal humerus fracture is also seen at age bracket 45-64 years old, and the number of emergency consults with proximal humerus fracture increased continuously at age 84.
Most of the cases are either due to a high-energy impact injury or low-energy falls, specifically in a forward direction . Fracture of the humeral shaft usually occurs distal to the
surgical neck of the proximal humerus and proximal to the supracondylar ridge distally, considered to be the main fracture line . Distal fracture is usually multifragmented, occurring in the osteopenic bone. In 70% of the time, distal fracture occurs after falling on their elbows after failing to outstretch the arms . Fracture of the proximal humerus, on the other hand, is caused by combination of external force and forces generated by the intrinsic shoulder musculature . During an impact injury, the humeral head is fractured by the glenoid which acts as an anvil in the shoulder .
There are no guidelines for the prevention of humerus fracture.
Fracture of the humerus is usually caused by trauma, most commonly by direct fall in the arm or shoulder in the elderly, and vehicular accidents in the younger adults. X-ray is still the primary diagnostic tool used to assess the fracture, although CT scan is gaining more attention in the past few years.
Due to difference in the composition of bone and in the surrounding anatomy, severity and management of humeral fracture depends on the site of injury. Fracture of the shaft is usually managed nonoperatively with high success rate, but fracture of proximal or distal humerus is managed operatively most of the time.
Fracture of the humerus (upper arm bone) is usually caused by falls, although a high number of cases in younger adults are caused by vehicular accidents. Swelling on the affected area is the usual symptom, but involvement of blood vessels and nerves must also be ruled out especially in the fracture of the arm near the shoulder and elbow. X-ray remains the primary choice of imaging modality used in diagnosis, although CT scan is increasingly preferred by orthopedic surgeons.
Management is dependent on the site of fracture. Fracture of the shaft can be managed without surgery with minimal and tolerable effect. Fracture of the arm near the shoulder or elbow is preferably managed through surgery, depending on the severity of the injury.