Proximal Humerus Fractures

The proximal humerus refers to the upper part of the arm. When we think about the shoulder as a ball (humeral head) and socket (glenoid) joint, the proximal humerus is the upper area of the arm that connects the humeral head to the rest of the arm (humeral shaft).

The proximal humerus itself can be subdivided into four distinct parts, which include:

1. The humeral head
2. The greater and lesser tuberosities: Outgrowths of bone where the important rotator cuff tendons attach
3. Neck of the humerus: A narrow bony region below the tuberosities that is a common site for proximal humerus fractures to occur

The proximal humerus is an important area surrounded by several important anatomical structures that are at risk of injury, such as

1. The rotator cuff tendons
2. The nerves that supply the entire upper extremity (brachial plexus) of which the axillary nerve running on the outside of the shoulder is at highest risk
3. The blood supply of the proximal humerus which is derived from the anterior and posterior humeral circumflex arteries. Disruption of this blood supply due to a fracture of the proximal humerus increases the risk of this part of the arm bone not being able to heal. This potential complication is called avascular necrosis.

Proximal humerus fractures often arise from two distinct mechanisms:

1. Low energy falls: In elderly patients with osteoporosis (age-related weakening of the bone), simple falls from a standing height such as falling in the shower, falling on an outstretched hand, or directly impacting the shoulder can cause a proximal humerus fracture.
2. High energy trauma: This is a common mechanism in young patients such as motor vehicle accidents or violent sporting injuries.

There are known risk factors for developing proximal humerus fractures, and these include:

1. Patients having osteopenia or osteoporosis: A fragile proximal humerus is more likely to break with an injury. This is typically diagnosed on a DEXA scan or if the patient has a clear history of previous fragility fractures with an elevated FRAX score (Fracture Risk Assessment)
2. Postmenopausal bone loss: A deficiency of estrogen accelerates the process of bone demineralization in women after menopause. Men also after the age of 65 begin to see hormonal related bone demineralization.
3. Vitamin D deficiency or malnutrition: Leads to decreased bone density and decreased potential of the body to biologically heal the fracture.
4. Chronic steroid use: Steroids slow down fracture healing
5. Metabolic conditions: Conditions such as hyperparathyroidism, diabetes, and chronic kidney disease profoundly affect normal bone metabolism.
6. Poor balance and proprioception: Patients with impaired neuromuscular coordination are at increased risk of falling. Conditions that cause this include patients with Parkinson’s disease, peripheral neuropathy, vestibular disorders (ex. Meniere’s disease), loss of visual acuity that increases risk of tripping, and poor hip abductor strength
7. Lifestyle factors:
   • Smoking reduces bone density and also impairs the blood supply to the fracture site which can delay healing
   • Excessive alcohol use interferes with intestinal calcium absorption and also impairs coordination which increases fall risk
   • Low physical activity: When muscles are not properly loaded, bones lose their physiologic loading and lose strength

Of the risk factors mentioned above, addressing these risk factors to improve bone health, improve balance, and reduce the risk of falling can significantly reduce the risk of not just shoulder fractures but also fragility fractures elsewhere in the body.

The common symptoms of a proximal femur fracture include

1. Sudden, severe shoulder pain after a fall or traumatic injury
2. Due to bleeding within the bone and surrounding soft tissue, there is often swelling, bruising that is visible in the skin, and difficulty lifting up the arm.
3. In displaced fractures, there can be obvious shoulder deformity.
4. Occasionally, in displaced fractures, there can be excessive tension on the surrounding nerves, causing numbness and tingling down the arm in that nerve distribution.

Proximal humerus fractures are diagnosed with a combination of the patient’s history and symptoms, physical exam, and imaging findings

Physical exam

• It is important to check for swelling, deformity, and tenting of the skin where a displaced bone fragment can be pushing up on the skin
• As is common in other fractures elsewhere in the body, there will be limited range of motion with an inability to lift up the arm due to pain
• Checking the neurovascular status of the rest of the arm is mandatory because as discussed before, significantly displaced fractures can stretch out the nerves and vessels that cross in the upper arm. Any nerve injuries noted should be documented at the time of the initial injury so we can track recovery as the patient progresses.

Imaging

• X-rays: A standard shoulder trauma series of X-rays are important to describe the fracture pattern and classify how many discrete parts the fracture involves. It is also essential on every shoulder injury to obtain a true axillary X-ray of the shoulder to confirm there is no associated dislocation that requires a reduction.
• CT: In more complex fracture patterns, CT scans are obtained to assess the severity of the fracture to determine if there is an intra-articular split of the humeral head and for preoperative surgical planning.

Non-surgical management

1. When patients learn that they have a fractured proximal humerus, most naturally assume their injury requires surgery. However, for many patients, non-surgical treatment provides excellent outcomes. Non-surgical treatment is most suitable for fractures that have minimal displacement meaning that there is a break but the fractured bone ends have not shifted much out of place.
2. For fractures that are indicated for non-surgical treatment, this typically involves utilizing a sling for around 2-3 weeks after the injury to provide some initial support and allow the fracture to heal where it is. If the fracture has had some initial healing, then some early gentle passive motion of the shoulder is useful to prevent excessive stiffness in the shoulder.
3. Early on after this injury, there is a careful balance of providing proper immobilization and support for the shoulder to allow the bone to heal but to avoid excessive immobilization that can cause secondary stiffness. This is why after a few weeks after the initial injury, getting into physical therapy to restore the motion and strength of the shoulder is essential to ensure a good outcome with non-surgical treatment.

Surgical management

Surgery is indicated when there are significantly displaced fractures at the proximal humerus that will not align properly with non-surgical management. Common indications for surgery include:

• Fractures that split into the humeral head often require surgery due to violation of the shoulder joint.
• Fractures that do not position properly with conservative treatment may require surgery to provide a more anatomic alignment.
• Fractures that risk the fragile blood supply to the proximal humerus may also need surgery to try and reduce the risk of avascular necrosis.
• Fractures of the greater tuberosity with more than 5 mm of displacement may be considered for surgical intervention as persistent displacement here often significantly alters the biomechanical function of the rotator cuff tendons that attach there.

Surgical options for proximal humerus fractures range from

• Open reduction and internal fixation (ORIF): This involves making an incision over the shoulder while the patient is asleep under anesthesia and utilizing plates and screws to properly align the fracture fragments
• Intramedullary (IM) nail: For certain fracture patterns, utilizing an intramedullary nail placed within the bone with screws to hold the nail in place at both ends may be considered. This is often used in segmental fractures with several distinct pieces along the shaft of the humerus, two part fractures that do not heal well with conservative treatment, and pathologic humerus fractures that occur due to the presence of cancer in the bone
• Shoulder replacement either in the form of a partial replacement such as a shoulder Hemiarthroplasty or a Reverse shoulder arthroplasty are indicated for severely comminuted or non-reconstructible fractures, especially in older adults. If the rotator cuff is still intact, then a Pyrocarbon Hemiarthroplasty offers an excellent option to restore function while not having to place an implant on the glenoid (socket).