Distal Humerus Fractures

Etiology

Distal humerus fractures are most often the result of trauma to the elbow. This can be in the form of a direct blow to the affected extremity by either foreign object or fall. High-energy mechanisms often are the result of a motor vehicle collision or motorcycle accident and have even been reported in instances of projectile injury. Patient age usually is an associated factor in whether the mechanism is low- or high-energy.

Epidemiology

These fractures have a bimodal distribution, with younger males typically experiencing traumatic injuries and elderly females experiencing direct trauma secondary to falls. They have a relatively low incidence, accounting for only about 2% of all fractures. Although rare, the incidence seems to be rising as shown by Pavlanen et al., who reported a 5-fold increase from 1970 to 1998.[1]

Pathophysiology

The distal humerus can be conceptualized into medial and lateral columns, both with their corresponding epicondyles as well as the condyles which make up the articular surface. The articular surface is made up of the capitellum as well as the trochlea which project anteriorly. The distal humerus is often thought of like a triangle with these two separate columns; this explains why there is often a need for bicolumnar fixation for mist fracture patterns.[1]

History and Physical

Patients will most often present with a chief complaint of pain and swelling of the elbow. They will have a reduced range of motion (ROM) secondary to pain, and ROM should be avoided due to the risk of neurovascular injury. Because of this risk, a thorough neurovascular exam should be performed, including checking the following:

• Sensory and motor function distally, including median, radial, ulnar, anterior interosseous nerve (AIN) and posterior interosseous nerve (PIN)
• Distal pulses
• Forearm compartments 

As is the case in any setting of trauma, a secondary exam should be performed to rule out any coexisting injuries that may possibly be masked by the primary injury. In the setting of the unresponsive or intoxicated patient in which a thorough secondary exam is not immediately attainable, inspection for any signs of skin ecchymosis, laceration, or edema should guide the physician to order appropriate imaging.

Evaluation

Imaging

Standard radiographs will include an AP and lateral of the elbow and humerus. For the distal humerus, the AP should be taken with the elbow flexed to 40 degrees.[2]

Imaging should be done of the entire forearm as well as humerus to rule out coexisting injuries. Additionally, traction views of the elbow may be beneficial to better characterize fracture fragments.

If suspicion of a coronal shear fracture of the distal humerus, the lateral x-ray is the most important film to obtain, and obtaining a true lateral is paramount. The appearance of the “double-arc sign” is pathognomonic for a coronal shear fracture that most likely extends into the trochlea.  

CT is useful with surgical planning and can be especially helpful when there is a shear component to the fracture. There is some support for the use of 3D reconstruction in addition to traditional 2D imaging for improved pre-operative planning. 

MRI is not usually indicated for acute injury.

Classification

   AO

• Extra-Articular
• Partial Articular
• Complete Articular 

Each of these groups is further broken down into subtypes that signify whether it is simple versus multi-fragmentary as well as the location for the partial articular group.

   Milch

• Type 1 - Lateral trochlear ridge intact
• Type 2 - Fracture through the lateral trochlear ridge

   Jupiter

• High-T
• Low-T
• Y
• H
• Medial Lambda
• Lateral Lambda
• Multiplane T

Treatment / Management

Treatment

Non-operative - Cast immobilization 

Indication: Rare. Non-displaced fractures or in patients that are a very high surgical risk.[1][2] 

Operative

Open Reduction Internal Fixation

Indication: displaced fractures, including supracondylar, intercondylar and/or bicolumnar fractures. Generally, plate fixation involves anatomic reduction of articular surface and rigid fixation with two strong plates, usually at least 3.5 mm at a minimum.[2] Plate fixation is the procedure of choice if possible because it allows the individual to begin early ROM of the elbow, reducing the change of post-op stiffness. 

Total Elbow Arthroplasty

Indication: Distal bicolumnar fractures in the elderly, low demand patient population. Total elbow arthroplasty has limited longevity due to aseptic loosening and should be reserved for elderly, sedentary patients that can comply with postoperative weight restrictions.

Approaches

Posterior approach utilizing one of the following techniques:

•  Triceps - Splitting
•  Triceps - Sparing
•  Olecranon Osteotomy

One thing that is paramount in the utilization of any one of these techniques is the need to identify the ulnar nerve. There is debate if there is more benefit in transposing the nerve versus performing an in situ decompression; however, visualizing the nerve and keeping it out of the field is essential.

Another detail that is critical no matter which approach is utilized is the need to identify the radial nerve if placing a plate that extends proximally on the humerus. The nerve can usually be found approximately 10 cm proximal to the medial edge of the olecranon fossa and 7.5 cm proximal to the lateral edge.[3] Special care must be taken to make sure that any hardware is placed under the nerve, and many surgeons will note across what hole within the plate the nerve is crossing in their documentation.

The lateral approach can be utilized in cases where an articular shear fracture of the capitellum, trochlea, or both need to be addressed.

Differential Diagnosis

• Acromioclavicular dislocation

• Dislocation of the shoulder joint with the fracture of upper end of the humerus

• Elbow fracture

• Fracture of clavicle

• Fracture of scapula

• Fracture of neck of the humerus with greater tuberosity

• Sternoclavicular dislocation

• Shoulder dislocation in emergency medicine

• Scapula( shoulder blade) fracture Management in the Emergency Department

Complications

Elbow Stiffness: Any injury to the elbow can result in stiffness as a result of immobilization. This is one of the reasons that early, rigid fixation is most often the treatment of choice for distal humerus fractures. This allows for a post-operative protocol that utilizes early range of motion exercises. Most protocols begin with at least partial, protected ROM within 14 days of operative fixation. 

Nerve Injury: In particular, ulnar nerve injury can be common, as much as 50%. This is due to its proximity to fracture fragments as well as the need to mobilize and retract the nerve during fracture fixation. This is often in the form of transient nerve palsy that does return but is more serious. Lasting deficits can happen as well. 

Heterotopic Ossification: As is the case in most settings of severe trauma, heterotopic ossification can be a postoperative complication. Risk factors that predispose individuals to develop heterotopic ossification include Type A and B distal humerus fractures, floating elbow injuries, and a longer time to surgery.[4] Prophylaxis against heterotopic ossification is not routinely utilized in most scenarios.

Nonunion: The risk for nonunion is relatively rare but can occur in distal humerus fractures. Another thing to consider is the risk for non-union of an olecranon osteotomy site if the surgeon chooses to utilize this approach. Risk factors that are generally accepted in association with nonunion are smoking, obesity, and diabetes mellitus.[5] Nonunion can almost always be treated with revision open reduction and internal fixation (ORIF) utilizing bone graft.