Pediatric Forearm Fractures: When Both Bones Break

Pediatric forearm fractures account for approximately 50% of all pediatric fractures with an incidence of about 1 in 100 children. A common type of fracture involves both forearm bones, the radius, or bone on the thumb side, and the ulna, or bone on the little finger side (Fig). This fracture type is often referred to as a “both-bone forearm fracture” and can occur when a child falls on an outstretched hand, or, less commonly, when there is a direct trauma to the forearm. Pediatric forearm fractures are also typically described as being in the proximal (upper), middle, or distal (lower) portion of the forearm and can be angulated (deviating from a straight line), rotated (turned away from the midline of the body), displaced, or non-displaced. The severity of these characteristics will determine treatment. Additionally, pediatric forearm fractures can be either complete fractures, where the break goes through the cortex or hard outer surface of the bone, or greenstick fractures where the cortex remains intact. Greenstick fractures are common because children’s bones are pliable and often bend, but don’t completely break.

Diagnosis

A child who sustains a forearm fracture will usually present with immediate onset of pain, unwillingness to use the arm, and obvious deformity of the forearm. The orthopaedist will carefully inspect the arm for swelling and deformity, as well as for open wounds that could indicate an open fracture where the bone has actually come out of the skin. In order to assess the neurological and vascular status of the hand, a thorough neurovascular exam is performed. To determine the full scope of injury, the joints above and below the fracture, namely the wrist and elbow, are also assessed. Finally, x-rays should be taken to determine the pattern and severity of the fracture.

Treatment

Once the nature of the forearm fracture has been pinpointed, treatment can be discussed. The primary treatment goal for pediatric forearm fractures is to restore the length, alignment, and rotation of the bones so they will heal in a position where the arm can function normally. While most of these fractures can be treated non-surgically, some will require surgery.

Non-surgical

Fractures that are displaced, angulated, or rotated can often be closed reduced, or brought into proper alignment without surgery, and then immobilized in either a cast or splint. This is usually done in the emergency room with the patient sedated and on pain medicine. The physician may use fluoroscopy, a type of medical imaging that shows a continuous x-ray image on a monitor, to guide the reduction.

The age of the patient dictates how much rotational and angular deformity is acceptable for both-bone forearm fractures. Younger children can tolerate more deformity as their bones have a greater potential to remodel and heal in correct anatomic alignment. Thus in children less than 10 years of age, up to 15° of angulation and up to 45° of rotation is acceptable while in older children, only up to 10° of angulation and 30° of rotation is acceptable.

Both-bone forearm fractures are initially immobilized in a long arm cast or in a splint that can later be converted, or overwrapped with fiberglass, into a cast. Within the coming week, an orthopaedist follows-up with the patient and x-rays are repeated to ensure that the reduction has been maintained. As long as the reduction and alignment remain within the acceptable parameters, the only treatment needed is 6 to 8 weeks of immobilization.

Surgical

While most pediatric fractures can be treated without surgery, some will require surgery. Surgical indications for both-bone forearm fractures include open fractures, unstable or irreducible fractures that fail initial attempts at closed (nonsurgical) reduction, floating elbow injuries (where there is a break both below and above the elbow joint), and soft tissue swelling about the forearm that will not allow the safe application of a cast. Additionally, up to 30% of patients may experience an early loss of reduction. Risk factors that contribute to this include older age, a fracture that is more proximal, and greater initial displacement. Children with less than 1 to 2 years of growth left who suffer both-bone forearm fractures are usually treated as adults and require surgical intervention.When surgery is necessary, the 2 most common options for internal fixation are intramedullary nails (metal rods set into the medullary cavity or inner canal of a bone) and plate and screw constructs. Intramedullary nails are placed through small incisions down the intramedullary canal of both the radius and the ulna in order to restore length, alignment, and rotation. They are left in place until several months after the fracture has healed and then removed. Plate and screw construct fixation is achieved with open techniques similar to those used for adults. Whether the construct should be removed once the fracture has healed is controversial.

Complications

In most children, forearm fractures heal with full return of function. Refracture occurs in 5 to 10% of patients. Malunion, where the bones fail to heal or are not aligned correctly, is rare as the potential for remodeling and aligning fractured bones is greater in children than adults. Malunion can result in a loss of range of motion and of arm function. Risk factors for malunion include poor reduction or casting technique, incomplete surgical correction, and failure to monitor the fracture with x-rays after the initial reduction. Additionally, compartment syndrome, one of the most serious complications in both-bone forearm fractures, can occur in either surgical or nonsurgical cases. Compartment syndrome happens when the swelling under the fascia or membrane that surrounds the muscles of the forearm becomes severe enough to compromise the blood flow to these muscles, which can lead to muscle necrosis (death). Compartment syndrome constitutes an emergency and must be treated immediately with fasciotomy (releasing the fascia) or, in some cases, a fasciectomy (excising strips of fascia) to decompress the compartment and prevent the limb from being permanently compromised.

Positive outcomes

Both-bone forearm fractures are common in the pediatric population. Most of the time, they can be treated nonsurgically with closed reduction and cast immobilization. Almost all fractures heal with appropriate length, alignment, and rotation; the patient suffers no lasting deformity and has full function of the limb. A small percentage of pediatric forearm fractures require surgical fixation, but the complication rate is low and the outcome overwhelmingly positive.

Author: Jake Gudger, MD Columbus, GA

Reprinted with permission from the Hughston Health Alert, Volume 29, Number 2, Spring 2017.