Femoral shaft fractures

An 18-month-old boy presents to the emergency department at 1am in the morning, brought in by ambulance with leg pain and inability to mobilise, with crying when being moved or attempting to move. His father tells you that he fell downstairs when they forgot to close the stairgate. On examination, his right thigh is swollen, possibly shortened and he is clearly guarding it. Given your high clinical suspicion of a femur fracture, you prescribe simple and opiate analgesia and organise an x-ray.

Incidence

Femoral shaft fractures account for 1.5 – 2% of paediatric fracture presentations. The average number of annual cases is 20 per 100,000. Despite accounting for a small proportion of all fractures, they are the most common cause for hospitalisation for a fracture.

Femoral shaft fractures can happen at any age depending on mechanism however, there is a clear bimodal age distribution with increased rates in toddlers (between 2-4 years of age) and adolescents (approximately greater than 10 years of age).  Any femur fracture before ambulatory age is uncommon and should be treated as suspicious for non accidental injury (NAI). This is especially true for femoral fractures in children less than 12 months of age (more on this later).

History

Toddlers commonly present as a result of a fall of some kind – sometimes from a height, but it can be from as little as 60cm or less. They are often running, or falling after tripping on an object.

Adolescents, on the other hand, tend to fracture their femur as a result of high mechanism trauma, such as motor vehicle accident or a fall or jump from a significant height.

Regardless of age, patients typically report thigh pain, swelling and an inability to weight bear.

Ask about the mechanism of injury, if it was witnessed, and the time of the injury particularly in the younger age group (<5 years). An unclear history, an unwitnessed fall and delay to presentation are risks factors for NAI.

Examination

The limb deformity may be gross or subtle. Significant swelling results in a tense, or firm-feeling, thigh on palpation and/or a shortened limb. Sometimes the swelling can be very mild, particularly in a toddler, but a clue to injury is a child who is not moving the leg. Always check for neurovascular compromise and for other injuries. One study by Rewers et al. (2005), suggested that 28.6% of children with a femur fracture had another associated injury.

Investigations

Plain radiograph with AP and lateral views of the femur. Imaging the ipsilateral knee and hip is recommended to rule out associated injuries.

Classification

There is no universal classification system for femur fractures so use description characteristics, location, stability of the fracture and whether it is open or closed.

Descriptive examples include: transverse, spiral, oblique, comminuted, greenstick, displaced/nondisplaced.

Location: proximal, middle, distal third

Stability:  stable or unstable. Stable fractures are typically transverse or short oblique; while unstable fractures are long spiral and comminuted.

Note: long spiral fractures occur when the fracture length is more than twice the diameter of the bone at that level.

Management

General principles should be adhered to as for any ED presentation. Start with a primary and secondary survey. These injuries occur as a result of trauma and other significant and life-threatening injuries need to be excluded. Next is analgesia, fracture reduction then immobilisation.

Adequate analgesia can be achieved with intranasal, oral and intravenous medications. Start with simple analgesia first (paracetamol, NSAIDS) as they are easy and quick to administer. Then move on to opioids via the oral, IV or intranasal route. Consider benzodiazepines, particularly diazepam, if muscle spasm is an issue (which it often is). While analgesia is taking its effect, start setting up for a regional nerve block. This can be a femoral nerve block (usually under ultrasound guidance), fascia iliaca block (landmark or ultrasound-guided) or a haematoma block.

Once adequate analgesia has been given, it is time to reduce the fracture using skin traction. Generally, femoral fractures are not put in a backslab in ED unless a traction splint is not available and transfer of the patient is required.

Skin traction

Skin traction requires 10% of the patient’s weight to be applied through an appropriate traction mechanism. This may occur in the ED if there are adequately trained personnel and equipment available. There are also traction splints available that can be used pre-hospital or if a traction bed is not available. Sedation may be required to apply skin traction or a traction splint.

There is a variety of traction splint available. The most common in use are the Thomas splint, CT-6 splint and Kendrick splint. Others include the Slishman Traction Splint, Mustang traction splint, Sager splint, Hare Splint and Donway splint.  The Thomas splint is recommended for transfer and is available in a paediatric size.

In Queensland, the ambulance service uses the CT-6 splint. It can also be used in the paediatric population. Have a look at this video by Queensland Ambulance Service on its application. The Slishman traction splint and Mustang traction splint are not specifically designed for children but the linked videos demonstrate brilliantly on child volunteers how you can adapt them for kids.

Definitive management

Spica cast application is typically done under general anaesthetic by the orthopaedic surgeons depending on the age of the child. Older children will require other definitive management.

The table summarises the guidance from The American Academy of Orthopaedic Surgeons (AAOS) of management of femoral fractures by age.

Complications

The most common complication is leg length discrepancy. This occurs due to overgrowth in younger patients. Conversely, shortening can also be an issue but is acceptable up to 2-3cm. Other complications include: osteonecrosis of the femoral head, non union, malunion and re-fracture. In terms of osteonecrosis of the femoral head, this can depend on the surgical procedure performed.

A note about other femoral injuries

Other types of fractures of the femur include proximal fractures (including neck of femur), distal femoral physeal fractures and slipped capital femoral epiphysis (SCFE, also known as SUFE)

Proximal femur fractures are rare in paediatric populations accounting for <1% of fractures. They most commonly occur due to high energy trauma such as motor vehicle accident [1,4,8]. They can occur with a low impact mechanism, but if this occurs a pathological fracture should be considered. Proximal fractures tend to need operative management with an ORIF. The most common complication for a proximal femur fracture is avascular necrosis.

The do not miss bits

Non accidental injury

The incidence of NAI in children with femoral fractures has been reported between 12-60%. In one study by Rewers et al. (2005), it was found that in children less than 3 years of age, NAI was the second most common cause of femoral fractures. This is supported by Schwend et al. (2000), who suggested that a femur fracture in children who are not yet of walking age was the strongest predictor of abuse.

Vigilance is the key to detecting NAI. The best predictors for NAI include: An unclear history, particularly with respect to the mechanism, a suspicious history, an unwitnessed fall (particularly in the younger age group), young age, a delayed presentation (typically >24hours), and associated injuries particularly of chest, abdomen and pelvis if not associated with a high speed mechanism. They also include physical and/or radiographic evidence of prior injury (multiple different aged bruises, old healing fractures on XR). In one study, 53% of children who had been abused and had a femoral fracture had evidence of polytrauma. 62% had physical and/or radiographic evidence of prior trauma and 33% had history suspicious for abuse. In terms of the risk factors listed above, children who had no risks factors had a 4% chance of NAI being the cause of their fracture compared to 24% with one risk factor, and 87% if they had 2 risk factors.

Is the type of femoral fracture a predictor of NAI? There is no current evidence that supports it being a strong predictor. Some evidence suggests that fractures associated with NAI are more likely to found in the distal femur, compared to diaphyseal fracture alone. In contrast to popular belief, there is no current evidence to strongly support that spiral fractures are more likely to be associated with NAI.

In essence, never forget to consider NAI. It is easy to miss if it isn’t thought about as a differential.

Associated injuries

Remember secondary and tertiary survey. Subtle injuries can be missed in patients with high velocity mechanisms or significant life-threatening injuries.

Pathological fractures

These should be considered if a femoral fracture occurs as a result of a low mechanism trauma. Children with metabolic disorders or malignancy are also at higher risk.

Traction

If considering applying a traction splint, don’t forget to assess for ankle/foot fractures as these are a contraindication to application. This is because the ankle and foot are generally support sites for the traction splint.

A femoral nerve block was completed with good effect after some intranasal opioid analgesia. The case was discussed with the orthopaedic team and concerns raised around NAI given the child’s age. The case was also discussed with the hospital child protection team. Traction was applied in the ED under ketamine sedation before he was admitted under orthopaedics and a spica cast was applied in theatre under general anaesthesia.