Vertebral Fractures in Children and Adolescents

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Definition/Description

A spinal fracture happens when a vertebral body collapses and when this happens in the paediatric population the bones are still developing and therefore can have severe consequences. A vertebral fracture is less obvious compared to a long bone fracture and is often very painful (Todd and Di Marco., 2019).

Clinically Relevant Anatomy

C- spine:

• Epiphyseal variants
• Epiphyseal plates are smooth and regular and have sclerotic lines
• Unique vertebral architecture
• Incomplete ossification of synchondroses and apophyses
• Hypermobility

C1:

• Anterior arch is ossified in only 20% of cases at birth
• Becomes visible as an ossification centre by 1 year of age
• Neural arches appear in 7th foetal week
• Anterior arch fuses with the neural arches by 7
• Non-fusion before this can be mistaken for a fracture
• The neural arches fuse posteriorly by 3 years of age.
• Occasionally, the anterior ossification centre of C1 does not develop and the neural arches attempt to fuse anteriorly- This fusion abnormality can be differentiated from a fracture in that it demonstrates sclerotic margins

C2 (the axis, has the most complex and unique development of all vertebrae):

There are four ossification centres at birth:

• One for each neural arch
• One for the body
• One for the odontoid process

The odontoid process forms in utero from two separate ossification centres that fuse in the midline by the 7th foetal month. A secondary ossification centre appears at the apex of the odontoid process (os terminale) between 3 and 6 years of age and fuses by age 12 years. The body of C2 fuses with the odontoid process by 3–6 years of age. This fusion line (subdental synchondrosis), or the remnant of the cartilaginous synchondrosis, can be seen until age 11 years and may be confused with a fracture. The neural arches fuse posteriorly by 2–3 years of age and with the body of the odontoid process between 3 and 6 years of age (16,17,19,20,22). C3 through C7 can be discussed as a unit because they exhibit the same developmental pattern.

Three ossification sites are present:

• The body - which arises from a single ossification site
• The two neural arches

The neural arches fuse posteriorly by age 2–3 years, and the body fuses with the neural arches between 3 and 6 years of age. Additionally, secondary ossification centres may be seen at the tips of the transverse processes and spinous processes that may persist until early in the 3rd decade of life and simulate fractures. Secondary ossification centres can also appear at the superior and inferior aspects of the cervical vertebral bodies and remain unfused until early adulthood (Fig 4) (1,16,17, 19,20)

Ligaments in the C-spine:

• The anterior and posterior atlanto-occipital membranes extend from the upper aspect of C1 to the anterior and posterior aspects of the foramen magnum.
• The anterior atlantoaxial ligament extends from the anterior midportion of the dens to the inferior aspect of the anterior arch of C1. *The tectorial membrane is the superior extension of the posterior longitudinal ligament and attaches to the anterolateral aspect of the foramen magnum.
• The transverse ligament extends from the tubercle on the inner aspect of one side of the atlas to the tubercle on the other side.
• The apical ligament lies between the superior longitudinal fasciculus of the cruciform ligament and the anterior atlanto-occipital membrane.
• The alar ligaments connect the lateral aspect of the dens and the medial inferior aspect of the occipital condyles- the main function of the alar ligaments is to limit rotation to the contralateral side (16,19, 20,23).

Paediatric Versus Adult Cervical Spine

Cervical spine injuries in children usually occur in the upper cervical spine from the occiput to C3. This fact may be explained by the unique biomechanics and anatomy of the paediatric cervical spine.

• The fulcrum of motion in the cervical spine in children is at the C2-C3 level; in the adult cervical spine, the fulcrum is at the C5-C6 level (11,13).
• The immature spine is hypermobile because of ligamentous laxity, shallow and angled facet joints, underdeveloped spinous processes, and physiologic anterior wedging of vertebral bodies, all of which contribute to high torque and shear forces acting on the C1-C2 region.
• Incomplete ossification of the odontoid process, a relatively large head, and weak neck muscles are other factors that predispose to instability of the paediatric cervical spine (6,13,17,19,20,24,25).

Epidemiology/Aetiology

Spinal fractures make up only 1-3% of all paediatric fractures (2). This is less incidence than in the adult population due to the child’s spine being more mobile and elastic and having a smaller mass compared to adults (9). Bone structure and strength are considered a vital predictors of fracture occurrence (Tan et al., 2014) in children a bone mass reduction of 6.4% doubles the risk of fracture (Colin et al., 2011). The incidence of these fractures are higher in children under the age of 5 and over the age of 10 years (1). Spinal fractures in adolescents can have devastating consequences such as spinal deformity, scoliosis and Syringomyelia (1).​

The cervical spine is the most common location for factures in infants, because of the anatomy of the infant spine such as a heavy head and less muscular development of the neck which puts more strain on the spine (1). As previously mentioned, the paediatric spinal anatomy is different to the adult which predisposes children to flexion and extension injuries. Some of these differences include the facet joints being orientated different meaning there is a greater mobility but worse stability in the spine (2).

The IV discs are strong and vertebral end plate hard meaning this child’s spine has a higher resistance against compression forces (1). In Japanese study (3) found the anterior compartment stress in these spines to be high predisposing this area in particular to fractures. Paediatric spinal fractures are normally caused by high impact and speed injuries. These include predominantly falls, sporting impact injuries and road traffic accidents. These include predominantly falls, sporting impact injuries and road traffic accidents. The most common fractures are compression fractures (8) where the vertebrae bodies collapse.​

In a review by Tan et al (2014) bone strength was the main outcome assessed which was defined as the ability to resist fractures including bones extrinsic properties of bone mineral mass and distribution of bone mass. Studies provide strong evidence of the relationship between physical activity on bone mass due to concentric and eccentric muscle contractions caused during physical activity which cause high loads being placed on the skeleton (Tan et al., 2014).​

In the review by Tan et al (2014) all physical activities and observational studies were included; it was found that bone apposition (diameter) was highly related to pubertal stage, fracture incidence peaks at early puberty, 10-12 year in girls and 13-15 years in boys (Colin et al., 2011). Because women have a higher risk of osteoporosis the review was limited by nearly all bar 3 observational studies being levels of girl gymnasts which may lead to osteoporosis being neglected in males (Tan et al., 2014).

Mechanism of Injury

Neck fractures are common in children due to their disproportionately large head in comparison to weak neck muscles, the upper cervical facet joints being horizontally orientated and shallow with laxity in the ligaments (Leonard et al,. 2007). Usually ligament laxity prevents injury in other body parts by transferring energy however this property is not shared by the spinal cord (Leonard et al,. 2007). ​

The positioning of the paediatric spine and it's increased elasticity from the increase in cartilage and IV disc thickness, there has to be a considerable amount of force obtained to cause an unstable fracture (Parisini et al., 2002).

• Motor Vehicle accidents – both passengers and pedestrians (Most Common) (Leonard et al,. 2007)(Saul and Dresing, 2018)​

• Cycling ​

• Falls from a height (also common)(Leonard et al,. 2007, Saul and Dresing, 2018)​

• Sporting Injuries (Saul and Dresing, 2018)(Leonard et al,. 2007)​

• Assault​

Fractures Types

Contiguous compression fractures are common in paediatrics - due to paediatrics having increased C- spine mobility, and commonly linked to flexion movements, however does mean there is reduced neurological compromise (Leonard et al,. 2007)​

Burst fractures – makes up 10% of all thoracolumbar injuries in paediatrics due to the increase in spinal flexibility in paediatric spines meaning the pressure isn't concentrated in one area (Leonard et al,. 2007)​

Chance fracture – common in children when wearing lap belts in motor traffic accidents as the belt acts as a fulcrum causing hyperflexion, commonly seen alongside intra-abdominal and head injuries (Leonard et al,. 2007). ​

Impression fractures (Saul and Dresing, 2018)

Figure 1

Characteristics/ Clinical Presentation

Signs and Symptoms​

• Commonly seen with associated severe and frequently fatal injuries (Leonard et al,. 2007)​

In a 10 year report at a children's university hospital, symptoms were found as: (Leonard et al,. 2007)​ and (Saul and Dresing, 2018))

C-spine Fracture (most commonly injured)​

• neck pain​

• neurological deficit​

• fixed abnormal head positions​

• Common Additional Injuries - facial/head injuries, skull and facial fractures, facial lacerations, intercranial injury​

T-spine Fracture​

• back pain​

• ecchymoses (skin discolouration due to bleeding below skin)​

• localised tenderness ​

• neurological deficit​

• Common Additional injuries - simple or multiple rib fractures, fractured sternum, pulmonary contusion, abdominal/visceral injuries including splenic haematoma

​

L-spine Fracture​

• Back pain​

• ecchymoses​ (skin discolouration due to bleeding below skin)

• localised tenderness​

• abdominal pain​

​ Due to children having a larger spinal canal than their spinal cord they can tolerate further compression than adults can before neural damage​

Make sure to look for fractures at all levels of the spine (C-spine, T-spine and L-spine) when assessing for potential spinal fracture (Saul and Dresing, 2018)​

Prevalence

In children below 5 the most common area to injure was T8 followed by lumbar (Saul and Dresing, 2018)​

Between the ages of 5-10 the most common fracture area was the thoracolumbar region (Saul and Dresing, 2018)​

In teenagers the most common area begins to shift to lumbar (Saul and Dresing, 2018)​

From 15 years and older the lumbar area is most affected (Saul and Dresing, 2018)

Differential Diagnosis

• Low Back Pain
• Spondylosis
• Juvenile Ankylosing Spondylitis
• Disc Herniation
• Spinal cord injury without radiographic abnormality

Diagnostic Procedures

• Sensation of ‘breath arrest’ - immediately after the trauma the children would feel extremely short of breath, this is a predictive factor for vertebral fracture, particularly thoracolumbar fractures. ​

• X-ray – due to cartilaginous nature of the vertebra, fractures were not always clear from routine x-rays and children can go undiagnosed. ​

• MRI – used to determine diagnosis of potential fractures shown on x-ray, they give clear images of the vertebra allowing for more accurate diagnosis. This allows for direct visualisation and confirmation of the fracture, where it is in the spine and what type of fracture has occurred. ​

• CT scan – CT scans have better prognostic ability than x-ray as they show bony details in higher definition than an x-ray, its therefore more likely to get a clearly diagnosis from a CT scan than x-ray. However, like with x-rays fractures can go unnoticed on CT scans, therefore if there is any doubt about the potential of a fracture it will be followed up with an MRI scan to clarify a potential diagnosis. ​

• Flexion/Extension C-spine x-rays – often used after CT scans if no findings are present to determine if there is any undiagnosed cervical instability ​

(Leroux J 2013), (Cui S 2016), (Murphy 2015)

Other Diagnostic Tools:

Nexus criteria – National Emergency R-ray Utilisation Group criteria assess low-risk patients for cervical spine injury, it is primarily used to determine if an x-ray is required or if further imaging is needed after an x-ray to determine possible diagnosis. ​

Nexus criteria: ​

• Absence of midline cervical tenderness​

• No evidence of intoxication​

• Normal level of alertness​

• Normal neurological exam​

• Absence of a painful, distracting injury​

(Stiell 2002)

Canadian C-spine Rule – these are a set of guidelines to help a clinician decide if cervical imaging (i.e. x-ray, CT or MRI scan) are appropriate for trauma patients. However, for children consideration needs to be taken around developmental stage, so applying these rules can be difficult. ​

C-spine rules: ​

1. Any high-risk factors which mandate radiography ​
   • Dangerous mechanism of injury ​
   • Age > 65 ​
   • Paraesthesia in extremities ​
2. Any low-risk factor which allows safe assessment of range of motion ​
   • Simple rear-end motor vehicle collision​ ​
   • Sitting position in ED​
   • Ambulatory at any time​
   • Delayed onset of neck pain​
   • Absence of midline spine tenderness
3. Able to actively rotate neck ​
   • 45 degrees left and right ​

(Fox 2019)

Management

Conservative Management

• Casting - There are two types, Minerva and Plaster and usually stay on for period of around 2 months (Parisini et al., 2002)

• Halo Vests - to be worn for an average of 8 weeks (Parisini et al., 2002)

• Bed Rest - until acute symptoms subside, followed by a moulded body cast (Parisini et al., 2002)

In a case series of adolescents below 16 with traumatic spine injury, of the 44 patients, 20 had stable injuries and were managed conservatively with the above methods. It was identified that the cervical fractures, 3, and wedge-shaped compression fractures, 9, healed without significant deformity (Parisini et al., 2002). The stable burst fractures, 8, with conservative management showed the vertebral body had non-perfect reconstruction, however at follow up the maximum deformity was maximum 10 degrees involving one vertebrae above and below (Parisini et al., 2002). The remaining fractures that were conservatively managed, 6, all had significant angular deformities (Parisini et al., 2002).

Conservative management, particularly of wedge fractures without neurological lesions can be successful, leaving only moderate residual deformity, however it is important there is an accurate diagnosis to confirm the stability of the fracture to ensure accurate treatment is provided (Parisini et al., 2002).Whilst nonoperative treatment is viable for burst fractures in children with no neurological deficits and minimal initial kyphosis, operative treatments are recommended for unstable burst fractures to correct the deformity (Parisini et al., 2002).

Surgical Management

• Stable fractures can be treated conservatively
• Unstable fractures will require surgical intervention

Overall surgical interventions depends on the type and severity of the fracture. The Denis classification can be used to differentiate between a stable and a unstable vertebral fracture which can help decide on management options. Generally according to the evidence lots of stable fractures can be treated conservatively however unstable fractures will require surgical management (Sayama., 2014)(Parsisni et al., 2002) Furthermore if the patient has a neurological deficit or a spinal cord injury, surgery is necessary to stabilise the fracture and gain neurological function (Ferrero et al, 2020). Surgical outcomes within the population have been positive, Vander et al (2009) found surgical intervention was positive in ensuring the correction of the kyphosis of the spine compared to conservative management that which led to worsening of kyphosis.

Types of surgery can vary depending on the type of fracture and the age. Adolescent’s can be treated using adult type instrumentation due to a more developed spine (Sayama), where as younger children have smaller pedicles so a normal screw placement in this area can be challenging (Sayama). Evidence suggest a shorted fusion is the prefered approach in peadiactric fractures in order to preserve growth and mobility (Lalonde et al, 2001). In the lumbar spine, lumbar fusion can be used which involves fusing the vertebral bodies together so no movement can occur between them enabling the fracture to be repaired, this can be managed via a posterior approach (Boddu, 2020). If the fracture is more severe reconstruction surgery such as vertebroplasty or kyphoplasty can take place (Boddu, 2020). Although conservative management has been proven to correct initial conditions and deformity’s these deformities can return overtime leading to a short term fix as opposed to a long term fix.

Figure 2

Prevention

Over recent years there has been an increased recognition of the need to identify children with bone fragility (Ward et al., 2020), this is due to osteoporosis being thought to root from childhood therefore preventative efforts should be initiated in early life to ensure life-long bone health (Golden et al., 2014).

• calcium: intake during infancy, childhood and adolescents contribute to bone mass gain. Dietary supplementations may be offered to those who cannot intake enough calcium. (Golden et al., 2014).

• vitamin D: testing for vitamin D deficiency is recommended for those who have recurrent traumatic fractures even on low-impact. (Golden et al., 2014).

 

• mechanical loading and weight bearing exercise: puts force on the skeleton that increases bone formation (Golden et al., 2014). In a review by Tan et al (2014) bone strength was the main outcome assessed which was defined as the ability to resist fractures including bones extrinsic properties of bone mineral mass and distribution of bone mass. Studies included in the review provided strong evidence of the relationship between physical activity on bone mass due to concentric and eccentric muscle contractions caused during physical activity which cause high loads being placed on the skeleton (Tan et al., 2014).

Dual Energy X-ray absorptiometry (DXA) is the most used method of assessment for bone mass, its preferred due to low radiation and is  used commonly used for the lumbar  (Golden et al., 2014). Fracture risk not only depends on the factors above but also history of fractures, there is growing literature showing an association between low bone mass measured using DXA and increased fracture risk in children. (Golden et al., 2014).In adolescent females if mensuration has not occurred for more than 6 months then a DXA should be considered and clinicians, athletes and parents should be educated on female the athlete triad (Golden et al., 2014).

There is a need to evaluate each child on an individual basis to identify if they need a bone health evaluation, in the figure (  ) it can be seen that health factors  should be considered in the decision of whether to conduct a bone health evaluation, for example joint hypermobility or family history of osteoporosis (Ward et al., 2020)

Figure 3

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