What is Subaxial Cervical Spine Fractures?
The subaxial cervical spine is composed of parts C3 through C7, which include both the bone structure and the ligament tissues. Damages to this area can affect either the bone, the soft tissue, or both. This text aims to discuss the various forms of subaxial cervical spine fractures and the different methods used to manage them. It also covers specific subjects such as spine injuries in children, athletes, and individuals with an ankylosed spine (a condition where the spine becomes stiff).
What Causes Subaxial Cervical Spine Fractures?
Fractures in the neck’s spine, often known as subaxial cervical spine fractures, can be caused by various types of accidents. These range from high-energy incidents like car accidents or falls from great heights, moderately energetic actions like sports, or even simple day-to-day slips and falls. The neck’s spine is particularly vulnerable to injuries because of the extensive mobility it allows.
The fractures in the bones of the spine, technically referred to as vertebral body fractures, can take different forms based on the type of incident. For instance, a certain kind of fracture called an “anteroinferior teardrop” can come from an incident that compressed the neck while it was bent, often when the back of the neck fails to hold. A different type of injury, called an “extension teardrop”, is due to a pull-away injury when the neck is extended and is otherwise more stable.
There are also compression and burst fractures which happen when a load is placed on the neck while it is in a neutral position. This load usually travels through the disc to the spine bone and then causes it to fail.
The combination of the neck’s anterior ligaments, the intervertebral disc, and posterior ligaments are known as the discoligamentous complex (DLC). Injuries in this area can come from body twisting incidents, often leading to a condition known as “facet joint subluxations”. This is where your joints dislodge with possible damage to the disc or capsule. Similarly, these ligaments can be injured by a sudden load applied when the neck is slightly bent, or during a click/jerk and extension moment that may cause the top spinal bone to shift backward resulting in possible spinal cord injuries.
Risk Factors and Frequency for Subaxial Cervical Spine Fractures
Cervical spine injuries, specifically in the region from C5 to C7, are a common result of blunt force trauma, with about 3% of these trauma patients experiencing them. They can happen to anyone but are usually seen in two types of patients: younger ones involved in high-energy accidents, like car crashes, or older ones injured in low-energy accidents, like simple falls.
People with a condition called ankylosing spondylitis (AS) are at a particular risk as even minor accidents can lead to cervical spine fractures. In fact, their chance of experiencing a vertebral fracture during their lifetime is four times greater than for those without AS, with over 75% of these fractures happening in the cervical spine. This higher risk is due to the increased rigidity of their spine caused by long-segment fusion, a characteristic of AS.
Cervical spine injuries are also not uncommon in the world of sports, especially in athletes under 30 years of age. The sports which cause these injuries can vary by geographical location. For instance, American football, wrestling, and gymnastics lead in numbers of injuries in the U.S., while rugby is the primary cause in Europe, and ice hockey in Canada. Athletes who have neck pain, torticollis (twisted neck), or who experienced the injury while diving, or show other specific neurological symptoms, warrant a higher suspicion for a cervical spine injury.
Signs and Symptoms of Subaxial Cervical Spine Fractures
It’s crucial to complete a detailed medical and imaging assessment if a neck (cervical spine) injury is suspected. After immediate trauma care is provided, the neck needs to be carefully handled, and the back of the neck should be checked for any significant discomfort or irregularities. Also, the whole spine requires an examination if there is suspicion of a neck injury.
Remember, around 10-15% of people with neck fracture also have injuries in other parts of their spine. The methods used for ensuring neck stability can depend on the patient’s age. For instance, as young children’s head size grows faster than their chest size, lying flat on an unmodified backboard can cause their necks to bend forward. A straight or neutral positioning can be achieved by aligning the ears with the shoulders. This may need the child’s back to be slightly elevated, or a cut out on the backboard to support the back of the head.
A meticulous evaluation of sensory and motor abilities, including reflexes in the arms and legs, should be done to spot any nerve damage or signs indicating pressure on the spinal cord. Any identified nerve issues can also provide clues about the exact location of the injury in the neck. It’s important to remember that in the neck, the specific named nerve exits above the corresponding spine bone, for instance, the C5 nerve comes out from the space between the C4 and C5 bones.
A thorough understanding of the patient’s history can paint a clear picture of how the injury occurred and can pinpoint any pre-existing conditions that may increase chances of neck injury, such as ankylosing spondylitis or previous surgery involving spinal fusion. This information is very important and should not be overlooked.
In a sports setting, when a player is suspected of suffering a neck injury, they need to be managed with extreme caution. It’s very important to perform a complete neurological examination, make sure the neck is kept still, and place the player on a backboard. Once the player is stable, they can be moved to a hospital for further evaluation.
Testing for Subaxial Cervical Spine Fractures
The standard curvature of the neck, or cervical spine, should show a curvature, or lordosis, of 15 to 30 degrees from the first to the seventh cervical vertebra. To check this, doctors usually use X-ray studies and look at the neck from three angles, using the anteroposterior, lateral, and open-mouth views. They must ensure that the X-rays capture the top and bottom of the cervical spine for a complete evaluation, including the overall alignment, changes in disc height, and any asymmetry in the spaces between the spines.
Traditionally, neck X-rays were popular for trauma patients or those suspected of cervical spine injuries. Nowadays, with the quick, sensitive, and readily available computed tomography or CT scans, this has become the standard procedure. CT scans are especially good at showcasing misalignments and fractures in the neck area.
If there’s a high suspicion of injury to the nerves, doctors often opt for magnetic resonance imaging or MRI of the cervical spine. MRI is better than CT scans for evaluating the spinal cord, nerve roots, the discs, and ligaments in the neck. It also allows for viewing soft tissues around the cervical spine and any potential blood collections.
However, due to the expense of healthcare, there’s been a move to determine which patients need an MRI and which don’t. Factors such as being over 60 years old, having multiple injuries, having cervical spine degeneration, showing neurological problems, or not being able to be examined due to severe unconsciousness can make an MRI necessary. On the other hand, an alert, cooperative patient who doesn’t show any neurological deficit or other symptoms, and doesn’t have other injuries, may not need an MRI.
In reviewing these X-ray studies, certain types of fractures may show up. For instance, fractures where the vertebra height reduces due to compression and fractures that involve the front and back parts of the vertebra and are often associated with nerve injuries. In such cases, it’s critical to examine if the back parts of the spine, or spinous processes, appear wider than the rest of the vertebra, which could indicate a back ligament injury leading to continued instability if not stabilized.
Dislocations and fractures can also exist in parts of the vertebra like the facets. In such cases, CT scans provide useful information about the facet joints and any fractures at the back of the spine that are difficult to diagnose on X-rays alone.
With a particular condition called Ankylosing Spondylitis (AS), which makes the spine fuse, it can be hard to see fractures on regular X-rays. In such cases, doctors should treat any patient with sudden neck pain or a change in posture as having a fracture until proven otherwise, and the complete spine should be imaged using CT scans or MRI.
Once doctors have gathered the patient’s history, examined them, and studied these images, they would decide on the best course of action. There are a couple of classification systems that have been designed to help in this decision-making process. These systems classify fractures, nerve injuries, and injuries to other structures in the neck based on a points system to determine whether surgical or conservative treatment would be the best course of action.
Treatment Options for Subaxial Cervical Spine Fractures
Initially, patients with fractures in the lower part of the neck, known as subaxial cervical spine fractures, need to wear a firm neck brace. If doctors suggest a non-surgical approach, patients often have to wear a rigid brace supporting the neck and upper back for 6 to 12 weeks. Regular check-ups and X-rays during this period help doctors monitor the neck’s alignment.
However, for patients with unstable fractures or compromised neurological conditions, surgery to relieve pressure and stabilize the neck is required. The decision on whether the surgeon operates from the front or the back is determined by the injury’s specific nature.
Patients with compression fractures, where the neck bone is crushed but there’s no injury to the connecting tissues at the back of the neck, can be treated non-surgically using a rigid neck brace. However, if these connecting tissues are involved, the patients would require surgery. Even athletes with these injuries but without nerve damage can be managed non-surgically with a rigid neck brace. Yet, if the fracture is at the C7 vertebra (the lowest one in the neck) and continues to bend forward (progressive kyphosis), the patient may require surgery.
Different than compression fractures, burst fractures with bone fragments pushed backward toward the spinal canal often require surgery. It’s possible to align these fractures with cervical traction, a technique that gently pulls the head away from the neck. Burst fractures, especially ones accompanied by neurological symptoms, usually require surgical fixation. Surgeons typically treat these injuries and specific other ones like flexion-type teardrop fractures, by removing the fractured bone, replacing it with a bone graft, and stabilizing it with a plate. Depending on the injury, they may need to perform the operation from the back.
If there’s a neck joint dislocation (facet dislocations), doctors may initially attempt to put it back in place (closed reduction) using cervical traction in an awake and aware patient. The procedure strategically applies weights to the head to pull it upwards. However, the effectiveness of the treatment varies, with single-sided facet dislocations proving more difficult to manage than double-sided ones. For more complex cases, doctors must conduct surgical fixation to maintain reduction.
If a patient is unresponsive or unable to cooperate during initial evaluation, doctors should conduct an MRI scan before attempting closed reduction or surgery. Surgeons can use a procedure called an anterior discectomy to remove a slipped disc in the neck and realign a dislocated joint. They can then stabilize the joint with a fusion surgery.
Patients with Ankylosing Spondylitis (AS) may not display any neurological deficit at first. However, continuous monitoring is vital because, in some cases, small unstable fractures in such patients can lead to progressive nerve damage. These fractures usually need surgical stabilization and possibly removal of blood clots inside the spinal canal. Doctors can approach these fractures from the front, back, or through a combined approach, based on the injury and the patient’s specific conditions.
What else can Subaxial Cervical Spine Fractures be?
Fractures in the lower part of the neck, known as the subaxial cervical spine, can take on several different shapes and types. These fractures can range from compression injuries (where the bone is squeezed or crushed), burst fractures (when the bone breaks into several pieces), distraction injuries (where the bone is stretched or pulled apart), or translational injuries (the bone moves out of place). In some cases, the ligaments, which are the bands of tough, flexible tissue that hold your bones together, can also be injured.
What to expect with Subaxial Cervical Spine Fractures
If a person takes a long time to have surgery after a spinal injury, has a more severe injury or a large amount of spinal cord compression, studies show their outcome may not be as good. The longer the spinal cord is under pressure, the lower the chance of recovery. However, in patients who had neurological problems and then had surgery, 60% didn’t have their condition worsen, and around 30% saw an improvement at their next appointment.
Having surgery can lower the overall rate of complications compared to not having treatment, both in the short term and the over a longer period. For patients with AS, a kind of condition, the chances of having significant neurological complications, like weakness, are higher after fracturing their neck bone than for patients without this condition.
Possible Complications When Diagnosed with Subaxial Cervical Spine Fractures
Not having an adequate x-ray or advanced imaging can result in overlooked injuries to the neck or spine. If these injuries go unnoticed, they can ultimately lead to nerve damage or even spinal cord injuries. It’s, therefore, essential that the entire spine gets assessed properly to avoid missing any other injuries.
Sometimes, trauma to the subaxial part of the cervical spine, which is the lower part of the neck, can lead to injury in the vertebral artery. This injury can also happen during a surgical operation.
There’s also a risk of secondary nerve damage that may happen after a cervical spine injury. This type of injury usually leads to a gradual loss of motor or sensory abilities at or above the place of the initial injury. Risk factors for this kind of nerve damage include having been injured through a bending mechanism or having an underlying fused spine (ankylosed spine). Ankylosing spondylitis, which is a type of arthritis that affects the spine, can also delay the diagnosis of a neck fracture if advanced imaging isn’t done soon enough.
It’s important to note that surgical treatment of these fractures can carry the typical risks of spine surgery, which include:
- Infection
- Dural tears (tears in the membrane that covers the brain and spinal cord)
- Nerve damage
- Pseudarthrosis (the non-healing of a fracture)
- Loosening of the implanted hardware
Preventing Subaxial Cervical Spine Fractures
For patients receiving non-surgical treatment, it’s vital to stress the importance of sticking to the prescribed use of their support device. They should be given clear instructions for care after leaving the hospital, and follow-up appointments should be made in advance.
As for patients who will be having surgery to stabilize their condition, a thorough discussion about the procedure is necessary. This will ensure patients can make an informed decision, understanding both the potential risks and benefits, along with other possible treatment options.
