Chapter 10 Orthoses for spinal trauma and postoperative care
With the exception of some fractures of the upper cervical spine and bilateral facet fractures, orthotic treatment of spinal trauma may be indicated only for clinically stable spinal fractures. Thus, the treatment team must have a common understanding of the definitions of the terms clinical “stability” and “instability” of the spine.
Before proceeding with orthotic treatment procedures, it is incumbent on the orthotist to independently verify the stability of the injury to the spine. The mechanism of injury, results of clinical examination, and radiologic evidence should be considered. In general, if the integrity of the anterior and/or posterior ligamentous complex is compromised, the injury should be considered unstable (Table 10-1).
|History of Mechanism of Injury||Physical and Neurologic Examinations||X-ray Examination Specific Criteria|
|Disruption of posterior ligamentous complex||Disruption of posterior ligamentous complex||Disruption of posterior ligamentous complex|
Hoppenfeld S: Orthopedic neurology: a diagnostic guide to neurologic levels, Philadephia, Lippincott Williams & Wilkins, 1977
An axial load applied to the top of the head and transferred through the condyles of the occiput can fracture the ring of the first cervical vertebra. This is known as a Jefferson fracture. Typically, C1 is split into multiple fragments, and the injury is unstable in all three anatomical planes. In the absence of external support, the patient is at high risk for neurologic damage because motion of the head is not constrained.
A hangman fracture is a fracture through the pedicles of C2 that separates the posterior neural arch from the vertebral body. The mechanism of injury, which consists of hyperextension followed by distraction, is called traumatic spondylolisthesis. The spinal cord may be compressed, with possible transient neurologic findings. This injury also is unstable in all three anatomical planes, and the risk of neurologic damage is high in the absence of external support.
Fractures of the odontoid are caused by a combination of shear and compression loading and may result from a blow to the back of the head. In the rare case where the fracture is through the tip of the odontoid (type I fracture), the injury is stable. A type II odontoid fracture is through the base of the odontoid body. With a type III fracture, the fracture line is into the body of the vertebra. Types II and III are considered unstable; however, the clinical outcome is better for type III fractures because of the higher rate of bony union.
Compression fractures in the region C3–7 are hyperflexion injuries where the endplates of the vertebra may be damaged and the vertebral body fractured. The most common level of injury is C5, and the brachial plexus may be involved.14 Hyperextension injuries (e.g., from whiplash) are mostly soft-tissue injuries, and the anterior longitudinal ligament may be ruptured. A full clinical assessment must be performed to determine whether the injury is stable.25
Facet joint dislocations involve disruption of the joint capsule and possibly the posterior ligament. Unilateral facet fractures are caused by lateral flexion and rotation and result in narrowing of the spinal canal and neural foramen. For example, a T3–4 unilateral facet fracture may be a shoulder belt injury from a motor vehicle accident. The vertebral body usually is dislocated less than 50% anteriorly, and approximately 75% of patients have no neurologic involvement. Unilateral facet joint dislocations are considered stable fractures but may result in isolated paralysis, such as Brown-Séquard syndrome (one-sided paralysis).
In bilateral facet dislocations, the facet capsules, posterior ligament, and intervertebral disc are disrupted. The mechanism of injury is severe flexion with some rotation, with the vertebral body displaced by more than half of its anterior-posterior dimension. Approximately 85% of patients have neurologic lesions because of the greater narrowing of the spinal canal. The most common level of injury is C5–6 where the range of motion is greatest (except for C1–2). Risk factors include spondylosis, degenerative disc disease, decreased range of motion, and age over 50 years. These fractures are considered unstable.
Normal thoracic kyphosis ranges from 20 to 50 degrees.2 Because of the kyphotic posture, the thoracic spine is especially vulnerable to flexion injuries. On the other hand, the ribs and their articulations provide considerable additional stability by restricting the mobility of the vertebrae. The lower thoracic vertebrae from T9–12 are considered transitional vertebrae and have more mobility.
Compression fractures are characterized by impaction of the anterior aspect of the vertebral body. The mechanisms of injury involve flexion and compression of the affected segments. These fractures are stable so long as the anterior and posterior longitudinal ligaments as well as the posterior ligamentous complex are intact. Moreover, the spinous processes must not be separated.
Spinal trauma can be categorized with the Denis classification7 of acute thoracolumbar spinal injuries using a three-column theory (Fig. 10-1). If the anterior column of the spine alone is injured (Denis type I), the mechanism of injury is flexion followed by compression. If the anterior and middle columns are injured, causing a burst fracture (Denis type II), the mechanism of injury is compression followed by flexion. The posterior and middle columns can be injured through the mechanism of flexion followed by distraction (Denis type III). They can be through bone (Chance fracture), soft tissue (slice fracture), or a combination of the two. Fractures through soft tissue usually are treated surgically.
From Lusardi MM, Nielsen CC: Orthotics and prosthetics in rehabilitation. Philadelphia, WB Saunders, 2007.
The Chance fracture often results from a motor vehicle accident. They are referred to as lap belt injuries because they occur when the occupant is wearing a lap belt with no shoulder harness. Other causes include the abdomen hitting a solid object such as a tree or pole. The most common Chance fracture involves the posterior elements of the involved vertebra and possibly the posterior aspect of the vertebra. The second type of Chance fracture involves the posterior elements as before; in addition there is a significant transverse fracture of the vertebral body. The third type of Chance fracture involves the interspinous ligaments, facets, and disc. In all types, the pedicles and the transverse and spinous processes are intact. Clearly, as the amount of damage increases, the likelihood of having a stable fracture decreases.
Compression fractures typically occur in the upper part of the lumbar spine. Regardless of the location, it is essential to check for the integrity of the anterior longitudinal ligament, which is well developed in the lumbar region and is largely responsible for stability in this region of the spine.
Early ambulation postoperatively is often in the patient’s best interest. However, additional loads that may be placed on the spine during gait must not damage the surgical construct of a spinal fusion. Besides upright posture and ambulation, even greater loads may be present in the seated posture, and caution must be exercised. Thus, the splinting effect of the orthosis may be helpful in protecting the surgical construct, bone–construct interface, and, if appropriate, biologic fusion. The excessive tissue between the spine and the orthosis may make the orthosis less effective in stabilizing the construct and preventing unwanted movements that may damage it and slow the healing process. Knowledge of common surgical procedures and surgical construct characteristics are important. Specifically, a good understanding of planes of motion where the construct is susceptible to failure can help with appropriate orthotic treatment.
Obesity occurs in near epidemic proportions in the United States.34 The presence of substantial excess adipose tissue may deteriorate the performance of an orthosis by compromising its stabilizing effects.1 Because the orthotic practitioner likely will treat patients with the comorbidity of obesity, strategies should be in place to cope with this complication.14
Orthotic treatments of spinal trauma have evolved over centuries. They all are based on the ideas of immobilization of the fracture to reduce pain and reduction of the deformities associated with particular injuries. Early devices were made of materials such as whalebone and wood. Plaster body casts became popular in more modern times. Orthoses for spinal trauma formerly constructed with metal components in the early to middle twentieth century have been replaced by orthoses constructed from thermoplastics. In 2006, ever increasing numbers of prefabricated orthoses were being used to treat spinal trauma.
Understanding the historical traditional approaches to spinal trauma and treatment provides a foundation for learning from previous successes and decreasing the probability of future mistakes. These approaches are related specifically to the mechanism of injury (of the trauma) and the mechanism of action (orthotic treatment) addressing the injury. The mechanism of injury in the past (and frequently in the present) was routinely categorized by terms such as lateral flexion, compression, rotation, and extension injuries. Although this approach can have meaningful clinical application, it also runs the risk of oversimplifying complex injury mechanisms that then are managed orthotically in an inappropriate manner (Fig. 10-2).37
For example, a patient may present with an anterior compression fracture that resulted from a small compressive load but also associated with a major forward bending moment that has simultaneously disrupted the posterior ligamentous structures. The result is a motion segment more susceptible to instability secondary to shear. This also has been liberally reported as the main factor for destabilization of a compression fracture.21,37,38 If the focus remains only on the compression fracture, then the logical orthotic treatment may result in use of a Jewett three-point hyperextension orthosis. Although the lumbar pad is an important element of this three-point hyperextension addressing the compression fracture, it also introduces the element of shear with its anteriorly directed transverse force. Ultimately the patient is at greater risk for further instability and increased discomfort. In this example, a better knowledge of the mechanism of injury may have resulted in a more logical and predictable treatment strategy and outcome.
Using the previous case as an example, the mechanism of action must be investigated thoroughly before a decision regarding orthotic treatment. In this case, the issue requiring greatest attention is not the hyperextension itself but how the hyperextension was achieved. A three-point hyperextension orthosis introduces the appropriate mechanism of hyperextension, but at the expense of introducing shear to the fracture site. A total-contact polymer thoracolumbosacral orthosis (TLSO) is a reasonable alternative because the patient can be hyperextended using a sagittal bending moment while not introducing shear. In addition to addressing the compression fracture, this orthosis likely will be more comfortable for the patient. It is important to note that the degree of ligamentous injury could eliminate completely the option for orthotic treatment and warrant future surgery. However, this case serves a purpose and underscores the need for greater consideration for the mechanism of injury and mechanism of action. Although previous thinking should not be abandoned, it should be the foundation for greater attention to detail and for a clear decision about the specific mechanism of action of orthotic treatment.
In the early days of spinal fusion, body jackets commonly were used postoperatively. Of course, the goal was to provide additional stability to the surgical construct to allow it to heal properly. Today, the role of postoperative orthoses remains controversial. Some argue that modern surgical techniques and devices provide all the stability necessary to allow for proper healing without an orthosis. On the other hand, surgical failures still occur, especially when postoperative bracing is omitted from the treatment plan. One of the problems with settling the controversy is that insufficient research demonstrates the efficacy of postoperative spinal orthoses in specific surgical procedures.
Choices of spinal orthoses for trauma and postoperative care include prefabricated and custom devices. However, definitive answers to the basic questions of when to use spinal orthoses and whether they are effective remain incomplete, and further research is needed. It is useful to divide the discussion between (a) nonsurgical treatments of spinal trauma and (b) postoperative care. In each case, orthotic management may or may not be part of the treatment plan.
When an orthosis is part of the treatment plan, the prescribing physician must decide from among prefabricated, made to measure, and custom-fit devices. The efficacy of the different choices often is not well understood, and further research is needed.
The primary orthotic goal is to immobilize a fracture of the cervical spine. The orthotist may be faced with the questions of which orthosis to recommend, and, in particular, whether the recommended device should be a cervical orthosis or a cervicothoracic orthosis. These devices are used for both nonoperative and postoperative care. To shed light on the issue, Gavin et al.11 analyzed two cervical orthoses (Aspen and Miami J) and two cervicothoracic orthoses (Aspen two-post and Aspen four-post) using video fluoroscopy. They concluded that cervicothoracic orthoses provided significantly more reduction of cervical intervertebral and gross range of motion in 20 normal subjects compared to cervical orthoses. The two collars performed the same.
In the elderly, half of cervical spine fractures occur at the C1-C2 level. Fractures of the odontoid are the most common cervical fractures in patients older than 70 years and account for 10% to 15% of all fractures of the cervical spine.30,33 Tashjian et al.33 studied 78 patients older than 65 years with type II or type III fractures of the odontoid, which were considered unstable. They found that the patients managed with a halo vest had a mortality rate of 21% as well as higher rates of complications such as pneumonia and cardiac arrest compared with patients managed surgically or with a rigid cervical orthosis. The study also suggested that when managing an elderly patient having an odontoid fracture with a halo vest, extreme caution and daily supervision are required.
Injuries to the cervical spine resulting from motor vehicle accidents are common. Reduction or reversal of cervical lordosis that can lead to abnormal forward head posture is associated with whiplash injuries. With the head forward of its normal position, loads on the posterior musculature and vertebral bodies can increase significantly. Cervical kyphosis is a known primary risk factor for chronic pain in whiplash-associated disorders.15 Some evidence indicates that correcting the posture can relieve the symptoms to a great extent.9 An orthosis for this purpose should use the mechanism of retraction of the head rather than extension.25