Burst Fracture Treatment

F. Cumhur Oner and J.J. Verlaan

Introduction

First described by Nicoll in the 1950s as a separate entity, the burst fracture has become an umbrella concept for many fracture patterns, especially in the thoracolumbar spine. Classification and treatment of these injuries, specifically in cases without neurologic deficits, has been a subject that engenders strong controversy. There is still a wide variation in treatment practices globally, without a clear justification for the variations.

A burst fracture is defined as a fracture of the vertebral end plate with involvement of the posterior wall of the vertebral body, thereby causing a violation of the vertebral canal (Figs. 8.1 and 8.2) and potential neurologic injury. Whether this fracture is a solitary injury or part of a more complex pattern involving the failure of the posterior tension band has been recognized as a crucial distinction with direct implications for treatment and prognosis. The posterior ligamentous complex (PLC) injury category in the Thoracolumbar Injury Classification and Severity Score (TLICS) system and the type A and type B distinction in the AO Spine classification reflect this importance (Fig. 8.3). In general, there is consensus among spine traumatologists that if burst fractures are associated with posterior tension band injury (TLICS: PLC injury +; AOSpine classification: type B2) or demonstrate displacement (type C), surgical stabilization is usually necessary, even in the absence of neurologic deficits, to prevent progressive deformity or secondary neurologic damage. As in the older literature, the distinction between injuries with and without involvement of the PLC was not always clear, so one should use the results of these studies with caution. However, many authors recognize the difficulty of this distinction even when advanced imaging techniques are used. It is also not always possible to establish the integrity of the PLC even with magnetic resonance imaging (MRI).¹

Another controversial issue is the degree of comminution of the vertebral body in a burst fracture. Observations based on the load-sharing classification point to the importance of the load-sharing capacity of the anterior column after a fracture in the development of progressive deformity or loss of correction. The distinction between type A3 (one end plate fractured) and type A4 (both end plates fractured) in the new AOSpine classification reflects this recognition (Figs. 8.1 and 8.2).

Another factor that affects the load-sharing capacity is the quality of bone architecture and bone strength, which can be severely affected by osteoporosis/osteopenia. As the median age of the spinal trauma patients is increasing, this becomes one of the factors contributing to the unpredictability of the burst fractures (Fig. 8.4).

Fig. 8.1a,b AOSpine classification A3. (a) Graphic representation of a burst fracture defined as an end-plate fracture with any involvement of the posterior wall of the vertebral body. Only a single end plate fractured. The posterior ligamentous complex (PLC) is intact. (b) A typical case with a burst fracture type A3 of L1. (Copyright by AO Foundation, Switzerland.)

Fig. 8.2a,b AOSpine classification A4. (a) Graphic representation of a burst fracture defined as an end-plate fracture with any involvement of the posterior wall of the vertebral body and both end plates. The PLC is intact. (b) A typical case with a burst fracture type A4 of T12. (Copyright AO Foundation, Switzerland. Reprinted with permission.)

Fig. 8.3a,b AOSpine classification B2. (a) A burst fracture with a bony and/or ligamentary failure of the posterior tension band is one of the most common type B2 injuries. (b) In this case there is bony and ligamentary failure of the posterior tension band, classified, according to the combination rules, as follows: T12-L1 type B2, with T12 type A4. (Copyright AO Foundation, Switzerland. Reprinted with permission.)

Fig. 8.4 Osteoporosis is a significant factor in the load-sharing capacity of a vertebral body with burst-type fracture. In this case with a definitely intact PLC confirmed with the initial magnetic resonance imaging (MRI), conservative treatment led to progressive collapse and secondary neurologic injury.

Operative Versus Nonoperative Treatment

Reflecting the above-mentioned unresolved issues, the indication for surgical reduction and stabilization of the type A3 and A4 fractures (sometimes called stable burst fractures, meaning with an intact PLC) is a subject of ongoing debate. Good to excellent results have been reported with nonoperative treatment but also with different surgical techniques. It is not always easy to compare the results in these series because of a lack of standardization of classification, observer variability when using classification schemes, and absence of validated disease-specific outcome instruments.

Three high-quality studies compared operative versus nonoperative treatment of thoracolumbar burst fractures without neurologic involvement.2 Shen et al³ prospectively compared the treatment of a customized hyperextension orthosis to posterior instrumentation in 80 patients with single-level T11–L2 burst fractures. Fracture dislocations and pedicle fractures were excluded. The study was initially randomized, but seven participants assigned to the operative group refused surgery and were reassigned to the nonoperative group. Radiological and functional outcomes were reported, with a mean follow-up of 2 years. In the operative group, the kyphosis angle was improved initially by 17 degrees, but this correction was gradually lost. At 1and 3-month follow-up evaluations, the Visual Analogue Scale (VAS) pain score and the Greenough Low-Back Outcome Scale score were significantly lower in patients treated surgically. This difference was no longer present at 1and 2-year follow-up assessments.

Wood et al⁴ conducted a randomized trial comparing the application of a body cast or orthosis to anterior or posterior instrumentation with fusion in 47 patients with T10–L2 burst fractures. Burst fractures with posterior column disruptions were excluded. Radiological and functional outcomes with a mean follow-up of 3.7 years were reported. There were no statistical differences in return to work, kyphotic deformity, VAS score for pain, Oswestry Disability Index (ODI) score, and Roland Morris Disability Questionnaire (RMDQ) score between the two groups. The nonoperative group scored higher on the Short Form 36 (SF-36) physical function and role subsections. Complications were more prevalent in the surgical group. In this study, neither the surgical sta bilization nor the conservative treatment was standardized. Various surgical stand-alone anterior and posterior techniques were used. The reported surgical complication rates were unusually high.

Siebenga et al 5 performed a randomized controlled trial (RCT) comparing bed rest followed by mobilization with a Jewett-type orthosis to short-segment posterior instrumentation in 32 patients with T10–L4 burst fractures. Data collection involved radiological and functional outcomes with a mean follow-up of 4.3 years. The operative group had superior VAS pain, VAS spine, and RMDQ scores, a higher percentage of patients returning to work, and less kyphotic deformity. Complications were similar in both groups.

In a systematic review, the authors pooled the results of these studies in a meta-analysis and found no differences in pain, kyphosis, RMDQ score, and return to work rates between the operative and nonoperative groups.⁶ The surgical group did have better radiographic correction (3.3 degrees in the nonoperative group versus 1.8 degree in the operative group at final follow-up), but there was a higher rate of complications and higher costs associated with surgery.

According to Bakhsheshian et al,² there is also low-level evidence that a higher load-sharing score may correlate with a lower functional outcome in patients treated conservatively. In fact, all of the above-mentioned studies comparing operative to conservative treatment regiments are underpowered and constitute low-level evidence.

Thus, there is no convincing evidence for the choice of either surgical or nonsurgical treatment in type A burst fractures without neurologic injury. However, it is probably quite difficult to make the distinction between stable and unstable types of burst fractures.⁷ It seems that in the majority of the cases these stable fractures heal well within 1 year without serious complications with or without surgical intervention (Fig. 8.5). The direct costs of surgical treatment are considerably higher, although the comparison of cost-effectiveness of different treatments is difficult to make.⁸

Apparently there are some issues yet unresolved causing a remarkable discrepancy between guidelines based on these literature findings and the preferences of treating surgeons. Although most of the guidelines and recommendations followed in North America suggest nonsurgical treatment, in a survey among orthopedic spine surgeons and neurosurgeons in practices at academic institutions and private practices throughout North America who attended a meeting of the Association for Collaborative Spine Research (ACSR), the majority of the participants chose surgical treatment in a fictional case of type A burst fracture without neurologic deficits.⁹ This may indicate a tension between surgeons’ actual practice and the recommendations in the literature. Thus, there are some issues that should be discussed. First, the clinical outcome of spinal trauma is poorly defined, and there is no outcome measurement instrument specifically designed for spine trauma patients.¹⁰ Although there may be no difference in the functional outcome after 1 year, surgically treated patients may recover more quickly in the first months with possible socioeconomic consequences for young and active persons.^3,5 The existing measurement tools most likely cannot detect these differences.

Second, the amount of residual deformity may have consequences in the long term beyond the scope of the reported outcomes, as many of these patients continue to experience back problems,¹¹ although good long-term results were also reported with nonsurgical treatment of stable burst fractures.¹² Growing attention among spine surgeons to the importance of sagittal balance may also be reflected in their reluctance to accept spinal deformity in young patients (Fig. 8.6). In fact, there is no consensus among spine surgeons on the amount of acceptable residual deformity or what constitutes a posttraumatic kyphosis, and the results of secondary corrective operations may be disappointing if conservative treatment fails.¹³