Methods. In this study of patients who underwent internal fixation without fusion for a burst thoracolumbar or lumbar fracture, we compared the serial changes in the injured disc height (DH), and the fractured vertebral body height (VBH) and kyphotic angle between patients in whom the implants were removed and those in whom they were not. Radiological parameters such as injured DH, fractured VBH and kyphotic angle were measured. Functional outcomes were evaluated using the Greenough low back outcome scale and a VAS scale for pain. Results. Between June 1996 and May 2012, 69 patients were analysed retrospectively; 47 were included in the implant removal group and 22 in the implant retention group. After a mean follow-up of 66 months (48 to 107), eight patients (36.3%) in the implant retention group had screw breakage. There was no screw breakage in the implant removal group. All radiological and functional outcomes were similar between these two groups. Although solid union of the fractured vertebrae was achieved, the kyphotic angle and the anterior third of the injured DH changed significantly with time (p < 0.05). . Discussion. The radiological and functional outcomes of both implant removal and retention were similar. Although screw breakage may occur, the implants may not need to be removed. Take home message: Implant removal may not be needed for patients with burst fractures of the thoracolumbar and lumbar spine after fixation without fusion. However, information should be provided beforehand regarding the possibility of screw breakage. Cite this article: Bone Joint J 2016;98-B:109–16

Introduction. The management of thoracolumbar burst fractures is controversial. The goal of our study was to evaluate whether the psychological factors or the late spinal deformities influence outcome and in particular quality of life following surgical treatment of burst fractures of the thoracolumbar spine. Material and methods. In a retrospective analysis, we evaluated outcome in 45 patients in whom burst fractures of the thoracolumbar spine without neurological deficits were surgically treated between April 2001 and November 2004. For this purpose, patient charts, surgery reports and x-ray images were analyzed consecutively. 29 patients could be examined physically and the outcome could be evaluated with VAS spine core, quality of life according to short-form 36 (SF36) and Beck Depression Inventory (BDI) with a minimum follow up of 30 months. Results. Mean VAS spine score was 60±26. Neither VAS spine score, nor quality of life results correlated with the following radiological findings: vertebral body angle, sagittal index and height of cranial disc space of the vertebra. Beck Depression Inventory (BDI) correlated with SF-36 score and VAS spine score (p< 0.05). Patients who were depressed showed significantly worse results in relation to the VAS spine score and the SF36 score (p< 0.01). Conclusion. For the first time, we could show, that psychological factors have high influence on functional outcome and health related quality of life in operative treated thoracolumbar burst fracture independent of x-ray findings. Therefore, we recommend inclusion of psychological components in the treatment and outcome-evaluation of the thoracolumbar burst fracture in future

Purpose: The mechanical integrity of vertebral bone is compromised when metastatic cancer cells migrate to the spine, rendering it susceptible to burst fracture under physiologic loading. Risk of burst fracture has been shown to be dependent on the magnitude of the applied load, however limited work has been conducted to determine the effect of load type on the stability of the metastatic spine. The objective of this study was to evaluate the effect of multiple loading conditions and the presence of the ribcage on a metastatically-involved thoracic spinal motion segment. Methods: A parametric biphasic finite element model was developed and validated against experimental data under axial compressive loading. Fifteen loading scenarios were analysed, including axial compression, flexion, extension, lateral bending, torsion, and combined loads. Axial loads were applied up to 800N and moment loads up to 2Nm. Multiple analyses were conducted with and without the ribcage to assess its impact on thoracic spinal stability. Vertebral bulge (VB) and load induced canal narrowing (LICN) were utilised as main outcome parameters to assess burst fracture risk. Results: For single loads, pure 800N axial loading yielded the highest level of VB (0.48mm) and LICN (0.26mm). The smallest increases in VB were measured in 1Nm pure flexion (0.018mm). Combined loading scenarios also demonstrated that axial loading is the principal factor contributing to VB, as changes in VB for combined loads were no greater than 4.35% of VB under axial loading alone. Inclusion of the ribcage was found to reduce the potential for burst fracture by 27% under axial load. Conclusions: Axial loading is the predominant load type leading to increased risk of burst fracture initiation. Rotational loading (bending, flexion and extension) led to only moderate increases in risk. The ribcage provides substantial stability to reduce overall risk of burst fracture. These findings are important in developing a more comprehensive understanding of burst fracture mechanics in the metastatic spine and in directing future modeling efforts. The results in this study may also be useful in advising less harmful activities for patients affected by lytic spinal metastases. Funding: Other Education Grant. Funding Parties: Natural Sciences and Engineering Research Council

Purpose: Stability of thoracic vertebrae affected by metastatic disease has been shown to be dependent on tumour size and bone density, but additional structural and geometric factors may also play a role in burst fracture risk assessment. The objective of this study was to use parametric finite element modeling to determine the effects of vertebral level, geometry, and metastatic compromise to the cortical shell on the risk of burst fracture initiation in the thoracic spine. Methods: An experimentally validated parametric biphasic finite element model of a metastatically involved spinal motion segment was analysed with scenarios representing motion segments from T2-T4 through T10-T12. Variations in vertebral geometry, kyphotic angulation and endplate angulation were evaluated. Additionally, four scenarios with transcortical breach of the tumour were compared to a central tumour scenario to determine the effect of cortical destruction. Vertebral bulge (VB), load induced canal narrowing (LICN), and posterior wall tensile hoop strain (PWTHS) were utilised as the main outcome parameters to assess burst fracture risk. Results: Burst fracture risk outcome parameters were largest in upper vertebrae, decreasing inferiorly at each subsequent level, with T11 exhibiting a 35.5% decrease in VB relative to T3, despite greater applied loads. An increase in endplate angles led to a 6.59% decrease in VB and a 2.38% decrease in LICN. A 5° increase in kyphotic angle further decreased VB and LICN by 7.29% and 4.34% respectively. Transcortical tumour scenarios led to an average decrease in PWTHS of 25.8%. Conclusions: Patients affected by spinal metastases in upper thoracic vertebrae may be at greater risk of burst fracture. Decreased burst fracture risk with greater thoracic kyphotic angulation may be due to a change in loading direction for curved segments, reducing the amount of pure axial load applied. Decreased tensile hoop strains are generated during loading of transcortical tumours. This may be attributed to large deformation of tumour tissue through the breach in the cortical shell, reducing the potential for burst fracture. Improved burst fracture risk assessment in the thoracic spine may motivate more informed clinical decision-making. Funding: Other Education Grant. Funding Parties: Natural Sciences and Engineering Research Council

Spinal metastatic disease can result in burst fracture and neurologic compromise. This study aims to examine the effects of tumour location, shape and surface texture on burst fracture risk in the metastatic spine using a parametric poroelastic finite element model. Tumours were found to be most hazardous in the posterior region of the vertebral body, whereas the multiple tumour scenarios reduced risk. Tumour shape may affect the mechanism of burst fracture. Serrated and smooth outer tumour surfaces yielded similar trends. These results can be used to improve guidelines for burst fracture risk assessment in patients with spinal metastases. This study aims to examine the effects of tumour location, shape and surface texture on burst fracture risk in the metastatic spine. Both tumour location and shape are important factors in assessing the risk of burst fracture in the meta-static spine. Improving risk prediction may reduce burst fracture in patients with spinal metastases. Vertebral bulge increased over 30% when the tumour was moved posteriorly. Conversely, for the multi-tumour scenarios, vertebral bulge and axial displacement decreased by 41% and 35% in comparison to a single central tumour. Anterior and lateral movement demonstrated only small effects. Vertebral bulge increased proportionally to mediolateral tumour length and axial displacement increased proportionally to superior-inferior tumour length. Similar trends were seen with smoothed and serrated tumour surfaces. Using a parametric poroelastic finite element model of a metastaticaly involved T7 spinal motion segment, fourteen single and two multi-tumour scenarios were analyzed, each comprising approximately 24% tumour volume. Ellispoidal tumours were positioned in central, anterior, posterior and lateral locations. Tumour shape was altered by adjusting tumour radii for a centrally located tumour. Tumours were modeled using smoothed and serrated outer surface configurations. Burst fracture risk was assessed by measuring maximum vertebral bulge and axial displacement under load. Tumours were found to be most hazardous in the posterior region of the vertebral body, whereas the multi-tumour scenarios reduced risk. Modeling of tumour surface texture did not impact shape or location effects. Tumour shape may affect the mechanism of burst fracture. Funding: This study was supported by the National Science and Engineering Research Council

We present a series of 14 patients presenting to the senior surgeon’s practice who sustained thoracolumbar burst fractures, with no neurological loss. The patients were treated with early mobilisation and extension bracing. We assessed their pain and disability, using VAS and ODI, and their fracture morphology. There was no statistical correlation between any measured parameter of fracture morphology and pain or disability. There was correlation between age at injury, time elapsed from injury and psychosocial aspects of the injury and the subsequent disability. The measured disability was low and compared favourably with the results of studies of patients treated surgically. We continue to treat all our neurologically intact burst fractures by early mobilisation and bracing, and take no account of fracture morphology in our decision making

Introduction: The management of thoraco-lumbar burst fractures remains controversial. Different authors have advocated immobilisation, external bracing or internal fixation by either anterior or posterior approaches. Advocates of posterior fixation have in general performed stabilisation one level above and one level below the site of the fracture, resulting in fixation of two motion segments. It is known that multi-segmental spinal fusion produces undesirable biomechanics. To stabilise the site of the fracture and avoid unnecessary fixation of an uninjured segment the senior author (T.S.) for selected patients has been using a novel technique of monosegmental fixation with placement of pedicle screws directly into the fractured vertebral body. Methods: All patients with thoraco-lumbar burst fractures admitted to St Vincents and Concord Hospitals between January 2001 and October 2003 were considered for monosegmental fixation. Patients with severe osteoporosis or complete loss of vertebral body height (“vertebra plana”) were excluded. All patients underwent surgical decompression and fixation within 10 days of injury. Fixation was obtained with 4 titanium pedicle screws and a single transverse connector (Xia System Stryker Spine). Reduction of kyphotic deformity was carried out in selected patients. Average blood loss for the procedure was 250 ml with no patients requiring transfusion. All patients had a minimum of 6 months radiological and clinical follow-up. Results: Since January 2001, 18 patients with thoracolumbar burst fractures (T10-L2) were treated with single-level pedicle screw fixation. All patients were mobilised within 10 days of surgery. One patient experienced a minor superficial wound infection. There were no other postoperative complications. All patients had a stable fusion construct at 6 weeks following surgery. No patient experienced neurological deficit or have developed a delayed kyphotic deformity. There were no instances of instrument failure. 17 out of 18 patients report no significant back pain with any limitation of function by three months following surgery. One patient reports mild mechanical lower back pain 12 months following the injury. Discussion: Single level fixation for selected cases of thoracolumbar burst fracture is a safe and effective procedure to decompress the neural elements and obtain fixation and fusion of the fractured segment. It allows for rapid mobilisation and avoids a two-level fusion procedure with its subsequent detrimental effect on spinal biomechanics. It is considerably less invasive than anterior/lateral approaches which require extensive muscle dissection, rib removal and even diaphragmatic division

The purpose of this study was to determine whether patients with a burst fracture of the thoracolumbar spine treated by short segment pedicle screw fixation fared better clinically and radiologically if the affected segment was fused at the same time. A total of 50 patients were enrolled in a prospective study and assigned to one of two groups. After the exclusion of three patients, there were 23 patients in the fusion group and 24 in the non-fusion group. Follow-up was at a mean of 23.9 months (18 to 30). Functional outcome was evaluated using the Greenough Low Back Outcome Score. Neurological function was graded using the American Spinal Injury Association Impairment Scale. Radiological outcome was assessed on the basis of the angle of kyphosis. Peri-operative blood transfusion requirements and duration of surgery were significantly higher in the fusion group (p = 0.029 and p < 0.001, respectively). There were no clinical or radiological differences in outcome between the groups (all outcomes p > 0.05). The results of this study suggest that adjunctive fusion is unnecessary when managing patients with a burst fracture of the thoracolumbar spine with short segment pedicle screw fixation

Many authors recommend surgery to remove retropulsed bone fragments from the canal in burst fractures to 'decompress' the spinal canal. We believe, however, that neurological damage occurs at the moment of injury when the anatomy is most distorted, and is not due to impingement in the resting positions observed afterwards. We studied 20 consecutive patients admitted to our spinal injuries unit over a two-year period with a T12 or L1 burst fracture. There was no correlation between bony or canal disruption and the degree of neurological compromise sustained but there was a significant correlation between the energy of the injury (as gauged by the Injury Severity Score) and the neurological status (p < 0.001). This suggests that neurological injury occurs at the time of trauma rather than being a result of pressure from fragments in the canal afterwards and questions the need to operate simply to remove these fragments

Introduction The precise contribution of the posterior longitudinal ligament (PLL) and disc annulus in the burst fracture setting and their potential relative roles during intra operative reduction manoeuvres remains unclear. The anatomical attachments of the posterosuperior fragment most often associated with canal occlusion and potential neurological compromise are not well described in a reproducible model. Methods Burst fractures were induced using a pendulum impact tester. The jig allowed for accurate positioning in all planes and for precise delivery of both the magnitude and vector of the impact force. This allowed for creation of fracture all three major groups of the AO classification. The A3 (burst fracture) was produced in 10 cadaveric sheep spines by delivering a neutral force vector on a physiologically flexed spine. The morphology of the fracture was confirmed by CT. Subsequent laminectomy was performed and the anatomical attachments of the large fragments were identified. Results The PLL was identified following laminectomy in each case. In six of the ten spines there had been significant disruption of the longitudinal structure of the PLL .In a further two cases there had been stripping of the PLL from the posterior aspect of the vertebral body in association with the retropulsed canal fragment. Subsequent excision of the PLL from the posterior aspects of vertebral body and discs did not compromise the attachment of the retropulsed fragment to the disc annulus in any case. Discussion This study confirms the anatomical relationship between disc fragment and disc annulus in the burst fracture setting. The strong attachment between fragment and disc facilitate rotation of the fragment about this hinge and into the canal. Subsequent intraoperative reduction of this fragment by restoration of disc height may require contribution both from this annular attachment and from tension set up in an intact PLL. The relative contributions of each of these structures in the reduction manoeuvre remains unclear

The purpose was to present a case of cauda equina entrapment in a lumbar burst fracture with associated lamina fracture and to review the literature and assess the appropriateness of current practices for cauda equina decompression. Reported incidence of cauda equina entrapment in the lamina fracture of lumbar burst fractures is 13–17%. Anterior surgery alone for decompressing the cauda equina in patients with lumbar burst fractures and associated lamina fractures will not always address the problem. We therefore suggest that posterior exploration may be the preferred approach if the aim of surgery is to decompress the neural elements

Plain radiographs of 67 acute spinal compression fractures in 49 patients were analysed by subjective and objective criteria, using CT scans as the diagnostic standard for the diagnosis of burst fracture. Discriminant analysis correctly predicted the type of fracture in 88% of cases. Burst fractures, however, were almost as frequently misdiagnosed as being wedge compression fractures using this technique, compared with the reading of 25 films from patients without previous information. A quarter of the injuries would have been misdiagnosed had reliance been placed solely on the plain radiographs. CT scans of all patients with acute spinal compression fractures should be considered to decrease this potentially serious diagnostic error

In 139 patients with burst fractures of the thoracic, thoracolumbar or lumbar spine, the least sagittal diameter of the spinal canal at the level of injury was measured by computerised tomography. By multiple logistic regression we investigated the joint correlation of the level of the burst fracture and the percentage of spinal canal stenosis with the probability of an associated neurological deficit. There was a very significant correlation between neurological deficit and the percentage of spinal canal stenosis; the higher the level of injury the greater was the probability. The severity of neurological deficit could not be predicted

Two cases of burst fracture of the upper lumbar spine are reported. In both cases the narrowing of the spinal canal shown by CT scans was progressively relieved by natural remodelling. The need for operative decompression should be assessed clinically and not from CT scans only

Aim of Study: (A) To study what causes Anterior Column Deficiency in Burst Fracture of Dorso Lumbar Spine in the acute and later phase. (B) To analyse radiologically, the significance of adjacent disc injuries in burst fracture of dorso lumbar spine. (C) To look into the effectiveness of posterior short segment stabilisation by pedicle screw fixation and fusion in these injuries, in relation to deformity and anterior column deficiency. Methods and Materials: Twenty consecutive cases of Superior Burst-split fracture of Dorsolumbar spine were studied prospectively. All cases underwent reduction, posterior short segment stabilisation by Steffee type pedicle screw fixation and two level posterolateral fusion. The average follow-up duration was 30.2 months. Standardised AP and lateral radiograph were taken pre-operatively and post-operatively at regular intervals (every three months). Radiological assessment using seven parameters (Vertebral body angle, Upper disc angle, Lower disc angle, Kyphotic angle, etc) were done from these radiographs. Result and Significance: The total average correction of kyphosis (in degree) at surgery was 21.5°, and the proportion of correction during surgery was – Upper disc 29% (6.3°), Vertebral body 68% (14.6°) and Lower disc 3% (0.6°). So 68% of the correction was at the vertebral body level and 32% at the adjacent discs levels. At follow-up, the total average loss of correction was 16.5°, and the proportion of loss at follow-up was – Upper disc 44% (7.2°), Vertebral body 14% (2.3°) and Lower disc 42% (7.0°). There was loss of 14.2° at the disc levels compared to 2.3° only at the vertebral body level. So 86% of the loss was at the adjacent disc levels. Conclusion: Distraction at the adjacent disc levels occurred at surgery while contouring the vertebral body using dorsal instrumentation. The distraction at the upper disc level was significant. Distraction at adjacent disc levels resulted in more anterior column deficiency. At follow-up, the loss in the vertebral body was minimal and most of the loss occurred at the adjacent disc levels. The anterior column deficiency caused by the injury to the adjacent disc is very major cause for failure of dorsal instrumentation than the deficiency caused by the vertebral body. The upper disc is more severely injured than the lower disc in the superior burst split fracture and so the degeneration is rapid in the upper disc and gradual in the lower disc. The CT cuts at the end plate levels of the vertebral body can help to judge roughly the extent of injury to the adjacent disc. Posterolateral fusion and late disc degeneration after consolidation of fusion result in collapse of the disc in kyphotic angulation, as it prevents collapse of posterior disc height

Spinal fractures are common following underbody blast. Most injuries occur at the thoracolumbar junction, and fracture patterns suggest the spine is flexed at the moment of injury. However, current mechanistic descriptions of vertebral fractures are based on low energy injuries, and there is no evidence to correlate fracture pattern with posture at the loading rates seen in blast injury. The T12-L1 segment of 4 human spines was dissected to preserve the paraspinal ligaments and potted in polymethylmecrylate. The specimens were impacted with a 14 kg mass at 3.5m/s in a drop tower; two specimens were impacted in neutral posture, one in flexion, and one in extension. A load cell measured the load history. CT scans and dissection identified the injury patterns. Each specimen sustained a burst fracture. The neutral specimens demonstrated superior burst fractures, the flexed specimen demonstrated a superior burst fracture with significant anterior involvement, and the extended specimen showed a posterior vertebral body burst fracture. At high loading rates, the posture of the spine at the moment of injury appears to affect the resulting fracture. This supports understanding the behaviour of the spine in blast injury and will allow improved mitigation system design in the future

Summary Statement. Burst fractures were simulated in vitro on human cadaveric spine segments. Displacement of the facet joints and pedicles were measured throughout the fracture process showing how these bony structures behave when an impact load is delivered. Introduction. Burst fractures account for almost 30% of all spinal injuries, which may result in severe neurological deficit, spinal instability and hence life impairment. 1. The onset of the fracture is usually traumatic, caused by a high-energy impact loading. Comminution of the endplates and vertebral body, retropulsion of fragments within the canal and increase of the intrapedicular distance are typical indicators of the injury. Experimental and numerical studies have reported strain concentration at the base of the pedicles, suggesting that the posterior processes play a fundamental role in the fracture initiation. 2,3. However, little is known about the dynamic behaviour of the vertebra undergoing an impact load. The aim of this study was to provide an in vitro cadaveric investigation on burst fracture, focusing on the widening of the facet joints and pedicles during the fracture development. Methods. Eight three-adjacent-vertebrae segments (T9-T10-T11, T12-L1-L2, L3-L4-L5) were harvested from three human spines preserving the ligaments and intervertebral discs. A testing frame was designed to hold the sample whilst undergoing an axial impact load (delivered through a drop-weight rig). Lateral displacement was recorded by two transducers (LVDT) sampled at 5000 Hz and data were used to calculate the percent maximum dynamic widening (MW) and percent residual widening after the impact (RW). LVDTs were positioned in contact with the most lateral region of the cranial facet joints where the central vertebra was lumbar; or posteriorly to the base of the pedicles for thoracic. Samples were divided into two groups to achieve two different grade of severity of the fracture by delivering two different amount of energy: High (HE) and Low (LE). Samples underwent HR-pQCT scanning prior and after fracturing to assess percent canal narrowing (CN), intrapedicular distance and grade the fracture. Differences between results were assessed using Mann-Whitney U test. Results. Burst fractures were induced in all the samples (fragment retropulsion was present in all HE samples). The median energy delivered to each group was 206J (HE) and 148J (LE) which led to a significant difference in the median CN (HE: 32.4%; LE: 11.8%; p=0.029). No significant difference was found between HE and LE in terms of MW (p=0.11), or RW (p=0.85). Furthermore, MW and CN were poorly correlated (R. 2. =0.13). In all the cases, the first peak in the widening data coincided with MW (median 12.8%, range 4.3–21.8%). RW measurements (median 2.8%, range −1.3–11.5%) were validated against HR-pQCT scans showing excellent agreement (R. 2. =0.93). Discussion/Conclusion. Results from this study provided further insight on the burst fracture process supporting the wedging effect of the adjacent facet joints when the impact load is transmitted. Indeed, the pedicles were forced to widen up to a critical value (MW), after which they fractured. Further experiments will help clarifying the influence of the amount of energy delivered