The value of computed tomography in thoracolumbar fractures. An analysis of one hundred consecutive cases and a new classification

Anterior-Only Stabilization of Three-Column Thoracolumbar Injuries

OBJECTIVE

The optimal treatment of "unstable" thoracolumbar injuries remains controversial. Studies have shown the advantages of direct anterior decompression of thoracolumbar injuries along with supplemental posterior instrumentation as a combined or staged procedure. Others have also shown success in decompression as a single-stage anterior procedure, largely limited to two-column (anterior and middle) injuries. A retrospective review of all available clinical and radiographic data was used to classify unstable three-column thoracolumbar fractures according to the Association for the Study of Internal Fixation (AO) classification system. This was conducted to evaluate the efficacy of stand-alone anterior decompression and reconstruction of unstable three-column thoracolumbar injuries, utilizing current-generation anterior spinal instrumentation.

METHODS

Between 1992 and 1998, 40 patients underwent anterior decompression and two-segment anteriorly instrumented reconstruction for three-column thoracolumbar fractures. Retrospective review of all available clinical and radiographic data was used to classify these unstable injuries according to the AO classification system, evaluating for neurologic changes, spinal canal compromise, preoperative and postoperative segmental angulation, and arthrodesis rate.

RESULTS

According to the AO classification system, there were 24 (60%) type B1.2, 10 (25%) type B2.3, 5 (12.5%) type C1.3, and 1 (2.5%) type C2.1 three-column injuries. Preoperative canal compromise averaged 68.5% and vertebral height loss averaged 44.5%. There were no cases of neurologic deterioration, and 30 (91%) patients with incomplete neurologic deficits improved by at least one modified Frankel grade. Mean preoperative segmental kyphosis of 22.7 degrees was improved to an early mean of 7.4 degrees (P < 0.0001). At latest follow-up, angulation had increased by an average 2.1 degrees but maintained significant improvement from preoperative measurements (P < 0.0001). There was one early construct failure due to technical error. Thirty-seven of the remaining patients (95%) went on to apparently stable arthrodesis.

CONCLUSIONS

Current types of anterior spinal instrumentation and reconstruction techniques can allow some types of unstable three-column thoracolumbar injuries to be treated in an anterior stand-alone fashion. This allows direct anterior decompression of neural elements, improvement in segmental angulation, and acceptable rates of arthrodesis without the need for supplemental posterior instrumentation.

Anterior Versus Posterior Treatment of Stable Thoracolumbar Burst Fractures Without Neurologic Deficit

OBJECTIVE

A prospective randomized study was conducted to determine whether there exist any differences in radiographic, clinical, or functional outcomes when individuals with stable burst fractures of the thoracolumbar junction without neurologic deficit are treated with either a posterior fusion with instrumentation or anterior reconstruction, fusion, and instrumentation. There exists relatively little literature evaluating the outcomes of individuals treated with anterior surgery, and no prospective randomized studies exist comparing the two treatment approaches.

METHODS

From May 1995 to March 2001, a consecutive series of subjects with acute isolated burst fractures of the thoracolumbar junction (T10-L2) without neurologic deficit were randomized to receive either an anterior fusion with instrumentation or a posterior fusion with instrumentation. Radiographs including computed tomography (CT) were obtained. Radiographs were repeated at 2, 4, 6, 12, and 24 months. The CT scan was also repeated at 24 months. Hospital stay, cost, operating time, blood loss, complications, and patient-related functional outcomes were measured.

RESULTS

Of 43 enrolled, 38 completed a minimum of 2-year follow-up (average: 43 months; range: 24-108 months). Eighteen received a posterior spine fusion and 20 an anterior approach. Hospital stay and operating time were similar. Blood loss was higher in the group treated anteriorly; however, the incidence of transfusion was the same. There were 17 "complications" including instrumentation removal for pain in 18 patients treated posteriorly, but only 3 minor complications in 3 patients treated anteriorly. Patient-related functional outcomes were similar for the two groups.

CONCLUSIONS

Although patient outcomes are similar, anterior fusion and instrumentation for thoracolumbar burst fractures may present fewer complications or additional surgeries.

Percutaneous vertebroplasty for treatment of thoracolumbar spine bursting fracture

OBJECTIVE

Percutaneous vertebroplasty can be very beneficial for patients with vertebral osteoporotic compression fractures. To the best of our knowledge, however, there has been no mention in any literature regarding the use of percutaneous vertebroplasty for the treatment of spinal burst fracture.

METHODS

A preliminary study was conducted on 6 patients with traumatic burst fractures of vertebrae treated with percutaneous vertebroplasty starting in June 2000. Fractures involving the anterior and middle columns of the vertebrae and the canal were mildly compressed by the retropulsed bone fragment. However, there was no obvious neurologic deficit in these patients. They initially underwent conservative treatment and thoracolumbar spinal orthosis (TLSO) brace for at least 3 months, but the intractable pain caused patients to be bedridden for prolonged periods of time and limited daily activity. As a result, the patients underwent percutaneous vertebroplasty with polymethylmethacrylate (PMMA) for treatment of spinal burst fractures.

RESULTS

Six male patients (mean age: 38.2) who suffered from burst fractures of vertebrae with disabling back pain refractory to analgesic therapy and TLSO brace were treated in this study. The duration of conservation treatment period was 3.5 months to 8 months (mean: 5.2 months). There was no motility. However, 4 vertebrae (66.7%), on radiographs revealed evidence of PMMA leakage through the endplate fracture site into either the disc space or the paravertebral space, without any evident clinical symptoms. No intracanal leakage was seen, and no patient needed a secondary surgical intervention. Pain decreased from 84.3 +/- 5.4 mm at baseline to 34.7 +/- 4.4 mm at the third postoperative day, 30.2 +/- 5.8 at 3 months and 24 +/- 3.5 mm at 12 months. The reduction in pain from baseline to the 3-day and 3 month mark was statistically significant (p < 0.05). The mobility was at least 2 levels of improvement (mean improvement 2.7 points) at 12-months postoperative.

CONCLUSION

In highly selective patients, percutaneous vertebroplasty can be an alternative method for the treatment of spinal burst fractures and the prevention of complications from major surgical procedures. However, this procedure still has potential risks and should be employed with extreme caution to prevent extravasation of PMMA into the spinal canal.

[Traumatic fracture of the thoracic spine T1-T10]

We describe the incidence, causes, management and prognosis of traumatic fractures of the thoracic spine from T1 to T10 in surgical cases of traumatic fractures of spine during the period from June 1994 to June 2003 studied retrospectively. The type of fracture was determined according to the Gertzbein classification, and the degree of stability using the Denis classification. The neurological picture at admission and 30 days after surgery was evaluated using the ASIA/IMSOP classification. Surgery was performed in patients with complete spinal cord injury (n=7) for the purpose of stabilization using the posterior approach. In cases without spinal cord injury or incomplete injury (n=12), the surgical procedure was performed aiming to decompress the nerve tissue, to correct the alignment of the spine and to stabilize the spine.

Posterior instrumentation for thoracolumbar fractures

Thoracolumbar fractures are relatively common injuries. Numerous classification systems have been developed to characterize these fractures and their prognostic and therapeutic implications. Recent emphasis on short, rigid fixation has influenced surgical management. Most compression and stable burst fractures should be treated nonsurgically. Neurologically intact patients with unstable burst fractures that have >25 degrees of kyphosis, >50% loss of vertebral height, or >40% canal compromise often can be treated with short, rigid posterior fusions. Patients with unstable burst fractures and neurologic deficits require direct or indirect decompression. Posterior stabilization can be effective with Chance fractures and flexion-distraction injuries that have marked kyphosis, and in translational or shear injuries. Advances in understanding both biomechanics and types of fixation have influenced the development of reliable systems that can effectively stabilize these fractures and permit early mobilization.

Course of nonsurgical management of burst fractures with intact posterior ligamentous complex: an MRI study

STUDY DESIGN

Prospective study.

OBJECTIVES

To evaluate the results of nonsurgical management of burst fractures with intact posterior ligamentous complex and to investigate the effect of trauma and/or residual kyphotic deformity on adjacent and next adjacent (neighboring) discs.

SUMMARY OF BACKGROUND DATA

Conservative treatment based on integrity of posterior ligamentous complex is controversial, probably because of poor evaluation by clinical and indirect radiographic findings. Degenerative changes in the adjacent discs due to trauma and/or residual kyphotic deformity is a common expectation.

MATERIAL AND METHODS

Fifteen consecutive patients who were intact neurologically with burst fractures (T11-L2) were treated nonsurgically with the indication based solely on the integrity of posterior ligamentous complex determined by MRI. Correction of deformity and stabilization with a total body cast under sedation were the mainstays of treatment. Patients were mobilized the next day, and casts were removed at the end of the third month follow-up period with no further external stabilization. Local kyphosis angle, sagittal index, and percent of compression of anterior body height were measured on pretreatment, post-treatment, third month, and latest follow-up radiographs. All of the preoperative and latest follow-up MRI studies of the patients were obtained to examine the discs adjacent and next adjacent to the fractured levels. The self-reported perceptions of the patients of function, pain and appearance were analyzed using the Likert Questionnaire.

RESULTS

There were eight female and seven male patients with an average age of 28 (range, 15-49) years. Average follow-up period was 31 (range, 24-51) months. Average local kyphosis angle was found to be 16.5 degrees (0-34 degrees ) after trauma. It was corrected to 5 degrees (range, 19-25 degrees ) and deteriorated to 14.6 degrees (range, 2-25 degrees ) at the third month and to 17 degrees (range, 2-29 degrees ) at the final follow-up review. There was a similar tendency for both sagittal index and percent anterior body height. The pretreatment MRI analysis revealed changes in the shape of the discs (narrowing or herniation into the body) with no change in the signal intensity of nucleus pulposus in eight of the cranial and four of the caudal adjacent discs. On follow-up MRI, there was only one intact disc with a normal shape cranially. All others had height loss, but only one had complete loss of signal intensity. Caudally, two additional discs had changes in shape without any gross changes in signal intensity of nucleus pulposus, whereas two had changes in signal intensity without change in shape. Only two of the next adjacent discs had changes in shape or signal intensity at the time of injury or at latest follow-up review. Average score of function, pain, and appearance were 3.9 (range, 3-5), 3.7 (range, 2-5), and 3.7 (range, 2-5), respectively, at the latest follow-up review. All patients were back at work in 3.6 (range, 1-9) months on average and all were satisfied with their treatment.

CONCLUSIONS

The present study revealed that an intact posterior ligamentous complex might not prevent loss of correction gained by nonsurgical management of burst fractures. Significant loss occurs in the first 3 months despite external stabilization. However, the magnitude of residual deformity usually remains close to the initial deformity. Although changes in the shape of adjacent discs occur due to trauma and/or natural course, significant loss in signal intensity of nucleus pulposus is unlikely. Patient outcome seems to be highly satisfactory despite residual deformity.

The Efficacy of Anterior Spine Exposure by An Orthopedic Surgeon

This retrospective study was designed to document the incidence and types of perioperative complications that occurred with anterior spinal fusion surgery performed solely by an orthopedic spine surgeon. This study is contrasted to previous studies that document complications from anterior approaches performed by an orthopedic surgeon with the assistance of a general or a vascular surgeon. Specifically, the procedures included thoracotomies, thoracolumbar retroperitoneal, and lumbosacral approaches. Our sample consisted of 450 patients who underwent anterior spinal fusion between levels T1 and S1, from 1985 to 1997. Patient and surgery characteristics included age, sex, diagnosis, levels of fusion, blood loss, operative time, hospitalization time, complications, American Society of Anesthesiologists state, assessment of risk factors, previous surgery, and surgical approach used. Average follow-up was 41.69 months, with a minimum of 12 months and a maximum of 132 months. Our results indicated that anterior procedures performed solely by our senior orthopedic surgeon had a lower incidence of complications, less blood loss, and shorter operative time than anterior procedures performed by an orthopedic surgeon and a vascular or a general surgeon. Our findings suggest that the anterior spinal exposure is a safe approach that may be performed solely by a spinal surgeon who is knowledgeable and experienced.

Thoracolumbar fracture management: anterior approach

The surgeon who treats patients with spine trauma must be able to apply a variety of management techniques to achieve optimal care of the patient. The anterior surgical approach is appropriate for some thoracolumbar burst fractures in patients with neurologic deficit and without posterior ligamentous injury. Surgery is most often indicated for patients with incomplete deficit, especially those with a large retropulsed fragment, marked canal compromise, severe anterior comminution, or kyphosis <30 degrees. This approach provides excellent visualization of the anterior aspect of the dura mater for decompression. Reconstruction of the anterior body defect can be done with autograft, allograft, or a cage. Supplementation of the graft with anterior internal fixation helps prevent kyphosis. Clinical results demonstrate improved neurologic function in most patients as well as low pseudarthrosis rates. In patients with incomplete deficit, improvement in neurologic function usually can be expected with few complications.

Thoracolumbar spine fractures in patients who have sustained severe trauma: depiction with multi-detector row CT

PURPOSE

To determine if multi-detector row computed tomography (CT) can replace conventional radiography and be performed alone in severe trauma patients for the depiction of thoracolumbar spine fractures.

MATERIALS AND METHODS

One hundred consecutive severe trauma patients who underwent conventional radiography of the thoracolumbar spine as well as thoracoabdominal multi-detector row CT were prospectively identified. Conventional radiographs were reviewed independently by three radiologists and two orthopedic surgeons; CT images were reviewed by three radiologists. Reviewers were blinded both to one another's reviews and to the results of initial evaluation. Presence, location, and stability of fractures, as well as quality of reviewed images, were assessed. Statistical analysis was performed to determine sensitivity and interobserver agreement for each procedure, with results of clinical and radiologic follow-up as the standard of reference. The time to perform each examination and the radiation dose involved were evaluated. A resource cost analysis was performed.

RESULTS

Sixty-seven fractured vertebrae were diagnosed in 26 patients. Twelve patients had unstable spine fractures. Mean sensitivity and interobserver agreement, respectively, for detection of unstable fractures were 97.2% and 0.951 for multi-detector row CT and 33.3% and 0.368 for conventional radiography. The median times to perform a conventional radiographic and a multi-detector row CT examination, respectively, were 33 and 40 minutes. Effective radiation doses at conventional radiography of the spine and thoracoabdominal multi-detector row CT, respectively, were 6.36 mSv and 19.42 mSv. Multi-detector row CT enabled identification of 146 associated traumatic lesions. The costs of conventional radiography and multi-detector row CT, respectively, were 145 and 880 US dollars per patient.

CONCLUSION

Multi-detector row CT is a better examination for depicting spine fractures than conventional radiography. It can replace conventional radiography and be performed alone in patients who have sustained severe trauma.

Thoracolumbar fracture in blunt trauma patients: guidelines for diagnosis and imaging

OBJECTIVE

The aim of the study was to determine a clinical diagnostic pathway for the imaging of the thoracolumbar spine in blunt trauma patients.

METHOD

A literature review was undertaken to determine the factors important in the detection of thoracolumbar injury and also to produce a trial protocol, which could be tested retrospectively. Two hundred patients admitted between 1998 and 2000 were reviewed retrospectively to form a database of the relevant clinical features. The diagnostic pathway protocol was tested retrospectively in two groups; one hundred with known thoracolumbar fractures and one hundred undifferentiated multi-trauma patients. Sensitivity and specificity indices were determined using the chi-squared test of association.

RESULTS

Falls and motor vehicle crashes were the most common mechanism of injury causing thoracolumbar fractures. No significant association could be found between mechanism of injury (MOI) and presence of thoracolumbar fracture. Clinical signs found to be associated with thoracolumbar fracture include: (1) back pain/midline tenderness (Sens 62.1% Spec 91.5%), (2) palpable midline step (Sens 13.8% Spec 100%), (3) back bruising (Sens 6.9% Spec 98.6%), (4) abnormal neurological signs (Sens 41.4% Spec 95.8%). Cervical level fractures were also found to be associated with an increased incidence of thoracolumbar fractures. Factors found to influence the detection of back pain/midline tenderness include: (1) GCS<15, (2) ETOH/drug intoxication, (3) major distracting injury. The proposed diagnostic pathway would have led to 92% of patients receiving TL imaging in group 2 (multi-trauma) with a sensitivity of 100%, specificity of 11.3% and a negative predictive value of 100%.

CONCLUSION

From the literature and the results of the study, we propose that imaging of the thoracolumbar spine is required in those patients suffering from a high force mechanism of injury if any of the following are present: (1) back pain/midline tenderness, (2) local signs of thoracolumbar injury, (3) abnormal neurological signs, (4) cervical spine fracture, (5) GCS<15, (6) major distracting injury, (7) ETOH/ drug intoxication. An evidence based diagnostic pathway has been shown to be highly sensitive in determining the presence of TL fracture in a retrospective study of blunt trauma patients.

Operative compared with nonoperative treatment of a thoracolumbar burst fracture without neurological deficit. A prospective, randomized study

BACKGROUND

To our knowledge, a prospective, randomized study comparing operative and nonoperative treatment of a thoracolumbar burst fracture in patients without a neurological deficit has never been performed. Our hypothesis was that operative treatment would lead to superior long-term clinical outcomes.

METHODS

From 1994 to 1998, forty-seven consecutive patients (thirty-two men and fifteen women) with a stable thoracolumbar burst fracture and no neurological deficit were randomized to one of two treatment groups: operative (posterior or anterior arthrodesis and instrumentation) or nonoperative treatment (application of a body cast or orthosis). Radiographs and computed tomography scans were analyzed for sagittal alignment and canal compromise. All patients completed a questionnaire to assess any disability they may have had before the injury, and they indicated the degree of pain at the time of presentation with use of a visual analog scale. The average duration of follow-up was forty-four months (minimum, twenty-four months). After treatment, patients indicated the degree of pain with use of the visual analog scale and they completed the Roland and Morris disability questionnaire, the Oswestry back-pain questionnaire, and the Short Form-36 (SF-36) health survey.

RESULTS

In the operative group (twenty-four patients), the average fracture kyphosis was 10.1 degrees at the time of admission and 13 degrees at the final follow-up evaluation. The average canal compromise was 39% on admission, and it improved to 22% at the final follow-up examination. In the nonoperative group (twenty-three patients), the average kyphosis was 11.3 degrees at the time of admission and 13.8 degrees at the final follow-up examination after treatment. The average canal compromise was 34% at the time of admission and improved to 19% at the final follow-up examination. On the basis of the numbers available, no significant difference was found between the two groups with respect to return to work. The average pain scores at the time of the latest follow-up were similar for both groups. The preinjury scores were similar for both groups; however, at the time of the final follow-up, those who were treated nonoperatively reported less disability. Final scores on the SF-36 and Oswestry questionnaires were similar for the two groups, although certain trends favored those treated without surgery. Complications were more frequent in the operative group.

CONCLUSION

We found that operative treatment of patients with a stable thoracolumbar burst fracture and normal findings on the neurological examination provided no major long-term advantage compared with nonoperative treatment.

Magnetic resonance imaging of sports injuries of the spine

Spinal injuries are relatively frequent events in professional athletes. Greater popularity of recreational athletic activities has increased the occurrence of sports-related spinal injuries in the general population. The demand of high-intensity sports places a constant load on the vertebral column. Several studies have demonstrated higher prevalence of spinal abnormalities in athletes than nonathletes. Direct correlation of the number and extent of injuries with the length in years of sports activity has been established. Diagnostic imaging, particularly magnetic resonance imaging (MRI), plays a crucial role in evaluating and detecting sports-related spinal injuries. Subtle bone marrow, soft-tissue, and spinal cord abnormalities, which may not be apparent on other imaging modalities, can be readily detected on MRI. Early detection often leads to prompt accurate diagnosis and expeditious management, in many cases avoiding unnecessary procedures. This article reviews the technical aspects of MRI for evaluation of the spine and the role of MRI in the assessment of sports-related spinal injuries.

Modeling of the naked facet sign in the lumbar spine

The study design is a computer visualization model that simulated flexion deformities about the lumbar spine for evaluation of the naked facet sign (NFS). The objectives were to ascertain the angles of rotation required for NFS to occur in the lumbar spine with various centers of rotation about the vertebral body and to assess whether NFS correlates with unstable flexion-distraction injuries in the lumbar spine. The presence of the NFS on axial computed tomography (CT) images occurs when the inferior articulating facet of the cephalad vertebra is not paired with an adjacent superior articulating facet of the caudal vertebra. This sign, when evidenced in the lumbar spine, is suggestive of significant injury secondary to a flexion-distraction force. A previous study using a computer-generated spine model challenged the utility of the NFS in the thoracolumbar spine. The NFS may prove to be more diagnostic of an unstable injury in the lumbar spine because of its normal lordotic resting position. A commercial spine computer visualization model was used to simulate various degrees of flexion injury in the lumbar spine. Lumbar functional spinal units (FSU) L2-L5 were each examined separately. The model simulated two CT scan slices (each 2 mm thick), which were created parallel to the inferior endplate of the cephalad vertebra of each FSU. The cephalad vertebra was rotated in 0.5 degrees increments until NFS was produced. The appearance of NFS required >/=11 degrees kyphotic angulation in more than two thirds of simulated centers of rotation about the lumbar vertebral bodies. The NFS was produced between a range of 8-24.5 degrees. For rotations about a point located 3 cm anterior to the vertebral body (to simulate seat-belt-type flexion-distraction injuries), the minimum angle required for NFS was 7.5 degrees. Our data correlate well with previously published results from in vitro and cadaveric studies. As opposed to the thoracolumbar spine, which normally rests in a neutral position, the lumbar spine normally rests in a lordotic position. Therefore, NFS in the lumbar spine may be more suggestive of an unstable injury and would warrant closer examination of the patient and additional radiographic studies.

Feasibility of ultrasound examination in posterior ligament complex injury of thoracolumbar spine fracture

STUDY DESIGN

A prospective study of 12 patients with thoracolumbar spinal fractures was conducted.

OBJECTIVE

To assess the feasibility of ultrasound examination for posterior ligament complex injury in thoracolumbar spinal fractures.

SUMMARY OF BACKGROUND DATA

In posterior ligament complex injury of thoracolumbar spine fracture, the reliability of magnetic resonance imaging (MRI) for diagnosis has been reported. Nevertheless the usefulness of ultrasound for diagnosis has not been studied, whereas diagnostic ultrasound has been applied in the musculoskeletal system.

METHODS

Two healthy volunteers without a history of spinal trauma were recruited for pilot examination of the ultrasound procedure to access normal findings of the posterior ligament complex. This study investigated 12 thoracolumbar spine fractures. Four were flexion distraction injury; six were stable or unstable burst fractures; and two were simple compression fractures. Osteoporotic spine fractures were excluded from this study. Ultrasound was performed over the injured area by an experienced musculoskeletal radiologist in addition to radiography and MRI. Five patients underwent operative procedures to stabilize the fractured spine. Imaging data and operative findings were correlated with ultrasound examination.

RESULTS

In the patients who did not undergo surgery, agreement in diagnosis between MRI and ultrasound was moderate (5 of 7). Difficulty evaluating ligament status was encountered when the region of interest was the lower thoracic level (T10, T11, T12) because of long overlapping spinous processes. In the patients who underwent surgery, correlation between MRI, ultrasound, and operative findings was excellent, especially in diagnosing the status of the supraspinous and interspinous ligaments. Nevertheless, it is impossible to visualize deep-seated structures (i.e., ligamentum flavum, deep muscles of the spine, and facet joint) with ultrasound.

CONCLUSIONS

This study demonstrated the excellent diagnostic ability of ultrasound to detect the status of the supraspinous and interspinous ligaments, especially in patients who undergo surgery. Although ultrasound examination appears to be less sensitive than MRI in predicting ligament status, the cost effectiveness of ultrasound and its use as an alternative to MRI in special situations (i.e., patients with pacemaker, ferromagnetic implant, or severe claustrophobia) should be emphasized. More clinical data concerning the sensitivity, specificity, and accuracy of ultrasound examination should be addressed in future studies.

Classifications of thoracic and lumbar fractures: rationale and supporting data

Classification systems are generalizations that attempt to identify common attributes within a group to predict behavior or outcome without sacrificing too much detail. Because of the inherent variability of fractures, classifying them can be difficult. To properly apply any of the commonly cited classification schemes for thoracic and lumbar fractures, one must not only know the injury categories described in the original studies but also be familiar with the rationale for developing the classification. Many original reports describing common thoracic and lumbar injury classifications lack a rigorous scientific foundation. They were based largely on the insights of experienced surgeons and researchers. Although the ideal classification for thoracic and lumbar fractures does not exist, it would incorporate neurologic as well as structural factors. Standardization of terminology as related to treatment decisions and prognosis is key to an improved understanding of the clinical behavior of these injuries and identification of optimal treatment options.

Internal pressure measurements during burst fracture formation in human lumbar vertebrae

STUDY DESIGN

In a laboratory study, 21 human lumbar spine segments were used to determine whether intraosseous pressure increases occur during axial-compressive loading conditions under two displacement rates.

OBJECTIVE

To determine whether an intraosseous pressure rise is associated with burst fracture formation.

SUMMARY OF BACKGROUND DATA

Burst fractures are high-speed injuries usually associated with neurologic deficit. An internal pressure rise has been implicated as a critical factor in burst fracture formation. The authors hypothesize that the internal pressure increases with increasing input velocity.

METHODS

The internal pressure changes were measured in spine segments using two displacement rates: 10 mm/s (slow speed) and 2500 mm/s (high speed). Failure load and energy absorption were determined for both groups. The resultant fracture types were determined from postinjury radiographs.

RESULTS

The initial peak internal pressure decreased from slow- to high-speed tests (P < 0.01). Overall peak pressure, failure load, and energy absorbed at failure were not significantly different. Slow-speed tests resulted in compression fractures, whereas high-speed tests resulted in burst and compression fractures.

CONCLUSIONS

The current research did not support the current theory of burst fracture formation. There was a decrease in measured internal pressure from the slow- to high-speed groups, and burst fractures still were produced. The theory could be potentially modified to suggest that the nucleus entering the vertebral body acts as a wedge, splitting the vertebral body apart and enabling the bony fragments to be pushed into the canal space.

Some complications of common treatment schemes of thoracolumbar spine fractures can be predicted with magnetic resonance imaging: prospective study of 53 patients with 71 fractures

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

To study the predictive value of magnetic resonance imaging (MRI) findings of thoracolumbar spine fractures concerning the radiologic and clinical outcome.

SUMMARY OF BACKGROUND DATA

Disagreement about the proper treatment of thoracolumbar spine fractures is caused by insufficiency of conventional imaging techniques. Previous studies have shown that MRI is capable of distinguishing injury to all structures of the fractured spine and thus may help develop schemes with higher predictive power.

METHODS

A total of 53 patients with 71 fractures were studied with MRI in a prospective fashion. A total of 24 patients with 39 fractures were treated conservatively and 29 patients with 32 fractures were treated operatively after a protocol concerning the treatment options. MRI scans were obtained within 1 week of injury and at the 2-year follow-up. Pain scores were obtained at the 2-year follow-up. Previously described MRI schemes concerning the trauma and post-trauma conditions were used.

RESULTS AND CONCLUSIONS

An unfavorable outcome in the conservative group was related to the progression of kyphosis, which in most cases was predictable with the use of trauma MRI findings concerning the endplate comminution and vertebral body involvement. In the operatively treated group, recurrence of the kyphotic deformity was predictable by the lesion of the posterior longitudinal ligamentary complex together with endplate comminution and vertebral body involvement as seen on trauma MRI. The authors recommend the use of MRI to develop reliable prognostic criteria for these injuries.

Noncontiguous unstable spine fractures

STUDY DESIGN

Evaluation of 1054 patient charts and 100 random roentgenogram charts as well as clinical investigation of 39 patients.

OBJECTIVES

Noncontiguous unstable spine fractures are rare, easy overlooked, and difficult to treat. The purpose of the study was to evaluate the delay in diagnosis and clinical and radiologic outcome of these fractures.

SUMMARY OF BACKGROUND DATA

Noncontiguous spine fractures are reported in about 1.6-16.7% in the literature. In most of the studies stable fractures, which did not need any special treatment, were also included. Therefore, in this study only unstable fractures requiring treatment were reinvestigated.

METHODS

A total of 1054 patients with fractures of the spine were treated over a period of 14 years in the spinal cord injury unit and retrospectively reviewed; 141 (13.4%) of the patients had multiple fractures, but only 39 (3.7%) had a noncontiguous spine fracture, most frequently from a fall or jump from a greater height, or traffic accidents.

RESULTS

Thirty patients (76.9%) had all fractures diagnosed at the first examination. Nine patients (23.1%) had a delayed diagnosis of the secondary lesion, but this delay resulted in no neurologic deterioration. A total of 32 extraspinal injuries were diagnosed and treated 14 times surgically. Loss of correction was seen after surgical treatment (n = 21), and increasing deformity occurred after conservative treatment (n = 18). The neurologic deficit improved in 10 conservatively (4) and operatively (6) treated patients and deteriorated in one patient after surgery.

CONCLUSION

A delayed diagnosis of the second fracture was frequently seen without clinical consequences, and neurologic improvement occurred after conservative and operative treatment. Surgical treatment resulted in significantly earlier mobilization and less kyphotic deformity.

Dural tears in lumbar burst fractures with greenstick lamina fractures

STUDY DESIGN

This study investigated the incidence, predictions, and treatment principles of greenstick lamina fractures in lumbar burst fractures.

OBJECTIVE

To determine the incidence of dural tears in lumbar burst fracture with greenstick lamina fracture and to find out if any specific clinical and radiographic factors or intraoperative pathologic findings are predictive of dural tears and nerve root entrapment.

SUMMARY OF BACKGROUND DATA

A retrospective review was conducted on 45 patients with 47 lumbar burst fractures treated operatively. Ages ranged from 15 to 70 years (average, 33 years). The duration of follow-up ranged from 32 months to 8 years (average, 52 months).

METHODS

All clinical charts and radiologic data of these patients were reviewed. Age, sex, etiology, and all the radiologic parameters were analyzed for their association with greenstick lamina fracture and dural tear. Student's t test and multiple logistic regression analysis were used for statistical analysis.

RESULTS

Greenstick lamina fracture occurred in 20 (42.5%) of 47 burst fractures. Dural tear was detected in 9 (19%) of 47 burst fractures and was predominantly higher in L3 (6 of 9 burst fractures). According to multiple logistic regression analysis of the data, a 20% increase in the interpedicular distance gives a 79% probability of greenstick lamina fracture. The distance between the edges of greenstick lamina fractures was obviously higher in fractures with dural tear. Neurologic status was completely normal before surgery in three of the patients with dural tear and nerve root entrapment.

CONCLUSIONS

It is not possible to detect dural tear and nerve root entrapment in greenstick lamina fracture before surgery. Therefore, if there is any suspicion of such an occurrence, it should be the rule to begin with posterior approach and use the open book technique to expose the dura safely before any reduction maneuver.

Modeling of the naked facet sign in the thoracolumbar spine

On transverse computed tomographic (CT) scan cuts of the thoracolumbar spine, the naked facet sign occurs when the inferior articular facets of the cephalad vertebra do not appear adjacent to the superior facets of the subjacent caudal vertebra. The objective of this study was to determine the angles of rotation required for the naked facet sign to occur in the thoracolumbar spine, with the center of rotation located at various points in or anterior to the vertebral body. A commercial spinal model and visualization software were used to simulate various flexion injuries. Each functional spinal unit (FSU; T11-T12, T12-L1, and L1-L2) was examined separately. In the model, two CT scan slices (each 2 mm thick) were created parallel to the inferior end plate of the cephalad vertebra of each FSU. The cephalad vertebra was rotated in 0.5 degrees increments, and after rotation both modeled CT slices were examined for the presence of the naked facet sign. If the sign did not occur, the process was repeated, rotating the cephalad vertebra an additional 0.5 degrees until the naked facet sign occurred. The angle of rotation necessary for the sign to occur increases as the point of rotation of the vertebra moves from anterior to posterior and from superior to inferior. The naked facet sign occurred at a minimum rotation angle of 5 degrees (with respect to the anterior-superior point on T11) and at a maximum rotation angle of 16.5 degrees (with respect to the posterior-inferior point on L1). For rotations about a point located 3 cm anterior to the vertebral body, the minimum angles required for the sign decreased only 1 degrees for each FSU. These results suggest that the naked facet sign does not consistently imply the presence of posterior column vertebral instability. This will help clinicians to relate the mechanism of injury, radiographic findings (including the naked facet sign), and the implied injury pattern to the determination of stability, and ultimately the management options for the injury.

Blunt abdominal aortic trauma in association with thoracolumbar spine fractures

All patients with blunt abdominal aortic disruption (BAAD) in the trauma registries at the three Regional Trauma Centres were retrospectively reviewed over the last decade. From the 11465 trauma admissions ISS>16,194 sustained aortic injuries. Eight cases of BAAD were identified, six with concurrent thoracolumbar spine (TLS) fractures (mean ISS 42). Patients with BAAD and TLS were subject to a detailed analysis. Clinically, three injury types were seen, hemodynamically unstable (uncontained full thickness laceration), stable symptomatic (intimal dissection with occlusion), and stable asymptomatic (contained full thickness laceration or intimal dissection without occlusion). All spinal column fractures involved a distractive mechanism, one with both distractive and translational fracture components. We propose that a distractive force, applied to the aorta lying anterior to the anterior longitudinal ligament, results in an aortic injury spectrum ranging from an intimal tear to a full thickness laceration, as a related injury. Computed tomography (CT) was an important imaging modality in the stable asymptomatic patients. All intimal dissections without occlusion were managed non-operatively. With distractive TLS fractures, BAAD needs to be considered.

Radiographic parameters for evaluating the neurological spaces in experimental thoracolumbar burst fractures

It is important to know the condition of neural spaces during the nonoperative treatment of thoracolumbar burst fractures. The goals of the current study were to identify the correlation between the degree of deformity of a fractured vertebra and the encroachment of neural spaces, and to determine how the encroachment and the deformity can be improved by the extension posture simulating the postural reduction. Experimental burst fractures were produced in L1 vertebrae of nine human thoracolumbar spine segments (T11-L3) with neural spaces lined with tiny steel balls. Lateral radiographs were taken in neutral and extended posture before and after the trauma. Anterior vertebral height, posterior vertebral height, vertebral height ratio, vertebral kyphotic angle, posterior vertebral body angle, and the cross diagonal angle were the geometric parameters used to describe the vertebral deformity. The canal diameter and superior and inferior intervertebral foramen areas were defined as the neural spaces. All parameters were measured on the scanned images of radiographs, as seen on the computer screen. Among the vertebral body parameters, the posterior vertebral height, posterior vertebral body angle, and cross diagonal angle showed significantly higher correlations with the canal encroachment. The extended posture did not improve the canal and intervertebral foramen encroachments. The kyphotic deformity (vertebral kyphotic angle and anterior vertebral height) was improved but the deformity of the vertebral posterior wall (posterior vertebral height and posterior vertebral body angle) was not improved because of the extended posture.

Noninvasive imaging predicts failure load of the spine with simulated osteolytic defects

BACKGROUND

The clinical management of lytic tumors of the spine is currently based on geometric measurements of the defect. However, the mechanical behavior of a structure depends on both its material and its geometric properties. Quantitative computed tomography and dual-energy x-ray absorptiometry were investigated as noninvasive tools for measuring the material and geometric properties of vertebrae with a simulated lytic defect. From these measures, yield loads were predicted with use of composite beam theory.

METHODS

Thirty-four fresh-frozen cadaveric spines were segmented into functional spinal units of three vertebral bodies with two intervertebral discs at the thoracic and lumbar levels. Lytic defects of equal size were created in one of three locations: the anterior, lateral, or posterior region of the vertebra. Each spinal unit was scanned with use of computed tomography and dual-energy x-ray absorptiometry, and axial and bending rigidities were calculated from the image data. Each specimen was brought to failure under combined compression and forward flexion, and the axial load and bending moment at yield were recorded.

RESULTS

Although the relative defect size was nearly constant, measured yield loads had a large dispersion, suggesting that defect size alone was a poor predictor of failure. However, image-derived measures of structural rigidity correlated moderately well with measured yield loads. Furthermore, with use of composite beam theory with quantitative computed tomography-derived rigidities, vertebral yield loads were predicted on a one-to-one basis (concordance, r(c) = 0.74).

CONCLUSIONS

Although current clinical guidelines for predicting fracture risk are based on geometric measurements of the defect, we have shown that the relative size of the defect alone does not account for the variation in vertebral yield loads. However, composite beam theory analysis with quantitative computed tomography-derived measures of rigidity can be used to prospectively predict the yield loads of vertebrae with lytic defects.

CLINICAL RELEVANCE

Image-predicted vertebral yield loads and analytical models that approximate loads applied to the spine during activities of daily living can be used to calculate a factor of fracture risk that can be employed by physicians to plan appropriate treatment or intervention.

Reliability of magnetic resonance imaging in detecting posterior ligament complex injury in thoracolumbar spinal fractures

STUDY DESIGN

Prospective study of 34 patients with thoracolumbar spinal fractures.

OBJECTIVES

To assess the reliability of magnetic resonance imaging (MRI) for posterior ligament complex injury in thoracolumbar spinal fractures.

SUMMARY OF BACKGROUND DATA

Some researchers have studied posterior ligament complex injury in spinal fracture using MRI. However, most did not evaluate the findings of MRI compared with the operative findings.

METHODS

Thirty-four patients with thoracolumbar spinal fracture were evaluated by palpation of the interspinous gap, plain radiography, and MRI before operation. In addition to conventional MRI sequences, a fat-suppressed T2-weighted sagittal sequence was performed. Surgery was performed by a posterior approach. During the operation, posterior ligament complex injury was carefully examined.

RESULTS

A wide interspinous gap was palpated in 14 patients and was found in 21 patients on plain radiography. Magnetic resonance imaging raised suspicion of injury to the posterior ligament complex in 30 patients. According to interpretation of MRI, injury to the supraspinous ligament was suspected in 27 patients, the interspinous ligament in 30 patients, and the ligamentum flavum in 9 patients. There were 28 supraspinous ligament injuries, 29 interspinous ligament injuries, and 7 ligamentum flavum injuries in operative findings. There was a significant relation between MRI interpretation and operative findings.

CONCLUSION

A fat-suppressed T2-weighted sagittal sequence of MRI was a highly sensitive, specific, and accurate method of evaluating posterior ligament complex injury. Based on the results of this study, a fat-suppressed T2-weighted sagittal sequence of MRIs is recommended for the accurate evaluation of posterior ligament complex injury and would be helpful in the selection of treatment options.

Successful short-segment instrumentation and fusion for thoracolumbar spine fractures: a consecutive 41/2-year series

STUDY DESIGN

A retrospective review of all the surgically managed spinal fractures at the University of Missouri Medical Center during the 41/2-year period from January 1989 to July 1993 was performed. Of the 51 surgically managed patients, 46 were instrumented by short-segment technique (attachment of one level above the fracture to one level below the fracture). The other 5 patients in this consecutive series had multiple trauma. These patients were included in the review because this was a consecutive series. However, they were grouped separately because they were instrumented by long-segment technique because of their multiple organ system injuries.

OBJECTIVES

The choice of the anterior or posterior approach for short-segment instrumentation was based on the Load-Sharing Classification published in a 1994 issue of Spine. The purpose of this review was to demonstrate that grading comminution by use of the Load-Sharing Classification for approach selection and the choice of patients with isolated fractures who are cooperative with spinal bracing for 4 months provide the keys to successful short-segment treatment of isolated spinal fractures.

SUMMARY OF BACKGROUND DATA

The current literature implies that the use of pedicle screws for short-segment instrumentation of spinal fracture is dangerous and inappropriate because of the high screw fracture rate.

METHODS

Charts, operative notes, preoperative and postoperative radiographs, computed tomography scans, and follow-up records of all patients were reviewed carefully from the time of surgery until final follow-up assessment. The Load-Sharing Classification had been used prospectively for all patients before their surgery to determine the approach for short-segment instrumentation. Denis' Pain Scale and Work Scales were obtained during follow-up evaluation for all patients.

RESULTS

All patients were observed over 40 months except for 1 patient who died of unrelated causes after 35 months. The mean follow-up period was 66 months (51/2 years). No patient was lost to follow-up evaluation. Prospective application of the Load-Sharing Classification to the patients' injury and restriction of the short-segment approach to cooperative patients with isolated spinal fractures (excluding multisystem trauma patients) allowed 45 of 46 patients instrumented by the short-segment technique to proceed to successful healing in virtual anatomic alignment.

CONCLUSIONS

The Load-Sharing Classification is a straightforward way to describe the amount of bony comminution in a spinal fracture. When applied to patients with isolated spine fractures who are cooperative with 3 to 4 months of spinal bracing, it can help the surgeon select short-segment pedicle-screw-based fixation using the posterior approach for less comminuted injuries and the anterior approach for those more comminuted. The choice of which fracture-dislocations should be strut grafted anteriorly and which need only posterior short-segment pedicle-screw-based instrumentation also can be made using the Load-Sharing Classification.

Epstein-Barr virus involvement in gastric cancer: biomarker for lymph node metastasis

EBV involvement in gastric cancer is characterized by episomal monoclonality, high antibody titers, EBV encoded small RNA and EBV nuclear antigen 1 expression in all tumor cells, and in the intramucosal stage, by a unique morphology. EBV involvement varies by population (approximately 7% of gastric cancers in Japan and >15% in Western countries), sex, histological type, and tumor location. The present study compares frequency of lymph node metastasis (LNM) between 170 EBV-positive and 1590 EBV-negative gastric cancer cases in Japan by level of invasiveness. Frequency of LNM increased with increasing depth of invasiveness but was consistently and significantly greater for EBV-negative cases (P = 0.0018). In particular, there were no instances of LNM among 75 EBV-positive cases as compared with 53 among 562 EBV-negative cases restricted to the mucosa and submucosa (odds ratio, 0; 95% confidence limits, 0-0.20). The finding suggests that genetic control of metastasis may differ between EBV-related and other gastric cancers. Also, the possibility that EBV-positive, noninvasive gastric cancers may not require lymph node dissection suggests that routine assay of biopsy specimens for EBV involvement could be important in populations, like that of Japan, where early gastric cancers are seen frequently.

Thoracic and lumbar trauma: rationale for selecting the appropriate fusion technnique

Despite recent advances in surgical techniques and instrumentation, two issues in the treatment of thoracic and lumbar remain contested: (1) the indications for surgical intervention; and (2) the optimal approach to obtain decompression, realignment, and fusion of the disrupted segment (anterior, posterior, or combined). Choosing among the options requires the ability to define accurately the extent of the injury to both the structural and the neurologic elements of the spine as well as an appreciation of the historic rationale of individual treatment methods.

Spontaneous remodeling of the spinal canal after conservative management of thoracolumbar burst fractures

STUDY DESIGN

Forty-two conservatively treated patients with a burst fracture of the thoracic, thoracolumbar, or lumbar spine with more than 25% stenosis of the spinal canal were reviewed more than 1 year after injury to investigate spontaneous remodeling of the spinal canal.

OBJECTIVES

To investigate the natural development of the changes in the spinal canal after thoracolumbar burst fractures.

SUMMARY OF THE BACKGROUND DATA

Surgical removal of bony fragments from the spinal canal may restore the shape of the spinal canal after burst fractures. However, it was reported that restoration of the spinal canal does not affect the extent of neurologic recovery.

METHODS

Using computerized tomography, the authors compared the least sagittal diameter of the spinal canal at the time of injury with the least sagittal diameter at the follow-up examination.

RESULTS

Remodeling and reconstitution of the spinal canal takes place within the first 12 months after injury. The mean percentage of the sagittal diameter of the spinal canal was 50% of the normal diameter (50% stenosis) at the time of the fracture and 75% of the normal diameter (25% stenosis) at the follow-up examination. The correlation was positive between the increase in the sagittal diameter of the spinal canal and the initial percentage stenosis. There was a negative correlation between the increase in the sagittal diameter of the spinal canal and age at time of injury. Remodeling of the spinal canal was not influenced by the presence of a neurologic deficit.

CONCLUSION

Conservative management of thoracolumbar burst fractures is followed by a marked degree of spontaneous redevelopment of the deformed spinal canal. Therefore, this study provides a new argument in favor of the conservative management of thoracolumbar burst fractures.

Long-term results of pedicle stabilized thoracolumbar fractures in relation to the neurological deficit

88 patients with thoracolumbar fractures and short-segment (mono or two segment) pedicle instrumentation from the years 1985-92 had a follow-up examination after an average time of 5.6 years. The 56 men and 32 women had an average age of 32.6 years at the time of injury, 24 patients primarily had a complete and 43 patients an incomplete paraplegia, 21 patients showed no neurological deficits. The operative decompression of the spinal cord and stabilization of the injured spine by short segment pedicle instrumentation led to a complete or partial remission of the neurological deficits in 93% of the patients with incomplete paraplegia. Operative stabilization allowed an early mobilization and rehabilitation of these patients. We found no tendency to an increased complication rate in patients with neurological deficits compared to patients without neurological deficits. Patients with initially incomplete paraplegia complained more often about pain than all the other patients. Despite intensive rehabilitation and retraining programs handicapped patients had obvious disadvantages regarding their further careers.

Thoracolumbar spine injuries

This article reviews some of the anatomic and mechanical aspects of thoracolumbar injuries as they relate to classification systems and stability. In addition, an overview of the initial management including surgical and conservative treatment options is provided.

Three-dimensional computed tomographic imaging in the diagnosis of vertebral column trauma: experience based on 21 patients and review of the literature

OBJECTIVE

To compare standard x-ray films, two-dimensional computed tomographic reconstructions and three-dimensional (3-D) computed tomographic reconstructions for assessing the grade, extent, and severity of vertebral fracture.

PATIENTS AND METHODS

3-D images were created from standard computed tomographic scans obtained using a General Electric PACE scanner. In 21 patients (17 men and four women) these images were obtained during both the acute phase and at long-term follow-up; there were six cervical, four dorsal, five dorso-lumbar, and six lumbar fractures.

RESULTS

The 3-D images supplied useful information in complex traumas with rotation and/or dislocation of the vertebral body and in cases with loss of spinal alignment. The 3-D images also proved to be useful as an adjunctive imaging method for evaluation of bone fusion integrity.

CONCLUSION

3-D images produced by recently available software provide a 3-D understanding much more readily than do multiple two-dimensional images. Because it would be very difficult to standardize this method of imaging, it seems best that the specialist (orthopedic surgeon, neurosurgeon, neuroradiologist) be present during the investigation to decide the viewing angles. An important limitation to this method is the presence of degenerative disease or osteoporosis, mainly in elderly patients.

Selection criteria and outcome of operative approaches for thoracolumbar burst fractures with and without neurological deficit

Criteria for choosing operative techniques for the treatment of thoracolumbar burst fractures remain disputed, particularly in neurologically intact patients. A retrospective study of 25 patients with thoracolumbar burst fractures was performed to assess fracture characteristics, operative approaches, fixation, radiographic results, and neurological, functional, and pain outcomes. Anterior corpectomy, allograft strut, and plate fixation were performed in 14 patients with or without neurological deficit when vertebral compression or canal encroachment was at least 40% or kyphosis was 15 degrees or more with a stable posterior column. In nine cases, an anterior operation and a posterior segmental fixation were combined for similar deformity and three-column instability. Posterior transpedicular decompression, fixation, and fusion were used primarily for two symptomatic patients with less than 40% encroachment and at most 40% compression. Overall, 21 patients (84%) were walking and 18 (72%) were continent at follow-up evaluation (mean 16.3 months) versus eight (32%) and 11 (44%) at presentation, respectively. Preoperatively, 17 patients experienced neurological deficit; 16 improved and 12 increased one Frankel grade. No patient deteriorated. Prior employment or activity level was resumed by 19 patients (76%) and only four patients professed incapacity. Pain was eliminated after 18 procedures (72%), all anterior or combined approaches. Restoration of anatomical alignment (< 5 degrees) was achieved in 19 cases. No anterior construct failed and only one patient treated posteriorly had postoperative kyphosis progression. Operative morbidity occurred in three cases (12%). Satisfactory neurological and functional outcomes were achieved in a majority of patients with thoracolumbar burst fractures after correction of canal compromise, middle column compression, and attendant deformity. These results indicate that anterior decompression and a weight-bearing strut graft are critical to clinical success in patients with significant vertebral destruction.

Emergency department approach to acute thoracolumbar spine injury

This review provides a literature-based approach to the management of acute thoracolumbar spine (TLS) injury. The epidemiology of spinal cord injury and pertinent spinal cord anatomy are reviewed. A review of current TLS fracture/dislocation classification schemes is provided. The principal focus of this review is the immediate diagnostic and therapeutic interventions needed to maximize the recovery of patients with acute TLS injury.

Unstable vertebral fractures in the lower third of the spine treated with closed reduction and transpedicular posterior fixation: a retrospective analysis of 82 fractures in 78 patients

Seventy-eight patients were treated with closed reduction and transpedicular fixation for 82 spine fractures. The fractures were localised in the lower third of the spine and were all, according to the Denis classification, considered unstable. Eighteen patients had neurological deficiencies. One patient with a fracture in T11 was completely paraplegic, four patients had a cauda equina syndrome while the rest had radicular symptoms only. Primary reconstruction of the vertebral height and the physiological curves of the spine was satisfactorily obtained. An improvement in the neurological symptoms was observed in all patients with fractures distal to the spinal cord, while the patient with the dislocated fracture of T11 remained completely paraplegic during the follow-up. The complication rate of the transpedicular fixation method used reported by other authors could not be confirmed in our material. Iatrogenic neurological damage was not observed. A partial loss in the correction of the traumatic kyphosis was observed after removal of the implant in 11 patients.

Restoration of the spinal canal by the internal fixator and remodeling

It has been observed that after reduction of an unstable vertebral fracture, treated either conservatively or operatively, the encroachment of the spinal canal remaining after reduction can decrease considerably with time. A series of 31 cases, each with a set of CT scans taken preoperatively, immediately after surgery and after implant removal respectively, was assessed using computer-aided planimetry. The mean initial narrowing of the spinal canal was 44.6%. Through surgery this was decreased by 20.4%, leaving a remaining deficit of 24.2%. After implant removal, 15 months after trauma and surgery, the area of the spinal canal increased a further 17.4%, leaving a remaining deficit of only 6.8%. Comparing the values of the spinal canal for T12-L5 directly after surgery and after implant removal, an almost identical degree of restoration for each level can be seen. This additional and gradual restoration of the spinal canal is termed remodeling. This study demonstrates that a residual postoperative narrowing of the spinal canal of up to 25% can be ignored, provided there is no initial neurologic damage.

Thoracolumbar burst fracture: evaluating stability

The burst fracture is an injury characterized by anterior vertebral body height loss and retropulsion of the posterior aspect of the vertebral body into the spinal canal. The vertebral body injury frequently is associated with fractures through the neural arch. Using a three-column concept of spinal stability, the division of these fractures into stable and unstable injuries is difficult. Radiographic signs of instability include widening of the interspinous and interlaminar distance, translation of more than 2mm, kyphosis of more than 20 degrees, dislocation, height loss of more than 50%, and articular process fractures. However, fractures may be unstable in the absence of these signs. Unrecognized supraspinous ligament disruption contributes to this instability. This structure is best evaluated by MR examination. Confirmation of posterior ligamentous disruption occurring in conjunction with the burst fracture leads to reevaluation of the presumed mechanism of injury. This article discusses the many issues surrounding the division of burst fractures into stable and unstable injuries and reexamines the common classification systems of thoracolumbar spine injuries.

A clinical study of the natural remodeling of burst fractures of the lumbar spine

Surgical decompression and fixation are considered by many to be the preferred treatment for burst fractures of the lumbar spine, regardless of neurologic deficit. For 6 patients with burst fracture of the lumbar spine but without neurologic deficit, computed tomography scans revealed >50% encroachment of the spinal canal. All 6 patients were treated conservatively, and during the followup period (range, 6-49 months), the narrowing of the spinal canal decreased progressively because of resorption of the fragments and natural remodeling. The presence of a neurologic deficit should be the primary indication for surgery in patients with a burst fracture of the lumbar spine.

Combined repair of a traumatic rupture of the aorta and anterior stabilization of a thoracic spine fracture: a case report

The combination of traumatic aortic rupture and spine fracture is rare. We describe the treatment of both injuries in a one-stage procedure with good results in a 47-year-old woman.

Surgical approaches for the correction of unstable thoracolumbar burst fractures: a retrospective analysis of treatment outcomes

The authors retrospectively studied 49 nonparaplegic patients who sustained acute unstable thoracolumbar burst fractures. All patients underwent surgical treatment and were followed for an average of 27 months. All but one patient achieved solid radiographic fusion. Three treatment groups were studied: the first group of 16 patients underwent anterior decompression and fusion with instrumentation; the second group of 27 patients underwent posterior decompression and fusion; and the third group of six patients had combined anterior-posterior surgery. Prior to surgical intervention, these groups were compared and found to be similar in age, gender, level of injury, percentage of canal compromise, neurological function, and kyphosis. Patients treated with posterior surgery had a statistically significant diminution in operative time and blood loss and number of units transfused. There were no significant intergroup differences when considering postoperative kyphotic correction, neurological function, pain assessment, or the ability to return to work. Posterior surgery was found to be as effective as anterior or anterior-posterior surgery when treating unstable thoracolumbar burst fractures. Posterior surgery, however, takes the least time, causes the least blood loss, and is the least expensive of the three procedures.