OBJECTIVETo compare the influence of normal and degenerative discs on stress distribution of the thoracolumbar vertebrae under destructive load, explore the biomechanical background and clinical meaning and provide theoretical basis for clinical diagnosis and treatment.

METHODSA mechanical model of thoracolumbar motion segment of normal and degenerative discs was built with a three dimensional finite element method and three stresses of vertical compression, compressive flexion and distractive flexion were comparatively analyzed.

RESULTSWith vertical compression and compressive flexion loads, the thoracolumbar motion segment of the normal disc showed that the central part of the upper and lower end-plates of the vertebrae and the central part of the trabecular bone adjacent to the end-plate were loaded with the most intensive stresses, meanwhile, the postero-lateral part of the annulus fibrosus was concentrated with stresses. Degenerative disc showed that the stress distribution of the trabecular bone was relatively averaged, the stresses of the central part adjacent to the end-plate were low, while at the same time, the stresses of the peripheral part were elevated relatively. With distraction flexion load, the stresses of the cortex bone, trabecular bone, end-plate and annulus fibrosus of the thoracolumbar vertebrae of degenerative discs were low, meanwhile, the stresses of the posterior structure of the vertebral body were relatively elevated compared with that of normal discs.

CONCLUSIONSThere is difference in influence between normal and degenerative discs on the stress distribution of the thoracolumbar vertebrae with destructive load. The transferring way of load is changed after disc degeneration.

Elasticity ; Finite Element Analysis ; Humans ; Lumbar Vertebrae ; physiology ; Spinal Injuries ; physiopathology ; Stress, Mechanical ; Tensile Strength ; Thoracic Vertebrae ; physiology

Fins incorporated into the design of a dynamic cervical spine implant have been employed to enhance axial load- bearing ability, yet their true biomechanical advantages, if any, have not been defined. Therefore, the goal of this study was to assess the biomechanical and axial load-bearing contributions of the fin components of the DOC ventral cervical stabilization system. Eighteen fresh cadaveric thoracic vertebrae (T1-T3) were obtained. Three test conditions were devised and studied: Condition A (DOC implants with fins were placed against the superior endplate and bone screws were not inserted) ; Condition B (DOC implant without fins was placed and bone screws were inserted) ; and Condition C (DOC implant with fins were placed against the superior endplate and bone screws were inserted). Specimens were tested by applying a pure axial compressive load to the superior platform of the DOC construct, and load-displacement data were collected. Condition C specimens had the greatest stiffness (459 +/- 80N/mm) and yield load (526 +/- 168N). Condition A specimens were the least stiff (266 +/- 53N/mm), and had the smallest yield loads (180 +/- 54N). The yield load of condition A plus condition B was approximately equal to that of condition C, with condition A contributing about one-third and condition B contributing two-thirds of the overall load-bearing capacity. Although the screws alone contributed to a substantial portion of axial load-bearing ability, the addition of the fins further increased load-bearing capabilities.
*Bone Plates ; Bone Screws ; Humans ; In Vitro ; Spinal Fusion/*instrumentation ; Thoracic Vertebrae/*physiology/*surgery ; *Weight-Bearing

OBJECTIVETo test the changes of the stiffness of the intact, released, and instrumented spines in an in vitro porcine model.

METHODSTwelve porcine spines (12 segments each) were harvested for the biomechanical tests with Material Test System. Stiffness during flexion, extension, lateral bending, and axial rotation were recorded; then the specimen was released with intervertebral discs and the facet joints removed, followed by repeating the biomechanical tests for stiffness; and finally, a double-rod titanium construct was applied for internal fixation to each released spine and stiffness tests were repeated again.

RESULTSCompared with the intact porcine spines [stiffness during flexion, extension, lateral bending, and axial rotation was 52.89 +/- 15.98, 105.43 +/- 56.38, 42.09 +/- 14.73, and (16.94 +/- 4.85) N x mm/degrees, respectively], the stiffness of the released porcine spines [stiffness during flexion, extension, lateral bending, and axial rotation was 44.04 +/- 13.73, 41.46 +/- 10.80, 31.75 +/- 7.23, and (9.10 +/- 2.07)N x mm/degrees, respectively] significantly decreased (P < 0.05), while significantly increased stiffness was found in the instrumented porcine spines [stiffness during flexion, extension, lateral bending, and axial rotation was 385.96 +/- 143.25, 138.96 +/- 59.41, 152.56 +/- 87.15, and (55.91 +/- 16.49) N x mm/degrees, respectively] (P < 0.05).

CONCLUSIONHigher instant stiffness was found in instrumented spine than the intact one during flexion, extension, lateral bending and axial rotation.

Animals ; Biomechanical Phenomena ; Diskectomy ; Fracture Fixation, Internal ; Internal Fixators ; Lumbar Vertebrae ; surgery ; Range of Motion, Articular ; physiology ; Spinal Fusion ; methods ; Spine ; surgery ; Stress, Mechanical ; Swine ; Thoracic Vertebrae ; surgery

OBJECTIVE: To discuss the relation between degree of body impairment and that of thoracolumbar spinal injuries resulting from road traffic accidents, and sum up the experiences in body impairment assessment and its regularity. METHODS: For comprehensive body impairment assessment, 477 cases of thoracolumbar spinal injuries in road accidents have been sorted out, reassessed and rediagnosed. In addition, analyses have been undertaken about their treatment, the assessment of the degree of their thoracolumbar dysfunction,nerve dysfunction and the relations between injuries and sequelaes. RESULTS: The analyses show that the degree of thoracolumbar dysfunction and that of the post-injury nerve dysfunction don't necessarily depend on the quantity and degree of spinal injuries. However, the position suffering from the thoracolumbar spinal injuries has an immense impact on the thoracolumbar dysfunction, and the nerve impairment result mainly from the T1-1L spinal injuries. The research also shows that there has been a high misdiagnosis rate in hospital about the spinal injuries. CONCLUSION In body impairment assessment, the cause and effect relations between the injury and degree of injury extent should be analyzed, the injury extent should be employed as principal evidence, and the degree of spinal dysfunction should be taken into greater consideration.
Accidents, Traffic ; Adolescent ; Adult ; Age Distribution ; Aged ; Aged, 80 and over ; Disability Evaluation ; Female ; Humans ; Injury Severity Score ; Lumbar Vertebrae/physiology* ; Male ; Middle Aged ; Nervous System/physiopathology* ; Retrospective Studies ; Spinal Injuries/physiopathology* ; Thoracic Vertebrae/physiology* ; Young Adult

Electrophysiologic examination of dorsal spinal cord injury (DSCI) is focused on transcranial magnetic stimulation induced motor evoked potentials. It were recorded at thenar muscles, exector spinae muscle, intercostals muscle, and internal oblique muscles. In complete spinal cord injury, the exector musle motor evoked potentials may occur although clinically that muscle shows no recovery. The ipsilateral exector and internal oblique muscles may be distributed by non-cross fibers in cerebrospinal tract. The progress in clinical sensory examination includes cutaneous electrical perceptional sensory threshold and quantitative sensory test. The former is more sensitive than two-points discrepentive test. Quantitative sensory test includes light touch threshold, vibration perceptual threshold, thermal threshold, pain, and cutaneous axon flare respone. It has been used in DSCI patients above and below the injury level. The thermal threshold elevates above the injury level in complete and incomplete DSCI patients.
Electric Stimulation ; Electromagnetic Fields ; Electromyography ; Evoked Potentials, Motor ; Evoked Potentials, Somatosensory ; Humans ; Neurologic Examination ; methods ; standards ; Sensory Thresholds ; physiology ; Spinal Cord Injuries ; physiopathology ; Thoracic Vertebrae

Since the late 20th century owing to the improvement of spinal surgery techniques, the diagnosis and treatment of thoracolumbar fracture have been perfected more and more. Although the advent of modern spinal surgery in China was late, we have gained some advanced achievements owing to various international communications benefited from the open policy. Therefore, it is essential to evaluate the current status and perspective of diagnosis and treatment of thoracolumbar fracture. There are several issues we would like to discuss here.
China ; Female ; Follow-Up Studies ; Fracture Fixation ; standards ; trends ; Fracture Healing ; physiology ; Humans ; Injury Severity Score ; Lumbar Vertebrae ; injuries ; Male ; Quality of Health Care ; Spinal Cord Injuries ; prevention & control ; Spinal Fractures ; diagnosis ; surgery ; Thoracic Vertebrae ; injuries

OBJECTIVE: We report magnetic resonance imaging (MRI) findings on focal anterior displacement of the thoracic spinal cord in asymptomatic patients without a spinal cord herniation or intradural mass. MATERIALS AND METHODS: We identified 12 patients (male:female = 6:6; mean age, 51.7; range, 15-83 years) between 2007 and 2011, with focal anterior displacement of the spinal cord and without evidence of an intradural mass or spinal cord herniation. Two radiologists retrospectively reviewed the MRI findings in consensus. RESULTS: An asymmetric spinal cord deformity with a focal dented appearance was seen on the posterior surface of the spinal cord in all patients, and it involved a length of 1 or 2 vertebral segments in the upper thoracic spine (thoracic vertebrae 1-6). Moreover, a focal widening of the posterior subarachnoid space was also observed in all cases. None of the patients had myelopathy symptoms, and they showed no focal T2-hyperintensity in the spinal cord with the exception of one patient. In addition, cerebrospinal fluid (CSF) flow artifacts were seen in the posterior subarachnoid space of the affected spinal cord level. Computed tomography myelography revealed preserved CSF flow in the two available patients. CONCLUSION: Focal anterior spinal cord indentation can be found in the upper thoracic level of asymptomatic patients without a spinal cord herniation or intradural mass.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Cerebrospinal Fluid/physiology ; Female ; Hernia/pathology ; Humans ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Retrospective Studies ; Spinal Cord Diseases/pathology/*radiography/surgery ; Spine/pathology/radiography ; Thoracic Vertebrae/pathology/*radiography ; Tomography, X-Ray Computed ; Young Adult

OBJECTIVETo analyze the pathogenic mechanism and the clinical significance of post-traumatic thoracolumbar syringomyelia through reviewing the clinical manifestations.

METHODSThe data of 15 patients (14 males and 1 female, aged from 28 to 56 years, with an average of 36 years) with post-traumatic syringomyelia treated in our hospital from December 1997 to February 2002 were studied retrospectively. Two patients suffered from T11 fractures, 7 from T12 fractures and 6 from L1 fractures. There were 12 patients with burst fractures and 3 with fracture dislocations. Anterior decompression, bone graft, bone fusion and internal fixation were made on 6 patients, posterior decompression, bone graft, bone fusion and internal fixation on 1 patient, and non-surgical treatment on 8 patients.

RESULTSSyringomyelia of the patients was diagnosed accurately with magnetic resonance imaging at 0.5-4 years after the original thoracolumbar fracture. The cavern was round in 6 cases, elliptic in 6 cases, and irregular in 3 cases. The patients also suffered from pain (80%), myodynamia attenuation in lower extremities (66.7%), aggravated spasm (46.7%), sensation loss or hypesthesia (46.7%), decreased coordinate function of lower extremities (20%) and autonomic nerve symptom (6.7%).

CONCLUSIONSPost-traumatic thoracolumbar syringomyelia should be suspected if the patient has new neurological symptoms, such as myodynamia attenuation in lower extremities, after the neural function becomes stable for certain time.

Adult ; Bone Transplantation ; methods ; Decompression, Surgical ; methods ; Female ; Follow-Up Studies ; Fracture Fixation, Internal ; methods ; Fracture Healing ; physiology ; Humans ; Lumbar Vertebrae ; injuries ; Magnetic Resonance Imaging ; Male ; Middle Aged ; Recovery of Function ; Retrospective Studies ; Risk Assessment ; Sampling Studies ; Spinal Fractures ; complications ; diagnosis ; Spinal Fusion ; methods ; Syringomyelia ; diagnosis ; etiology ; surgery ; Thoracic Vertebrae ; injuries ; Tomography, X-Ray Computed ; Treatment Outcome

INTRODUCTIONThis retrospective review aimed to examine the relationship between preoperative pulmonary function and the Cobb angle, location of apical vertebrae and age in adolescent idiopathic scoliosis (AIS). To our knowledge, there have been no detailed analyses of preoperative pulmonary function in relation to these three factors in AIS.

METHODSA total of 38 patients with thoracic or thoracolumbar scoliosis were included. Curvature of spinal deformity was measured using the Cobb method. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) were used to evaluate preoperative pulmonary function. Statistical methods were used to analyse the relationship between preoperative pulmonary function and the factors that may contribute to poor pulmonary function.

RESULTSThe mean age of the patients was 16.68 ± 6.04 years. An inverse relationship was found between the degree of the Cobb angle and FVC as well as FEV1; however, the relationships were not statistically significant (p = 0.057 and p = 0.072, respectively). There was also a trend towards a significant negative correlation between the thoracic curve and FVC (p = 0.014). Patients with larger thoracic curves had lower pulmonary function. A one-year increase in age significantly decreased FVC by 1.092 units (p = 0.044). No significant relationship between age and preoperative FEV1 was found. The median FVC was significantly higher in patients with affected apical vertebrae located at levels L1-L3 than at T6-T8 or T9-T12 (p = 0.006).

CONCLUSIONLung function impairment was seen in more severe spinal deformities, proximally-located curvature and older patients.

Adolescent ; Adult ; Female ; Follow-Up Studies ; Forced Expiratory Volume ; physiology ; Humans ; Kyphosis ; diagnosis ; physiopathology ; surgery ; Lumbar Vertebrae ; Lung ; physiopathology ; Male ; Preoperative Period ; Respiratory Function Tests ; Retrospective Studies ; Scoliosis ; diagnosis ; physiopathology ; surgery ; Severity of Illness Index ; Spinal Fusion ; methods ; Thoracic Vertebrae ; Young Adult

OBJECTIVETo investigate the diagnostic value of multidetector spiral CT (MSCT) in acute thoracolumbar spinal fracture and fracture-dislocation.

METHODSCT imaging files of 152 consecutive traumatic patients with thoracolumbar fractures were retrospectively reviewed. MSCT scannings were performed with a collimation of 3-5 mm and a pitch of 5.5. The postprocessing included sagittal and coronal multiplannar reconstruction, and 3-D reconstruction.

RESULTSThere were 88 cases of compression fracture, 54 cases of burst fracture and 10 cases of fracture-dislocation. Transverse images of MSCT could visualize all fractures directly and determine whether spinal canal was intact. Postprocessing image was helpful in depicting the displacement of fragment and orientation of dislocation.

CONCLUSIONSMSCT plays an important role in diagnosis and management of acute thoracolumbar spinal fracture and fracture-dislocation.

Adult ; Aged ; Cohort Studies ; Female ; Follow-Up Studies ; Fracture Fixation ; methods ; Fracture Healing ; physiology ; Humans ; Image Processing, Computer-Assisted ; Injury Severity Score ; Lumbar Vertebrae ; injuries ; Male ; Middle Aged ; Retrospective Studies ; Risk Assessment ; Sensitivity and Specificity ; Spinal Fractures ; diagnostic imaging ; surgery ; Thoracic Vertebrae ; injuries ; Tomography, Spiral Computed ; Treatment Outcome