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Biomechanics of Thoracolumbar Burst and Chance-Type Fractures during Fall from Height.

ABSTRACT: Study Design In vitro biomechanical study. Objective To investigate the biomechanics of thoracolumbar burst and Chance-type fractures during fall from height. Methods Our model consisted of a three-vertebra human thoracolumbar specimen (n = 4) stabilized with muscle force replication and mounted within an impact dummy. Each specimen was subjected to a single fall from an average height of 2.1 m with average velocity at impact of 6.4 m/s. Biomechanical responses were determined using impact load data combined with high-speed movie analyses. Injuries to the middle vertebra of each spinal segment were evaluated using imaging and dissection. Results Average peak compressive forces occurred within 10 milliseconds of impact and reached 40.3 kN at the ground, 7.1 kN at the lower vertebra, and 3.6 kN at the upper vertebra. Subsequently, average peak flexion (55.0 degrees) and tensile forces (0.7 kN upper vertebra, 0.3 kN lower vertebra) occurred between 43.0 and 60.0 milliseconds. The middle vertebra of all specimens sustained pedicle and endplate fractures with comminution, bursting, and reduced height of its vertebral body. Chance-type fractures were observed consisting of a horizontal split fracture through the laminae and pedicles extending anteriorly through the vertebral body. Conclusions We hypothesize that the compression fractures of the pedicles and vertebral body together with burst fracture occurred at the time of peak spinal compression, 10 milliseconds. Subsequently, the onset of Chance-type fracture occurred at 20 milliseconds through the already fractured and weakened pedicles and vertebral body due to flexion-distraction and a forward shifting spinal axis of rotation.

SUBMITTER: Ivancic PC

PROVIDER: S-EPMC4111950 | biostudies-other | 2014 Aug

REPOSITORIES: biostudies-other

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Project description:ObjectiveThis study aimed to compare the clinical and radiological results of percutaneous mesh-container-plasty (PMCP) versus percutaneous kyphoplasty (PKP) in the treatment of osteoporotic thoracolumbar burst fractures.MethodsA prospective study of 122 patients with osteoporotic thoracolumbar burst fractures was conducted. The patients were nonrandomly assigned to receive PKP (62; 16 men, 46 women) and PMCP (60; 14 men, 46 women). The epidemiological data, surgical outcomes, and clinical and radiological features were compared between the 2 groups. Cement leakage, height restoration, deformity correction, canal compromise, and cement distribution were calculated from the radiographs. Visual pain analog scale (VAS), the Oswestry disability index (ODI), and short-form 36 health survey domains role physical (SF-36 rp) and bodily pain (SF-36 bp) were calculated before surgery and immediately and 2 years after surgery.ResultsAlthough VAS, ODI, SF-36 bp, and SF-36 rp scores improved from 7 (6-9), 71.28±16.38, 22 (0-32), and 25 (0-50) preoperatively to 2 (1-3), 20.02±8.97, 84 (84-84), and 75 (75-100) immediately postoperatively in the PMCP group (p<0.05) and from 7 (6-8), 71.40±13.52, 22 (10.5-31.75), and 25 (0-50) preoperatively to 2 (1-3), 21.78±11.21, 84 (84-84), and 75 (75-100) immediately postoperatively in the PKP group (p<0.05), there was no difference between the 2 groups. The mean cost in the PKP group was less than that in the PMCP group ($5109±231 vs. $6699±201, p<0.05). Anterior, middle, and posterior vertebral body height ratios in the PMCP group were greater than those in the PKP group postoperatively (88.44%±3.76% vs. 81.10%±11.78%, 86.15%±3.50% vs. 82.30%±11.02%, and 93.91%±3.01% vs. 91.43%±6.71%, respectively, p<0.05). The Cobb angle in the PMCP group was lower than that in the PKP group postoperatively (6.67°±4.39° vs. 8.99°±4.06°, p<0.05). Cement distribution in the PMCP group was higher than that in the PKP group (30.48%±5.62% vs. 27.18%±4.87%, p<0.05). Cement leakage was observed to be lesser in the PMCP group (2/60) than in the PKP group (10 vs. 62, p<0.05).ConclusionBoth PKP and PMCP treatments seem to have significant ability in pain relief and functional recovery. Despite its higher cost, PMCP treatment may have a better inhibition ability of cement leakage, cement distribution, height restoration, and improvement in segmental kyphosis than PKP treatment for osteoporotic thoracolumbar burst fractures.Level of evidenceLevel II, Therapeutic Study.

Project description:BackgroundThoracolumbar burst fractures are a common traumatic vertebral fracture in the spine, and pedicle screw fixation has been widely performed as a safe and effective procedure. However, after the stabilization of the thoracolumbar burst fractures, whether or not to remove the pedicle screw implant remains controversial. This review aimed to assess the benefits and risks of pedicle screw instrument removal after fixation of thoracolumbar burst fractures.MethodsData sources, including PubMed, EMBASE, Cochrane Library, Web of Science, Google Scholar, and Clinical trials.gov, were comprehensively searched. All types of human studies that reported the benefits and risks of implant removal after thoracolumbar burst fractures, were selected for inclusion. Clinical outcomes after implant removal were collected for further evaluation.ResultsA total of 4051 papers were retrieved, of which 35 studies were eligible for inclusion in the review, including four case reports, four case series, and 27 observational studies. The possible risks of pedicle screw removal after fixation of thoracolumbar burst fractures include the progression of the kyphotic deformity and surgical complications (e.g., surgical site infection, neurovascular injury, worsening pain, revision surgery), while the potential benefits of pedicle screw removal mainly include improved segmental range of motion and alleviated pain and disability. Therefore, the potential benefits and possible risks should be weighed to support patient-specific clinical decision-making about the removal of pedicle screws after the successful fusion of thoracolumbar burst fractures.ConclusionsThere was conflicting evidence regarding the benefits and harms of implant removal after successful fixation of thoracolumbar burst fractures, and the current literature does not support the general recommendation for removal of the pedicle screw instruments, which may expose the patients to unnecessary complications and costs. Both surgeons and patients should be aware of the indications and have appropriate expectations of the benefits and risks of implant removal. The decision to remove the implant or not should be made individually and cautiously by the surgeon in consultation with the patient. Further studies are warranted to clarify this issue.Level of evidencelevel 1.

Project description:BackgroundPosterior short-segment pedicle screw fixation is used to treat thoracolumbar burst fractures. However, no randomized controlled studies have compared the efficacy of the two approaches--the Wiltse's paraspinal approach and open book laminectomy in the treatment of thoracolumbar burst fractures with greenstick lamina fractures.Materials and methodsPatients with burst fractures of the thoracolumbar spine without neurological deficit were randomized to receive either the Wiltse's paraspinal approach (group A, 24 patients) or open book laminectomy (group B, 23 patients). Patients were followed postoperatively for average of 27.4 months. Clinical and radiographic data of the two approaches were collected and compared.ResultsOur results showed the anterior segmental height, kyphotic angle, visual analog scale (VAS) score, and Smiley-Webster Scale (SWS) score significantly improved postoperatively in both groups, indicating that both the Wiltse's paraspinal approach and open book laminectomy can effectively treat thoracolumbar burst fractures with greenstick lamina fractures. The Wiltse's paraspinal approach was found to have significantly shorter operating time, less blood loss, and shorter length of hospital stay compared to open book laminectomy. However, there were two (2/24) patients in group A that had neurological deficits postoperatively and required a second exploratory operation. Dural tears and/or cauda equina entrapment were subsequently found in four patients in group B and all two patients of neurological deficits in group A during operation. No screw loosening, plate breakage, or other internal fixation failures were found at final follow-up.ConclusionsThe results demonstrated that either of the two surgical approaches can achieve satisfactory results in treating thoracolumbar burst fractures in patients with greenstick lamina fractures. However, if there is any clinical or radiographic suspicion of a dural tear and/or cauda equina entrapment pre-operation, patients should receive an open book laminectomy to avoid a second exploratory operation. More research is still needed to optimize clinical decision-making regarding surgical approach.

Project description:BackgroundFor thoracolumbar burst fractures, traditional four-screw (one above and one below) short-segment instrumentation is popular and has a high failure rate. Additional augmentation at the fractured vertebrae is believed to reduce surgical failure. The purpose of this study was to examine the clinical and radiographic results of patients who underwent short-segment posterior instrumentation with augmentation by screws and bone substitutes at the fractured vertebrae and to compare these data to those of patients who underwent long-segment instrumentation for thoracolumbar burst fractures.MethodsThe study group had twenty patients who underwent short-segment instrumentation with additional augmentation by two screws and bone substitutes at the fractured vertebrae. The control group contained twenty-two patients who underwent eight-screw long instrumentation without vertebra augmentation. Local kyphosis and the anterior body height of the fractured vertebrae were measured. The severity of the fractured vertebrae was evaluated with the load sharing classification (LSC). Any implant failure or loss of correction >10° at the final follow-up was defined as surgical failure.ResultsBoth groups had similar distributions in terms of age, sex, the injured level, and the mechanism of injury before operation. During the operation, the study group had significantly less blood loss (136.0 vs. 363.6 ml, p=0.001) and required shorter operating times (146.8 vs. 157.5 minutes, p=0.112) than the control group. Immediately after surgery, the study group had better correction of the local kyphosis angle (13.4° vs. 11.9°, p=0.212) and restoration of the anterior height (34.7% vs. 31.0%, p=0.326) than the control group. At the final follow-up, no patients in the study group and only one patient in the control group experienced surgical failure.ConclusionsPatients with thoracolumbar burst fractures who received six-screw short-segment posterior fixators with augmentation at the level of the fractured vertebrae via injectable artificial bone substitute achieved satisfactory clinical and radiographic results, and this method could replace long-segment instrumentation methods used in unstable thoracolumbar burst fractures.

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Biomechanics of Thoracolumbar Burst and Chance-Type Fractures during Fall from Height.

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