Correlation between the schanz screw insertion angle and the loss of kyphosis correction in thoracolumbar fractures / Correlação entre o ângulo de inserção do pino de schanz e a perda de correção da cifose em fraturas toracolombares / Correlación entre el ángulo de inserción del tornillo de schanz y la pérdida de corrección de la cifosis en fracturas toracolumbares

ABSTRACT Objective To compare the Schanz screw insertion angle and the loss of the regional kyphosis correction in thoracolumbar burst fractures following posterior short instrumentation surgery. Methods Patients with a thoracolumbar burst fracture between levels T11-L2 were divided into two groups (parallel and divergent) according to the angle formed between the Schanz screw and the vertebral plateau. Regional kyphosis was evaluated in preoperative, immediate postoperative and last follow-up radiographs. Results Of the 58 patients evaluated, 31 had a parallel assembly and 27 had a divergent assembly. When we analyzed the angle of kyphosis, no statistical difference was observed between the pre- and postoperative radiographs. However, a statistical difference in the last follow-up radiographs and in the final loss of the kyphosis correction was confirmed. Conclusion The insertion of Schanz screws with a divergent assembly presents better radiographic results with less loss of kyphosis correction angle when compared with the parallel assembly technique. Level of Evidence III; Retrospective cohort study.

RESUMO Objetivo Comparar o ângulo de inserção do pino de Schanz e os resultados da perda de correção da cifose regional nas fraturas toracolombares do tipo explosão após tratamento cirúrgico com instrumentação curta por via posterior. Métodos Os pacientes com fratura toracolombar do tipo explosão entre os níveis de T11-L2 foram divididos em dois grupos (paralelo e divergente) de acordo com o ângulo formado entre o pino de Schanz e o platô vertebral. Foi avaliada a cifose regional nas radiografias pré-operatória, pós-operatória imediata e do último acompanhamento. Resultados Dos 58 pacientes avaliados, 31 apresentaram uma montagem paralela e 27 uma montagem divergente. Ao analisarmos o ângulo da cifose, não se observou diferença estatística nas radiografias pré- e pós-operatória imediata. Porém, verificou-se uma diferença estatística nas radiografias do último acompanhamento e na perda final de correção da cifose. Conclusões A inserção do pino de Schanz com uma montagem divergente apresenta melhores resultados radiográficos com menor perda do ângulo de correção da cifose quando comparada com a técnica de montagem paralela. Nível de Evidência III; Estudo de coorte retrospectivo.

RESUMEN Objetivo Comparar el ángulo de inserción del tornillo de Schanz y los resultados de la pérdida de corrección de la cifosis regional en las fracturas toracolumbares del tipo explosión después del tratamiento quirúrgico con instrumentación corta por vía posterior. Métodos Los pacientes con fractura toracolumbar del tipo explosión entre los niveles de T11-L2 fueron divididos en dos grupos (paralelo y divergente) de acuerdo con el ángulo formado entre el tornillo de Schanz y la meseta vertebral. Fue evaluada la cifosis regional en las radiografías preoperatoria, posoperatoria inmediata y del último acompañamiento. Resultados De los 58 pacientes evaluados, 31 presentaron un montaje paralelo y 27 un montaje divergente. Al analizar el ángulo de la cifosis, no se observó diferencia estadística en las radiografías pre y postoperatoria inmediata. Sin embargo, se verificó una diferencia estadística en las radiografías del último acompañamiento y en la pérdida final de corrección de la cifosis. Conclusiones La inserción del tornillo de Schanz con un montaje divergente presenta mejores resultados radiográficos con menor pérdida del ángulo de corrección de la cifosis cuando comparada con la técnica de montaje paralelo. Nivel de Evidencia III; Estudio de cohorte retrospectivo.

Comparison of short-segment and long-segment bone cement-augmented fixation combined with vertebroplasty in treatment of stage Ⅲ Kümmell disease / 中国修复重建外科杂志

Objective: To compare the effectiveness of short-segment and long-segment bone cement-augmented fixation combined with vertebroplasty in treatment of stage Ⅲ Kümmell disease. Methods: A clinical data of 44 patients with stage Ⅲ Kümmell disease met the selection criteria between January 2014 and December 2017 was retrospectively analyzed. Eighteen cases were treated with short-segment bone cement-augmented fixation combined with vertebroplasty (short-segment group) and 26 cases were treated with long-segment bone cement-augmented fixation combined with vertebroplasty (long-segment group). There was no significant difference in gender, age, disease duration, fracture segment, bone mineral density (T value), Frankle grading, and preoperative pain visual analogue scale (VAS) score, Oswestry disability index (ODI), anterior edge height of injured vertebrae, kyphosis Cobb angle, and thoracolumbar kyphosis (TLK) between the two groups ( P>0.05). The operation time, intraoperative blood loss, bone cement injection volume, bone cement leakage rate, VAS score, ODI, anterior edge height of injured vertebrae, kyphosis Cobb angle, and TLK were compared between the two groups. Results: The operation time and the intraoperative blood loss in the short- segment group were significant lower than those in the long-segment group ( P0.05). All patients were followed up 12-36 months, with an average of 24.4 months. The VAS score, ODI, anterior edge height of injured vertebrae, kyphosis Cobb angle, and TLK significantly improved at 1 week after operation and last follow-up in the two groups ( P0.05). At last follow-up, the neurological function of the two groups recovered, and there was no significant difference in Frankle grading between the two groups ( P>0.05). There were 3 cases (16.67%) of non-surgical vertebral fractures in the short-segment group and 6 cases (23.08%) in the long-segment group, showing no significant difference between the two groups ( P>0.05). Bone rejection occurred in 1 case in the short-segment group, and neither internal fixation failure nor collapse of the injured vertebrae occurred during follow-up. Conclusion: Both short-segment and long-segment bone cement-augmented fixation combined with vertebroplasty can achieve good effectiveness in treatment of stage Ⅲ Kümmell disease, and can maintain the height of the injured vertebra and prevent the collapse of the injured vertebra. Compared with long-segment fixation, short-segment fixation has the advantages of shorter operation time and less intraoperative bleeding.

Comparison of the short-segment and long-segment cement-augmented pedicle screw fixation for osteoporotic thoracolumbar fracture: A finite element study / 中国组织工程研究

BACKGROUND: Pedicle screw fixation combined with cement-augmented is an effective method for the treatment of severe osteoporotic vertebral fractures, but there is no uniform standard. The range of fixed segments is one of the focus of clinical controversy. OBJECTIVE: To establish a three-dimensional finite element model of the short-segment and long-segment cement-augmented pedicle screw fixation for osteoporotic thoracolumbar fracture, and to analyze the biomechanical characteristics of adjacent segment structures, fractured vertebral bodies and internal fixation devices. METHODS: The T 9 -L 5 segment of a volunteer without obvious degenerative disease was selected for CT scan. The CT images of Dicom format were obtained, and the engineering software was imported to establish a finite element geometric model to simulate the thoracolumbar fracture and the short-segment and long-segment cement-augmented pedicle screw fixation models. The relevant material parameters were set and the biomechanical characteristics of the two groups were compared and analyzed. RESULTS AND CONCLUSION: (1) The stress on the vertebrae was mainly concentrated on the periphery of the vertebral body and the small facet of the attachment. In the four directions flexion, extension, left-sided and right-sided curvature, the maximum stress of the proximal and distal adjacent vertebrae in the long-segment group was greater than that in the short-segment group. The stress of the intervertebral disc was mainly concentrated in the peripheral annulus. The maximum stress of the proximal and distal adjacent intervertebral discs was greater in the short -segment than in the long-segment, but the high stress area of the long-segment was larger than that of the short-segment. Therefore, long-segment fixation might accelerate the degeneration of adjacent segments.(2) The vertebral bodies of the long-segment group and the short-segment group were displaced to different extents, and the displacements in the left and right directions were the most obvious. In the six movement directions, the displacement and maximum stress of the injured segment of the short-segment group were greater than those of the long-segment group. So the long-segment fixation could better maintain the stability of the fractured vertebra. (3) The stress on the internal fixing device was mainly concentrated on the screws at both ends and the part of the rod. The maximum stress of the long-segment group was greater than that of the short-segment group, but the main stress area of the screws at both ends was smaller compared with the short- segment group.and the displacements in the left and right directions were the most obvious. In the six movement directions, the displacement and maximum stress of the injured segment of the short-segment group were greater than those of the long-segment group. So the long- segment fixation could better maintain the stability of the fractured vertebra. (3) The stress on the internal fixing device was mainly concentrated on the screws at both ends and the part of the rod. The maximum stress of the long-segment group was greater than that of the short-segment group, but the main stress area of the screws at both ends was smaller compared with the short-segment group.and the displacements in the left and right directions were the most obvious. In the six movement directions, the displacement and maximum stress of the injured segment of the short-segment group were greater than those of the long-segment group. So the long- segment fixation could better maintain the stability of the fractured vertebra. (3) The stress on the internal fixing device was mainly concentrated on the screws at both ends and the part of the rod. The maximum stress of the long-segment group was greater than that of the short-segment group, but the main stress area of the screws at both ends was smaller compared with the short-segment group.So the long-segment fixation could better maintain the stability of the fractured vertebra. (3) The stress on the internal fixing device was mainly concentrated on the screws at both ends and the part of the rod. The maximum stress of the long-segment group was greater than that of the short-segment group, but the main stress area of the screws at both ends was smaller compared with the short-segment group. So the long-segment fixation could better maintain the stability of the fractured vertebra. (3) The stress on the internal fixing device was mainly concentrated on the screws at both ends and the part of the rod. The maximum stress of the long-segment group was greater than that of the short-segment group, but the main stress area of the screws at both ends was smaller compared with the short-segment group.

Imaging evaluation of short-segment fixation and fusion for degenerative lumbar scoliosis assisted by highly selective nerve root block / 中国组织工程研究

BACKGROUND: Short-or long-segment fixation is still controversial in the treatment of adult degenerative lumbar scoliosis. OBJECTIVE: To investigate the effectiveness and feasibility of accurate treatment of short-segment fixation in adult degenerative lumbar scoliosis patients assisted by highly selective nerve root block. METHODS: Thirty-five patients with adult degenerative lumbar scoliosis treated in Chinese PLA General Hospital and People’s Hospital of Peking University from May 2014 to September 2017 were analyzed retrospectively, including 14 males and 21 females aged (64.2±8.1) years. The fixation segments were determined by a highly selective nerve root block. All patients were subjected to transforaminal lumbar interbody fusion. During the follow-up, visual analogue scale score and Oswestry disability index were evaluated. Parameters including lumbar curvature Cobb angle, lumbar lordosis angle, sacral slope, and pelvic tilt and interbody fusion condition were obtained by imaging; and complications were recorded. This study was approved by the Ethics Committee of Chinese PLA General Hospital and People’s Hospital of Peking University. RESULTS AND CONCLUSION: (1) Of the 35 patients, 27 underwent single-segment minimally invasive transforaminal lumbar fusion, 5 underwent double-segment minimally invasive transforaminal lumbar fusion, and 3 underwent three-segment minimally invasive transforaminal lumbar fusion. (2) The follow-up time of 35 patients was (25.6±1.5) months. All patients achieved the grade I fusion. Within 3 months, there were 3 cases of dural tear and cerebrospinal fluid leakage, 1 case of lower-extremity muscular venous thrombosis, 1 case of pneumonia and 1 case of wound fat liquefaction. Three months later, there was 1 case of adjacent segment degeneration; no nerve injury or nonunion, no screw or titanium rod breakage. (3) Visual analogue scale score, Oswestry disability index, Cobb angle, lumbar lordosis angle, sacral slope, and pelvic tilt at the last follow-up were significantly improved in 35 patients compared with those before surgery (P < 0.01). (4) Short-segment precision treatment of adult degenerative lumbar scoliosis with highly selective nerve root block can achieve good clinical effect.

Posterior short-segment fixation including the fractured vertebra for severe unstable thoracolumbar fractures / 中国修复重建外科杂志

Objective: To discuss the effectiveness of posterior short-segment fixation including the fractured vertebra for severe unstable thoracolumbar fractures using pedicle screw fixation.

COMPARISON OF SHORT SEGMENTAL FIXATION WITH AND WITHOUT FUSION IN TREATMENT OF THORACOLUMBAR BURST FRACTURE BY POSTERIOR APPROACH / 中国修复重建外科杂志

OBJECTIVE: To compare the effectiveness of short segmental pedicle screw fixation with and without fusion in the treatment of thoracolumbar burst fracture. METHODS: A retrospective analysis was made on the clinical data of 57 patients with single segment thoracolumbar burst fractures, who accorded with the inclusion criteria between February 2012 and February 2014. The patients underwent posterior short segmental pedicle screw fixation with fusion in 27 cases (fusion group) and without fusion in 30 cases (non-fusion group). There was no significant difference in gender, age, cause of injury, time between injury and admission, fracture segment and classification, and neurologic function America Spinal Injury Association (ASIA) classification between 2 groups, which had the comparability (P>0.05). The operative time, blood loss, and hospitalization days were compared between 2 groups. The height of the injured vertebra, the kyphotic angle, and the range of motion (ROM) were measured on the X-ray film. The functional outcomes were evaluated by using the Greenough low-back outcome score and the visual analogue scale (VAS) for back pain. The neurologic functional recovery was assessed by ASIA grade. RESULTS: The operative time was significantly shortened and the blood loss was significantly reduced in the non-fusion group when compared with the fusion group (P0.05). The patients were followed up for 2.0-3.5 years (mean, 3.17 years) in the fusion group and for 2-4 years (mean, 3.23 years) in the non-fusion group. X-ray films showed that 2 cases failed bone graft fusion, the fusion time was 12-17 weeks (mean, 15.6 weeks) in the other 25 cases. Complication occurred in 2 cases of the fusion group (1 case of incision deep infection and 1 case of hematoma at iliac bone donor site) and in 1 case of the non-fusion group (fat liquefaction); primary healing of incision was obtained in the others. The Cobb angle, the height of injured vertebrae showed no significant difference between 2 groups at pre-operation, immediate after operation, and last follow-up (P>0.05). The ROM of injured vertebrae showed no significant difference between 2 groups at 1 year after operation (before implants were removed) (P>0.05). The implants were removed at 1 year after operation in all cases of the non-fusion group, and in 11 cases of the fusion group. At last follow-up, the ROM of injured vertebrae in the non-fusion group was significantly higher than that in the fusion group (P0.05). CONCLUSIONS: Fusion is not necessary when thoracolumbar burst fracture is treated by posterior short segmental pedicle screw fixation, which can preserve regional segmental motion, shorten the operative time, decrease blood loss, and eliminate bone graft donor site complications.

Short-segment fixation via versus across the injured vertebrae for thoracolumbar vertebral fractures / 医学研究生学报

Objective Short-segment fixation is one of the most commonly used methods for the management of thoracolumbar vertebral fractures.In this study, we compared the clinical effects of short-segment fixation via and across the injured vertebrae in the treatment of thoracolumbar vertebral fractures . Methods We retrospectively analyzed 75 cases of thoracolumbar vertebral fractures treated by short-segment fixation, 39 via the injured vertebrae (group A) and 36 across the injured vertebrae (group B).We obtained the pre-and post-operative anterior vertebral body height ratio (AVBHr) and sagittal Cobb angle, operation time, and intraoperative blood loss, and compared them between the two groups of patients . Results Compared with the baseline, the AVBHr and the sagittal Cobb angle were significantly restored after surgery in both groups A ([56.32 ±12.53] vs [85.76 ±11.48]%and [20.41 ±5.73] vs [8.72 ±5.34]°, P0.05).The losses of the AVBHr and Cobb angle were (3.78 ±1.24)%and (2.25 ±1.06)°in group A, signifi-cantly lower than (6.69 ±2.52)% and (6.31 ±2.18)°in group B (P<0.05). Conclusion For thoracolumbar fractures, short-segment fixation either via or across the injured vertebrae can effective-ly improve the vertebral height and Cobb angle , but fixation via the injured vertebrae may achieve a better maintenance of correction .

Bone Cement Augmentation of Short Segment Fixation for Unstable Burst Fracture in Severe Osteoporosis

OBJECTIVE: The purpose of this study was to determine the efficacy of short segment fixation following postural reduction for the re-expansion and stabilization of unstable burst fractures in patients with osteoporosis. METHODS: Twenty patients underwent short segment fixation following postural reduction using a soft roll at the involved vertebra in cases of severely collapsed vertebrae of more than half their original height. All patients had unstable burst fracture with canal compromise, but their motor power was intact. The surgical procedure included postural reduction for 2 days and bone cement-augmented pedicle screw fixations at one level above, one level below and the fractured level itself. Imaging and clinical findings, including the level of the vertebra involved, vertebral height restoration, injected cement volume, local kyphosis, clinical outcome and complications were analyzed. RESULTS: The mean follow-up period was 15 months. The mean pain score (visual analogue scale) prior to surgery was 8.1, which decreased to 2.8 at 7 days after surgery. The kyphotic angle improved significantly from 21.6+/-5.8degrees before surgery to 5.2+/-3.7degrees after surgery. The fraction of the height of the vertebra increased from 35% and 40% to 70% in the anterior and middle portion. There were no signs of hardware pull-out, cement leakage into the spinal canal or aggravation of kyphotic deformities. CONCLUSION: In the management of unstable burst fracture in patients with severe osteoporosis, short segment pedicle screw fixation with bone cement augmentation following postural reduction can be used to reduce the total levels of pedicle screw fixation and to correct kyphotic deformities.

Dorsal Short-Segment Fixation for Unstable Thoracolumbar Junction Fractures

OBJECTIVE: This study is to evaluate the efficacy of dorsal short-segment fixation in unstable thoracolumbar junction fractures. METHODS: The cases of 20 patients who underwent dorsal short-segment fixation were reviewed retrospectively. Clinical outcomes were analysed using Sonntag's pain level, work status, and neurological scale according to the modified Frankel classification. Radiological outcomes were analysed using Mumford's anterior body compression(%), canal compromise ratio, and Cobb's kyphotic angle. RESULTS: At the latest clinical follow-up (average=14.6 months), there were 19 (95.0%) in group I and 1 patient (5.0%) in II in pain level35). The postoperative work status were 17 (85.0%) in group I, 2 patients (10.0%) in II, and 1 patient (5.0%) in V. Surgery brought to improve the neurologic status. In success group (19 cases, 95%), the average canal compromise ratio was reduced from 0.57 (+/-0.07) to 0.05 (+/-0.08) (P<0.05), the average anterior body compression (%) was reduced from 41% (+/-17) to 18% (+/-14) (P<0.05), and the average preoperative kyphotic angle was 20.0 degrees (+/-9.0), and corrected to 5.7 degrees (+/-7.1) postoperatively, and progressed to 7.8 degrees (+/-6.2) at the latest follow-up. There was a case of implantation failure in an elderly osteoporotic patient. CONCLUSION: Although there are limitations in the patient number and follow-up period, the present study favors dorsal short-segment fixation for selective cases in unstable thoracolumbar junction fractures.

Short Segment Fixation of Flexion-Distraction Injuries in Thoracolumbar Spines

PURPOSE: To evaluate the efficacy of short segment fixation in flexion-distraction injuries of thoracolumbar junction. MATERIALS AND METHODS: Twenty-five patients with a flexion-distraction injury in thoracolumbar junction confirmed by radiogram or MRI and stabilized with a short construct spanning short segment were included in this study. We investigated the location of fractures, type of fractures, anterior or posterior vertebral body height, and preoperative and postoperative kyphotic angle of injuried motion-segments on radiologic examinations and clinical outcome on the Oswestry score. RESULTS: A significant correction of deformity was achieved, from a mean preoperative kyphosis of 17.3 degrees to a mean postoperative kyphosis of 8.4 degrees. The loss of correction were minimal. The mean Oswestry score was 6.9, with 84% of patients having minimal disability (<20%) and no correlation with age, sex, the location of fractures, type of fractures, change of kyphotic angle. CONCLUSION: This study demonstrates the efficacy of posterior open reduction and short segment fixation of flexion-distraction injuries.

Long-term Follow-up Results of Short-segment Posterior Screw Fixation for Thoracolumbar Burst Fractures

OBJECTIVE: Despite general agreement on the goals of surgical treatment in thoracolumbar burst fractures, considerable controversy exists regarding the choice of operative techniques. This study is to evaluate the efficacy of short-segment fixation for thoracolumbar burst fractures after long-term follow-up and to analyze the causes of treatment failures. METHODS: 48 out of 60 patients who underwent short-segment fixation for thoracolumbar burst fractures between January 1999 and October 2002 were enrolled in this study. Their neurological status, radiological images, and hospital records were retrospectively reviewed. Simple radiographs were evaluated to calculate kyphotic angles and percentages of anterior body compression (%ABC). RESULTS: The average kyphotic angles were 20.0degrees preoperatively, 9.6degrees postoperatively, and 13.1degrees at the latest follow-up. The average %ABC were 47.3% preoperatively, 31.2% postoperatively, and 33.3% at the latest follow-up. The treatment failure, defined as correction loss by 10?or more or implant failure, was detected in 6 patients (12.5%). 5 out of 6 patients had implant failures. 2 out of 5 patients were related with osteoporosis, and the other 2 were related with poor compliance of spinal bracing. 3 patients with poor initial postoperative alignment had implant failure. 4 patients with screws only on the adjacent vertebrae and not on the injured vertebra itself showed poor initial and overall correction. CONCLUSION: With proper patient selection, adequate intraoperative reduction with screw fixation involving the injured vertebra, and strict postoperative spinal bracing, the short-segment fixation is an efficient and safe method in the treatment of thoracolumbar burst fracture.

A Management for Osteoporotic Bursting Fractures of the Thoracic and Lumbar Spines in the Aged: Posterior Approach with Intraoperative Vertebroplasty

OBJECTIVE: Treatments of osteoporotic bursting vertebral body fracture(OBF) of thoracic and lumbar spines have been limited to conservative managements especially in the elderly patients. The authors correct kyphosis and stabilize the spine by the posterior approach with intraoperative polymethylmethacrylate(PMMA) vertebroplasty. METHODS: From March 1999 to June 2000, eight patients with OBF underwent posterior approach with intraoperative vertebroplasty. The patients included 7 women and 1 man aged 54-82 year. Average T-score on bone marrow density was -3.02. In the case of old fracture with sclerosis in the posterior wall, after laminectomy, the retropulsed posterior wall of the fractured spine was reduced with L-shaped micro-bone impactor through the lateral epidural spaces, in prone position. About 6cc of PMMA was injected into the fractured vertebral body via transpedicular route, and then, small amount of PMMA was also injected into each entry point of the screws. All patients underwent one above and one below short segment fixation followed by correction of kyphotic deformity. RESULTS: The preoperative clinical symptoms improved gradually in all patients. During postoperative follow-up for more than 7 months, there was no recurrence of the preoperative clinical symptoms, aggravation of kyphosis or instrumentation failure. CONCLUSIONS: It is suggested that posterior approach with short segment fixation and intraoperative PMMA vertebroplasty could be a new surgical modality for osteoporotic bursting fracture of the thoracic and lumbar spines especially in the aged.

Short Segment Pedicle Screw Fixation with Augmented Intra-Operative Vertebroplasty in Unstable Thoraco-Lumbar Fracture: Preliminary Report

OBJECTIVES: Since vertebroplasty has been introduced, we performed short segment pedicle screw fixation with augmented intra-operative vertebroplasty in patients with unstable thoraco-lumbar fracture. Our intentions are to demonstrate the efficacy and indication of this new technique compare to conventional methods. MATERIAL AND METHODS: The surgery comprised of pedicle screw fixations on one level above and below the fracture site, and the fractured level itself, if pedicle is intact, and intra-operative vertebroplasty under the fluoroscopic guide with in-situ postero-lateral bone graft. Also, in cases of bone apposition, we removed those with small impactor through a transfascetal route. During the last 2 years, we performed in seven(7) unstable thoraco-lumbar fracture patients who consisted of two different characteristics, those four(4) with primary or secondary osteoporosis and three(3) of young and very healthy. All patients were followed clinically by A.S.I.A. score and radiography. RESULTS: Mean follow up period was 14 months. We observed well decompressed state via transfascetal route in cases of bone fragments apposition and no hardware pullout in osteoporotic cases, no poly-methyl-methacrylate (PMMA) leakage through the fracture sites into the spinal canal, and no kyphotic deformities in both cases during follow-up periods. All patients demonstrated solid bony fusion except one following osteoporotic compression fracture on other sites. CONCLUSIONS: In the management of unstable thoraco-lumbar fracture, we believe that this short segment pedicle screw fixation with augmented intra-operative vertebroplasty reduce the total length or levels of pedicle screw fixation without post-operative kyphotic deformity.