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This study sought to investigate and evaluate a modified axial translaminar screw fixation for treating odontoid fractures. We performed a retrospective study at Wenzhou Medical University Affiliated Second Hospital between March 2016 and June 2018. We retrospectively collected and analyzed the medical records of 23 cases with odontoid fractures. All patients were identified as type II odontoid fractures without neurological deficiency and serious diseases following the classification of Anderson. The average age, gender ratio, and body mass index (BMI) were 54.3 ± 11.1 years, 12 men to 11 women, and 22.6 ± 2.4 kg/m 2 , respectively. Patients in this study accepted screw fixation using our modified axial translaminar screw fixation combined with atlas pedicle or lateral mass screw fixation. Within the technique, a small cortical "window" was dug in the middle of the axial contralateral lamina, such that the screws in the lamina were visualized to prevent incorrectly implanting the posterior spinal canal through the visualized "window." A total of 46 bone screws were accurately inserted into the axial lamina without using fluoroscopy. The length of all translaminar screws ranged between 26 and 30 mm, while the diameter was 3.5 mm. During the follow-up survey, the visual analog scale (VAS) and neck disability index (NDI) were measured. We provide a simple modification of Wright's elegant technique with the addition of "visualized windows" at the middle of the axial lamina. In all patients, screws were inserted accurately without bony breach and the screw angle was 56.1 ± 3.0°. Mean operative time was 102 ± 28 min with an average blood loss of 50 ± 25 mL. Postoperative hemoglobin and mean length of hospital stay were 12.0 ± 1.4 g/dL and 10.4 ± 3.4 days, respectively. The average follow-up time of all cases was 14.7 months and no internal fixation displacement, loosening, or breakage was found. All patients with odontoid fractures reported being satisfied with the treatment during the recheck period and good clinical outcomes were observed. At 1, 6, and 12 months, NDI and VAS showed that the symptoms of neck pain and limitations of functional disability improved significantly during follow-up. Our results suggest that the modified translaminar screw fixation technique can efficiently treat Anderson type II odontoid fracture, followed by the benefits of less soft tissue dissection, simple operation, no fluoroscopy, and accurate placement of screws., (© 2021 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.)

Background: Anterior odontoid screw fixation (AOSF) has been suggested as the optimal treatment for type II and some shallow type III odontoid fractures. However, only the classical surgical trajectory is available; no newer entry points or trajectories have been reported., Methods: We evaluated the anatomic feasibility of a new trajectory for AOSF using 3-dimensional (3D) screw insertion simulation software (Mimics). Computed tomography (CT) scans of patients (65 males and 59 females) with normal cervical structures were obtained consecutively, and the axes were reconstructed in 3 dimensions by Mimics software. Then simulated operations were performed using 2 new entry points below the superior articular process using bilateral screws of different diameters (group 1: 4 mm and 4 mm; group 2: 4 mm and 3.5 mm; group 3: 3.5 mm and 3.5 mm). The success rates and the required screw lengths were recorded and analyzed., Results: The success rates were 79.03% for group 1, 95.16% for group 2, and 98.39% for group 3. The success rates for groups 2 and 3 did not differ significantly, and both were significantly better than the rate for group 1. The success rate was much higher in males than in females in group 1, but the success rate was similar in males and females in the other 2 groups. Screw lengths did not differ significantly among the 3 groups, but an effect of sex was apparent., Conclusions: Our modified trajectory is anatomically feasible for fixation of anterior odontoid fractures, but further anatomic experiments and clinical research are needed., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Study Design: Retrospective cohort study., Objective: To reveal the risk factors for dural tears in thoracic and lumbar (TL) burst fractures associated with vertical laminar fractures through multivariate analysis., Summary of Background Data: Dural tears associated with laminar fractures in patients with TL burst fractures represents a special group requires distinct treatment with different surgical prognosis. It is still very difficult to predict dural tears in patients with vertical laminar fractures. The risk factors for dural tears have seldom been evaluated., Methods: Medical records of 113 patients of TL burst fractures with vertical laminar fractures were reviewed. The data were subdivided into two groups consisting of patients with and without dural tears. Demographic information, preoperative clinical, and radiological characteristics were compared between the groups. Multivariate logistic regression models were employed to determine the independent risk factors for dural tears., Results: The incidence of dural tear was 27.4% in this retrospective cohort. When compared with the dural intact group, the dural tear group had significantly worse preoperative neurological status, wider interpedicular distance, greater separation of laminar fractures, and larger encroachment of retropulsed fragment in the bony spinal canal. Multivariate stepwise logistic regression analysis showed that the ratio of interpedicular distance greater than 125% (odds ratio = 9.5; P < 0.001) and the ratio of encroachment of retropulsed fragment in the bony spinal canal of more than 50% (odds ratio = 61.2; P < 0.001) were independent risk factors for dural tears., Conclusion: Patients with wider interpedicular distance and larger encroachment of retropulsed fragment in the bony spinal canal were more likely to have dural tears in TL burst fractures with vertical laminar fractures., Level of Evidence: 3.

Background: Some studies have reported that the conventional intersegmental pedicle screws (4-screw fixation [4S]) device for thoracolumbar fractures was associated with inadequate reduction of fractured vertebrae, insufficient correction of kyphosis, and implant failure. Recently, a series of biomechanical studies has confirmed that the addition of intermediate fixation screws (6-screw fixation [6S]) could provide stronger fixation and better reduction of fractured vertebrae. Nevertheless, the clinical and radiologic efficacy of the additional intermediate screws remains unclear., Methods: A meta-analysis of randomized controlled trials was used to compare clinical and radiologic outcomes and complications of posterior pedicle screws combined with intermediate screws fixation versus conventional intersegmental pedicle screw fixation. We comprehensively searched MEDLINE, OVID, and Springer according to a search strategy, selecting articles based on inclusion criteria, and extracted data from these reports. Risk of bias in included studies was assessed. Pooled estimates and corresponding 95% confidence intervals were calculated., Results: Six randomized controlled trials involving 310 patients were evaluated in this meta-analysis. Pooled estimates showed statistically similar baseline characteristics, hospital stays, postoperative visual analog scale scores, and infection rates between the 4S group and the 6S group. The 6S group had significantly less correction loss of segmental angle and of anterior vertebral height compression, and lower implant failure rate. The 6S group also showed a slightly longer operative time and more blood loss than did the 4S group., Conclusions: Based on our analysis, the combined intermediate screws fixation technique was associated with significantly improved radiologic outcomes but did not seem to compromise other perioperative outcomes., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Patients with laminar fractures have a higher chance of experiencing severe trauma and neurologic deficit. In previous studies, laminar fractures were divided into different types based on the axial plane of computed tomographic scans. No report described the morphology of vertical laminar fractures in the coronal plane. Furthermore, the correlation between a specific type of laminar fracture and the extent of severity of thoracolumbar (TL) burst fractures has rarely been mentioned., Methods: A retrospective evaluation of 341 patients with TL burst fractures with or without laminar fractures were divided into 6 groups based on the morphology observed across reconstructed coronal and axial computed tomographic planes. The Thoracolumbar Injury Classification and Severity Score (TLICS), Load Sharing Classification (LSC), and American Spinal Injury Association (ASIA) impairment scale were evaluated for each patient. Intergroup comparisons were also performed for all metrics., Results: The TLICS, LSC, and ASIA impairment scale were determined for each laminar fracture group. Statistical differences were found in most intergroup comparisons across all metrics. Significantly higher injury scores were observed in the groups with a more severe coronal and axial laminar fracture, and the injury severity in the coronal scan played a more decisive role., Conclusions: The morphology of vertical laminar fractures as observed across multiple image planes was more complex and accurate than an analysis based solely on the axial plane. Different morphologies indicated differences in the severity of associated TL burst fractures. The laminar fracture in the coronal plane was associated with the severity of spinal injury., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Context/objective: To describe the technique and clinical results of percutaneous atlantoaxial anterior transarticular fixation combined with limited exposure posterior C1/2 arthrodesis in patients with a high-riding vertebral artery., Design Setting: Zhejiang Spine Center, China., Participants: Five patients with a high-riding vertebral artery and an upper cervical fracture., Interventions: Percutaneous atlantoaxial anterior transarticular screw fixation combined with limited exposure posterior C1/2 wire fusion., Outcome Measures: Computed tomography scans were used to assess the high-riding vertebral artery and feasibility of anterior transarticular screw fixation preoperatively. A Philadelphia collar was used to immobilize the neck postoperatively. Anteroposterior (open-mouth) and lateral views were obtained at pre/postoperation and at the follow-up., Results: The operation was performed successfully on all of the patients, and no intraoperative operation-related complications such as nerve injury, vertebral artery, and soft tissue complications occurred. The mean follow-up period was 33.8 months (range: 24 to 58 months). No screw breakage, loosening, pullout, or cutout was observed. Bone union was achieved in all patients at the last follow-up., Conclusions: Our small case series results suggested that percutaneous anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion is a technically minimally invasive, safe, feasible, and useful method to treat patients with a high-riding vertebral artery.

Background Context: Surgical stabilization is recommended for odontoid fractures with mechanical instability. Compared with C1-C2 fusion, percutaneous anterior odontoid screw fixation has the advantages of preserving C1/C2 motion and being a minimally invasive procedure. However, determining the optimal screw trajectory is often difficult. When an initial suboptimal K-wire hole is drilled, it is especially difficult to drill a second optimal K-wire trajectory because the initial hole will be entered inadvertently., Purpose: To design a novel device, two-hole guide tube, to make drilling a second optimal K-wire trajectory easier, and thus, avoid unnecessary additional surgical time and reduce the likelihood of needing to change the procedure to traditional open surgery., Study Design: A technical report., Methods: Fifty-three patients with odontoid fractures were treated by percutaneous anterior odontoid screw fixation in our hospital, and the initial K-wire trajectories of 16 cases (12 men and 4 women) among the 53 patients were imperfect. The two-hole guide tube was applied for drilling the second trajectory in each of these 16 cases., Results: No complications associated with this technique occurred. Satisfactory results and good screw placement was achieved in all patients. Radiographic fusion was confirmed for 15 of 16 patients. None of the patients experienced clinical symptoms or screw loosening or breakage in this study., Conclusions: Our novel device, two-hole guide tube, can be used to reduce the difficulty associated with redrilling an optimal K-wire trajectory if the initial trajectory is imperfect during percutaneous anterior odontoid screw fixation. Moreover, by referring to the initial misplaced K-wire, a more accurate trajectory for the second K-wire can be achieved., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Anterior occiput-to-axis screw fixation is more suitable than a posterior approach for some patients with a history of posterior surgery. The complex osseous anatomy between the occiput and the axis causes a high risk of injury to neurological and vascular structures, and it is important to have an accurate screw trajectory to guide anterior occiput-to-axis screw fixation. Thirty computed tomography (CT) scans of upper cervical spines were obtained for three-dimensional (3D) reconstruction. Cylinders (1.75 mm radius) were drawn to simulate the trajectory of an anterior occiput-to-axis screw. The imitation screw was adjusted to 4 different angles and measured, as were the values of the maximized anteroposterior width and the left-right width of the occiput (C0) to the C1 and C1 to C2 joints. Then, the 3D models were printed, and an angle guide device was used to introduce the screws into the 3D models referring to the angles calculated from the 3D images. We found the screw angle ranged from α1 (left: 4.99±4.59°; right: 4.28±5.45°) to α2 (left: 20.22±3.61°; right: 19.63±4.94°); on the lateral view, the screw angle ranged from β1 (left: 13.13±4.93°; right: 11.82±5.64°) to β2 (left: 34.86±6.00°; right: 35.01±5.77°). No statistically significant difference was found between the data of the left and right sides. On the 3D printed models, all of the anterior occiput-to-axis screws were successfully introduced, and none of them penetrated outside of the cortex; the mean α4 was 12.00±4.11 (left) and 12.25±4.05 (right), and the mean β4 was 23.44±4.21 (left) and 22.75±4.41 (right). No significant difference was found between α4 and β4 on the 3D printed models and α3 and β3 calculated from the 3D digital images of the left and right sides. Aided with the angle guide device, we could achieve an optimal screw trajectory for anterior occiput-to-axis screw fixation on 3D printed C0 to C2 models.

Study Design: A retrospective clinical study., Objective: To evaluate the efficacy and safety of transforaminal decompression and interbody fusion in the treatment of thoracolumbar fracture and dislocation with spinal cord injury., Methods: Twenty-six spinal cord injured patients with thoracolumbar fracture and dislocation were treated by transforaminal decompression and interbody fusion. The operation time, intraoperative blood loss, and complications were recorded; the Cobb angle and compressive rate (CR) of the anterior height of two adjacent vertebrae were measured; and the nerve injury was assessed according to sensory scores and motor scores of the American Spinal Injury Association (ASIA) standards for neurological classification of spinal cord injury., Results: The operative time was 250±57 min, and intraoperative blood loss was 440±168 ml. Cerebrospinal leakage was detected and repaired during the operation in two patients. A total of 24 of 26 patients were followed up for more than 2 years. ASIA sensory scores and motor scores were improved significantly at 3 months and 6 months after operation; the Cobb angle and CR of the anterior height of two adjacent vertebrae were corrected and showed a significant difference at post-operation; and the values were maintained at 3 months after operation and the last follow-up., Conclusion: We showed that transforaminal decompression together with interbody fusion is an alternative method to treat thoracolumbar fracture and dislocation.

Study Design: Imaging study., Summary of Background Data: X-ray and computed tomography (CT) sagittal reconstruction images are used to evaluate the stability of the spine. However, we did not know the extent of difference between them., Objective: The aim of the study was to compare the differences seen in thoracolumbar burst fractures on lateral radiographs and CT sagittal reconstruction images and investigate their clinical relevance., Materials and Methods: Lateral radiographs and CT sagittal reconstruction images of 45 patients with thoracolumbar burst fractures were used to record the following measurements: the compressed area of the fractured vertebrae, from lateral radiographs, and the sagittal compressed area, bony fragment area, and total fracture-involved area, from CT sagittal reconstruction images., Results: The percentage of compressed area of fractured vertebrae was 29.32±13.80% on lateral radiographs and 27.93±12.21% on CT sagittal reconstruction images; there was no significant difference between them (P>0.05). The percentage of total fracture-involved area was 53.20±20.64% on CT sagittal reconstruction images, higher than the compressed area measured on lateral radiographs (P<0.01) and CT sagittal reconstruction images (P<0.01). The percentage of bony fragment area was 25.27±15.18% on CT sagittal reconstruction images; there was no significant relationship between bony fragment area and the compressed area (r=0.1258, P>0.05)., Conclusions: The compressed area of fractured vertebrae on lateral radiographs could not represent the fracture-involved area and underestimated the total fracture-involved area. We suggested that the above 3 parameters could be easily obtained on CT sagittal reconstruction images, which might be better for assessing the potential instability of the thoracolumbar burst fracture and could become a valuable and indispensable examination for therapeutic decision making.

Study Design: A retrospective comparative study., Objective: The purpose of this study is to assess radiologic features of intravertebral cleft (IVC) in nonacute osteoporotic vertebral compression fractures (OVCFs) patients, and analyze the existence of IVC impact on outcomes of percutaneous kyphoplasty (PKP)., Summary of Background Data: The IVC sign is regarded as vertebral instability and the cause of persisting pain. It is more likely to happen at nonacute OVCFs patients. Patients with IVC sign have different outcomes from these without IVC treated by percutaneous vertebroplasty. There were rare reports about the outcomes of patients with IVC sign treated by PKP., Materials and Methods: We divided 92 nonacute OVCFs patients (total of 113 vertebrae) into 2 groups according to the existence of IVC. Preoperative and postoperative Visual Analogue Scales, Oswestry Disability Index, kyphotic angulation (KA), and anterior vertebral height were recorded; the incidence and radiologic features of IVC were analyzed., Results: The diagnostic sensitivity of IVC on plain radiograph, computed tomography, and magnetic resonance imaging were 35.4%, 89.3%, and 83.3%, respectively. The IVC group had an average correction KA of 9.14 degrees and reduction of ratio of compression of 20.09%, and the non-IVC group was 8.76 degrees and 20.23%, respectively. Cleft pattern of cement accounted for 64.6% in IVC group and 27.7% in non-IVC group. Five/7 of cement leakage in IVC group was intradiscal leakage, whereas 7/9 of cement leakage in non-IVC group was perivertebral leakage., Conclusions: Computed tomography and magnetic resonance imaging were more sensitivity to diagnose IVC sign than X-ray. PKP could improve pain, functional activity, KA, and anterior height of both IVC and non-IVC groups, however, there was more cleft pattern of cement and higher intradiscal cement leakage in the IVC group.

Purpose: The purpose of this study was to quantify the intra- and postoperative complications of an interspinous process device (Coflex) in managing degenerative lumbar diseases and to investigate corresponding therapeutic strategies., Methods: Between January 2008 and December 2012, we retrospectively analysed a total of 131 patients who underwent decompressive surgery along with the Coflex system for the treatment of degenerative lumbar diseases. The related complications were reported, and appropriate measures were taken. Clinical outcomes and radiological data were collected and analysed, and clinical outcomes were evaluated with paired-samples T test., Results: Related complications occurred in 11 patients. Among them, six cases were found with surgical technique-related complications, including device-related complications in three cases: spinal process fracture (n = 1), Coflex loosening (n = 1), fixed-wing breakage (n = 1), dura mater tear in two cases and superficial wound infection in one case. All of them received corresponding conservative treatment and obtained a good result. The other five cases had non-device-related complications and required additional spinal surgery. The conservative therapy group had apparent improvement of VAS score and ODI, and remained well to final follow-up (P < 0.05). The second operation group also improved postoperatively (each P < 0.05)., Conclusion: The Coflex dynamic interspinous process device shows a low complication and re-operation rate. Standard operation and strict follow-up observation can effectively avoid surgical technique-related complications. The key points to ensure surgical effect and to reduce non-device-related complications are mastering surgical indications and thorough intra-operative decompression.

Purpose: This study describes a percutaneous technique for C2 transpedicular screw fixation and evaluates its safety and efficacy in the treatment of patients with hangman's fracture., Methods: Ten patients with hangman's fracture were treated by percutaneous C2 transpedicular screw fixation. There are six males and four females, who were, based on the classification of Levine and Edwards, sorted as follows: type I fracture, three cases; type II, five cases; type IIa, two cases. The causes of injury were road traffic accident in six patients and falling injury in four patients. Other associated lesions included rib fractures (7 patients), head injuries (4 patients), and fractures of extremities (6 patients)., Results: The new technique was performed successfully in all cases. The average operation time was 98 min (range 60-130 min) and the estimated blood loss was 25 ml (range 15-40 ml). No complications such as vascular or neural structures injuries were found intraoperatively. Postoperative CT scans demonstrated that 17 (85 %) of 20 screws were placed satisfactorily, and 3 (15 %) screws showed perforations of the pedicle wall (<2 mm). These patients were asymptomatic and no further intervention was required postoperatively. After 8-25 months follow-up (mean 15.3 months), solid fusion was demonstrated by computed tomography. All cases got well-sagittal alignment and no angulation or dislocation was found at the segment of C2-C3. There was no loss of fixation. Clinical examination showed a full range of motion in the neck in all patients., Conclusions: The fluoroscopically assisted percutaneous C2 transpedicular screw fixation method is a technically feasible and minimally invasive technique for hangman's fracture.

An intravertebral vacuum cleft (IVC) is not an uncommon finding; it is more likely to occur in patients with osteoporotic vertebral compression fractures (OVCF). There are scarce data on the treatment of these patients with percutaneous balloon kyphoplasty (PKP). Between August 2005 and March 2010, 35 single vertebral fracture patients with an IVC sign were treated by PKP. Visual Analogue Score (VAS), Oswestry Disability Index (ODI), Kyphotic Angulation (KA), and Compression Ratio (CR) improved significantly postoperatively (p < 0.05). These values were maintained at the one year follow-up. Balloon kyphoplasty leads less often to leakage (here in only 14.3% of the patients) than vertebroplasty (in 75% according to the literature). On the other hand, balloon kyphoplasty seems to predispose to intradiscal leakage: here in 3 out of 5 cases. This may cause a compression fracture of the adjacent vertebra.

Objectives: To study incidence and radiological features of intravertebral cleft (IVC) in patients with chronic pain due to osteoporotic vertebral compression fractures (OVCFs), and analyze influence of IVC for surgery of percutaneous kyphoplasty (PKP)., Methods: Seventy-six patients with osteoporotic vertebral compression fractures and pain duration more than one month were underwent procedures of PKP between August 2005 and August 2010. The incidence and radiological features of IVC were analyzed. Sixty-one patients with single-level OVCFs were divided into two groups with and without IVC. Preoperative and postoperative kyphotic angle and relative anterior vertebral height were recorded, as well as visual analogue scales (VAS) and Oswestry disability index (ODI). Cement patterns of opacification and leakage were also recorded., Results: Thirty two patients with 39 vertebrates were found with IVC sign. The diagnostic sensitivity of X ray, CT and MRI for IVC was respectively 33.3%, 85.7% and 84.6%. Two groups with IVC and without IVC both had apparent correction of kyphotic angle and reduction of anterior height at 3 days after surgery and last follow-up (F = 21.82 - 72.18, P < 0.01). There was no statistical significance between two groups (P > 0.05). In addition, both groups had significant improvement as regard to VAS and ODI (F = 131.06 - 364.12, P < 0.01). Solid pattern accounted for 72.0% of all cemented vertebrates in the group with IVC and 19.4% in the group without IVC. Four cement leakage were found in the group with IVC and another four in the group without IVC., Conclusions: There is a high incidence of IVC in patients with chronic pain due to osteoporotic vertebral compression fractures. CT and MRI are sensitive for detection of IVC. The procedure of PKP is effective for both groups with and without IVC. IVC produces an apparent influence on cement opacification and leakage location during the procedure of PKP.

Objective: To study the therapeutic method and effect of minimally invasive surgery for the thoracolumbar fractures., Methods: A retrospective review of the minimally invasive surgically treatment thoracolumbar fractures from February 2005 to June 2010 was performed. There were 183 cases, 126 males and 57 females, aged 18 to 68 years, average 38.9 years. The involved levels of fractures were T(11) in 22, T(12) in 61, L(1) in 71, L(2) in 29. According to Gertzbein classification, 145 cases were type A fractures, 34 cases were type B fractures, 4 cases were type C fractures; According to Load-sharing score, 51 cases were 4 scores, 56 cases were 5 scores, 17 cases were 6 scores, 12 cases were 7 scores, 24 cases were 8 scores, 23 cases were 9 scores. Different surgical methods were selected according to the minimally invasive surgical strategy, 22 patients were treated with the minimally invasive percutaneous pedicle screws osteosynthesis (MIPPSO group), 102 patients were treated with the small-incision pedicle screws osteosynthesis (SISPSO group), 31 patients were treated with the small incision anterior thoracolumbar surgery (SIATS group) assisted by thoracoscope or headlight, and 28 patients were treated with the 270° decompression and reconstruction surgery (270° DRS group) via a posterior small incision. Preoperative and postoperative neurological status, the correction and loss of Cobb's angle, the decompression scope of spinal canal, the location and union of bone graft were followed up and reviewed., Results: All of 183 cases had successful surgery and were followed up. In the MIPPSO group, operative time was 52 - 100 min, blood loss was 35 - 55 ml. In the the SISPSO group, operative time was 48-68 min, the blood loss was 45 - 65 ml the correction of Cobb's angle in the two groups was 8° - 19°. In the SIATS group, operative time was 140 - 220 min, the blood loss was 160 - 1500 ml the correction of Cobb's angle was 15° - 25°, 1 case had pleural effusion, 1 had lateral femoral cutaneous nerve damage, the complications disappeared after treatment. In the 270° DRS group the operative time was 160-280 min, the blood loss was 700 - 4700 ml, the correction of Cobb's angle was 15° - 28°. The spinal canal mass was removed, the spinal canal was enlarged and completely decompressed. Neurological status improved in all of the preoperative incomplete paraplegia patients except 1 case whose neurological symptoms aggravated., Conclusion: It is satisfactory that the minimally invasive surgical strategy was rational used in the treatment of thoracolumbar fractures.

Objective: To investigate the therapeutic effects and complications of percutaneous pedicle screw fixation for thoracolumbar fractures., Methods: From January 2002 to December 2008, 103 patients with thoracolumbar fractures were treated with percutaneous pedicle screw fixation, including 75 males and 28 females, the average age was 45.6 years (range, 18 - 72 years). All of them were of no neurological deficits. There were 65 cases of traffic injury, 23 cases of fall injury and 15 cases of smashed injury. According to the Denis classification, 64 patients were of compression fractures, and 39 patients of burst fractures. There were 5 cases had fractures in T(11), 30 in T(12), 42 in L(1), 15 in L(2), 4 in L(3), 3 in L(4), 2 in T(11-12), 1 in L(1-2), and 1 in L(2-3). Radiological examinations, including X-ray and CT examinations, and clinical examinations were carried out to evaluate the therapeutic effects., Results: Twenty one patients were lost to follow up, the remaining were followed up from 10 to 48 months with an average of 27.4 months. Before the operation, the vertebral height, the kyphosis angle and the occupation of spinal canal were (54.5 ± 8.7)%, 16.4° ± 2.9° and 1.2 ± 1.0, and were improved to (88.6 ± 6.4)%, 11.6° ± 2.7° and 0.5 ± 0.6 respectively after the operation. Preoperatively the visual analogue scale and the Oswestry disability index were 8.0 ± 1.2 and 41.2 ± 9.3, and were improved to 1.7 ± 1.8 and 6.7 ± 5.6 postoperatively, respectively. All of these values between pre- and post-operatively were significantly different (P < 0.01). Screw misplacement was found in 7 patients, superficial wound infection in 1, screw breakage in 3, screw dislodgment in 2, cement leakage in 5, transient neurological symptoms in 4, and 8 patients with low back pain remained, of which 2 patients required occasional oral analgesics. Bone fusion achieved in all cases., Conclusions: The clinical efficacy of percutaneous pedicle screw fixation is similar with conventional open surgery. With the advantages of convenient procedure, less invasive, and rapid recovery, percutaneous pedicle screw fixation is an alternative method for thoracolumbar fractures without neurological deficits.

Study Design: Prospective consecutive series., Objective: To evaluate the efficacy and safety of percutaneous pedicle screw fixation (PPSF) for thoracolumbar AO type A3 fractures with a specially designed surgical instrument system., Summary of Background Data: Minimally invasive surgery including PPSF is becoming increasingly widespread in the spine surgery. The technique of PPSF was mostly used as supplemental fixation combined with minimally invasive posterior or anterior lumbar interbody fusion in management of lumbar degenerative disorders. There are fewer studies available in literature regarding PPSF without additional kyphoplasty or vertebroplasty for management of thoracolumbar burst fractures., Methods: Thirty-six adult patients, who had single thoracolumbar AO type A3 fractures and the load-sharing score of 6 or less, underwent application of percutaneous short-segment pedicle screw fixation. Radiologic parameters including kyphotic angle and vertebral height loss were assessed before and after surgery, and functional outcome was evaluated by Prolo questionnaire., Results: All patients were successfully managed with percutaneous minimal invasive procedures. The average operative time was 78 minutes (range 62 to 117 min). The average intraoperative blood loss was 75 mL (range 50 to 220 mL). After a mean follow-up of 48.5 months (range 32 to 63 mo), 31 of 36 (86.1%) patients had a satisfactory result (19 excellent and 12 good) and 5 of them fair., Conclusions: Our clinical results suggest that PPSF can be an alternative for management of thoracolumbar AO type A3 fractures that have no neurologic deficits. With a specially designed percutaneous instrument and pedicle screw system, the procedure has been proved as relatively safe and a minimally invasive approach for the management of thoracolumbar burst fracture without neurologic deficit.

Background: No consensus has been reached on the optimal radiographic evaluation of thoracolumbar burst fractures. The role of MRI in the treatment decision is not fully documented. The objectives was to measure the agreement of MRI in detecting posterior ligamentous complex (PLC) and posterior longitudinal ligament (PLL) injury, and to determine whether the findings by MRI is correlated with the results of plain radiography and computed tomography (CT) scanning as well as neurological examination and with the treatment planning., Methods: Sixty-one patients with acute thoracolumbar burst fracture were retrospectively reviewed for the presence of supraspinous ligament (SSL), interspinous ligament (ISL) or posterior longitudinal ligament (PLL) injury. The overall interobserver agreement between the three different observers was assessed by a kappa coefficient for multiple raters. The status of ligaments was correlated with the neurological function as assessed by Frankel scale and fracture severity as defined by the Load Sharing Classification. These patients were surgically treated according to the Load Sharing Classification and followed up for at least 5 years., Results: The kappa coefficients for ISL or SSL injury ranged 0.601 to 0.736, representing substantial to almost perfect agreement, whereas the kappa coefficients for PLL injury were 0.441 to 0.574, representing moderate agreement. No significant difference (P > 0.05) of Frankel scale or load sharing score was found between patients with and without ligamentous injuries. Satisfactory results were achieved in all patients regarding the clinical and radiological assessment., Conclusions: MRI is reliable for detecting the ligamentous injury, especially PLC injury in thoracolumbar burst fractures but the ligamentous injury as shown by MRI is not correlated with the neurological function or fracture severity. As MRI finding is of little value in treatment planning of thoracolumbar burst fractures, MRI examination is not necessary to be used routinely for excluding occult ligamentous injury.

Study Design: The role of plain radiography in the diagnosis and management of thoracolumbar burst fractures was evaluated when compared with computed tomography (CT) scans., Objective: To determine the accuracy of plain radiography in detecting thoracolumbar burst fractures when CT scans were used as the gold standard, and to assess the impact of disagreement of the results between plain radiographs and CT scans on treatment plan., Summary of Background Data: There have been few studies comparing the value of plain radiography with that of CT scans in the diagnosis and management of thoracolumbar burst fractures., Methods: Radiographs of 73 patients with a compression or burst fracture were reviewed independently by 3 residents and 3 spine surgeons. The results of CT scans were used as the gold standard to determine the accuracy of plain radiography for the diagnosis. More quantitative results of 57 patients with a burst fracture based on plain radiographs alone were compared with those after addition of CT scans. The disagreement between the results was analyzed, and the impact of disagreement on treatment plan was defined as the changes of load sharing score between or=7., Results: The accuracy of plain radiography improved with the experience of observers. The results on the load sharing score agreed between plain radiographs alone and radiographs with CT scans only for 56%, indicating moderate agreement. The impact of disagreement on treatment plan was significant (P < 0.05). This disagreement was most contributed by the underestimation for vertebral body comminution based on plain radiographs., Conclusion: The accuracy of plain radiography is acceptable in the qualitative sense, and would improve with the experience of observers. However, plain radiography alone would not be adequate when used for more quantitatively assessing the fractures. Addition of CT scanning is necessary for treatment planning.

A fractured vertebra does not transfer load as effectively as the intact vertebra. Patients who undergo surgery using short-segment pedicle screw instrumentation for middle-column injury may experience implant failure when vertebral body comminution is ignored. The purpose of this study was to investigate biomechanical effects of the extent of vertebral body fracture on the thoracolumbar spine after pedicle screw fixation and to evaluate the biomechanical role of anterior reconstruction. Twelve fresh porcine T12-L3 specimens were harvested and divided into two groups. A 2-mm drill bit was used to create holes in the L1 vertebra with two different extents: 1/6 and 1/3 vertebral body involvement. After the pre-injury had been created, specimens were subjected to flexion-compression to create a fracture in the body of the spine. Stiffness under axial-compression and flexion-compression were measured in intact specimens, after the fractured segments had been stabilized using transpedicular fixation, and after transpedicular fixation with anterior grafting. Despite fixation of the injured spine with pedicle screw instrumentation, the axial-compression and flexion-compression stiffness was still significantly lower than that of the intact group (p<0.01). The stiffness was associated with the extent of vertebral body involvement; 1/6 vertebral body involvement was stiffer than the 1/3 involvement (p<0.01). Additional anterior grafting significantly improved stiffness compared with posterior fixation alone (p<0.01), and restored stiffness to the intact level. In any state, stiffness under axial-compression was always significantly greater than that under flexion-compression (p<0.01). In conclusion, transpedicular fixation alone cannot provide sufficient stability for thoracolumbar fractures; the construct stability is related to the extent of vertebral body involvement. Recovering mechanical properties of the anterior and middle spinal column is a valuable measure for reducing the load-sharing of the posterior instrument.

Objective: To compare clinical outcome of the percutaneous versus open pedicle screw fixation in the treatment of thoracolumbar burst fracture with neurological intact., Methods: Sixty patients with thoracolumbar burst fracture without neurological deficit underwent either percutaneous (n = 30) or traditional open pedicle screw fixation (n = 30). Radiographs obtained before surgery, immediately after surgery, 4 months and 2 years after surgery were used to access the restoration of spinal anatomy. Also, operation time, blood loss, blood drainage, hospital stay and soft tissue dissection were evaluated. The level of pain was assessed by visual analog scale (VAS), function by the Oswestry questionnaire., Results: The average followed up was 2 years. There were no significant differences between both groups concerning age, sex, cause of injury and the presence of other severe injuries. Significant differences were observed between the two groups in blood loss, blood drainage, hospital stay and soft tissue dissection (P < 0.01), whereas no significant differences in operation time (P > 0.05). The vertebral height, the kyphosis angle, and the occupation of spinal canal after surgery and at follow-up were not significantly (P > 0.05). The pain systems and functions were similar in both groups at final follow-up (P > 0.05), however, less pain was found in the percutaneous group than that in the open group at the first 3 months after surgery (P < 0.01)., Conclusion: Percutaneous pedicle screw fixation for thoracolumbar fracture has the advantage of less trauma, quickly recovery and better esthetic outcome, however, it has the same results with the traditional open produce after 2 years of surgery.

Minimally invasive techniques have revolutionized the management of a variety of spinal disorders. The authors of this study describe a new instrument and a percutaneous technique for anterior odontoid screw fixation, and evaluate its safety and efficacy in the treatment of patients with odontoid fractures. Ten patients (6 males and 4 females) with odontoid fractures were treated by percutaneous anterior odontoid screw fixation under fluoroscopic guidance from March 2000 to May 2002. Their mean age at presentation was 37.2 years (with a range from 21 to 55 years). Six cases were Type II and four were Type III classified by the Anderson and D'Alonzo system. The operation was successfully completed without technical difficulties, and without any soft tissue complications such as esophageal injury. No neurological deterioration occurred. Satisfactory results were achieved in all patients and all of the screws were in good placement. After a mean follow-up of 15.7 months (range 10-25 months), radiographic fusion was documented for 9 of 10 patients (90%). Neither clinical symptoms nor screw loosening or breakage occurred. Our preliminary clinical results suggest that the percutaneous anterior odontoid screw fixation procedure using a new instrument and fluoroscopy is technically feasible, safe, useful, and minimally invasive.

Object: Experimental burst fracture models are often developed by using either single or incremental impacts. In both protocols, the weight-drop technique produces the impact. However, to the authors' knowledge in no study have researchers attempted to compare the equivalence of the spine burst fracture produced using the different impact protocols. This study was performed to investigate whether the single and incremental trauma approaches produce equivalent degrees of severity in thoracolumbar burst fractures., Methods: Twenty bovine thoracolumbar spines comprising three vertebrae were divided evenly into the single impact and incremental impact groups. The specimens in the incremental impact group were subjected to three axial compressive impacts of increasing energy (78.4, 107.8, and 137.2 J), whereas specimens in the other group were subjected to a single impact (137.2 J). Before and after the final trauma, multidirectional flexibility of each specimen was measured under flexion/extension, right/left lateral bending, and right/left axial rotation, thus quantifying the instability of the fracture. The flexibility parameters were then compared between the two groups., Results: A significant increase in flexibility parameters was found after the final trauma in both groups, indicating the instability of the spine (p < 0.01). No significant differences in flexibility parameters were observed in either intact status or injured status between the two groups (p > 0.05)., Conclusions: In this study the authors have confirmed that the single and incremental impact protocols produced a similar degree of severity in producing an in vitro bovine burst fracture. The results of this study support the use of the incremental impact protocol in future experimental biomechanical studies.

Objectives: To compare short-term and long-term change of paraspinal muscle between percutaneous and open pedicle screw fixation in the treatment of thoracolumbar fractures., Methods: Thirty-three patients were divided into four groups: short-term percutaneous pedicle screw fixation group, short-term open pedicle screw fixation group, long-term percutaneous pedicle screw fixation group, and long-term open pedicle screw fixation group. Paraspinal muscle were studied by needle electromyography and CT. Cross-sectional area and color grade information of paraspinal muscle were measured using CT image., Results: The area and color grade of paraspinal muscle changed significantly after surgery. The color grade of paraspinal muscle showed significant change while the muscle area observed no significant change in the two short-term groups; There was significant change in paraspinal muscle area, however no significant change was found in muscle color grade of the two long-term groups. In electromyography study the results showed that there was significant difference in the two short-term groups, however no significant difference existed in the long-term groups. There was no significant difference of patients treated by the two surgical technique in long-term function evaluation., Conclusion: Both percutaneous and open pedicle screw fixation damage paraspinal muscle, however the muscle showed less injury treated by percutaneous pedicle fixation.

Study Design: An in vitro biomechanical investigation., Objectives: The purpose of this study was to investigate the association between various load-sharing score and the acute flexibility of thoracolumbar fractures by measuring the 3-dimensional flexibility data., Summary of Background Data: The load-sharing classification is a way to describe the injury severity of a spinal fracture and can be very useful in determining successful candidates for the choice of operative approaches. However, this classification needs to be validated by biomechanical and more clinical studies before its widespread use. To date, no biomechanical study was available., Methods: Eighteen fresh bovine T12-L3 specimens were harvested and divided into 3 groups, and subjected to axial compressive impact with 63.8, 107.8, and 137.2 J energy, respectively. Radiograph films and computed tomography scans of the experimental spine were taken in neutral posture after trauma. Multidirectional flexibility of each specimen was measured under flexion-extension, right/left lateral bending, and right/left axial rotation before and after trauma. The association between the multidirectional instabilities and the vertebral injuries to each of load-sharing point score was analyzed., Results: The load-sharing score of a fracture increased with the level of impact energy. Significant positive correlations were found between the load-sharing score and the motion parameters (average R = 0.434, average P = 0.004). Fractures with mild comminution (< or =6 points) showed more stability as compared to those with more comminution (> or =7 points) (P < or = 0.016)., Conclusion: This study confirms that assessing the load-sharing score should be helpful in evaluating the acute instability of thoracolumbar fractures, and justifies the use of load-sharing classification in the thoracolumbar fractures.

The most common pattern among thoracolumbar burst fractures involves failure of the superior vertebra end-plate. There have been many biomechanical studies of thoracolumbar burst fractures, but the biomechanics related to the internal architecture of thoracolumbar vertebrae has been rarely documented. The objective of this study was to test the hypotheses that distribution of the bone mineral density (BMD) of the thoracolumbar spine is related to the stress concentration in this region and therefore, supports the pattern of burst fractures that occur most commonly. We measured spinal BMD of the first lumbar vertebra in 22 individuals using quantitative computed tomography (QCT) in three levels. At each level, the BMD for the trabecular compartment was determined from each of six sites and from one site within each pedicle. Thus the trabecular density was measured at a total of 20 sites for each person. The highest average QCT BMD was in the pedicle (sites 13 and 14), whereas the BMD was abruptly decreased at the posterior part of the vertebral body near the pedicles. The results of the study indicate that stress concentration of the spine related to the regional variation in vertebral bone density may be implicated in the biomechanical mechanism underlying thoracolumbar burst fractures. This finding may be correlated with the injury mechanism of thoracolumbar burst fractures and of clinical significance.

Objective: To investigate the therapeutic effects and complications of percutaneous anterior screw fixation for odontoid fractures., Methods: Twenty-eight patients with odontoid fractures, 21 males and 7 females, aged 38.6 (21-72), 12 with type II fractures and 16 with type III fractures, including 10 cases with shallow type III fractures, according to Anderson's classification system, underwent percutaneous anterior odontoid screw fixation with one screw implant. Five to seven days after the operation the patients got out of bed to conduct dirigation. Prostheses were used for 8-12 weeks post-operationally. The patients were followed up for 43.2 months (26-62 months). Radiological examination, including X-ray and CT examinations, and clinical examinations were carried out to observe the therapeutic effects., Results: Radiological examination showed bony union in 25 cases (89.3%), and non-union developed in 2 cases, 1 case was switched to posterior fusion surgery because of redisplaced fracture. The union rate was 83.3% in the type II fracture, and was 93.8% in the type III. Majority of the patients resumed an excellent cervical motion. No severe complication such as esophagus and carotid artery injury related with puncture was found. One patient had temporary superior laryngeal nerve paralysis, The screw tail was detained at the superior margin of C3 vertebral body in 5 cases, the screw penetrate the tip of odontoid process in 1 case, and the screw thread failed to pass the fracture site entirely in 1 case., Conclusion: An innovative alternative method with the advantages of convenient procedure, less bleeding, gentle injury for surrounding tissue, and rapid recovery, percutaneous anterior odontoid screw fixation is similarly effective as open anterior odontoid screw fixation, for the treatment of odontoid fractures. Related complication is rare and not severe. The surgery has.

Objective: To introduce the technique of minimally invasive percutaneous pedicle screws osteosynthesis (MIPPSO) and compare the preliminary clinical outcomes of the treatment of thoraco-lumbar vertebra fracture with traditional open pedicle screws osteosynthesis (TOPSO)., Methods: Using the "C" arm fluoroscopic guidance, the pedicle screws were put through new-designed instrumentation and inserted percutaneously with fifty cases of thoraco-lumbar vertebra fracture. Semi-Laminectomy were made in the heavy-occupation side through the incision of 4 cm. Vertebroplasty were made through pedicle of disease vertebrae. perioperative parameter and the index of image were compared with the treatment of traditional open pedicle screws osteosynthesis in other fifty cases., Results: The consumed time of operation in the MIPPSO group and the TOPSO group made no significant difference (P >0.05), but the length of incision, injury of paraspinal muscles, bleeding of operation, drain of postoperation, pain of postoperation, spending time of hospitalization were all significantly different between the two group (P <0.05). Each group compared to itself between preoperation and postoperation, the vertebral height, the height of intervertebral disk, Cobb's angle and the occupation index of vertebral canal were all significantly different (P <0.05). however compared to each other, whether preoperation or postoperation, there were not significant different in the index of image (P >0.05)., Conclusions: The technique of minimally invasive percutaneous pedicle screws osteosynthesis (MIPPSO) has the advantages of simple manipulation, safety, small trauma, less bleeding, light pain, quickly recovery and short hospitalization time.