Complications and radiographic changes after implantation of interspinous process devices: average eight-year follow-up.

PURPOSE: This study aims to evaluate complications, clinical outcomes, and radiographic results following Coflex implantation. METHODS: We retrospectively studied 66 patients who had decompressive surgery combined with Coflex implantation to treat lumbar spinal stenosis. All imaging data were collected and examined for imaging changes. Clinical outcomes, included Oswestry Disability Index (ODI), back and leg visual analog scale (VAS) scores, were evaluated before surgery, six months after surgery and at the last follow-up. The number of complications occurring after five years of follow-up was counted. All reoperation cases were meticulously recorded. RESULTS: 66 patients were followed up for 5-14 years. The VAS and ODI scores were significantly improved compared with baseline. Heterotopic Ossification (HO) was detectable in 59 (89.4%). 26 (39.4%) patients had osteolysis at the contact site of Coflex with the spinous process. Coflex loosening was detected in 39 (60%) patients. Spinous process anastomosis was found in 34 (51.5%) patients. There was a statistically significant difference in the VAS score of back pain between patients with and without spinous process anastomosis. Nine cases of lumbar spinal restenosis were observed, and prosthesis fracture was observed in one case. CONCLUSION: Our study identified various imaging changes after Coflex implantation, and majority of them did not affect clinical outcomes. The majority of patients had HO, but osteolysis and Coflex loosening were relatively rare. The VAS score for back pain of these patients was higher if they have spinous process anastomosis. After five-year follow-up, we found lumbar spinal restenosis and prosthesis fracture cases.

Percutaneous posterior transdiscal oblique screw fixation with lateral interbody fusion: a radiological and cadaveric study.

PURPOSE: To design and investigate a novel technique of percutaneous posterior transdiscal oblique screw fixation with lateral interbody fusion. METHODS: CT scans of 45 patients were collected and imported into Mimics software for three-dimensional (3D) reconstruction. Cylinders were drawn to simulate the trajectory of the oblique screw. Six measurements were obtained for each unit to design a right size cage: a the distance between the intersection of the simulated trajectory of the screw with the inferior border of the upper vertebra and its anteroinferior corner; b the distance between the intersection of the simulated trajectory of the screw with the superior border of the inferior vertebra and its anterosuperior corner; h the height of the intervertebral space; θ the angle between simulated trajectory of screw and the upper endplate of inferior vertebra; uw: the width of the inferior endplate of upper vertebra; iw: the width of upper endplate of inferior vertebra. Three intact adult fresh-frozen cadaveric specimens were obtained, percutaneous posterior transdiscal oblique screw fixation was performed under X-ray apparatus, and interbody cage was implanted by assistance with special self-retaining retractor system and endoscope. RESULTS: According to the results of data measured from 3D images, trapezoid shape interbody cages with suitable size were designed. Percutaneous posterior oblique screw fixation with lateral interbody fusion was performed on three cadaveric specimens successfully. CONCLUSION: Using specially designed trapezoid shape interbody cages, assisted by intra-operative image intensification and endoscope, it is feasible to perform percutaneous posterior transdiscal oblique screw fixation with lateral interbody fusion technique.

Development of a Deep-Learning Model for Diagnosing Lumbar Spinal Stenosis Based on CT Images.

STUDY DESIGN: Retrospective study. OBJECTIVES: This study aimed to develop an initial deep-learning (DL) model based on computerized tomography (CT) scans for diagnosing lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: Magnetic resonance imaging is commonly used for diagnosing lumbar spinal stenosis due to its high soft tissue resolution, but CT is more portable, cost-effective, and has wider regional coverage. Using DL models to improve the accuracy of CT diagnosis can effectively reduce missed diagnoses and misdiagnoses in clinical practice. MATERIALS AND METHODS: Axial lumbar spine CT scans obtained between March 2022 and September 2023 were included. The data set was divided into a training set (62.3%), a validation set (22.9%), and a control set (14.8%). All data were labeled by two spine surgeons using the widely accepted grading system for lumbar spinal stenosis. The training and validation sets were used to annotate the regions of interest by the two spine surgeons. First, a region of interest detection model and a convolutional neural network classifier were trained using the training set. After training, the model was preliminarily evaluated using a validation set. Finally, the performance of the DL model was evaluated on the control set, and a comparison was made between the model and the classification performance of specialists with varying levels of experience. RESULTS: The central stenosis grading accuracies of DL Model Version 1 and DL Model Version 2 were 88% and 83%, respectively. The lateral recess grading accuracies of DL Model Version 1 and DL Model Version 2 were 75% and 71%, respectively. CONCLUSIONS: Our preliminarily developed DL system for assessing the degree of lumbar spinal stenosis in CT, including the central canal and lateral recess, has shown similar accuracy to experienced specialist physicians. This holds great value for further development and clinical application.

Enhancing Diagnostic Accuracy of Fresh Vertebral Compression Fractures with Deep Learning Models.

STUDY DESIGN: Retrospective study. OBJECTIVES: The study aimed to develop and authenticated a deep learning model based on X-ray images to accurately diagnose fresh thoracolumbar vertebral compression fractures. SUMMARY OF BACKGROUND DATA: In clinical practice, diagnosing fresh vertebral compression fractures often requires MRI. However, due to the scarcity of MRI resources and the high time and economic costs involved, some patients may not receive timely diagnosis and treatment. Using a deep learning model combined with X-rays for diagnostic assistance could potentially serve as an alternative to MRI. METHODS: In this study, the main collection included X-ray images suspected of thoracolumbar vertebral compression fractures from the municipal shared database between December 2012 and February 2024. Deep learning models were constructed using frameworks of EfficientNet, MobileNet, and MnasNet respectively. We conducted a preliminary evaluation of the deep learning model using the validation set. The diagnostic performance of the models was evaluated using metrics such as AUC value, accuracy, sensitivity, specificity, F1 score, precision, and ROC curve. Finally, the deep learning models were compared with evaluations from two spine surgeons of different experience levels on the control set. RESULTS: This study included a total of 3025 lateral X-ray images from 2224 patients. The dataset was divided into a training set of 2388 cases, a validation set of 482 cases, and a control set of 155 cases. In the validation set, the three groups of DL models had accuracies of 83.0%, 82.4%, and 82.2%, respectively. The AUC values were 0.861, 0.852, and 0.865, respectively. In the control set, the accuracies of the three groups of DL models were 78.1%, 78.1%, and 80.7%, respectively, all higher than spinal surgeons and significantly higher than junior spine surgeon. CONCLUSION: This study developed deep learning models for detecting fresh vertebral compression fractures, demonstrating high accuracy.

Mini-open anterior approach to the cervicothoracic junction: a cadaveric study.

PURPOSE: To investigate the feasibility of mini-open anterior approach to the cervicothoracic junction (CTJ) in cadaveric specimens. METHODS: Four adult fresh-frozen cadaveric specimens were used for this study. On the cadaveric specimen, an osteotomy window was made in manubrium sterni to remove the bony obstacle. To bypass the vital vascular and neural structures over the operative field, we used the surgical corridor which was located medially by the brachiocephalic artery and laterally by the right brachiocephalic vein, or in combination with another surgical corridor between the ascending aorta and the superior vena cava. And we used a special self-retaining retractor system and an endoscope to facilitate the procedures. RESULTS: Surgical procedures performed on the four fresh-frozen cadaveric specimens to expose the CTJ through mini-open anterior approach were successful. The anterior surface of C6-T5 could be exposed, allowing complete decompression and application of locking plate and screws. The most caudal accessible vertebral body was T5 vertebral body in our study. CONCLUSION: It is feasible to expose the CTJ through this mini-open anterior approach.

Minimally invasive versus open transforaminal lumbar interbody fusion: a meta-analysis based on the current evidence.

PURPOSE: This is a meta-analysis of randomized and non-randomized studies comparing the clinical and radiological efficacy of minimally invasive (MI) and conventional open transforaminal lumbar interbody fusion (open-TLIF) for degenerative lumbar diseases. METHODS: A literature search of the MEDLINE database identified 11 studies that met our inclusion criteria. A total of 785 patients were examined. Pooled estimates of clinical and radiological outcomes, and corresponding 95% confidence intervals were calculated. RESULTS: The pooled data revealed that MI-TLIF was associated with less blood loss, shorter hospital stay, and a trend of better functional outcomes when compared with open-TLIF. However, MI-TLIF significantly increased the intraoperative X-ray exposure. Both techniques had similar operative time, complication rate, and re-operation rate. CONCLUSIONS: Based on the available evidence, MI-TLIF for degenerative lumbar diseases might lead to better patient-based outcomes. MI-TLIF would be a promising procedure, but extra efforts are needed to reduce its intraoperative radiation exposure. More randomized controlled trials are needed to compare these two surgical options.

Management of hangman's fracture with percutaneous transpedicular screw fixation.

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.

Incidence of heterotopic ossification after implantation of interspinous process devices.

OBJECT: This study aimed to investigate the incidence rate of heterotopic ossification (HO) after implantation of Coflex interspinous devices. Possible risk factors associated with HO were evaluated. METHODS: The authors retrospectively analyzed patients who had undergone single-level (L4-5) implantation of a Coflex device for the treatment of lumbar spinal stenosis. Patient data recorded were age, sex, height, weight, body mass index, smoking habits, and surgical time. Heterotopic ossification was identified through lumbar anteroposterior and lateral view radiographs. The authors developed a simple classification for defining HO and compared HO-positive and HO-negative cases to identify possible risk factors. RESULTS: Among 32 patients with follow-up times of 24-57 months, HO was detectable in 26 (81.2%). Among these 26 patients, HO was in the lateral space of the spinous process but not in the interspinous space in 8, HO was in the interspinous space but did not bridge the adjacent spinous process in 16, and interspinous fusion occurred at the level of the device in 2. Occurrence of HO was not associated with patient age, sex, height, weight, body mass index, smoking habits, or surgical time. CONCLUSIONS: A high incidence of HO has been detected after implantation of Coflex devices. Clinicians should be aware of this possible outcome, and more studies should be conducted to clarify the clinical effects of HO.

Complications in degenerative lumbar disease treated with a dynamic interspinous spacer (Coflex).

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.

Safranal inhibits estrogen-deficiency osteoporosis by targeting Sirt1 to interfere with NF-κB acetylation.

BACKGROUND: Osteoporosis is a prevalent bone metabolic disease in menopause, and long-term medication is accompanied by serious side effects. Estrogen deficiency-mediated hyperactivated osteoclasts is the initiating factor for bone loss, which is regulated by nuclear factor-κB (NF-κB) signaling. Safranal (Saf) is a monoterpene aldehyde produced from Saffron (Crocus sativus L.) and possesses multiple biological properties, particularly the anti-inflammatory property. However, Saf's role in osteoporosis remains unknown. PURPOSE: This study aims to validate the role of Saf in osteoporosis and explore the potential mechanism. STUDY DESIGN: The RANKL-exposed mouse BMM (bone marrow monocytes) and the castration-mediated osteoporosis model were applied to explore the effect and mechanism of Saf in vitro and in vivo. METHOD: The effect of Saf on osteoclast formation and function were assessed by TRAcP staining, bone-resorptive experiment, qPCR, immunoblotting and immunofluorescence, etc. Micro-CT, HE, TRAcP and immunohistochemical staining were performed to estimate the effects of Saf administration on OVX-mediated osteoporosis in mice at imaging and histological levels. RESULTS: Saf concentration-dependently inhibited RANKL-mediated osteoclast differentiation without affecting cellular viability. Meanwhile, Saf-mediated anti-osteolytic capacity and Sirt1 upregulation were also found in ovariectomized mice. Mechanistically, Saf interfered with NF-κB signaling by activating Sirt1 to increase p65 deacetylation and inactivating IKK to decrease IκBα degradation. CONCLUSION: Our results support the potential application of Saf as a therapeutic agent for osteoporosis.

Pedicle screw insertion accuracy with different assisted methods: a systematic review and meta-analysis of comparative studies.

Studies revealed that navigation systems that provided intraoperative assistance might improve pedicle screw insertion accuracy, and also implied that different systems provided different pedicle screw insertion accuracy. A systematic review and meta-analysis was conducted to focus on the pedicle screw insertion accuracy with or without the assistance of image-guided system, and the variance among the different navigation systems. Comparative studies were searched on pedicle screw insertion accuracy between conventional and navigated method, and among different navigation systems. A total of 43 papers, including 28 clinical, 14 cadaveric and 1 model studies, were included in the current study. For clinical articles, there were 3 randomized clinical trials, 4 prospective comparative studies and 21 retrospective comparative studies. The incidence of pedicle violation among computer tomography-based navigation method group was statistically significantly less than that observed among the conventional group (OR 95% CI, in vivo: 0.32-0.60; in vitro: 0.24-0.75 P < 0.01). Two-dimensional fluoroscopy-based navigation system (OR 95% CI, in vivo: 0.27-0.48; in vitro: 0.43-0.88 P < 0.01) and three-dimension fluoroscopy-based navigation system (OR 95% CI, in vivo: 0.09-0.38; in vitro: 0.09-0.36 P < 0.01) also obtained significant reduced screw deviation rate over traditional methods. Between navigated approaches, statistically insignificant individual and pooled RR values were observed for all in vivo subgroups. Pooled estimate of in vitro studies show that computer tomography-based and three-dimension fluoroscopy-based navigation system provided more accurate pedicle screw insertion over two-dimension fluoroscopy-based navigation system. Our review showed that navigation provided a higher accuracy in the placement of pedicle screws compared with conventional methods. The superiority of navigation systems was obvious when they were applied to abnormal spinal structure. Although no strong in vivo evidence has detected significantly different pedicle screw placement accuracy among the three major navigation systems, meta-analysis revealed the variance in pedicle screw insertion accuracy with different navigation methods.

Projection of the Most Anterior Line of the Spinal Canal on Lateral Radiograph: An Anatomic Study for Percutaneous Kyphoplasty and Percutaneous Vertebroplasty.

ABSTRACTPurpose: To measure the projection of the most anterior line of the spinal canal on lateral radiographs of the vertebra (C3-L5) and evaluate the efficacy of the safety line (SL) in preventing intraspinal cement leakage in percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP). Materials and Methods: Fifteen adult dry-bone spine specimens were analyzed. The projection of the SL was viewed on lateral radiographs. The distance between the SL and the posterior vertebral body line (PVBL) was measured. Two groups of patients were treated by PKP, and cement injection was stopped either before the PBVL (group 1) or before the SL (group 2) under lateral fluoroscopy. The rate of cement leakage was compared between the two groups. Results: The largest distance between the SL and PVBL was at L1 (5.22 ± 0.62 mm). From L1 to L5, the distance decreased progressively to 1.05 ± 0.64 mm. Similar variation was also observed from L1 to T1 (0.19 ± 0.18 mm). The postoperative computed tomography scan was more sensitive and accurate in detecting intraspinal leakage than radiography in group 1 (p = 0.000); however, there was no significant difference in sensitivity or accuracy between methods in group 2 (p = 0.063). The rate of intraspinal cement leakage was significantly higher in group 1 than group 2 (p = 0.000). Conclusions: The operator should frequently check to ensure that cement injection has stopped upon reaching the SL. Surgeons may benefit from this quantitative anatomical study of PKP and PVP.

Image-guided pedicle screw insertion accuracy: a meta-analysis.

Improved pedicle screw insertion accuracy has been reported with the assistance of computer tomography-based navigation. Studies also indicated that fluoroscopy-based navigation offers high accuracy and is comparable to CT-based assistance. However, different population characteristics and assessment methods resulted in inconsistent conclusions. We searched OVID, Springer, and MEDLINE databases to conduct a meta-analysis of the published literature specifically looking at accuracy of pedicle screw placement with different navigation methods. Subgroups and descriptive statistics were determined based on the subject type (in vivo or cadaveric), navigational method, and spinal level. A total number of 7,533 pedicle screws were summarised in our database with 6,721 screws accurately inserted into the pedicles (89.22%). Overall, the median placement accuracy for the in vivo CT-based navigation subgroup (90.76%) was higher than that with the use of two-dimensional (2D) fluoroscopy-based navigation (85.48%). We concluded that CT-based navigation could provide a higher accuracy in the placement of pedicle screws for all subgroups presented. In the lumbar level, 2D fluoroscopy-based navigation was comparable with CT-based navigation. Discrepancy between the two navigation types increased in the thoracic level for the in vivo populations, where there was less potential in the use of 2D fluoroscopy-based navigation than CT-based navigation.

Inhibition of EZH2 ameliorates cartilage endplate degeneration and attenuates the progression of intervertebral disc degeneration via demethylation of Sox-9.

BACKGROUND: Cartilaginous endplate (CEP) degeneration is considered as one of the major causes of intervertebral disc degeneration (IVDD) which causes low back pain. Recent studies have proved that epigenetic alteration is involved in a variety of diseases. This work explored the role of histone methyltransferase enhancer of zeste homologue 2 (EZH2) in CEP degeneration, as well as its underlying epigenetic mechanisms, and confirmed the effect of EZH2 knockdown on delaying IVDD development. METHODS: Western blotting, immunofluorescence staining, and ChIP assay were applied to demonstrate the molecular mechanism of EZH2 in CEP tissue. The therapeutic potential of EZH2 was investigated using puncture-induced rat models. FINDINGS: The EZH2 expression was upregulated in human and rat CEP tissue. It was also found that the overexpression of EZH2 suppressed the expression of Collagen II, aggrecan and Sox-9, and promoted the expression of ADTAMTS5 and MMP13 in rat endplate chondrocytes (EPCs), which could be reversed by EZH2 silencing. The correlation between EZH2 and Sox-9 was further explored, while overexpression of Sox-9 could reverse the effect of EZH2 in rat EPCs. Moreover, inhibition of EZH2 upregulated the level of Sox-9 by demethylating H3K27me3 at Sox-9 promoter sites, revealing the regulatory mechanism of EZH2 on Sox-9. Meanwhile, puncture-induced rat models showed that EZH2 knockdown exerted a protective effect on CEP and disc degeneration. INTERPRETATION: This study reveals that EZH2 inhibition is a promising strategy for mitigating the symptoms and progression of IVDD. FUNDING: This study was funded by the Natural Science Foundation of Zhejiang Province (Y16H060034). Authors declare that the funders had no involvement in the study design, data analysis and interpretation of the results.

Feasibility of Modified Anterior Odontoid Screw Fixation: Analysis of a New Trajectory Using 3-Dimensional Simulation Software.

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.

Vacuum-assisted closure combined with a closed suction irrigation system for treating postoperative wound infections following posterior spinal internal fixation.

BACKGROUND: Wound infections after posterior spinal surgery are a troublesome complication; patients are occasionally forced to remove the internal fixation device, which can lead to instability of the spine and injury to the spinal cord. The purpose of this study was to evaluate the efficacy of modified vacuum-assisted closure (VAC) for treating an early postoperative spinal wound infection. METHODS: We conducted a retrospective study of 18 patients with wound infections after posterior spinal surgery from 2014 to 2017 at a single tertiary center. All patients included in the study received modified VAC treatment (VAC combined with a closed suction irrigation system, CSIS) until the wound satisfied the secondary closure conditions. Detailed information was obtained from the medical records. RESULTS: Wound size decreased significantly after 1 week of the modified VAC treatment. Three patients were treated with VAC three times and one patient received the VAC treatment four times; the remaining patients received the VAC treatment twice. The patients had excellent wound beds after an average of 8 days. The wound healed completely after an average of 17 days, and the average hospital stay was 33 days. There was no recurrence of infection at the 1-year follow-up. CONCLUSIONS: This study demonstrates that VAC combined with a CSIS is a safe, reliable, and effective method to treat a wound infection after spinal surgery. This improved VAC procedure provides an excellent wound bed to facilitate wound healing and shorten the hospital stay.

Efficacy of Using Intermediate Screws in Short-Segment Fixation for Thoracolumbar Fractures: A Meta-Analysis of Randomized Controlled Trials.

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.

Risk Factors for Dural Tears in Thoracic and Lumbar Burst Fractures Associated With Vertical Laminar Fractures.

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.

Acceptable Chin-Brow Vertical Angle for Neutral Position Radiography: Preliminary Analyses Based on Parameters of the Whole Sagittal Spine of an Asymptomatic Chinese Population.

OBJECTIVE: We sought to acquire the whole sagittal spine parameters and investigated the acceptable chin-brow vertical angle (CBVA) for neutral position radiography in an asymptomatic Chinese population. METHODS: The parameters measured in 257 asymptomatic volunteers included CBVA, occipital slope, orbital tilt, occipital incidence, C0-C2 Cobb angle, C2-C7 Cobb angle, C1-C7 Cobb angle, C2-C7 sagittal vertical axis and absolute rotation angle, cervical tilt, cranial tilt, T1 slope, and thoracic kyphosis, and others. We used Pearson correlation analyses to find relationships between CBVA and other variables. The subjects were divided into 5 groups according to the CBVA percentile: group A, 0%-20% CBVA; group B, 20%-40% CBVA; group C, 40%-60% CBVA; group D, 60%-80% CBVA; and group E, 80%-100% CBVA. We used analysis of variance to analyze differences among the 5 groups. RESULTS: Orbital tilt, Occipital incidence, C1-C7 Cobb angle, C2-C7 sagittal vertical axis, and cranial tilt all increased with increasing CBVA (P < 0.001). The occipital slope, C2-C7 Cobb angle, C2-C7 absolute rotation angle, cervical tilt, T1 slope, and thoracic kyphosis decreased with decreasing CBVA (P < 0.05). No correlations between other sagittal parameters and the CBVA were found. A slight deviation was found in groups B-D, with a greater deviation in groups A, C, and E. CONCLUSIONS: An acceptable range of -1.5° to 5.8° is recommended for the CBVA for cervical radiography in the neutral position. When spinal surgeons evaluate the cervical plane, the effects of the CBVA deviation on cervical curvature must be considered.