Safety of anterior cervical corpectomy and fusion (ACCF) for the treatment of subaxial cervical spine injuries, a single center comparative matched analysis.

INTRODUCTION: Anterior Cervical Discectomy and Fusion (ACDF) and Anterior Cervical Corpectomy and Fusion (ACCF) are both common surgical procedures in the management of pathologies of the subaxial cervical spine. While recent reviews have demonstrated ACCF to provide better decompression results compared to ACDF, the procedure has been associated with increased surgical risks. Nonetheless, the use of ACCF in a traumatic context has been poorly described. The aim of this study was to assess the safety of ACCF as compared to the more commonly performed ACDF. METHODS: All patients undergoing ACCF or ACDF for subaxial cervical spine injuries spanning over 2 disc-spaces and 3 vertebral-levels, between 2006 and 2018, at the study center, were eligible for inclusion. Patients were matched based on age and preoperative ASIA score. RESULTS: After matching, 60 patients were included in the matched analysis, where 30 underwent ACDF and ACCF, respectively. Vertebral body injury was significantly more common in the ACCF group (p = 0.002), while traumatic disc rupture was more frequent in the ACDF group (p = 0.032). There were no statistically significant differences in the rates of surgical complications, including implant failure, wound infection, dysphagia, CSF leakage between the groups (p ≥ 0.05). The rates of revision surgeries (p > 0.999), mortality (p = 0.222), and long-term ASIA scores (p = 0.081) were also similar. CONCLUSION: Results of both unmatched and matched analyses indicate that ACCF has comparable outcomes and no additional risks compared to ACDF. It is thus a safe approach and should be considered for patients with extensive anterior column injury.

Validation of the Subaxial Cervical Spine Injury Classification score in children: a single-institution experience at a level 1 pediatric trauma center.

OBJECTIVE: The Subaxial Cervical Spine Injury Classification (SLIC) score has not been previously validated for a pediatric population. The authors compared the SLIC treatment recommendations for pediatric subaxial cervical spine trauma with real-world pediatric spine surgery practice. METHODS: A retrospective cohort study at a pediatric level 1 trauma center was conducted in patients < 18 years of age evaluated for trauma from 2012 to 2021. An SLIC score was calculated for each patient, and the subsequent recommendations were compared with actual treatment delivered. Percentage misclassification, sensitivity, specificity, positive (PPV) and negative predictive value (NPV), and area under the receiver operating characteristic (ROC) curve (AUC) were calculated. RESULTS: Two hundred forty-three pediatric patients with trauma were included. Twenty-five patients (10.3%) underwent surgery and 218 were managed conservatively. The median SLIC score was 2 (interquartile range = 2). Sixteen patients (6.6%) had an SLIC score of 4, for which either conservative or surgical treatment is recommended; 27 children had an SLIC score ≥ 5, indicating a recommendation for surgical treatment; and 200 children had an SLIC score ≤ 3, indicating a recommendation for conservative treatment. Of the 243 patients, 227 received treatment consistent with SLIC score recommendations (p < 0.001). SLIC sensitivity in determining surgically treated patients was 79.2% and the specificity for accurately determining who underwent conservative treatment was 96.1%. The PPV was 70.3% and the NPV was 97.5%. There was a 5.7% misclassification rate (n = 13) using SLIC. Among patients for whom surgical treatment would be recommended by the SLIC, 29.6% (n = 8) did not undergo surgery; similarly, 2.5% (n = 5) of patients for whom conservative management would be recommended by the SLIC had surgery. The ROC curve for determining treatment received demonstrated excellent discriminative ability, with an AUC of 0.96 (OR 3.12, p < 0.001). Sensitivity decreased when the cohort was split by age (< 10 and ≥ 10 years old) to 0.5 and 0.82, respectively; specificity remained high at 0.98 and 0.94. CONCLUSIONS: The SLIC scoring system recommended similar treatment when compared with the actual treatment delivered for traumatic subaxial cervical spine injuries in children, with a low misclassification rate and a specificity of 96%. These findings demonstrate that the SLIC can be useful in guiding treatment for pediatric patients with subaxial cervical spine injuries. Further investigation into the score in young children (< 10 years) using a multicenter cohort is warranted.

A perioperative predictive model of early mortality in acute cervical spinal cord injury: A prospective cohort study.

Background: Traumatic cervical spine injury is common among spinal cord injury which requires an intensive, multidisciplinary approach which can affect the immediate postoperative hospital survival rate. By identifying the risk factors leading to early mortality in cervical spine trauma patients, the prognosis of patients with TCSCI can be better predicted. Objective: The study aims to analyze the variables influencing in-hospital mortality in cervical spine trauma patients treated at a Level I trauma Center. Methods: Prospective study was conducted on subaxial cervical spine injuries from July 2019 to March 2022. Patients were divided into two groups: Group A, with in-hospital mortality, and Group B, who got discharged from hospital, and mortality predictors were reviewed and analyzed for as potential risk factors for in-hospital mortality. Results: Out of 105 patients, 83.8 % were male with mean age of 40.43 ± 12.62 years. On univariate analysis, AIS (p-value: <0.01), ICU stay (p-value: <0.01), level of injury (p-value: <0.01), and MRI parameters like the extent of Parenchymal damage (p-value: <0.01), MSCC (p-value: <0.01), and MCC (p-value: <0.01) were potential risk factors for in-hospital mortality. On multivariate regression analysis AIS at presentation (p-value: 0.02) was the only significant independent parameter for in-hospital mortality. Conclusions: AIS grading at presentation, duration of ICU stay, level of injury, rate of tracheostomy, and MRI parameters like the extent of parenchymal damage, MCC, and MSCC influence and predicts in-hospital mortality, whereas AIS is the only independent risk factor.

Predictors of early mortality following surgical or nonsurgical treatment of subaxial cervical spine fractures: a retrospective nationwide registry study.

BACKGROUND: Traumatic subaxial cervical spine fractures are a significant public health concern due to their association with spinal cord injuries (SCI). Despite being mostly caused by low-energy trauma, these fractures significantly contribute to morbidity and mortality. Currently, research regarding early mortality based on the choice of treatment following these fractures is limited. Identifying predictors of early mortality may aid in postoperative patient monitoring and improve outcomes. PURPOSE: This study aimed to identify predictors of 30-days, 90-days, and 1-year mortality in adults treated for subaxial fractures. STUDY DESIGN: A retrospective review of the nationwide Swedish Fracture Register (SFR). PATIENT SAMPLE: All adult patients in the SFR who underwent treatment for a subaxial cervical fracture (n = 1,963). OUTCOME MEASURES: Analyzed variables included age, sex, injury mechanism, neurological function, fracture characteristics, and treatment type. The primary endpoints were 30-days, 90-days, and 1-year mortality. METHODS: About 1,963 patients in the SFR, treated for subaxial cervical fractures between 2013 and 2021, were analyzed. Surgical procedures included anterior, posterior, or anteroposterior approaches. Nonsurgical treatment included collar treatment or medical examinations without intervention. Stepwise regression and Cox regression analysis were used to determine predictors. Model performance was tested using the area under the receiver operating characteristic curve (AUC). RESULTS: 620 patients underwent surgery and 1,343 received nonsurgical treatment. Surgical cases had primarily translation fractures, with 323 (52%) displaying no neurological deficits. Mortality rates at 30 days, 90 days, and 1 year were 22/620 (3.5%), 35/620 (5.6%), and 53/620 (8.5%), respectively. Age and SCI were predictors of mortality. Nonsurgically treated patients mostly had compression fracture, with 1,214 (90%) experiencing no neurological deficits. Mortality rates at 30 days, 90 days, and 1 year were 41/1,343 (3.1%), 71/1,343 (5.3%), and 118/1,343 (8.7%). Age, male sex, SCI and fractures occurring at the C3 or C6 levels were predictors of mortality. An intact neurological function was a positive predictor of survival among nonsurgically treated patients (AUC >0.78). CONCLUSIONS: Age and SCI emerged as significant predictors of early mortality in both surgically and nonsurgically treated patients. An intact neurological function served as a protective factor against early mortality in nonsurgically treated patients. Fractures at C3 or C6 vertebrae may impact mortality.

The Attallah screw: Where safety meets robustness in posterior subaxial cervical instrumentation.

Posterior fixation of the subaxial cervical spine (SCS) commonly relies on the application of lateral mass screws (LMS), with pedicle screws being a less prevalent alternative. The present study provides another option: A recently introduced novel approach, the Attallah screw, intended to ensure a safety profile comparable to that of LMS, combined with a strength profile similar to that of pedicle screws. The focus of the present study is the comparative analysis of peak insertion torques for these three screw types. Employing standard surgical techniques and instruments, Attallah screws were scheduled for insertion on the right side of the SCS in 15 cadavers, pedicle screws on the left side in 8 cadavers, and LMS on the left side in the remaining 7 cadavers. The peak insertion torque was recorded using an electronic torque screwdriver. The results revealed that the peak insertion torques were similar in the pedicle and the Attallah screw at C3, C4 and C7, but differed at C5 (mean ± SD; pedicle, 79.5±19.6 cNm; Attallah, 56.7±18.5 cNm; P=0.029) and C6 (pedicle, 85.4±28.7 cNm; Attallah, 49.8±17.9 cNm; P=0.004) in favor of the superior pedicle screw measurements. The peak insertion torques of the pedicle screw were superior to the corresponding data from the LMS from C4 to C7. By contrast, the peak insertion torques of the Attallah screw were only superior to those of the LMS at C7 (Attallah, 69.5±24.5 cNm; lateral mass, 40.5±21.4 cNm; P=0.030), although similar trends were observed at the other cervical levels. On the whole, the findings presented herein indicate the level-dependent superior robustness of the Attallah screw as a posterior cervical fixation method compared to the LMS. However, from a biomechanical perspective, the pedicle screw remains the preeminent choice for fixation within the C5-C6 range.

Predictors of failure after primary anterior cervical discectomy and fusion for subaxial traumatic spine injuries.

INTRODUCTION: Traumatic subaxial fractures account for more than half of all cervical spine injuries. The optimal surgical approach is a matter of debate and may include anterior, posterior or a combined anteroposterior (360º) approach. Analyzing a cohort of patients initially treated with anterior cervical discectomy and fusion (ACDF) for traumatic subaxial injuries, the study aimed to identify predictors for treatment failure and the subsequent need for supplementary posterior fusion (PF). METHODS: A retrospective, single center, consecutive cohort study of all adult patients undergoing primary ACDF for traumatic subaxial cervical spine fractures between 2006 and 2018 was undertaken and 341 patients were included. Baseline clinical and radiological data for all included patients were analyzed and 11 cases of supplementary posterior fixation were identified. RESULTS: Patients were operated at a median of 2.0 days from the trauma, undergoing 1-level (78%), 2-levels (16%) and ≥ 3-levels (6.2%) ACDF. A delayed supplementary PF was performed in 11 cases, due to ACDF failure. On univariable regression analysis, older age (p = 0.017), shorter stature (p = 0.031), posterior longitudinal ligament (PLL) injury (p = 0.004), injury to ligamentum flavum (p = 0.005), bilateral facet joint dislocation (p < 0.001) and traumatic cervical spondylolisthesis (p = 0.003) predicted ACDF failure. On the multivariable regression model, older age (p = 0.015), PLL injury (p = 0.048), and bilateral facet joint dislocation (p = 0.010) remained as independent predictors of ACDF failure. CONCLUSIONS: ACDF is safe and effective for the treatment of subaxial cervical spine fractures. High age, bilateral facet joint dislocation and traumatic PLL disruption are independent predictors of failure. We suggest increased vigilance regarding these cases.

The Effect of Concomitant Spinal Cord Injury on Postoperative Health-related Quality of Life After Traumatic Subaxial Cervical Spine Injuries: A Nationwide Registry Study.

OBJECTIVE: To evaluate the effect of spinal cord injury (SCI) on the health-related quality of life (HRQoL) in patients surgically treated for traumatic subaxial cervical spine injuries and investigate the agreement between objective neurologic outcomes and patient reported outcome measures (PROMs) in that context. STUDY DESIGN: Observational study on prospectively collected multi-institutional registry data. SETTING: Sweden. PARTICIPANTS: Patients with traumatic subaxial spine injuries identified in the Swedish Spine Registry (Swespine) between 2006 and 2016. INTERVENTIONS: Anterior, posterior, or anteroposterior cervical fixation surgery. MAIN OUTCOMES: Patient-reported outcome measures (PROMs) consisting of EQ-5D-3Lindex and Neck Disability Index (NDI). RESULTS: Among the 418 identified patients, 93 (22%) had a concomitant SCI. In this group, 30 (32%) had a complete SCI (Frankel A), and the remainder had incomplete SCIs (17%) Frankel B; 25 (27%) Frankel C; 22 (24%) Frankel D. PROMs significantly correlated with the Frankel grade (P<.001). However, post hoc analysis revealed that the differences between adjacent Frankel grades failed to reach both statistical and clinical significance. On univariable linear regression, the Frankel grade was a significant predictor of a specific index derived from the EQ-5D-3L questionnaire (EQ-5D-3Lindex) at 1, 2, and 5 years postoperatively as well as the NDI at 1 and 2 years postoperatively (P<.001). Changes of PROMs over time from 1, to 2, and 5 years postoperatively did not reach statistical significance, regardless of the presence and degree of SCI (P>.05). CONCLUSION: Overall, the Frankel grade significantly correlated with the EQ-5D-3Lindex and NDI and was a significant predictor of PROMs at 1, 2, and 5 years. PROMs were stable beyond 1 year postoperatively regardless of the severity of the SCI.

Adverse events after surgery for injuries to the subaxial cervical spine: analysis of incidence and risk factors.

PURPOSE: To determine the incidence of severe surgical adverse events (sSAE) after surgery of patients with subaxial cervical spine injury (sCS-Fx) and to identify patient, treatment, and injury-related risk factors. METHODS: Retrospective analysis of clinical and radiological data of sCS-Fx patients treated surgically between 2010 and 2020 at a single national trauma center. Baseline characteristics of demographic data, preexisting conditions, treatment, and injury morphology were extracted. Incidences of sSAEs within 60 days after surgery were analyzed. Univariate analysis and binary logistic regression for the occurrence of one or more sSAEs were performed to identify risk factors. P-values < .05 were considered statistically significant. RESULTS: Two hundred and ninety-two patients were included. At least one sSAE occurred in 49 patients (16.8%). Most frequent were sSAEs of the surgical site (wound healing disorder, infection, etc.) affecting 29 patients (9.9%). Independent potential risk factors in logistic regression were higher age (OR 1.02 [1.003-1.04], p = .022), the presence of one or more modifiers in the AO Spine Subaxial Injury Classification (OR 2.02 [1.03-3.96], p = .041), and potentially unstable or unstable facet injury (OR 2.49 [1.24-4.99], p = .010). Other suspected risk factors were not statistically significant, among these Injury Severity Score, the need for surgery for concomitant injuries, the primary injury type according to AO Spine, and preexisting medical conditions. CONCLUSION: sSAE rates after treatment of sCS-Fx are high. The identified risk factors are not perioperatively modifiable, but their knowledge should guide intra and postoperative care and surgical technique.

Emergency Treatment of Cervical Vertebromedullary Trauma: 10 Years of Experience and Outcome Evaluation.

OBJECTIVE: The aim of the study is to identify and validate, through the recording of clinical and radiological data, the different surgical approaches and treatments valid for most subaxial cervical dislocation fractures and whether there is an advantage from using an anterior approach rather than a posterior approach and conversely.. MATERIAL AND METHODS: A retrospective study was carried out analyzing the case history of the last 10 years of vertebromedullary traumas treated at the spine surgery unit of the Policlinico Gemelli in Rome. Data on surgical timing, American Spinal Injury Association (ASIA) scores for neurological damage, and subsequent assessments on recovery, survival, and mortality were also examined. RESULTS: A total of 80 patients were treated: 50 by the posterior approach, 24 by the anterior approach, and six by the double approach. Our average follow-up time was 4.2 years. A prevalence of surgery with the posterior approach was noted. We observed the worsening of cervical kyphosis about 15 months after the trauma in two cases treated with the posterior approach alone. A second surgical treatment was performed in these patients. One of these patients underwent an anterior fusion; the other case underwent a posterior revision because the patient had ankylosing spondylitis. Although we found no statistically significant difference in outcomes between the various surgical treatments, in this retrospective study, we analyzed the characteristics and outcomes of cervical spine injuries that required surgical treatment. CONCLUSION: The aim of surgery in unstable cervical spine injuries should be to reduce and stabilize the damaged segment, maintain lordosis, and decompress when indicated. The optimal choice of surgical approach and treatment, or its superiority in terms of outcomes, remains a debated issue.

Accuracy of Patient-Specific, 3D-Printed Laminofacetal Based Trajectory-Guide for Pedicle Screw Placement in Subaxial Cervical and Thoracic Spine.

Background: Conventional methods of pedicle-screw placement have higher breach rates due to variations in pedicle trajectories. Objective: We studied the accuracy of patient-specific, three-dimensional (3D)-printed laminofacetal-based trajectory guide for pedicle-screw placement in the subaxial-cervical and thoracic spine. Materials and Methods: We enrolled 23 consecutive patients who underwent subaxial cervical and thoracic pedicle-screw instrumentation. They were divided into two groups: group A (cases without spinal deformity) and group B (cases with pre-existing spinal deformity). Patient-specific, 3D-printed laminofacetal-based trajectory guide for each instrumented level was designed. The accuracy of screw placement was assessed on postoperative computed tomography (CT) using the Gertzbein-Robbins grading. Results: A total of 194 pedicle screws (114 cervical and 80 thoracics) were placed using trajectory guides, of which 102 belonged to group B (34 cervical and 68 thoracics). Out of a total of 194 pedicle screws, 193 had clinically acceptable placement (grade A: 187; grade B: 6; and grade C: 1). In the cervical spine, 110 pedicle screws out of a total of 114 had grade A placement (grade B: 4). In the thoracic spine, 77 pedicle screws out of a total of 80 had grade A placement (grade B: 2; grade C: 1). Out of a total of 92 pedicle screws in group A, 90 had grade A placement, and the rest 2 had grade B breach. Similarly, 97 out of a total of 102 pedicle screws in group B were placed accurately, 4 had grade B and another had a grade C breach. Conclusions: Patient-specific, 3D-printed laminofacetal-based trajectory guide may help in accurate placement of subaxial cervical and thoracic pedicle screws. It may help reduce surgical time, blood loss, and radiation exposure.

Efficacy, Safety, and Reliability of the Single Anterior Approach for Subaxial Cervical Spine Dislocation.

Background Though there is ongoing controversy regarding the best treatment option for cervical spine dislocation (CSD), anterior cervical surgery with direct decompression is becoming widely accepted. However, managing all cases of subaxial CSD entirely by a single anterior approach is rarely seen in the published literature. Methods The study comprised patients with subaxial CSD who underwent surgical stabilization utilizing a single anterior approach. Most of the CSD was reduced and anterior cervical discectomy and fusion (ACDF) were performed. Anterior cervical corpectomy and fusion (ACCF) were done in unreduced dislocations. The patient's neurological condition, radiological findings, and functional outcomes were assessed. SPSS version 25.0 (IBM Corp., Armonk, NY) was used for statistical analysis. Results The total number of operated cases was 64, with an average of 42 months of follow-up. The mean age was 34.50±11.92 years. The most prevalent level of injury was C5/C6 (57.7%). Reduction was achieved in 92.2% of cases; only 7.8% of patients needed corpectomy. The typical operative time was 84.25±9.55 minutes, with an average blood loss of 112.12±25.27 ml. All cases except complete spinal cord injury (CSI) were improved neurologically (87.63%). The mean Neck Disability Index (NDI) was 11.14±11.43, and the pre-operative mean visual analog score (VAS) was finally improved to 2.05±0.98 (P<0.05). In all cases, fusion was achieved. The most common complication was transient dysphagia (23.4%). After surgery, no patient developed or aggravated a neurological impairment. Implant failure was not observed at the final follow-up except for two cases where screws were pulled out partially. Conclusion Based on the results of this study, a single anterior approach is a safe and effective procedure for subaxial CSD treatment with favorable radiological, neurological, and functional outcomes.

Subaxial Cervical Pedicular Screw Insertion via the Nonanatomic Axis: Technical Notes and Preliminary Clinical Report.

STUDY DESIGN: Retrospective study. OBJECTIVE: To report the technical details of subaxial cervical pedicular screw insertion via the nonanatomic axis (nAA-CPS) and evaluate its clinical safety and accuracy. METHODS: The nAA-CPS technique was performed in 21 patients. Preoperative and intraoperative management-related details are described, and a manipulation protocol is presented. Clinical outcomes were used to assess the safety and accuracy of screws was evaluated using postoperative computed tomography (CT) according to the pedicle perforation grading system, and the nonanatomic pedicle transverse angle (nPTA) and nonanatomic pedicle axis length (nPAL) were assessed based on pre- and postoperative CT images. RESULTS: According to "one constant entry point (EP) and two perpendicular trajectory angles" protocol, nAA-CPS was performed without much interference from the muscles. No intraoperative or postoperative neurovascular complications related to the technique were observed. Of the 112 inserted screws, 78 (69.64%) were assessed as grade 0, 24 (21.43%) as grade 1, 4 (3.57%) as grade 2 and 6 (5.36%) as grade 3. The overall rate of correct position (grades 0 and 1) was 91.07% (102/112), and the rate of malposition was 8.93% (10/112), including five screws implanted medially and the other five laterally. The nPTA was highly consistent on pre- and postoperative CT (P < .05), while postoperative nPAL was significantly shorter than preoperative nPAL (P > .05). CONCLUSIONS: Clinically, the accuracy and safety of nAA-CPS was similar to the traditional CPS technique. The protocol, derived from previous radiological studies and workshops, greatly helped standardize clinical manipulation; thus, nAA-CPS is a promising alternative to the traditional CPS.

Spontaneous fusion several years after undiagnosed cervical distractive flexion injury: a report of 3 cases.

We report three cases of spontaneously fused distractive flexion injury (DFI) in the cervical spine detected several years after the trauma. This is the first report in the literature that describes such late presentation of healed DFI. Although injuries are considered highly unstable requiring fusion surgery, all three healed spontaneously without intervention or immobilization. Despite significant misalignment, stability was confirmed with flexion-extension radiographs. All the three patients had no neurologic deficits. The possibility of healed old DFI should be kept in mind for patients who present with neck pain and a history of high-energy trauma.

Facet cysts in the subaxial cervical spine: Case series focused on radiological and histopathological findings with a scoping review.

BACKGROUND: Facet cysts in the subaxial cervical spine are a relatively rare cause of neuropathy. This case series aimed to investigate the radiological and histopathological features and surgical results of these lesions, and provide possible mechanisms of cyst development. METHODS: Thirteen subaxial cervical facet cysts in 12 patients were diagnosed on the basis of magnetic resonance imaging and computed tomography with facet arthrography. Surgical outcomes were evaluated according to the Japanese Orthopaedic Association scores for cervical myelopathy, or Tanaka's scores for cervical radiculopathy. These results were presented in combination with a scoping review of the literature. RESULTS: Seven cysts were found in the posteromedial region, and six in the posterolateral portion of the spinal canal. Computed tomography revealed degeneration of all involved facet joints. All patients underwent decompression, and the mean recovery rates of Japanese Orthopaedic Association scores and Tanaka's scores were 57.1% and 87.5%, respectively. Histopathologically, all cysts were continuous with the degenerated ligamentum flavum. In the scoping review, the patients' mean age was 65.1 years. The cysts were distributed as follows: 3.6% at C2-3, 10.7% at C3-4, 14.3% at C4-5, 5.4% at C5-6, 7.1% at C6-7, and 58.9% at C7-T1. The presenting symptoms were myelopathy (49.4%) and radiculopathy (50.0%). Radiologically, 55% and 45% of the cysts were of the posteromedial and posterolateral types. Of the patients, 76.9% underwent decompression only, and 23.1% had concomitant fusion. Cyst recurrence was not observed in the mean follow-up period of 15.1 months. CONCLUSIONS: The pathogenesis of cysts is closely related to degenerative changes in the facet joint and ligamentum flavum, and rupture in degenerated ligaments can develop into a cavity, which contributes to cyst formation. The scoping review suggests that cyst resection generally results in positive outcomes without recurrence in either decompression alone or concomitant fusion.

Biomechanical effects of different lateral mass injury patterns on subaxial cervical fracture dislocations after anterior cervical surgery: a finite element study.

OBJECTIVE: The lateral mass joint plays an important role in maintaining the mechanical stability of the subaxial cervical spine. We first performed a three-dimensional finite element (FE) biomechanical study to evaluate the local mechanical stability of subaxial cervical fracture dislocations after anterior-only fixation for lateral mass injuries of varying severity. METHODS: A three-dimensional FE model of the subaxial cervical spine with simple anterior fixation for C5-6 fracture dislocation was reconstructed. According to their different morphological characteristics of unilateral lateral mass injuries, the lateral mass injury was divided into six types. The range of motion (ROM) of each part and the stress of the cage, each intervertebral disc, titanium plate, and screw stress were recorded. RESULTS: The ROM of C3-4, C4-5, C5-6, and C6-7 in type 4 was higher than that of the other five types. The maximum equivalent stress on C4-5 intervertebral discs, titanium plates, and screws in type 4 under various sports loads was higher than that produced by the other load types. In the stress cloud diagram of the front titanium plate and screws, the degree of stress was the highest in type 4. Stress placed on each part of the model, from high to low, was as follows: plate, screw, C6, C5, and C7. CONCLUSION: Greater injury severity is associated with higher stress on the plate and screw with exercise loads. Type 4 lateral mass injuries, characterized by ipsilateral pedicle and lamina junction fractures, significantly affected biomechanical stability after simple anterior fixation.

Unilateral spacer distraction of the subaxial cervical facet joint for the treatment of fixed coronal malalignment of the craniovertebral junction.

Introduction: The standard treatment for a fixed coronal malalignment of the craniovertebral junction is an anterior and/or posterior column osteotomy (PCO) plus instrumentation. However, the procedure is very challenging, carrying an inherently high risk of complications even in experienced hands. This case series demonstrates the usefulness of an alternative treatment that adds a unilateral spacer distraction (USD) to the subaxial cervical facet joint to promote coronal realignment and fusion. Materials and Methods: A single-center retrospective study of the patients with fixed coronal malalignment of the craniovertebral junction caused by different etiologies treated with USD in the concavity side with PCO in the convexity side of the subaxial cervical spine. Demographic characteristics and radiological parameters were collected with special emphasis on clinical and radiological measurements of coronal alignment of the cervical spine. Results: From 2012 to 2019, four patients were treated with USD of the subaxial cervical spine complementing an asymmetrical PCO at the same level. The causes of coronal imbalance were congenital, tuberculosis, posttraumatic, and ankylosing spondylitis. The level of USD was C2-C3 in three patients and C3-C4 in one patient. A substantial coronal realignment was achieved in all four. One patient had an iatrogenic vertebral artery injury during the dissection and facet distraction and developed Wallenberg's syndrome with partial recovery. Conclusions: USD of the concave side with unilateral PCO of the convexity side in the subaxial cervical spine is a promising alternative treatment for fixed coronal malalignment of the craniovertebral junction from different causes.

Technical Feasibility of Subaxial Cervical Pedicle Screws for Distal Anchoring of Occipitocervical Fixation Constructs in the Mid-Cervical Spine: Early Clinical Experience.

Occipitocervical fixation and fusion (OCF) is performed for patients who have destabilizing traumatic injuries or pathologies affecting the complex bony and ligamentous structures of the occipitoatlantal and atlantoaxial joint structures. Distal fixation failure and pseudoarthrosis are known risks of these constructs, especially for those constructs ending in the mid-cervical spine. We present the technical feasibility of using cervical pedicle screws (CPSs) as distal fixation anchors to strengthen OCF constructs ending in the mid-cervical spine and present a case series describing our early clinical experience with this technique. We used a freehand technique to place subaxial pedicle screws in the mid-cervical spine as the distal fixation point in OCF constructs. This technique involves performing a laminotomy to provide direct visualization of the pedicle borders to safely guide freehand pedicle screw placement. Our early clinical experience with this technique is presented. Three patients received OCF constructs ending in the mid-cervical subaxial spine between C3 and C6. CPSs were placed at the distal vertebra in each construct. Stable instrumentation and arthrodesis were confirmed postoperatively in all patients. This freehand technique uses direct visualization of the pedicle to aid in safe and accurate subaxial pedicle screw placement. CPS placement is clinically feasible and increases the robustness of OCF constructs in appropriately selected patients. Larger case series are needed to further validate the safety and effectiveness of this technique.

Efficacy of anterior debridement and bone grafting with fusion using internal fixation combined with anti-tuberculosis chemotherapy in the treatment of subaxial cervical tuberculosis.

BACKGROUND: To evaluate the efficacy of anterior debridement and bone grafting with fusion using internal fixation (BFIF) combined with anti-tuberculosis chemotherapy in the treatment of subaxial cervical spine tuberculosis (SCS-TB). METHODS: Clinical and radiographic data of patients with SCS-TB treated by anterior debridement and BFIF at our hospital from January 2010 to December 2017 were analyzed retrospectively. The SCS sagittal parameters at the preoperative, postoperative, and final follow-up were documented and compared, including the Occiput-C2 angle, C2-C7 Cobb angle, local Cobb angle, spinal canal angle (SCA), C2-C7 sagittal vertical axis (C2-C7 SVA), the center of gravity of the head-C7 sagittal vertical axis (CGH-C7 SVA), T1 slope (T1S), neck tilt (NT), and thoracic inlet angle (TIA). The ASIA grade, NDI index, JOA score, and VAS score were utilized to assess the postoperative function recovery, and the complications were recorded. RESULTS: A total of 23 patients were included in the study with a mean age of 46.74 ± 15.43 years, including 8 males and 15 females. All patients with SCS-TB were treated with anterior debridement and BFIF, with a mean postoperative follow-up time of 37.17 ± 12.26 months. The poisoning symptoms of TB were relieved in all patients, and ESR (42.09 ± 9.53 vs 8.04 ± 5.41, P < 0.05) and CRP (30.37 ± 16.02 vs 7.4 ± 2.68, P < 0.05) were decreased at the 3 postoperative months in the comparison of the preoperative. The C0-C2 Cobb angle, C2-C7 Cobb angle, local Cobb angle, SCA, TIS, C2-C7 SVA, and CGH-C7 SVA were corrected remarkably after surgery (P < 0.05). Further, there was a significant improvement in the JOA, VAS, and NDI with the comparison of the preoperative (P < 0.05). CONCLUSIONS: Anterior debridement and BFIF combined with anti-TB chemotherapy was a practical tool for the treatment of SCS-TB with the help of SCS sagittal parameters, which can remove the lesion completely, decompress the spinal cord compression, and correct the kyphotic deformity to restore the spine sagittal balance.

A finite element study on the effects of follower load on the continuous biomechanical responses of subaxial cervical spine.

In spine biomechanics, follower loads are used to mimic the in vivo muscle forces acting on a human spine. However, the effects of the follower load on the continuous biomechanical responses of the subaxial cervical spines (C2-T1) have not been systematically clarified. This study aims at investigating the follower load effects on the continuous biomechanical responses of C2-T1. A nonlinear finite element model is reconstructed and validated for C2-T1. Six levels follower loads are considered along the follower load path that is optimized through a novel range of motion-based method. A moment up to 2 Nm is subsequently superimposed to produce motions in three anatomical planes. The continuous biomechanical responses, including the range of motion, facet joint force, intradiscal pressure and flexibility are evaluated for each motion segment. In the sagittal plane, the change of the overall range of motion arising from the follower loads is less than 6%. In the other two anatomical planes, both the magnitude and shape of the rotation-moment curves change with follower loads. At the neutral position, over 50% decrease in flexibility occurs as the follower load increases from zero to 250 N. In all three anatomical planes, over 50% and 30% decreases in flexibility occur in the first 0.5 Nm for small (≤100 N) and large (≥150 N) follower loads, respectively. Moreover, follower loads tend to increase both the facet joint forces and the intradiscal pressures. The shape of the intradiscal pressure-moment curves changes from nonlinear to roughly linear with increased follower load, especially in the coronal and transverse planes. The results obtained in this work provide a comprehensive understanding on the effects of follower load on the continuous biomechanical responses of the C2-T1.