Effective Method of Pedicle Screw Fixation in Patients with Neurologically Intact Thoracolumbar Burst Fractures: A Systematic Review of Studies Published Over the Last 20 Years.

OBJECTIVE: To conduct a systematic review of studies on various posterior pedicle screw fixation (PSF) methods used for treating neurologically intact thoracolumbar burst fractures and to identify the most effective and safe approaches. METHODS: We conducted a systematic review adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, with the study registered in PROSPERO (CRD42024531093). The inclusion criteria were: (1) publication dates from January 1, 2004, to December 31, 2023; (2) availability of full-text articles in English; (3) thoracolumbar burst fractures without neurological deficits; (4) patients aged over 18; (5) reports on treatment outcomes or complications; (6) a mean follow-up period of at least 12 months. RESULTS: A total of 69 articles covering 116 patient groups were included. Our analysis highlighted the advantages of short-segment fixation without fusion over monosegmental, short-segment and long-segment fusion in terms of shorter operation times and reduced intraoperative blood loss (p = 0.001 and p < 0.001, respectively). Extensive fusion was associated with a significantly higher frequency of deep surgical site infections compared to other PSF methods (p = 0.043). Percutaneous pedicle screw fixation, applied to patients with lower body compression rates and kyphotic deformities, led to less potential for correction (p = 0.004), yet significantly decreased blood loss (p = 0.011), operation duration (p < 0.0001), and hospitalization duration (p < 0.0001). No significant benefits were observed with the use of additional intermediate screws in short-segment PSF. CONCLUSIONS: Short-segment pedicle screw fixation could be the optimal surgical treatment method for neurologically intact thoracolumbar burst fractures. The use of posterior lateral fusion in this context may increase the deep surgical site infection rate without reducing the frequency of implant-related complications or improving long-term treatment outcomes. The percutaneous approach remains the preferred technique; however, its limited reduction capabilities should be carefully considered during surgical planning for patients with severe kyphotic deformities. The application of intermediate screws in such patients has not demonstrated significant advantages. Removing the fixation system has not led to a significant decrease in implant-related complications or improvement in quality of life. The data obtained from the systematic review may assist surgeons in selecting the most appropriate surgical treatment method for patients with neurologically intact thoracolumbar burst fractures, thereby avoiding ineffective procedures and improving both short-term and long-term outcomes.

Short-term and long-term results of odontoid screw fixation in patients with Type II and rostral Type III dens fractures.

OBJECTIVES: To evaluate both the short-term and long-term outcomes of odontoid screw fixation (OSF), identifying potential risk factors for implant-related complications in patients with odontoid fractures. METHODS: This is a retrospective observational cohort study. Inclusion criteria were as follows: 1) Type II fractures and rostral Type III fractures, according to the Anderson and D'Alonzo classification; 2) patients older than 15 years. Exclusion criteria were: 1) other Type III injuries; 2) osteoporosis confirmed by densitometry or a CT bone density score below 100 Hounsfield units; 3) odontoid fractures related to tumors or aneurysmal bone cysts. RESULTS: In total, 56 patients were considered for the analysis of short-term results, and 26 patients were evaluated for long-term outcomes. No significant differences were observed in the preoperative imaging data and intraoperative features of OSF between patients with Type II and rostral Type III fractures. The mean operative duration was 63.9 ± 20.9 min, and the mean intraoperative blood loss was 22.1 ± 22.9 ml. Screw cut-out was identified in four patients with rostral Type III fractures (p = 0.04). The rate of screw cut-out was found to correlate with the degree of dens fragment displacement. The bone fusion rate was 95.7%. CT scans identified stable pseudarthrosis in two cases. We observed C2-C3 ankylosis in all cases following partial disc resection. One third of patients with screws placed through the anterior lip of C2 showed no C2-C3 ankylosis. A strong trend towards lateral joint ankylosis formation in patients with a median lateral mass dislocation of 11.9 mm was observed. Most SF-36 scores either matched or exceeded the corresponding normal median values in the published reference database. CONCLUSIONS: OSF is a reliable treatment method of Type II and rostral Type III odontoid fractures with fragment displacement of 4 mm or less. The minimally invasive OSF through the anterior-inferior lip of C2, using monocortical screw placement and cannulated instruments, without rigid intraoperative head immobilization, is sufficient to achieve favorable clinical and fusion results. This technique reduces the risk of ankylosis in the C2-C3 segment. OSF restore the quality of life for patients with odontoid fractures to levels comparable to those of the general population norm.

Necessity of fusion following decompression surgery in patients with single-level lumbar stenosis: study protocol for an open-label multicentre non-inferiority randomized controlled clinical trial.

BACKGROUND: The necessity of spinal segment fusion after decompression is one of the most controversial and unresolved issues in single-level lumbar spinal stenosis surgery. To date, only one trial carried out 15 years ago focused on this problem. The key purpose of the current trial is to compare the long-term clinical results of the two surgical methods (decompression vs. decompression and fusion) in patients with single-level lumbar stenosis. METHODS: This study is focused on the non-inferior clinical results of decompression compared with the standard fusion procedure. In the decompression group, the spinous process, the interspinous and supraspinous ligaments, part of the facet joints, and corresponding parts of the vertebral arch are to be preserved intact. In the fusion group, decompression is to be supplemented with transforaminal interbody fusion. Participants meeting the inclusion criteria will be randomly divided into two equal groups (1:1), depending on the surgical method. The final analysis will include 86 patients (43 per group). The primary endpoint is Oswestry Disability Index dynamics at the end of the 24-month follow-up compared to the baseline level. Secondary outcomes included those estimated using the SF-36 scale, EQ-5D-5L, and psychological scales. Additional parameters will include sagittal balance of the spine, fusion results, total cost of surgery, and hospital stay followed by two-year treatment. Follow-up examinations will be performed at 3, 6, 12, and 24 months DISCUSSION: Authors suggest that this study will improve the evidence for application of various surgical techniques for lumbar spine stenosis surgery and verify the existing protocol for surgical management. TRIAL REGISTRATION: ClinicalTrials.gov NCT05273879 . Registered on March 10, 2022.

Teachability of lower cervical spine injury classifications / Educabilidad de las clasificaciones de lesiones de la columna cervical subaxial

Objectives To compare the teachability of the Allen–Ferguson, Harris, Argenson, AOSpine, Subaxial Cervical Spine Injury Classification (SLIC), Subaxial Cervical Spine Injury Classification (CSISS) and to identify the classification that a group of residents and junior neurosurgeons find easiest to learn. Methods We used data from 64 consecutive patients. Answers of nine residents and junior neurosurgeons and four experienced surgeons in two assessment procedures were used. Six raters (workshop group) participated in special seminars between assessments. Three other raters formed the control group. Experienced surgeon's answers were used for comparison. Teachability was measured as the median value of the difference (ΔK) in the interrater agreement on the same patients by the same pairs of subjects. Results Median Δ K for the Allen–Ferguson, Harris, Argenson and AOSpine classifications were: (1) 0.01, 0.02, 0.29, and 0.39 for the workshop group; (2). 0.09, −0.03, 0.06 and 0.04 for the control group, respectively. Between numerical scales, median ΔK was higher for SLIC but did not exceed 0.16. Interrater consistency with expert's opinion was increased in the workshop group for Allen–Ferguson, Argenson and AOSpine and did not differ in either group for SLIC and CSISS. Conclusion The AOSpine classification was the most teachable. Among numeric scales, SLIC demonstrated better results. The successful application of these classifications by residents and junior neurosurgeons was possible after a short educational course. The use of these scales in educational cycles at the stage of residency can significantly simplify the communication between specialists, especially at the stage of patient admission (AU)

Objetivos Comparar la educabilidad de las clasificaciones de Allen-Ferguson, Harris, Argenson, AOSpine, Subaxial Cervical Spine Injury Classification (SLIC), Subaxial Cervical Spine Injury Classification (CSISS) e identificar la clasificación que un grupo de residentes y neurocirujanos jóvenes encuentran más fácil para aprender. Métodos Usamos los datos de 64 pacientes consecutivos. Se utilizaron las respuestas de 9 residentes y neurocirujanos jóvenes y 4 cirujanos experimentados en 2 procedimientos de evaluación. Seis evaluadores (grupo de talleres) participaron en seminarios especiales entre evaluaciones. Otros 3 evaluadores formaron el grupo de control. Se utilizaron las respuestas de cirujanos experimentados a modo de comparación. La educabilidad se midió como el valor mediano de la diferencia (ΔK) en el acuerdo entre observadores sobre los mismos pacientes por los mismos pares de evaluadores. Resultados La mediana de ΔK para las clasificaciones de Allen-Ferguson, Harris, Argenson y AOSpine fue: 1) 0,01; 0,02; 0,29 y 0,39 para el grupo del taller; 2) 0,09; −0,03; 0,06 y 0,04 para el grupo de control, respectivamente. Entre las escalas numéricas, la mediana de ΔK fue mayor para SLIC pero no excedió 0,16. La coherencia entre evaluadores y los expertos aumentó en el grupo de taller para Allen-Ferguson, Argenson y AOSpine y no difirió en ninguno de los grupos para SLIC y CSISS. Conclusión La clasificación AOSpine tuvo la mejor educabilidad. Entre las escalas numéricas, SLIC demostró mejores resultados. La aplicación exitosa de estas clasificaciones por residentes y neurocirujanos junior fue posible después de un breve curso educativo. El uso de estas escalas en los ciclos educativos en la etapa de residencia puede simplificar significativamente la comunicación entre especialistas, principalmente en la etapa de ingreso del paciente (AU)

Teachability of lower cervical spine injury classifications.

OBJECTIVES: To compare the teachability of the Allen-Ferguson, Harris, Argenson, AOSpine, Subaxial Cervical Spine Injury Classification (SLIC), Subaxial Cervical Spine Injury Classification (CSISS) and to identify the classification that a group of residents and junior neurosurgeons find easiest to learn. METHODS: We used data from 64 consecutive patients. Answers of nine residents and junior neurosurgeons and four experienced surgeons in two assessment procedures were used. Six raters (workshop group) participated in special seminars between assessments. Three other raters formed the control group. Experienced surgeon's answers were used for comparison. Teachability was measured as the median value of the difference (ΔK) in the interrater agreement on the same patients by the same pairs of subjects. RESULTS: Median Δ K for the Allen-Ferguson, Harris, Argenson and AOSpine classifications were: (1) 0.01, 0.02, 0.29, and 0.39 for the workshop group; (2). 0.09, -0.03, 0.06 and 0.04 for the control group, respectively. Between numerical scales, median ΔK was higher for SLIC but did not exceed 0.16. Interrater consistency with expert's opinion was increased in the workshop group for Allen-Ferguson, Argenson and AOSpine and did not differ in either group for SLIC and CSISS. CONCLUSION: The AOSpine classification was the most teachable. Among numeric scales, SLIC demonstrated better results. The successful application of these classifications by residents and junior neurosurgeons was possible after a short educational course. The use of these scales in educational cycles at the stage of residency can significantly simplify the communication between specialists, especially at the stage of patient admission.

Efficacy and Safety of Goel-Harms Technique in Upper Cervical Spine Surgery: A Systematic Review and Meta-Analysis.

OBJECTIVE: The main purpose of this systematic review and meta-analysis was to estimate the incidence of implant-associated complications and fusion rates for the Goel-Harms technique (GHT) and to show potential factors affecting the complications and nonunion development. METHODS: A systematic search of the PubMed database according to PRISMA guidance was performed. The main inclusion criteria comprised description of fusion rate and/or implant-associated complications rate. RESULTS: This systematic review included 86 articles focused on the results of surgery in 4208 patients. The rate of screw-related complications was as follows: 1) vertebral artery (VA) injury, 2.8%; 2) screw malposition in the direction of the VA, 5.8%; and 3) C2 nerve root irritation, 6.1%. The nonunion rate was 4.2%. Transpedicular screw insertion to the C1 and C2 vertebrae were the safest regarding VA injury and correlated with lower blood loss. For C1-C2 fusion, there was no statistical difference for the different bone graft localization. C2 nerve root irritation rate did not depend on screw insertion technique. The use of a freehand technique did not correlate with a high rate of screw-related complications. CONCLUSIONS: The Goel-Harms technique is a promising method of C1-C2 fusion, with a relatively low nonunion and VA injury rate. It can be performed safely without C-arm or navigation system assistance. Transpedicular screw insertion trajectories to the C1 and C2 vertebrae were safest regarding VA injury and blood loss volume. Further comparative studies of various C1-C2 stabilization methods with a high level of significance should be carried out to identify the optimal approach.

Factors Affecting the Outcomes of Traumatic Atlanto-Occipital Dislocations in Adults: A Systematic Review.

OBJECTIVE: The objectives of this study were to conduct a systematic review of the literature to determine the optimal treatment method for patients with atlanto-occipital dislocation (AOD) and to identify possible factors influencing their outcomes. METHODS: We conducted a systematic review of the PubMed database between January 1966 and December 2020. The main inclusion criterion was articles that discussed AOD treatment methods, and outcome descriptions were selected for analysis. Intergroup differences were assessed using nonparametric statistical methods. RESULTS: Of the 657 articles identified initially, only 54 met the inclusion criteria, resulting in data from 139 patients. Type I or II AODs were more frequent in patients injured in road traffic accidents, whereas type III AODs were more frequent in patients with catatrauma (P = 0.027). Spinal cord injury was more frequently observed in patients with types I and II AODs than in those with type III AOD (P = 0.026). Improved outcomes were more common in the surgical treatment group (P < 0.001). Significant differences in treatment outcomes between the halo device and orthosis groups were not observed (P = 0.32). CONCLUSIONS: Prognosis of AOD is unfavorable in adults with dislocations resulting from road traffic accidents, those with types I and II AOD, and patients younger than 22 years and older than 47 years. Surgical treatment was optimal for adult patients with an AOD, and treatment outcomes did not depend on the number of occipitocervical fusion levels. Immobilization with the halo device showed no advantages over use of an external orthosis.

Systemic Administration of Allogeneic Cord Blood Mononuclear Cells in Adults with Severe Acute Contusion Spinal Cord Injury: Phase 1/2a Pilot Clinical Study-Safety and Primary Efficacy Evaluation.

OBJECTIVE: Phase 1 of the SUBSCI I/IIa (Systemic Umbilical Cord Blood Administration in Patients with Acute Severe Contusion Spinal Cord Injury) study focused on safety and primary efficacy of multiple systemic infusions of allogeneic unrelated human umbilical cord blood mononuclear cells in patients with severe acute spinal cord contusion having severe neurologic deficit. The primary end point was safety. The secondary end point was the restoration of motor and sensory function in lower limbs within a 1-year period. METHODS: Ten patients with acute contusion spinal cord injury (SCI) and American Spinal Injury Association (ASIA) level A/B deficit were enrolled into phase 1. Patients were treated with 4 infusions of group-matched and rhesus-matched cord blood samples after primary surgery within 3 days after SCI. All patients were followed up for 12 months after SCI. Safety was assessed using adverse events classification depending on severity and relation to cell therapy. Primary efficacy was assessed using dynamics of deficit (ASIA scale). RESULTS: The overall number of adverse events reached 419 in 10 patients. Only 2 were estimated as possibly related to cell therapy, and the remaining 417 were definitely unrelated. Both adverse events were mild and clinically insignificant. No signs of immunization were found in participants. Analysis of clinical outcomes also showed that cell therapy promotes significant functional restoration of motor function. CONCLUSIONS: The data obtained suggest that systemic administration of allogeneic, non-human leukocyte antigen-matched human umbilical cord blood is safe and shows primary efficacy in adults with severe acute contusion SCI and ASIA level A/B deficit.

Posterior percutaneous transarticular stand-alone screw instrumentation of C1-C2 with endoscopic assistance: A report of two cases / Exploración instrumental percutánea posterior con tornillo independiente transarticular en C1-C2 mediante endoscopia: informe de dos casos

We present two cases of minimally invasive posterior transarticular screw fixation of C1-C2. The points for screw insertion were visualized by endoscopy via the instrumental port. A patient with a type III odontoid fracture with subluxation underwent a minimally invasive posterior stand-alone transarticular screw fixation. Despite the application of compression screws, for technical reasons, only minimal compression on the anterior third of the C1-C2 lateral joint was achieved. However, complete fracture fusion was achieved with stable fibrous C1-C2 fusion 2.5 years postoperatively. A second patient with a chronic type II odontoid fracture underwent percutaneous C1-C2 fixation by the same method. After 2 years, fracture fusion and C1-C2 lateral mass ankylosis were achieved. The use of a tubular retractor and endoscopy in stand-alone screw fixation of C1-C2 allows direct visualization of the screw entry point and decreases surgical trauma. This procedure might be an alternative to other methods of transarticular instrumentation (AU)

Presentamos dos casos de fijación posterior artroscópica con tornillo transarticular en C1-C2. Las ubicaciones para la inserción del tornillo se visualizaron mediante un trocar para el endoscopio. Un paciente con una fractura de apófisis odontoides de tipo III con luxación parcial se sometió a fijación posterior artroscópica con tornillo independiente transarticular. A pesar de la aplicación de tornillos de compresión y, por motivos técnicos, solo se logró una compresión mínima del tercio anterior de la articulación lateral C1-C2. Sin embargo, se logró la artrodesis completa de la fractura, con una artrodesis en C1-C2 fibrosa estable después de dos años y medio de la intervención quirúrgica. Un segundo paciente con una fractura de apófisis odontoides de tipo II crónica se sometió a fijación percutánea en C1-C2 con el mismo método. Después de dos años, se logró la artrodesis de la fractura y de la masa lateral en C1-C2. El uso de un separador tubular y de la endoscopia en la fijación con tornillo independiente en C1-C2 permite la visualización directa del punto de entrada del tornillo y disminuye el traumatismo quirúrgico. Este procedimiento puede ser una alternativa a otros métodos de exploración instrumental transarticular (AU)

Transcervical approach with endoscopic assistance for surgical treatment of patient with irreducible atlantoaxial dislocation: a case report / Abordaje transcervical con asistencia endoscópica para el tratamiento quirúrgico de pacientes con luxación atloaxoidea irreductible: un informe de caso

We demonstrate the case of a surgery in a patient with irreducible atlantoaxial dislocation (IrAAD) after C2 fracture. The challenges of this case were the flexed head in a forced position, impossibility of neck extension, and revision operation after posterior occipito-cervical fixation. The patient underwent the following surgeries: 1. A ventral release of C1-C2 using transcervical endoscopy; 2. Removal of occipito-cervical system and fibrous block resection in the posterior surfaces of the C1-C2; 3. Reducing of AAD and odontoid screw fixation; 4. Posterior C1-C2-C3 screw fixation. Ankylosing of C1-C2 and C2-C3-C4 fusion was verified by computed tomography scan. There was an improvement in patient status as observed by the increase of the SF-36 scale scores. The use of endoscopic transcervical approach is a good alternative to the transoral approach. Comparative studies of these methods should be performed regarding the choice of an optimal method of decompression in cases of IrAAD (AU)

Mostramos el caso de una cirugía de un paciente con luxación atloaxoidea irreductible (LAAIr) después de una fractura en C2. Las dificultades de este caso fueron la flexión de cabeza en posición forzada, la imposibilidad de extensión cervical y la intervención de revisión después de la fijación occipitocervical posterior. El paciente se sometió a las siguientes intervenciones: 1) Liberación ventral de C1-C2 mediante endoscopia transcervical; 2) Extracción del sistema occipitocervical y resección del bloque fibroso en las superficies posteriores de C1-C2; 3) Reducción de la LAA y fijación con tornillo de la odontoides, y 4) Fijación con tornillo de C1-С2-С3 posterior. El anquilosamiento de C1-C2 y la fusión de C2-C3-C4 se verificó mediante tomografía computarizada. Hubo una mejora en el estado del paciente, tal como mostró el aumento de las puntuaciones de la escala SF-36. El abordaje transcervical endoscópico es una buena alternativa al abordaje transoral. Deberán realizarse estudios comparativos de estos métodos en relación con la elección de un método óptimo de descompresión en casos de LAAIr (AU)

Fluoroscopic landmarks and trajectories for safe posterior percutaneous transarticular C1-C2 screw insertion: a CT-based simulation study.

PURPOSE: To determine the safe screw trajectory for posterior transarticular fixation of C1-C2 without direct visualisation of C2 lateral masses and by using fluoroscopic landmarks only. METHODS: Fluoroscopic models of the craniovertebral region in frontal and sagittal planes were reconstructed using 1-mm interval computed tomography scans of the cervical spine in 30 patients. The imitation model of the screw trajectory was then applied with verification of the exact screw localisation using multiplanar reconstruction. Twenty-seven trajectories for 60 oblique C1-C2 reformations were tested. RESULTS: In the frontal plane, all correct trajectories passed through the medial waistline point (WstP) of C3 and through the middle of the lateral mass of C1. In the lateral plane, the posterior spinal process-lateral mass (SpLM) point-middle C1 anterior tuberculum point (ATP), middle SpLM-upper ATP, and lower SpLM-odontoid point (ODP)-had relatively low rates of vertebral artery (VA) injury (2.3%, 4.6%, and 7%, respectively) and other screw malpositions (6.9%, 4.6%, and 4.6%, respectively). In cases of an isthmus height exceeding 8 mm, there were no incidences of VA injury. Patients with an isthmus width greater than 7 mm had a lower risk of screw malposition. CONCLUSION: We identified potentially safe trajectories for percutaneous posterior transarticular fixation of C1-C2. Using SpLM, ATP, and ODP landmarks in the lateral plane, and WstP and C1 middle landmarks in the frontal plane, it is possible to achieve an acceptable screw position without direct visualisation of the C2 lateral mass.

Posterior percutaneous transarticular stand-alone screw instrumentation of C1-C2 with endoscopic assistance: A report of two cases.

We present two cases of minimally invasive posterior transarticular screw fixation of C1-C2. The points for screw insertion were visualized by endoscopy via the instrumental port. A patient with a type III odontoid fracture with subluxation underwent a minimally invasive posterior stand-alone transarticular screw fixation. Despite the application of compression screws, for technical reasons, only minimal compression on the anterior third of the C1-C2 lateral joint was achieved. However, complete fracture fusion was achieved with stable fibrous C1-C2 fusion 2.5 years postoperatively. A second patient with a chronic type II odontoid fracture underwent percutaneous C1-C2 fixation by the same method. After 2 years, fracture fusion and C1-C2 lateral mass ankylosis were achieved. The use of a tubular retractor and endoscopy in stand-alone screw fixation of C1-C2 allows direct visualization of the screw entry point and decreases surgical trauma. This procedure might be an alternative to other methods of transarticular instrumentation.

Transcervical approach with endoscopic assistance for surgical treatment of patient with irreducible atlantoaxial dislocation: a case report.

We demonstrate the case of a surgery in a patient with irreducible atlantoaxial dislocation (IrAAD) after C2 fracture. The challenges of this case were the flexed head in a forced position, impossibility of neck extension, and revision operation after posterior occipito-cervical fixation. The patient underwent the following surgeries: 1. A ventral release of C1-C2 using transcervical endoscopy; 2. Removal of occipito-cervical system and fibrous block resection in the posterior surfaces of the C1-C2; 3. Reducing of AAD and odontoid screw fixation; 4. Posterior C1-C2-C3 screw fixation. Ankylosing of C1-C2 and C2-C3-C4 fusion was verified by computed tomography scan. There was an improvement in patient status as observed by the increase of the SF-36 scale scores. The use of endoscopic transcervical approach is a good alternative to the transoral approach. Comparative studies of these methods should be performed regarding the choice of an optimal method of decompression in cases of IrAAD.

The impact of odontoid screw fixation techniques on screw-related complications and fusion rates: a systematic review and meta-analysis.

PURPOSE: The primary goal of this study was to conduct a systematic review and meta-analysis of articles focused on odontoid screw fixation (OSF) and screw-related complications or non-union rates. METHODS: We conducted a systematic review of the PubMed and Crossref databases between January 1982 and December 2019. Inclusion criteria comprised detailed descriptions of the surgical technique and screw-related complications (screw cut-out, loosening, breakage, malposition) or fusion rates. RESULTS: The initial selection consisted of 683 abstracts. A total of 150 full texts were chosen for detailed study, and 83 articles were included in the analysis. The point estimates for screw-related complications were as follows: 1. screw malposition frequency-4.8%; 2. screw cut-out rate-5.0%; 3. screw loosening/pull-out-3.8%; and 4. screw fracture rate-3.1%. The point estimate for the non-union rate was 9.7%. Statistical analysis of the screw-related complications rate based on surgical technique details was also performed CONCLUSIONS: Double-screw OSF performance in elder patients resulted in a higher risk of post-operative screw cut-out. In other cases, the development of screw-related complications did not depend on the method of intraoperative head fixation, selection of the implant entry point for OSF, type of the used screws, or cannulated instruments application. The outcomes of single-screw fixation through the anterior lip of the C2 vertebra were comparable to other techniques of OSF. Further, statistically reliable studies should be carried out to identify the optimal technique of OSF.

External Multicenter Study of Reliability and Reproducibility for Lower Cervical Spine Injuries Classification Systems-Part 2: An Analysis of the Subaxial Cervical Spine Injury Classification and Cervical Spine Injury Severity Score Scale.

STUDY DESIGN: A multicenter observational survey. OBJECTIVE: To quantify and compare inter- and intraobserver reliability of the subaxial cervical spine injury classification (SLIC) and the cervical spine injury severity score (CSISS) in a multicentric survey of neurosurgeons with different experience levels. METHODS: Data concerning 64 consecutive patients who had undergone cervical spine surgery between 2013 and 2017 was evaluated, and we surveyed 37 neurosurgeons from 7 different clinics. All raters were divided into 3 groups depending on their level of experience. Two assessment procedures were performed. RESULTS: For the SLIC, we observed excellent agreement regarding management among experienced surgeons, whereas agreement among less experienced neurosurgeons was moderate and almost twice as unlikely. The sensitivity of SLIC relating to treatment tactics reached as high as 92.2%. For the CSISS, agreement regarding management ranged from medium to substantial, depending on a neurosurgeon's experience. For less experienced neurosurgeons, the level of agreement concerning surgical management was the same as for the SLIC in not exceeding a moderate level. However, this scale had insufficient sensitivity (slightly exceeding 50%). The reproducibility of both scales was excellent among all raters regardless of their experience level. CONCLUSIONS: Our study demonstrated better management reliability, sensitivity, and reproducibility for the SLIC, which provided moderate interrater agreement with moderate to excellent intraclass correlation coefficient indicators for all raters. The CSISS demonstrated high reproducibility; however, large variability in answers prevented raters from reaching a moderate level of agreement. Magnetic resonance imaging integration may increase sensitivity of CSISS in relation to fracture management.

External Multicenter Study of Reliability and Reproducibility for Lower Cervical Spine Injuries Classification Systems-Part 1: A Comparison of Morphological Schemes.

STUDY DESIGN: Multicenter observational survey study. OBJECTIVES: To quantify and compare the inter- and intraobserver reliability of Allen-Fergusson (A-F), Harris, Argenson, and AOSpine (AOS) classifications for cervical spine injuries, in a multicentric survey of neurosurgeons with different levels of experience. METHODS: We used data of 64 consecutive patients. Totally, 37 surgeons (from 7 centers), were included in the study. The initial assessment was returned by 36 raters. The second assessment performed after 1.5 months included 24 raters. RESULTS: We received 15 111 answers for 3840 evaluations. Raters reached a fair general agreement of the A-F scale, while the experienced group achieved κ = 0.39. While all groups showed moderate interrater reliability for primary assessment of Harris scale (κ = 0.44), the κ value for experts decreased from 0.58 to 0.49. The Argenson scale demonstrated moderate and substantial agreement among all raters (κ = 0.47 and κ = 0.55, respectively). The AOS scheme primary assessment general kappa value for all types of injuries and across all raters was 0.49, reaching substantial agreement among experts (κ = 0.62) with moderate agreement across beginner and intermediate groups (κ = 0.48 and κ = 0.44, respectively). The second assessment general agreement kappa value reached 0.56. CONCLUSIONS: We found the highest values of interobserver agreement and reproducibility among surgeons with different levels of experience with Argenson and AOSpine classifications. The AOSpine scale additionally incorporated more detailed description of compression injuries and facet-joint fractures. Agreement levels reached for Allen-Fergusson and Harris scales were fair and moderate, respectively, indicating difficulty of their application in clinical practice, especially by junior specialists.

Minimally Invasive Posterior Transarticular Stand-Alone Screw Instrumentation of C1-C2 Using a Transmuscular Approach: Description of Technique, Results and Comparison with Posterior Midline Exposure.

PURPOSE: The aim of this study was to compare the feasibility, safety, and fusion results of posterior transarticular stand-alone screw (SAS) instrumentation of C1-C2 with a minimally invasive technique to those of a posterior midline exposure. METHODS: Between 2008 and 2016, 164 patients underwent surgical treatment for traumatic injuries to the upper cervical vertebrae at our institution. We included 38 patients (27 men and 11 women; age range, 17-81 years) in the study. The posterior midline approach (PMA) group (23 patients) included patients who underwent surgery by means of a conventional midline incision after percutaneous screw insertion. The transmuscular approach (TMA) group (15 patients) included patients who underwent SAS fixation by use of a minimally invasive technique. The mean follow-up period was 58 months (range, 12-118 months). RESULTS: Statistical analysis revealed that the operative time, blood loss volume, and severity of postoperative pain were lower in the TMA group. No significant excess of radiation exposure to the surgical team and the patients occurred in TMA group compared with the PMA group. C1-C2 fusion was observed in 37 patients. Stable fibrous fusion between the C1 and C2 vertebrae was found in 1 patient. CONCLUSIONS: A minimally invasive technique by use of a paravertebral transmuscular approach provides an alternative to routine posterior transarticular SAS fixation of C1 and C2 through a posterior midline approach. The minimally invasive technique reduces the duration of surgery and the volume of blood loss, decreases the severity of postoperative pain, and does not increase the amount of radiation exposure for the surgical team and the patient.

A Comparison of the Long-Term Results of Posterior Transarticular Stand-Alone Screw Instrumentation and Magerl Technique in Patients with Traumatic Atlantoaxial Instability: Mean 5-Year Follow-Up Study with Radiological and Patient-Rated Outcomes Assessments.

OBJECTIVE: To perform a radiological analysis of the degeneration of C1-C2 joints after C1-C2 transarticular fixation (TAF) and compare the long-term results of a routine Magerl technique (RMT) to a posterior transarticular C1-C2 stand-alone screw instrumentation (SAS) application. METHODS: A total of 40 patients (26 men and 14 women) were included in the present retrospective observational cohort study. The mean follow-up period was 61.7 months (range, 11-118). The mean patient age at the baseline examination was 48.4 years (range, 22-82). Of the 40 patients, 11 were included in the RMT group and 29 in the SAS group. RESULTS: The structure of 80 atlantoaxial joints was analyzed, with grade 4 degenerative changes observed in 57 joints (71.3%). Of the 40 analyzed atlanto-odontoid joints, grade 4 degenerative changes were revealed in 18 joints (45%). C1-C2 bone fusion was observed in 38 patients (95%) and stable fibrous fusion in 2 patients (5%). No cases of C1-C2 nonunion were revealed. No statistically significant differences in the frequency of C1-C2 fracture consolidation or C1-C2 fusion were revealed between the RMT and SAS groups. CONCLUSIONS: The application of cortical lag screws in TAF might result in stable atlantoaxial joint fusion formation without joint curettage. Atlanto-odontoid joint fusion was also observed after C1-C2 TAF. The application of cortical lag screws for bilateral fixation using the SAS technique resulted in C1-C2 fusion in 93.1% of cases, comparable to the results with the Magerl technique.

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis.

PURPOSE: This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation. METHODS: A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications. RESULTS: The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed. CONCLUSIONS: The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Endoscopic Endonasal Resection of the Odontoid Process in a Patient with Chronic Injury of the C1 Transverse Ligament.

Atlas dislocation after transverse ligament injury is one of the most rare types of trauma to the upper cervical level. If magnetic resonance imaging of the craniovertebral junction reveals the Kassam line passing through the cervix of the odontoid process, a transnasal approach can be used for surgical treatment. Here, we present a case in which an endoscopic endonasal approach was used to treat chronic traumatic transligamentous atlas dislocation. A 26-year-old male underwent two-stage surgical treatment; during the first stage, posterior decompression and fixation were performed under halo immobilization. In the second stage, a transnasal endoscopic approach to the odontoid process was used. A transnasal approach permitted complete decompression of the medulla oblongata and facilitated early extubation of the patient without any postoperative complications such as respiratory or pharyngopalatine deficiency. The patient was discharged in good condition 9 days after the surgery.