Lateral Mass Research Articles

Is the Ossification of the Posterior Longitudinal Ligament a Positive Factor for the Fusion after Posterior Cervical Fusion and Decompression?

Objective: Multilevel posterior cervical fusion (PCF) and decompression surgery is a viable treatment option for multilevel ossification of posterior longitudinal ligament (OPLL) and spondylotic myelopathy. Since OPLL is known to affect bone formation, this study aimed to examine the effect of OPLL on the incidence of pseudarthrosis following PCF in a cohort study. Methods: We conducted a retrospective cohort study of patients with PCF and laminectomy at our institution. This study included patients who underwent C3 to C6 posterior fusion surgery involving lateral mass screw fixation without anterior surgery for OPLL or spondylotic myelopathy. Fusion status was evaluated 1 year postoperatively with computed tomography. Bone mineral density (BMD) and sagittal parameters were also evaluated as potential contributing factors to the fusion rate.Results: Eighty patients were included. Pseudarthrosis was observed in 22.5% (n=18) of patients. Pseudarthrosis incidence was lower in patients with OPLL (spondylosis vs. OPLL, 33.3% vs. 12.2%; p=0.003), and a higher BMD T-score (pseudarthrosis vs. fusion, -1.9 ± 0.7 vs. -0.6 ± 1.3; p<0.01), a larger preoperative range of motion (ROM) (26.7 ± 13.3 vs. 17.6 ± 10.9; p=0.01), and a greater preoperative-to-postoperative decrease in cervical lordosis (-8.1 ± 7.9 vs. -2.7 ± 7.9; p<0.01). Pseudarthrosis was associated with worsening neck pain after surgery. Conclusion: The absence of OPLL, lower BMD, larger preoperative ROM, and a greater decrease in postoperative cervical lordosis were identified as risk factors for pseudarthrosis after multiple PCF.

CT imaging analysis of the C7 pedicle and lateral mass in children aged 0–14 years

Background and objectiveThere is currently a lack of anatomical research on the C7 pedicle and lateral mass in children aged 0–14 years, and experience with pediatric lower cervical spine surgeries remains limited. This study aims to investigate the anatomical structure of the C7 pedicle and lateral mass in a large pediatric sample to understand their growth patterns, providing imaging and anatomical references for pediatric lower cervical spine surgeries and the design of pediatric C7 screws. MethodsWe measured 12 parameters, including the width, length, height, and angles of the C7 pedicle and lateral mass in children aged 0–14 years. The t-test was used to analyze bilateral and gender differences, and least squares regression was applied for curve fitting analysis. ResultsThe size parameters of the C7 pedicle and lateral mass generally increased with age, while angular parameters fluctuated within specific ranges. The average values for each parameter between ages 0–14 were as follows: D1: 2.78–5.28 mm, D2: 18.15–30.54 mm, D3: 2.44–6.01 mm, angle A: 38.05–44.48°; D4: 6.81–10.94 mm, D5: 5.37–11.23 mm, D6: 8.07–13.28 mm, D7: 1.94–4.88 mm, D8: 5.67–9.39 mm, angle C: 18.50–28.80°, angle D: 43.23–52.01°, angle E: 33.74–44.96°. Bilateral analysis showed no significant differences for most parameters across most age groups, with differences mainly observed in angle A, angle C, D6, and D8. Gender differences were primarily noted in length parameters across different age groups, especially in the 3–4, 6–7, 9–11, and 13–14 age groups. Regression analysis indicated that most parameters followed cubic function curves, while a few followed power or quadratic function curves. ConclusionThis study provides detailed CT imaging anatomy of the C7 pedicle and lateral mass in children aged 0–14 years. Preoperative thin-slice CT scans and careful measurements of key parameters are essential for pediatric lower cervical spine surgeries. The findings offer valuable imaging and anatomical references for pediatric posterior cervical fixation surgery and screw design.

Posterior Reduction and Temporary Fixation Through Intermuscular Approach for Odontoid Fracture.

Posterior reduction and temporary fixation (PRTF) through open approach can effectively avoid the loss of C1-C2 motion caused by posterior atlantoaxial fusion in the treatment of odontoid fracture. PRTF through intermuscular approach can preserve the integrity of the paravertebral muscle. However, its contribution to the preservation of C1-C2 rotation remains unassessed in the context of fresh odontoid fractures. The data of 31 patients with odontoid fractures who underwent PRTF through intermuscular approach were retrospectively reviewed. Operation time, intraoperative blood loss, the time of ambulation and surgery-related complications were recorded. After fracture healing, the instrumentation was removed. The Japanese Orthopedic Association score, Visual Analog Scale score for neck pain, and patient satisfaction were recorded. The range of motion in rotation of C1-C2 was calculated 1 month after removing the instrumentation. Fracture healing was observed in all patients, and the instrumentation was removed. After removing the instrumentation, the range of motion of C1-C2 in rotation was returned to 35.6° ± 4.8°. Patient satisfaction was improved (P < .05). There was no significant difference in Japanese Orthopedic Association scores and Visual Analog Scale score for neck pain between 2 values before and after removing the instrumentation (P > .05). No osteoarthritis was observed at the C1-C2 lateral mass joints. There were no perioperative complications. PRTF through intermuscular approach can be used as a salvage treatment of an odontoid fracture with an intact transverse ligament in cases of failure of, or contraindication to, anterior screw fixation. This minimally invasive technique can effectively preserve the rotational function of the atlantoaxial complex.

Ancient cervical vagal schwannoma and an interposition great auricular to vagus nerve graft

Introduction: Schwannomas of the cervical vagus nerve are exceedingly rare and have a myriad of clinical presentations depending on the tumor size and its proximity to neurovascular structures. We report a rare case of a cervical vagal schwannoma that was successfully treated with en bloc resection and reconstruction with a great auricular to vagus nerve graft. Case Report: A 42-year-old male presented with an asymptomatic, right lateral neck mass. Magnetic resonance imaging revealed a lesion 2.4 cm × 1.4 cm × 4.0 cm in size, located between the carotid arteries and internal jugular vein displacing the internal carotid artery anteromedially. En bloc resection of the lesion and reconstruction of the vagus nerve with a great auricular interposition graft was performed. Conclusion: Vagal schwannomas are rare, benign neurogenic tumors. Complete surgical excision is the mainstay of treatment. When a safe surgical plane cannot be identified between the neurogenic tumor and the main nerve trunk, en bloc resection with reconstruction should be considered.

Anaplastic transformation of papillary thyroid carcinoma in the cervical lymph nodes showing a variety of rhabdoid, epithelioid and spindle cell phenotype

Abstract Introduction/Objective Anaplastic thyroid carcinoma (ATC) is a rare undifferentiated tumor of thyroid follicular cells with a dismal prognosis. Most ATCs derive from pre-existing, well-differentiated thyroid carcinomas, most commonly papillary thyroid carcinoma (PTC). In nearly all instances, ATC arises within the thyroid gland. Completely divergent morphologies of this tumor between the bilateral cervical nodes as well as the almost exclusive presence of ATC in the metastatic and nodal locations are very unusual and are reported here. Methods/Case Report A 67-year-old man presented with a rapidly enlarging left cervical mass, hoarseness, dry cough, and drooping left eye. MRI demonstrated bilateral enlarged cervical lymph nodes spanning levels II to V, and nodules in thyroid lobes. Subsequent total thyroidectomy with bilateral radical neck dissection was performed. Histologically, the left lateral cervical masses revealed undifferentiated tumor cells with rhabdoid, epithelioid and spindle cells features. Conversely, the tumor within the thyroid lobes and the right cervical lymph nodes exhibited PTC with tall cell features. All undifferentiated tumor components stained positive with AE1-3, CK7, PAX8, and negative with thyroglobulin, EMA, CD34, S100, Melan-A, Sox 10, desmin, myogenin, and P40. INI-1 staining is retained. Only the spindle cell component stained positive with TTF1. Based on the morphology and immunoprofile, a diagnosis of anaplastic thyroid carcinoma was rendred. Results (if a Case Study enter NA) NA Conclusion Diagnosing anaplastic thyroid carcinoma outside the thyroid lesion can be challenging. In our case, only extensive sampling of the surgical specimen identified a small focus of well-differentiated PTC, staining positive for thyroglobulin, in the left cervical anaplastic carcinoma component, identifying its origin. This case adds to the scarce literature documenting unilateral anaplastic transformation in the left cervical metastatic lymph nodes, while the right cervical lymph nodes contained pure well differentiated PTC. This represents a significant potential pitfall in presurgical fine needle aspiration (FNA) evaluation of patients with ATC.

C1-ring оsteosynthesis as a functionally preserving operation for unstable atlas fractures

Objective. To analyze the dynamics of pain syndrome, quality of life and functional status of patients with unstable atlas fractures after C1-ring osteosynthesis.Material and Methods. Study design: observational retrospective case series study (n = 15). The intensity of pain syndrome was assessed using the VAS scale before surgery, 3 days, and 3 and 6 months after surgery. The quality of life was assessed using the Neck Disability Index (NDI) before surgery, and 3 and 6 months after surgery. Functional status, as well as cervical spine range of motion (head turn left/right, flexion/extension) was assessed 3 and 6 months after surgery. The integrity of the atlas bone ring and the degree of fusion after fixation were assessed using axial CT scans; and the lateral mass separation was assessed using frontal CT scans. The criterion for transverse ligament injury was a separation of lateral masses of more than 8.1 mm. Results. All patients had C1 fractures type 3B according to Gehweiler, out of them 7 patients (46.7 %) had traumatic injury to the atlas transverse ligament according to Dickman type 1, and 8 patients (53.3 according to Dickman type 2. The average age of patients was 40 years (12; 71), the male/female ratio was 2/1. In 7 patients (46.7 %), the cause of injury was diving, in 6 (40.0 %) it was a traffic accident, and in 2 (13.3 %) – a fall from a standing height. Observation of patients revealed a positive dynamics in the form of statistically significant regression of pain according to VAS before and 6 months after surgery from 6.8 (6.0; 8.0) to 1.0 (1.0; 0.0) points (Z = -3.434; p = 0.001). A positive trend was also noted in the form of a decrease in NDI scores and an improvement in the quality of life after 3 (Z = -3.411; p = 0.001) and 6 months after surgery (Z = -3.410; p = 0.001). The range of motion (turn left/right, flexion/extension) increased statistically significantly by the 6th month after C1-ring osteosynthesis, and its indicators were close to physiological ones. Postoperative CT scans showed positive dynamics in the form of statistically significant regression of the lateral mass separation from 10.4 mm (8.9; 11.4) to 2.2 mm (1.8; 2.6); Z = -3.408; p = 0.001. Complete fusion of the atlas fracture was observed after 12.5 months (8.5; 16.5).Conclusion. Isolated posterior osteosynthesis of the atlas ring for Gehweiler type 3B injury using a repositioning compression maneuver under distraction conditions is physiologically justified. It is a reliable method of stabilization, ensures the restoration of congruence and the entire range of motion in the atlanto-occipital and atlantoaxial joints and stability of the occipital-atlantoaxial complex. This operation contributes to a considerable and long-term reduction in the intensity of pain syndrome and a significant improvement in the quality of life.

Migration of cervical spine screws to the sacral canal: a case report

Cervical open door laminoplasty is widely used in multilevel decompression, which is a motion-sparing decompression treatment option for multilevel cervical myelopathy. Implant distance migration in cervical laminoplasty has not been reported. A 61-year-old woman underwent cervical laminoplasty, three months postoperatively, she experienced left shoulder pain and left upper limb pain, and underwent cervical magnetic resonance imaging, which showed no abnormalities. She gradually developed dizziness, headache, unstable walking, incomplete urinary incontinence, and fluctuating neck lumps. The X-ray showed that the screws of the C7 lateral mass had disappeared and migrated to the sacral canal. The patient underwent cerebrospinal leakage repair and removal of the screws in the spinal canal. Displacement of fixators implanted into the spinal canal after cervical laminoplasty is a rare complication that can cause permanent neurological injury.

Current research status and prospects for clinical application of robotics in spinal surgery

With the rapid advancement of artificial intelligence and the increasing integration of medical engineering, robot-assisted (RA) technology in spinal surgery has made significant strides, with its clinical application range continuously expanding. This article provides a comprehensive review of relevant literature on spinal surgery robots over the past decade, summarizing recent advancements in screw placement techniques such as cervical, thoracic, and lumbar pedicle screws; cortical bone trajectory (CBT) screws; cervical lateral mass screws; and S2 sacroiliac (S2AI) screws. It also discusses RA-guided targeted puncture and endoscope placement through intervertebral foramen as well as decompressive laminectomy procedures. Furthermore, this article systematically analyzes the advantages and disadvantages of RA technology while elucidating its accuracy, safety, and practicality. We believe that this article will help clinicians to gain a deeper understanding of the current clinical application status of spinal surgery robots while promoting further enhancements and wider adoption of RA technology to ultimately benefit more patients.

Biomechanical study of the stability of posterior cervical expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation: a finite element analysis

BackgroundPosterior cervical expansive open-door laminoplasty (EODL) may cause postoperative C5 palsy, and it can be avoided by EODL with bilateral C4/5 foraminotomy. However, prophylactic C4/5 foraminotomy can compromise cervical spine stability. To prevent postoperative C5 palsy and boost cervical stability, We propose a new operation method: EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation. However, there are no studies on the biomechanical properties of this surgery.PurposeEvaluating the biomechanical characteristics of EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation and other three classic surgery.MethodsAn original model (A) and four surgical models (B-E) of the C2-T1 vertebrae of a female patient were constructed. (B) EODL; (C) EODL combined with bilateral C4/5 foraminotomy; (D) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation; (E) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and C3-6 lateral mass screw system. To compare the biomechanical properties of cervical posterior internal fixation; (E) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and C3-6 lateral mass screw system. To compare the biomechanical properties of cervical posterior internal fixation methods, six physiological motion states were simulated for the five models using a 100N load force and 1.5Nm torque. The biomechanical advantages of the four internal fixation systems were evaluated by comparing the ranges of motion (ROMs) and maximum stresses.Results The overall ROM of Model C outperformed the other four models, reaching a maximum ROM in the extension state of 10.59°±0.04°. Model C showed a significantly higher ROMs of C4/5 segment than other four models. Model D showed a significantly lower ROM of C4/5 segment than both Model B and Model C. Model E showed a significantly lower ROM of C4/5 segment than Model D. The stress in the four surgical models were mainly concentrated on the internal fixation systems.ConclusionEODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation can maintain the stability of the spine and has minimal effects on the patient’s cervical spine ROMs in the extension and flexion state. As a result, it may be a promising treatment option for cervical spondylotic myelopathy (CSM) to prevention of postoperative C5 palsy.

A Complete Facet Resection and Cervical Pedicle Screw Placement Enhances Both Gross Total Resection and Motion Preservation for the Cervical Spinal Dumbbell Tumor

To describe single-index-level fusion surgery using a cervical pedicle screw (CPS) after the complete facet resection of spinal dumbbell tumors and to compare it with partial facet resection without fusion. We retrospectively reviewed patients who underwent surgery for dumbbell-shaped cervical spine tumors. They were categorized into the fused group (complete facet resection with fusion using CPS) and the unfused group (partial facet resection without fusion). We compared demographics, tumor characteristics, resection rates (gross total, subtotal, or partial), and regrowth rates between the groups. Complete facet resection was performed for maximal tumor removal. In the fused group, single-index-level fusion was achieved using CPS. Despite tumor-associated erosion of the index vertebra's pedicle and/or lateral mass, the CPS was directly inserted into the vertebral body through an imaginary virtual pedicle without a lateral mass or pedicle purchase. A total of 34 patients underwent surgery for dumbbell-shaped cervical tumors; half were classified into each group. There were no significant differences in demographic or tumor characteristics, including Asazuma classification, or histological diagnosis (P > 0.05). However, the gross total resection rate was significantly higher in the fused group (16/17, 94.1% vs. 9/17, 52.9%; P value= 0.011). Tumor recurrence was observed in 3 (17.6%) patients in the unfused group; no recurrence (0%) occurred in the fused group. Complete facet resection with fusion using CPS significantly increased the gross total tumor removal rate, compared with partial resection without fusion. Therefore, CPS improved fusion surgery for maximal motion preservation, resulting in single-level fusion surgery.

Stable and reversible zinc metal anode with fluorinated graphite nanosheets surface coating

A highly stable zinc metal anode modified with a fluorinated graphite nanosheets (FGNSs) coating was designed. The porous structure of the coating layer effectively hinders lateral mass transfer of Zn ions and suppresses dendrite growth. Moreover, the high electronegativity exhibited by fluorine atoms creates an almost superhydrophobic solid−liquid interface, thereby reducing the interaction between solvent water and the zinc substrate. Consequently, this leads to a significant inhibition of hydrogen evolution corrosion and other side reactions. The modified anode demonstrates exceptional cycling stability, as symmetric cells exhibit sustained cycling for over 1400 h at a current density of 5 mA/cm2. Moreover, the full cells with NH4V4O10 cathode exhibit an impressive capacity retention rate of 92.2% after undergoing 1000 cycles.

Comparative Analysis of Metastatic Thyroid Carcinoma versus Ectopic Thyroid Carcinoma in Lateral Neck Masses without Identifiable Primary Thyroid Carcinoma

Background/Objectives: Thyroid carcinoma, presenting as a lateral neck mass without an identifiable primary tumor within the thyroid, poses a diagnostic challenge. This comparative analysis aimed to explore the differences between metastatic thyroid carcinoma and ectopic thyroid carcinoma, as both present with a lateral neck mass without evidence of primary thyroid carcinoma. Methods: Searches were conducted for studies on thyroid carcinoma in the lateral neck without evidence of primary thyroid carcinoma. A total of 39 patients were identified from 32 reported studies. Results: Metastatic and ectopic thyroid carcinomas were found in 11 and 28 patients, respectively. Metastatic thyroid carcinoma is characterized by evidence of spontaneous primary tumor regression within the thyroid and commonly associated with multiple lymph node metastases in central and lateral neck compartments. Ectopic thyroid carcinoma is more commonly diagnosed in younger patients and is frequently identified in branchial cleft cysts. The coexistence of normal thyroid tissue adjacent to the ectopic thyroid carcinoma was confirmed, and patients with ectopic thyroid carcinoma exhibited significantly higher rates of second-stage thyroidectomy or neck dissection. When complete surgical excision was considered adequate, excision alone was chosen for patients with ectopic thyroid carcinoma. Conclusions: Identifying these differences is valuable for the differential diagnosis and development of treatment strategies for metastatic and ectopic thyroid carcinomas in lateral neck masses without evidence of primary thyroid tumor.

Impact of the Shape of the Skull Base on Morphometric Parameters of the First and Second Cervical Vertebrae in 8–12-Year-Old Children: Assessment of the Condition Under Norm and Recurrent Subluxation in the C1–C2 System

The aim of the study is to determine the impact of the shape of the skull base on the morphometric parameters of the first (C1) and second (C2) cervical vertebrae in children aged 8–12 under normal conditions and under recurrent subluxation of C1–C2. Materials and methods. The authors analysed computed tomography (CT) scans of 212 children aged 8–12 without pathology of the cervical spine and 65 patients of the same age group with recurrent subluxations of the C1-C2 vertebrae. Computed tomography was performed on a computer tomography GE OPTIMA CT 660, 64-slice machine (Russia). CT morphometry was carried out using the Radiant program (Russia). The width and length of the skull base, parameters of the first (C1) and second (C2) cervical vertebrae, and interosseous parameters were determined, the basilar index was calculated; three groups of individuals with dolicho-, meso-, or brachybasilar shape of the skull base were formed based on the value of the basilar index. One-way analysis of variance was carried out. Results The impact of the shape of the skull base of moderate strength on the transverse dimensions of the upper articular surfaces of C1 on the right and left in children without pathology of the cervical spine was revealed. Among the examined individuals with recurrent subluxation in the C1–C2 system, there was a strong connection between the shape of the skull base and the longitudinal dimensions of the upper articular surfaces of the atlas. A moderately close relationship was revealed between the shape of the skull base and the height of the body of the second cervical vertebra and with the angle of inclination of the C2 tooth in the sagittal plane in those examined without pathology of the cervical spine. In children with recurrent subluxation, a strong relationship of the controlled factor was determined with the height of the C2 body and the angle of inclination of its tooth in the sagittal plane, and a mediumstrong relationship with the sagittal diameter of the tooth. The influence of the shape of the skull base of moderate strength on the size of the anterior atlantoaxial joint space was revealed both in children without pathology of the cervical spine and in children with recurrent subluxation. In case of right-sided subluxation, a mediumstrong relationship between the shape of the skull base and the lateral distance between the base of the tooth and the medial surface of the lateral mass of C1 on the side contralateral to the subluxation was revealed. Conclusion. The shape of the skull base affects a number of anatomical structures of the first two cervical vertebrae in children aged 8–12.

Outcome of Management of Multilevel Cervical Disc by Anterior Discectomy and Cage versus Posterior Decompression and Lateral Mass Fixation

Outcome of Management of Multilevel Cervical Disc by Anterior Discectomy and Cage versus Posterior Decompression and Lateral Mass Fixation

Ultrahigh-resolution imaging of biogenic phosphorus and molybdenum in palaeoproterozoic gunflint microfossils

Phosphorus and molybdenum play important roles in the formation of microbial cell structures and specific enzymes crucial for metabolic processes. Nevertheless, questions remain about the preservation of these elements within ancient microfossils. Here, we present shape-accurate ion images capturing phosphorus and molybdenum on Palaeoproterozoic filamentous microfossils by pioneering a methodology using lateral high-resolution secondary ion mass spectrometry. Introducing electrically conductive glass for mounting isolated microfossils facilitated clearer observations with increased secondary ion yields. Phosphorus was detected along the contours of microfossils, providing direct evidence of phospholipid utilization in the cell membrane. Trace amounts of molybdenum were detected within microfossil bodies, suggesting potential remnants of molybdenum-bearing proteins, such as nitrogenase. These findings align with the hypothesized cyanobacterial origin of filamentous gunflint microfossils. Our methodology introduces a groundbreaking tool for obtaining crucial insights into the cellular evolution and metabolic pathways of microorganisms, allowing comparisons of their morphological characteristics.

Diagnostic Accuracy of Circulating Tumor HPV DNA Testing in Patients With a Lateral Neck Mass

The most frequent presenting symptom for patients with human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC) is a lateral neck mass. Circulating tumor tissue-modified viral (TTMV)-HPV DNA is a unique biomarker produced by the fragmentation of HPV DNA during the degradation of HPV-associated tumors, and its detection and quantitation are currently being used as an adjunct to imaging in monitoring for disease recurrence and may have utility for diagnosis. To measure the diagnostic characteristics of TTMV-HPV DNA compared with gold standard tissue biopsy for diagnosing HPV-OPSCC in patients presenting with an indeterminate lateral neck mass. This prospective diagnostic test study enrolled patients 18 years or older who presented with a lateral neck mass to a large urban tertiary health care system from December 2021 to June 2023. Participants underwent standard-of-care testing to obtain a tissue diagnosis and a single TTMV-HPV DNA measurement. The primary outcome of interest was sensitivity, while specificity, positive predictive value, and negative predictive value were secondary end points. A subset analysis was performed comparing test performance metrics between TTMV-HPV DNA testing and fine-needle aspiration. A total of 138 patients were included, of whom 80 (58.0%) were men, with median age of 57.5 years (IQR, 43.3-67.0 years). Of 138 patients, 87 (63.0%) had neck masses in level 2 and 47 (34.1%) had HPV-OPSCC. TTMV-HPV DNA testing exhibited a sensitivity of 95.7% (95% CI, 85.5%-99.5% [45 of 47 patients]), specificity of 97.8% (95% CI, 92.3%-99.7% [89 of 91 patients]), positive predictive value of 95.7% (95% CI, 85.5%-99.5% [45 of 47 patients]), and negative predictive value of 97.8% (95% CI, 92.3%-99.7% [89 of 91 patients]). In this diagnostic study of patients presenting with a lateral neck mass, circulating TTMV-HPV DNA demonstrated excellent diagnostic test characteristics for the detection of HPV-OPSCC. Such testing may have particular utility for patients in whom obtaining adequate tissue is problematic, as is often the case with cystic neck masses and unknown primary tumors.

Minimally Invasive Surgery for Posterior Atlantoaxial Lateral Mass Joint Fusion (MIS-PALF): A Muscle-Sparing Procedure for Atlantoaxial Instability or Dislocation.

Conventional surgical procedures for atlantoaxial instability or dislocation (AAI/D) have been associated with a high prevalence of postoperative occipitocervical pain and dysfunction, as well as substantial perioperative blood loss. We hypothesized that minimally invasive surgery for posterior atlantoaxial lateral mass joint fusion (MIS-PALF), a procedure that can largely avoid disruption of suboccipital musculature, would be superior to the standard Goel-Harms technique in terms of postoperative pain and perioperative blood loss. This was a prospective cohort study of patients undergoing MIS-PALF for AAI/D at Peking University Third Hospital's Department of Orthopaedics from January 2021 to December 2021 and a historical control group of patients with the same diagnoses who were treated with the Goel-Harms technique. The duration of surgery, perioperative blood loss, postoperative length of hospital stay, postoperative body temperature, pain, supplementary use of narcotics, spinal cord function/improvement (assessed using the Japanese Orthopaedic Association [JOA] scores), reduction of AAI/D (determined based on radiographic parameters), rate of successful fusion, and complication rate were all compared between the 2 groups. No significant differences were noted between the groups (43 MIS-PALF cases, 86 control cases) regarding baseline data, operative time, spinal cord function or improvement, reduction of AAI/D, rate of successful fusion, and complication rate. MIS-PALF was associated with significantly less perioperative blood loss, a shorter postoperative hospital stay (decreased by 30.8%), lower intensity and frequency of postoperative pain (decreased by 10.6% and 61.9%, respectively), less need for supplementary narcotics, and less frequent postoperative fever (decreased by 48.7%). This was the first prospective cohort study of which we are aware on minimally invasive procedures for atlantoaxial fusion. Clinical efficacy (AAI/D reduction, rate of successful atlantoaxial fusion, JOA score improvement), efficiency (operative time), and safety (complications) of MIS-PALF appeared to be noninferior to those of the Goel-Harms technique. MIS-PALF was superior in terms of postoperative occipitocervical pain and length of hospital stay, both of which directly affect overall patient satisfaction and postoperative recovery of quality of life. Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Prevalence of occipitalisation in a South African Black population: An original study of 1119 skulls with a review of the literature

BackgroundOccipitalisation is the most prevalent congenital abnormality at the craniovertebral junction; however, it is rare in the general population. There is a paucity of literature on osteological prevalence studies within the South African Black and broader African populations. This study aimed to establish baseline data for the prevalence of occipitalisation in the South African Black population group. MethodsOne thousand two hundred thirteen skulls from a South African Black population were initially sampled, and after exclusion criteria were applied, the sample was reduced to 1119 skulls (male 766; female 353). A morphological description of the skulls that exhibited occipitalisation was included in this study. ResultsOccipitalisation was observed in three skulls (3/1119; 0.27 %); two of the skulls were female (2/353; 0.57 %), and one was male (1/766; 0.13 %). The three occipitalised skulls exhibited fusion in three areas of the atlas: the anterior arch, lateral masses, and transverse processes. No skulls exhibited posterior arch fusion of the atlas. ConclusionThis study established a baseline prevalence of occipitalisation in the South African Black population at 0.27 % and found no significant association between sex and occipitalisation (p = 0.236). This study highlights the need for further studies in the other African population affinity groups.

A screw algorithm for congenital C2-3 fusion with high-riding vertebral arteries: feasibilities and clinical outcomes of five different fixation techniques.

To propose a screw algorithm and investigate the anatomical feasibilities and clinical outcomes of five distinct fixation methods for C2-3 fused vertebra with high-ridding vertebral arteries (VA) (HRVA) when the C2 pedicle screw placement is unfeasible. Thirty surgical patients with congenital C2-3 fusion, HRVA, and atlantoaxial dislocation (AAD) were included. We designed a algorithm for alternative screw implantation into C2-3 fused vertebrae, including C2 pedicle screw with in-out-in (passing VA groove) technique (in-out-in screw), subfacetal screw, translaminar screw, lateral mass screw, C3 pedicle screw. VA diameter and position, C2 and C3 pedicles, superior facets, fused lamina, and fused lateral mass dimensions were evaluated for screw implantation indication. Implant failure, reduction loss, implant placement accuracy were investigated by computed tomography. A total of 5 VAs were identified as distant VAs; a total of 2 VAs were categorized as occlusive VAs. Sufficient dimension of lateral mass and lamina provided the broadest indications for screw implantation, while the distant or occlusive VA provided the most limited indications for in-out-in screw. The indications of five alternative methods ranged from narrowest to widest as follows: in-out-in screw, C3 pedicle screw, subfacetal screw, translaminar screw, lateral mass screw. The translaminar screws and the lateral mass screws increased the probability of implant failure. All patients who received in-out-in screws, C3 pedicle screws, and subfacetal screws achieved fusion. The accuracy ranged from lowest to highest as follows: C3 pedicle screw, lateral mass screw, in-out-in screw, subfacetal screw, translaminar screw. No translaminar screws deviated. The algorithm proved to be a valuable tool for screw selection in cases of C2-3 fused vertebrae with HRVAs. The subfacetal screw, boasting broad indications, a high fusion rate, and exceptional accuracy, stood as the primary preferred alternative.

Biomechanical differences of three cephalic fixation methods for patients with basilar invagination and atlantoaxial dislocation in the setting of congenital atlas occipitalization: a finite element analysis

Background contextIn cases of basilar invagination-atlantoaxial dislocation (BI-AAD) complicated by atlas occipitalization (AOZ), the approach to cranial end fixation has consistently sparked debate, generally falling into two categories: C1–C2 fixation and occipitocervical fixation. Several authors believe that C1–C2 fixation carries a lower risk of fixation failure than occipitocervical fixation. PurposeTo study the biomechanical differences among 3 different cranial end fixation methods for BI-AAD with AOZ. Study designThis was a finite element analysis. Patient sampleA 35-year-old female patient diagnosed with congenital BI-AAD and AOZ. Outcome measuresrange of motion (ROM), peak von Mise stress (PVMS), cage micro-subsidence, cage micro-slippage MethodFour finite element models were constructed, including unstable group (BI-AAD with AOZ), C1 lateral mass screw group, occipital plate group, occipitocervical rod group. The flexion and extension (FE), lateral bending (LB) as well as axial rotation (AR) were simulated under a torque of 1.5 Nm. Parameters include C1–C2 ROM, PVMS on screw-rod construct, cage micro-subsidence, cage micro-slippage. ResultsThe ROM of the C1 lateral mass screw group was smaller than that of the other fixation groups in LB and AR, but not FE. Compared with the occipitocervical rod group, the ROM in LB and AR of the occipital plate group was higher, but not in FE. The PVMS of C1 lateral mass screw group was significantly higher than that of the other groups. The ROM and PVMS of the occipitocervical rod group were in between the other 2 groups. Regarding the screws at the cranial end, the PVMS of the 4-screw occipitocervical rod group was significantly lower than that of the other groups. In general, the cage micro-motion follows the ascending order: C1 lateral mass group < occipitocervical rod group < occipital plate group. ConclusionIn cases of BI-AAD with AOZ, the C1 lateral mass screw group provided the least ROM and cage micro-motion, but the screw-rod PVMS was the largest. The advantage of occipital plate fixation lies in the lowest screw-rod PVMS, but the ROM and cage micro-motion is the highest. Four-screw fixation at the cranial end of occipitocervical rod group helps to reduce the PVMS and may prevent screw failure at the cranial end.