Perioperative complications associated with fluoroscopy C1 lateral mass screw fixation (Goel technique) versus computed tomography-guided navigation technique: A review of 202 cases from the German Spine Registry (DWG-Register).

Background: Overview of the literature - Fractures of the C1 constitute 3%-13% of all cervical spine injuries in adults. Most isolated C1 fractures are stable and can be treated nonoperatively with external immobilization. Traditional surgical options for C1 fracture treatment are occiput-to-C2 fusion or C1 with lateral mass screws (LMSs). Purpose - The aim is to assess the management and perioperative complications of C1 fractures undergoing LMS fusion between fluoroscopy and computed tomography (CT)-guided navigation. Methods: This was a retrospective multicenter study of data from the DWG-Register of patients who underwent operative treatment for C1 traumatic fracture with LMSs from January 2017 to September 2022. Inclusion criteria - traumatic injury and age > 18 years old. Results: In total, 202 patients with traumatic C1 fracture requiring spinal surgery were identified in the registry; n = 175 (Group 1) were treated conventionally without CT-guided navigation and n = 27 were treated with CT-guided navigation (Group 2). C1-LMS was principally performed by spine surgeons n = 90 (53.4%) and n = 72 (18.5%) by neurosurgeons in both the groups. Intraoperative adverse events were as follows: dural tear in group 1 n = 0 and in group 2 n = 1, vascular injury, with one case in group 1 and no cases in group 2. General complications were: cardiovasculars in group 1 n = 6 (3.4%) and Group 2 n = 4 (14.8%) (P = 0.03), pulmonary complications in group1 n = 2 (1.1%) and n = 9 in group 2 (33.3%) (P < 0.001), stroke n = 1 (0.57%) in group1 and n = 4 in group 2 (14.8%) (P < 0.001), gastrointestinal bleeding n = 1 (0.57%) in group1 and no cases in group 2, renal insufficiency n = 2 (1.1%) in group 1 and n = 3 (11.1%) in group 2 (P = 0.01). One death was recorded in group 2 (3.7%). Conclusion: This series of 404 screws placed in 202 patients over 5 years who underwent two types of C1 fracture fixation had a considerably lower incidence of screw malposition and vertebral artery injury than has previously been reported in the literature. C1 screws can be safely placed with a low risk of vertebral artery and neurologic injury with and without CT-guided navigation support.

Biportal endoscopy-assisted lateral mass screw fixation using a third portal.

BACKGROUND: The technique of spinal decompression under endoscopy has been widely applied, but reports on endoscopic cervical fixation are rare. The unilateral biportal endoscopic (UBE) technique stands out for its lesser muscle intrusion and more flexible surgical approach. METHOD: We applied the UBE approach for cervical fixation and laminectomy. We achieved bilateral lateral mass screw fixation by making an auxiliary UBE portal combined with the Roy-Camille and Magerl techniques. CONCLUSIONS: Our successful implementation of cervical fixation using the UBE technique at the C3/4 level suggests its efficacy. This approach is a valuable and minimally invasive option for cervical fixation.

Investigation of long lateral mass screw insertion torque.

Background: Here, we assessed a new trajectory and insertion torque for the placement of a long lateral mass screw (LLMS) that offers stronger posterior fixation versus a shorter lateral mass screw (LMS) in the posterior cervical spine. We report a short technical note of the insertion torque of LLMS. Methods: The insertion trajectory/torque was evaluated in 30 patients (10 males and 20 females) undergoing posterior cervical LLMS fusions (2021-2023). Patients averaged 65 years of age. Pathology included eight cervical spine injuries, ten cord injuries, four dislocations/fractures, and eight other entities. Variables studied included the length of the LLMS inserted from C3-7, screw deviation rates, insertion torque, and adverse events. Results: A total of 146 screws were inserted: 11 pedicle screws (PSs) and 135 LLMS. The average insertion torque was 105.9 cNm for PS and 64.9 cNm for LLMS. As the screw lengthened by 1 mm, the insertion torque increased by approximately 4.4 cNm. Conclusion: Here, we documented that the insertion torque of LLMS was 66.1 cNm, greater than the 51.0 cNm for LMS, which should provide stronger posterior cervical fixation.

Comparison of radiological and clinical outcomes of cervical laminoplasty versus lateral mass screw fixation in patients with ossification of the posterior longitudinal ligament.

PURPOSE: This study aimed to compare cervical sagittal parameters and clinical outcomes between patients undergoing cervical laminoplasty(CL) and those undergoing lateral mass screw fixation(LMS). METHODS: We retrospectively studied 67 patients with multilevel ossification of the posterior longitudinal ligament (OPLL) of the cervical spine who underwent lateral mass screw fixation (LMS = 36) and cervical laminoplasty (CL = 31). We analyzed cervical sagittal parameters (C2-7 sagittal vertical axis (C2-7 SVA), C0-2 Cobb angle, C2-7 Cobb angle, C7 slope (C7s), T1 slope (T1s), and spino-cranial angle (SCA)) and clinical outcomes (visual analog scale [VAS], neck disability index [NDI], Japanese Orthopaedic Association [JOA] scores, recovery rate (RR), and minimum clinically significant difference [MCID]). The cervical sagittal parameters at the last follow-up were analyzed by binary logistic regression. Finally, we analyzed the correlation between the cervical sagittal parameters and each clinical outcome at the last follow-up after surgery in both groups. RESULTS: At the follow-up after posterior decompression in both groups, the mean values of C2-C7 SVA, C7s, and T1s in the LMS group were more significant than those in the CL group (P ≤ 0.05). Compared with the preoperative period, C2-C7 SVA, T1s, and SCA gradually increased, and the C2-C7 Cobb angle gradually decreased after surgery (P < 0.05). The improvement in the JOA score and the recovery rate was similar between the two groups, while the improvement in the VAS-N score and NDI score was more significant in the CL group (P = 0.001; P = 0.043). More patients reached MCID in the CL group than in the LMS group (P = 0.036). Binary logistic regression analysis showed that SCA was independently associated with whether patients reached MCID at NDI postoperatively. SCA was positively correlated with cervical NDI and negatively correlated with cervical JOA score at postoperative follow-up in both groups (P < 0.05); C2-7 Cobb angle was negatively correlated with cervical JOA score at postoperative follow-up (P < 0.05). CONCLUSION: CL may be superior to LMS in treating cervical spondylotic myelopathy caused by OPLL. In addition, smaller cervical SCA after posterior decompression may suggest better postoperative outcomes.

Finite Element Analysis Comparing the Biomechanical Parameters in Multilevel Posterior Cervical Instrumentation Model Involving Lateral Mass Screw versus Transpedicular Screw Fixation at the C7 Vertebra.

STUDY DESIGN: Basic research. PURPOSE: This finite element (FE) analysis (FEA) aimed to compare the biomechanical parameters in multilevel posterior cervical fixation with the C7 vertebra instrumented by two techniques: lateral mass screw (LMS) vs. transpedicular screw (TPS). OVERVIEW OF LITERATURE: Very few studies have compared the biomechanics of different multilevel posterior cervical fixation constructs. METHODS: Four FE models of multilevel posterior cervical fixation were created and tested by FEA in various permutations and combinations. Generic differences in fixation were determined, and the following parameters were assessed: (1) maximum moment at failure, (2) maximum angulation at failure, (3) maximum stress at failure, (4) point of failure, (5) intervertebral disc stress, and (6) influence of adding a C2 pars screw to the multilevel construct. RESULTS: The maximum moment at failure was higher in the LMS fixation group than in the TPS group. The maximum angulation in flexion allowed by LMS was higher than that by TPS. The maximum strain at failure was higher in the LMS group than in the TPS group. The maximum stress endured before failure was higher in the TPS group than in the LMS group. Intervertebral stress levels at C6-C7 and C7-T1 intervertebral discs were higher in the LMS group than in the TPS group. For both models where C2 fixation was performed, lower von Mises stress was recorded at the C2-C3 intervertebral disc level. CONCLUSIONS: Ending a multilevel posterior cervical fixation construct with TPS fixation rather than LMS fixation at the C7 vertebra provides a stiff and more constrained construct system, with higher stress endurance to compressive force. The constraint and durability of the construct can be further enhanced by adding a C2 pars screw in the fixation system.

Pediatric atlas anatomy and its implications for fracture treatment: an anatomical and radiological study.

INTRODUCTION AND OBJECTIVES: The objective of the study was: (1) to describe changes in the shape of the atlas during growth, including gender and side differences; (2) to assess the dimension essential for identification of the optimal entry point; (3) to determine the age limit for a safe insertion of 3.5-mm screws into the lateral masses according to our own limiting parameters. MATERIALS AND METHODS: Dimensions of the atlas were measured on 200 CT scans of the craniocervical junction in individuals aged 0-18 years and on 34 anatomical specimens of the first cervical vertebra (aged 2.5-18 years). Both series were divided according to the gender and age. The values measured on CT scans were used for statistical comparison of data in boys and girls and comparison of the right and left sides. RESULTS: The atlas reaches its maximum growth rate between 0 and 2 years of age, then the growth decelerates and continues until the age of 18 years. The proportion of dimensions of C1 vertebral foramens changes with age. The youngest children show a relatively greater distance from the left to the right medial pedicle; around the age of 5 the values get even and subsequently the distance from the inner wall of anterior to posterior arch gets relatively greater. The transverse foramen has a slightly oval shape throughout the period of growth. Statistically significant differences between boys and girls were observed primarily between 12 and 18 years of age. CONCLUSION: The study has proved adequate size of lateral masses for insertion of 3.5-mm screws in all patients from the age of 5 years. In younger children, the patient´s anatomy should be respected and the surgical technique tailored accordingly.

Nuance in Craniovertebral Junction Surgical Approach for Posterior C1-C2 Harms Stabilization: "Window Transposition" of the External Vertebral Venous Plexus for Bloodless C1 Lateral Mass Screw Insertion: Anatomical Aspects and Technical Notes.

Atlas and axis instrumentation may be necessary in cases of several craniocervical junction pathologies. According to the Harms technique, C1-C2 polyaxial screws are inserted respectively in the C1 lateral masses and in C2 pedicles. C1 lateral mass screw insertion requires the careful subperiosteal dissection of the posterior elements of C1, the identification of the screw entry point by the downward distraction of C2 nerve root, and the cautious sparing of the overlying posterior external vertebral venous plexus (peVVP), whose bleeding, obstructing the surgical field, is sometimes barely controlled by hemostatic agents and swabbing. The authors describe in detail the anatomical aspects of an alternative surgical technique developed for the microsurgical transposition of the C1-C2 interposed external vertebral venous plexus in the case of Harms C1-C2 screw stabilization. The longitudinal median incision of the atlantoaxial membrane, followed by bilateral subperiosteal dissection and microsurgical section respectively at the inferior borders of the C1 laminae and at the superior borders of the C2 laminae, allows, as a "window opening," the symmetrical mediolateral transposition of the peVVP. This procedure provides a faster and cleaner anatomical exposition of the posterior surface of the C1 lateral mass and the C2 isthmus, preventing troublesome intraoperative venous bleeding that hinders C1 lateral mass screw insertion.

Two-year results of single-level fixation with lateral mass screws for cervical degenerative spondylolisthesis: patient series.

BACKGROUND: In surgery for cervical spondylotic myelopathy (CSM) with spondylolisthesis, there is no consensus on the correction and fixation for spondylolisthesis. The authors retrospectively studied whether the correction of single-level fixation with lateral mass screws (LMSs) could be maintained. OBSERVATIONS: The records of patients with CSM with spondylolisthesis who had been treated with posterior decompression and single-level fusion with LMSs from 2017 to 2021 were retrospectively reviewed. Radiographic measurements included cervical parameters such as C2-7 lordosis, T1 slope, and the degree of spondylolisthesis (percent slippage) before surgery, immediately after surgery, and at the final observation. Ten cases (mean age 72.8 ± 7.8 years) were included in the final analysis, and four cases (40%) were on hemodialysis. The median observation period was 26.5 months (interquartile range, 12-35.75). The mean percent slippage was 16.8% ± 4.7% before surgery, 5.3% ± 4.0% immediately after surgery, and 6.5% ± 4.7% at the final observation. Spearman's rank correlation showed a moderate correlation between preoperative slippage magnitude and correction loss (r = 0.659; p = 0.038). Other parameters showed no correlation with correction loss. LESSONS: For CSM with spondylolisthesis, single-level fixation with LMSs achieved and maintained successful correction in the 2-year observation.

A Novel Semi-Cannulated Screw Enhanced Bone Cement Augmentation and Pullout Strength in Posterior Cervical Lateral Mass Screw Fixations: An In Vitro Biomechanical and Morphological Study.

OBJECTIVE: To develop a novel semi-cannulated lateral mass screw (SC-LMS) for cervical posterior fixations and compare the fixation stability and safety of SC-LMS with regular solid lateral mass screw (S-LMS) in bone cement augmentation and pullout strength using fresh cadaveric cervical vertebrae. METHODS: The conventional multiaxial screw for cervical lateral mass fixation was modified to a cannulated screw with two lateral holes, used for bone cement injection in situ. Eight fresh human cervical vertebrae (C3, C4, and C5) were collected and used. µCT scan was performed to evaluate the bone quality of the lateral masses, including bone mineral density (BMD), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp). SCLMS or S-LMS were randomly inserted into the paired cervical vertebrae and pulled out as a screw loosening model. These screws were reinserted in with bone cement augmentation, scanned by µCT to obtain the bone cement distribution along the screws, and pulled out to test the screw purchase strength. RESULTS: Fmax values exhibited strong positive correlations with the local BMD (𝑟 = 0.8640, p < 0.0001) and Tb.Th (𝑟 = 0.6795, p = 0.0038), whereas a negative correlation with Tb.Sp (𝑟 = -0.5567, p = 0.0251). A significant difference was observed between the Fmax before and after PMMA injection on the SC-LMS side (p = 0.019). The SC-LMS exhibited lower risk of cement leakage than S-LMS after PMMA injection, and a positive correlation was observed between 𝐹max and the distribution volumes on the SC-LMS side. CONCLUSION: The novel SC-LMS provides more robust fixation stability and is safer than the S-LMS for PMMA augmentation, which may be related to the cement-screw-cement-bone complex formation.

Comparison of Anterior Cervical Discectomy Fusion Combined with Lateral Mass Screw and with Cervical Pedicle Screw Fixation Surgery under O-Arm Navigation for Single-Stage Management of Severe Lower Cervical Fracture Dislocation.

OBJECTIVE: The incidence of severe lower cervical fractures and dislocations due to trauma has increased significantly, and the optimal treatment remains controversial. This study compares the safety and efficacy of anterior cervical discectomy fusion (ACDF) combined with lateral mass screw (LMS) and with cervical pedicle screw (CPS) fixation surgery under O-arm navigation as single-stage treatments of severe lower cervical fracture dislocations. METHODS: Data from 48 patients who underwent ACDF + CPS (Group A) or ACDF + LMS (Group B) for severe lower cervical fracture dislocation between January 2016 and September 2020 were retrospectively reviewed. Groups A and B comprised 25 and 23 cases, respectively. Clinical parameters, such as operative time, intraoperative blood loss, number of fixed segments, posterior incision length, operative complications, and hospitalization days were recorded. Preoperatively and postoperatively, the sub-axial injury classification (SLIC) score, the American Spinal Injury Association (ASIA) impairment scale, and the Japanese Orthopaedic Association (JOA) score were recorded and analyzed using Student's t-test. RESULTS: The SLIC scores were 7.1 ± 1.2 and 7.5 ± 1.1, ASIA were 1.5 ± 0.6 and 1.2 ± 0.6, JOA score improvements were 3.2 ± 2.4 and 3.0 ± 2.1, operative times were 282.1 ± 91.7 and 266.5 ± 88.2 min, intraoperative blood losses were 437.8 ± 118.5 and 418.7 ± 104.2 mL, fixed segments were 2.8 ± 0.7 and 4.8 ± 1.1, and lengths of posterior incisions were 12.7 ± 2.8 and 13.8 ± 3.2 cm in Groups A and B, respectively. There was no significant difference between the two groups in the operative time, intraoperative blood loss, incision length, and postoperative recovery; however, group A had more fixed segments. At the final follow-up, no intraoperative or postoperative complications directly caused by the implant were present. Throughout the follow-up, all cases showed recovery and progressive improvement. CONCLUSION: Both ACDF + LMS and ACDF + CPS under O-arm navigation can safely and effectively restore cervical vertebral sequence, fully release spinal canal compression, and promote patients' neurological recovery. Thus, both are effective treatments for severe lower cervical fracture dislocations. However, compared to LMS, CPS under O-arm navigation has shorter fixed segments and induces less trauma.

A Novel Trajectory of C7 Laminar Screws Determined Using Three-Dimensional Computed Tomography and Surgical Simulation Software: Comparison with a Pre-existing Trajectory.

STUDY DESIGN: Examination using three-dimensional screw trajectory software and computed tomographic scans. PURPOSE: To evaluate the feasibility of a novel trajectory for C7 laminar screws and to compare it with an old trajectory. OVERVIEW OF LITERATURE: The previously reported trajectory of C7 laminar screws has a horizontal direction without a fixed target point. Our new trajectory has a cephalad direction with a fixed target point. METHODS: Computed tomographic scans of a total of 50 male and 50 female patients were utilized. The placement of C7 laminar screws was activated employing the new and old trajectories. The success rate, the causes of failure, and the maximum allowable length of each trajectory were compared. RESULTS: Employing the new trajectory, the success rates of the unilaminar and bilaminar screws were 93% and 83%, respectively, which were significantly better than the old trajectory (80%, p<0.0001 and 70%, p=0.0003). The most prevalent cause of failure was laminar cortical breach followed by facet joint violation. The new trajectory also offered significantly longer maximum allowable screw length in unilaminar (32.5±4.3 mm vs. 26.5±2.6 mm, p<0.001), bilaminar cephalic (29.5±3.8 mm vs. 25.9±2.6 mm, p<0.0001) and bilaminar caudal (33.1±2.6 mm vs. 25.8±3.1 mm, p<0.001) screws than the old trajectory. With the new and old trajectories, 70% vs. 6% of unilaminar, 60% vs. 2% of bilaminar caudal, and 32% vs. 4% of bilaminar cephalic screws could be protracted perfectly into the corresponding lateral mass without any laminar cortical or facet joint violation (p<0.0001). CONCLUSIONS: The novel trajectory possesses a substantially higher success rate, longer maximum allowable screw length, and higher chance to be extended into the lateral mass (a condition known as a lamino-lateral mass screw) than the old trajectory.

Assessment of Biomechanical Advantages in Combined Anterior-Posterior Cervical Spine Surgery by Radiological Outcomes: Pedicle Screws over Lateral Mass Screws.

BACKGROUND: The combined anterior-posterior approach has shown good clinical outcomes for multilevel cervical diseases. This work describes the biomechanical advantage of cervical-pedicle-screw fixation over lateral-mass-screw fixation in combined anterior-posterior cases. METHOD: Seventy-six patients who received combined cervical surgery from June 2013 to December 2020 were included. The patients were divided into two groups: the lateral-mass-screw group (LMS) and the pedicle-screw group (PPS). Radiological outcomes were assessed with lateral cervical spine X-rays for evaluating sagittal alignment, subsidence, and bone remodeling. RESULTS: At 1 year postoperatively, the numbers of patients whose C2-C7 cervical lordosis was less than 20 degrees decreased by more in the PPS group (p-value = 0.001). The amount of vertical-length change from immediately to 1 year postsurgery was less in the PPS group than in the LMS group (p-value = 0.030). The mean vertebral-body-width change was larger in the PPS group than in the LMS group during 3 months to 1 year postsurgery (p-value = 0.000). CONCLUSIONS: In combined anterior-posterior cervical surgery cases, maintenance of cervical lordosis and protection of the vertebral body from subsidence were better with the pedicle-screw fixation. More bone remodeling occurred when using the pedicle-screw fixation method.

Atlantoaxial Subluxation Associated With Chronic Motor Tics.

Head jerking is one of the most common symptoms of motor tics, and because of this, patients are at an increased risk of cervical spine disorders. However, there have been no reports of atlantoaxial subluxation in the English literature. To the best of our knowledge, this is the first case of atlantoaxial subluxation associated with chronic motor tics. A 41-year-old man with a history of chronic motor tics since childhood was diagnosed with high cervical myelopathy due to atlantoaxial subluxation. The patient underwent posterior fusion surgery using atlantoaxial instrumentation and an autologous bone graft. Although screw breakage occurred as an early postoperative instrumentation failure, the clinical outcome was excellent after surgery without recurrence of subluxation. Other techniques such as atlantoaxial transarticular fixation and occipitocervical fusion followed by long-term external immobilization might be treatment options at the initial surgery, or in case of postoperative recurrent atlantoaxial subluxation.

Clinical Outcomes of Open-Door Laminoplasty Combined with Bilateral Lateral Mass Screw Fixation for Multi-Level Cervical Spinal Stenosis with Traumatic Cervical Instability and Spinal Cord Injury: A Retrospective Study.

OBJECTIVES: The prevalence of multi-level cervical spinal stenosis complicated with traumatic cervical instability and spinal cord injury (MCSS-TCISCI) is low, and the optimal surgical approach remains unclear. Open-door laminoplasty combined with bilateral lateral mass screw fixation (ODL-BLMSF) is a relatively new surgical technique; however, its clinical effectiveness in managing MCSS-TCISCI has not been well-established. This study aims to assess the clinical value of ODL-BLMSF against MCSS-TCISCI. METHODS: We retrospectively analyzed 20 cases of MCSS-TCISCI treated with ODL-BLMSF from July 2016 to June 2020. Radiographic alterations of all included patients were measured using plain radiographs, CT scans, and MRI scans. Cervical lordosis was evaluated using C2-C7 Cobb angle and cervical curvature index (CCI) on lateral radiographs, and Pavlov ratio at the C5 level. Neurological functional recovery was assessed using Japanese Orthopaedic Association (JOA) scores and Nurick grade, while neck and axial symptoms were assessed using the neck disability index (NDI) and the visual analog scale (VAS). The paired t-test was utilized for statistical analysis. RESULTS: All included patients were followed up for an average period of 26.5 months (range: 24-30 months) after ODL-BLMSF. The average Pavlov ratio at the C5 level significantly improved from 0.57 ± 0.1 preoperatively to 1.13 ± 0.1 and 1.12 ± 0.04 at 6 months postoperatively and at the last follow-up (t = 16.347, 16.536, p < 0.001). Importantly, this approach significantly increased the JOA score from 5.0 ± 2.6 before surgery to 11.65 ± 4.3 and 12.1 ± 4.3 at 6 months postoperatively and at the last follow-up (t = 9.6, -9.600, p < 0.001), with an average JOA recovery rate of 59.1%; and the average Nurick disability score decreased from 3.0 ± 1.3 (preoperative) to 1.65 ± 1.22 and 1.5 ± 1.2 (6 months postoperatively and at last follow-up) (t = 5.111, 1.831, p < 0.001). Meanwhile, the NDI score decreased from 30.3 ± 4.3 preoperatively to 13.2 ± 9.2 at 6 months (t = 12.305, p < 0.001), and to 12.45 ± 8.6 at the final follow-up (t = 13.968, p < 0.001), while the VAS score decreased from 4.0 ± 1.5 preoperatively to 1.5 ± 0.7 at 6 months (t = 9.575, p < 0.001), and to 1.15 ± 0.7 at the final follow-up (t = 10.356, p < 0.001). CONCLUSION: ODL-BLMSF can effectively dilate the stenotic spinal canal to decompress the spinal cord, maintain good cervical alignment and stability, and improve the recovery of neurological function and neck function. This technique is suitable for treating selected cases of MCSS-TCISCI.

Atlantoaxial Stabilization Using C1 Lateral Mass and C2 Pedicle/Translaminar Screw Fixation by Intraoperative C1- and C2-Direct-Captured Navigation with Preoperative Computed Tomography Images.

In C1-C2 posterior fixation, the C1 lateral mass and C2 pedicle/translaminar screw insertion under spine navigation have been used frequently. To avoid the risk of neurovascular damage in atlantoaxial stabilization, we assessed the safety and effectiveness of a preoperative computed tomography (CT) image-based navigation system with intraoperative independent C1 and C2 vertebral registration. It is ideal when a reference frame can be linked directly to the C1 posterior arch for C1-direct-captured navigation, but there is a mechanical challenge. A new spine clamp-tracker system was implemented recently, which allows reliable C1- and C2- direct-captured navigation in nine patients with traumatic C2 fractures. In this way, there was no misalignment of C1-C2 screws. C1 lateral mass screws were used except for one case, and translaminar screws were primarily used as an anchor for C2. The C1 lateral mass screw locations, which are 19 mm laterally from the C1 posterior arch's center, are taken to be constant. However, there is one unusual circumstance in which using a C1 laminar hook instead of a C1 lateral mass screw appears to be a beneficial substitute. The increase of surgical accuracy for posterior C1-C2 screw fixation without cost constraints is significantly facilitated by intraoperative C1- and C2-direct-captured navigation with preoperative computed CT images.

The Impact of Rigid Cervical Collars on Outcome of Patients Who Underwent Posterior Cervical Laminectomy and Fusion: A Retrospective Comparative Study.

STUDY DESIGN: Retrospective cohort study. PURPOSE: This study aimed to investigate the cervical collar impact on the functional outcomes of patients after posterior cervical laminectomy and lateral mass screw fixation (PCLF) surgery. OVERVIEW OF LITERATURE: The safety and possible benefits of implementing rigid cervical collars subsequent to PCLF are insufficiently investigated. METHODS: Patients who underwent PCLF and received postoperative cervical collars from 2018 to 2020 were included in this retrospective cohort study. Their data were compared with an age- and sex-matched group of subjects who did not receive collars after PCLF during the same period. Pain intensity (using the Visual Analog Scale), Neck Disability Index, and quality of life (using 36-item Short Form Health Survey) of the patients were compared at baseline, 1, 3, 6, and 12 months postoperatively. RESULTS: A total of 36 patients who received cervical collars after surgery and 40 controls were included. At baseline and 1-month follow-up, there were no differences in pain intensity, functional status, and quality of life between the groups. However, at 3 months postoperatively, the quality of life of the subjects with no orthosis was higher than those who received cervical collars (p =0.01). At 6- and 12-month follow-up, there were no differences between the groups in pain intensity, functional status, and quality of life. CONCLUSIONS: No difference in the pain intensity and functional status of patients who used cervical collars and controls was shown in our study. Patients who did not wear cervical collars had a higher quality of life during the 3-month postoperative evaluation. Future prospective, well-controlled studies with longer follow-ups are needed to further investigate the effects of cervical orthosis on the clinical outcome of patients after PCLF.

Preliminary experience with a novel facet-based lateral mass drill guide for the placement of lateral mass screws compared to freehand technique: a cadaveric study.

BACKGROUND CONTEXT: Lateral mass screw fixation is the standard for posterior subaxial cervical fixation. Several freehand surgical techniques for placing lateral mass screws have been described which rely on anatomical landmarks and surgeon mastery of the technique to safely place screws. The accuracy of these freehand techniques is inherently variable and can be influenced by a surgeon's level of clinical experience. A novel technique was developed that utilizes the plane of the facet joint to create lateral mass screw pilot holes parallel with the joint line to improve the safety and accuracy of lateral mass screw placement regardless of experience. PURPOSE: To assess the safety and accuracy of lateral mass screw placement using a novel lateral mass drill guide instrument (LM Guide), compared to standard freehand technique. STUDY DESIGN: Randomized cadaveric study utilizing multiple surgeon evaluators to compare the safety and accuracy of guided cervical lateral mass placement compared to traditional freehand techniques. MATERIALS AND METHODS: Lateral mass screws were placed from C3 to C7 in 20 cadaver specimens by 8 spine surgeons of varying levels of clinical experience (4 attendings, 4 fellows). Screws were placed bilaterally using standard anatomic landmarks ("freehand") randomly allocated on one side and using the LM Guide on the other. Cadaveric specimens were imaged with high-resolution CT to assess screw placement. Zone grading for safety was conducted based on screw tip position and clinical severity of screw breach was based on proximity to surrounding neurovascular anatomy. Screws were graded as safe, at-risk, or critical, with at-risk and critical screws considered malpositioned. To assess the accuracy of screw trajectory placed using the LM Guide compared to freehand, sagittal screw angle was measured and compared to an "ideal" screw path parallel to the facet joint line. Freehand and LM Guide groups were compared using Pearson's chi-square correlation. RESULTS: Screw placement using the LM guide yielded a significantly lower rate of screw malpositioning, with 7 of 91 (7.7%) compared with 18 of 99 (18.2%) screws placed in the At-Risk or Critical Zones, p<.05. Of the 91 screws inserted using the LM Guide, 84 (92.3%) were in the Safe Zone, 7 (7.7%) were At-Risk, and 0 were in Critical zones. There was no incidence of neural or transverse foramen breaches with the LM Guide. In comparison, for the 99 screws inserted freehand, 81 (81.8%) were Safe, 14 (14.1%) were At-Risk, and 4 (4.1%) were in Critical zones. The 4 Critical zone freehand screw breaches included 1 neural foramen breach, 2 transverse foramen breaches, and 1 facet breach. The LM Guide also resulted in higher accuracy of screw trajectory, as indicated by a significant reduction in sagittal screw angle compared with freehand, p<.01. Notably, in the less-experienced surgeon cohort, the LM Guide significantly reduced the sagittal screw angle and resulted in no critical screw breaches compared to 3 critical breaches with freehand technique suggesting there might be a benefit in decreasing the learning curve associated with lateral mass screw placement. CONCLUSIONS: Lateral mass screw placement with a novel LM Guide that uses the facet joint to control screw trajectory improved the accuracy and reproducibility of screw placement with a significant reduction in screw breach rate and sagittal screw angle compared to freehand techniques regardless of surgeon experience level. CLINICAL SIGNIFICANCE: The inherent variability of freehand lateral mass screw placement can increase the risk of clinical complications associated with screw malpositioning. The technique presented in this cadaveric study may be a viable alternative to standard freehand technique that can improve the overall safety of lateral mass screw placement.

Evaluation of enlarged laminectomy with lateral mass screw fixation in relieving nerve root symptoms and correcting kyphosis for cervical myelopathy and radiculopathy.

Purpose: This study aimed to compare the surgical efficacy of enlarged laminectomy with lateral mass screw fixation (EL-LMSF) and anterior cervical decompression and fusion (ACDF) for multilevel cervical myelopathy and radiculopathy (CMR) related to kyphosis. Methods: 75 patients were retrospectively reviewed and divided into ACDF and EL-LMSF group. Clinical results including operative time, blood loss, and postoperative complications were compared. The JOA scoring system was used to evaluate spinal cord function and the VAS score evaluate nerve root pain severity. Cervical alignment a C2-C7 was measured with Cobb method and compared to confirm the reconstruction effect. Results: Data on 75 patients (M/F: 41:34; EL-LMSF/ACDF:42/33) with the mean age of 57.5 years (range 43-72 year old) were reviewed retrospectively. Discectomy and/or sub-toal corpectomy in ACDF group was performed with a mean of 3.24 levels (range, 3-4). Enlarged laminectomy in EL-LMSF group was performed with a mean of 3.89 enlarged levels (range, 3-5). The procedure of ACDF group showed a shorter operation time (103 ± 22 min vs. 125 ± 37 min, P = 0.000) and less blood loss (78 ± 15 ml vs. 226 ± 31 ml, P = 0.000) compared than that of the EL-LMSF group. Patients treated with EL-LMSF indicated lower VAS for upper extremity (1.3 ± 1.7 vs. 3.3 ± 1.3, P = 0.003) and better curvature corrected (10.7 ± 4.2° vs. 8.5 ± 3.5°, P = 0.013). The difference were of statistical significance. No statistical difference was found after surgery in the JOA score (14.1 ± 1.7 vs. 13.5 ± 2.1, P = 0.222). During the follow-up period, 15.2% of patients in the ACDF group had complications including 2 cases with transient dysphagia, 1 case with C5 palsy, 1 case with axial pain, and 1 case with screw pullout 3 month after surgery. However, only 9.5% of cases in the EL-LMSF group experienced complications, including 3 cases of axial pain and 1 case of epidural hematoma. Conclusion: The EL-LMSF procedure requires a longer operation time and more blood loss because of the incision of the stenosed foramen. However, the procedure has obvious advantages in relieving nerve root symptoms and correcting cervical curvature with fewer postoperative complications.

Strategies to avoid internal carotid artery injury in "sandwich" atlantoaxial dislocation patients during surgery.

PURPOSE: To elucidate the anatomic relationship between the internal carotid artery (ICA) and the bony structures of the craniovertebral junction among "sandwich" atlantoaxial dislocation (AAD) patients, and to analyze the risks of injury during surgical procedures. METHODS: The distance from the medial wall of ICA to the midsagittal plane (D1), the shortest distance between the ICA wall and the anterior cortex of the lateral mass of atlas (LMA) (D2) on the most caudal and cranial levels of LMA and the angle (A) between the sagittal plane passing through the screw entry point of C1 lateral mass(C1LM) screw and the medial tangent line of the vessel passing through the entry point were measured. Besides, the location of ICA in front of the atlantoaxial vertebra was divided into 4 categories (Z1-Z4). RESULTS: There was a statistically difference between the male and female patients regarding D1, and the difference between D2 at level a and level b as well as angle A between the left and right sides were statistically different (p < 0.05). Ninety-two ICAs (57.5%) were anteriorly located in Z3, 50 (31.3%) were located in Z4, 17 were located in Z2, and only one ICA was located in Z1 in all 80 patients. CONCLUSIONS: In "sandwich" AAD patients, particular attention should be paid to excessively medialized ICA to avoid ICA injury during trans-oral procedures, and the risk of injuring the ICA with more cranially and medially angulated C1LM screw placement was relatively less during posterior fixation procedures. A novel classification of ICA location was used to describe the relationship between ICA and LMA.

C7 distal fixation anchor and its influence on sagittal profile in posterior cervical fusion; a retrospective analysis of 44 cases.

Study design: Retrospective. Purpose: In multilevel posterior cervical fusion, whether to stop distal fixation at C7 or T1, remains a matter of debate. We aimed to assess clinical feasibility of C7 as distal fixation point and sought to compare complication rates and radiological outcome between lateral mass screws and pedicle screws at C7. Overview of literature: Current literature remains inconclusive regarding need for thoracic extension of instrumentation in multilevel posterior cervical fusion. Methods: We did a retrospective review of 44 consecutive patients who underwent posterior instrumented cervical decompression and fusion for degenerative cervical myelopathy with C7 as distal fixation point, and a minimum follow-up period of two years. We had two groups of patients based on C7 instrumentation. Group 1: Lateral mass screw fixation. Group 2: Pedicle screw fixation. Primary outcome: Post-operative clinico-radiological evaluation of whole study population Secondary outcome: Comparison of complication rates and radiological outcome between groups 1 and 2. Results: Mean age was 58.06 ± 14.4 years with average follow-up duration of 35.4 ± 4.5 months. There were 18 patients in Group 1 and 26 patients in Group 2. Mean pre-operative mJOA score was 10.51 and post-operative mJOA score was 15.74 with mean recovery rate (RR) 69.82%, of which 30 patients (70.23%) had good recovery and 14 patients (29.77%) had fair recovery at final follow up. The two groups didn't show any significant difference in complication rates and outcome. Conclusion: C7 as distal fixation anchor is safe and effective in maintaining cervical sagittal balance following multilevel posterior cervical fusion. C7 lateral mass screws are found to be equally efficacious as pedicle screws in preventing worsening of sagittal profile.