Lateral Mass Screw Fixation Research Articles

A case-control study:the clinical efficacy of total laminectomy with lateral mass screw fixation and single open-door laminoplasty for cervical spinal cord injury without fracture and dislocation

To compare the clinical effects of total laminectomy with lateral mass screw fixation and single open-door laminoplasty in the treatment of cervical spinal cord injury without fracture and dislocation. The clinical data of 75 patients with cervical spinal cord injury without fracture and dislocation treated from December 2014 to April 2020 were retrospectively analyzed, including 65 males and 10 females, aged from 33 to 83 years old with an average of (60.1±11.4) years. According to surgical method, the patients were divided into observation group (36 cases) and control group (39 cases). The observation group was treated with C3-C6 single open-door laminoplasty. In the control group, the C3-C6 whole lamina was opened by "uncovering", and the lateral mass screw was fixed and fused. The general conditions including operation time, intraoperative blood loss, hospital stay and complications such as axial pain, cerebrospinal fluid leakage, postoperative C5 nerve palsy were recorded. Visual analogue scale(VAS), Nurick pain scale, Japanese Orthopaedic Association(JOA) scores and American Spinal Injury Association(AISA) injury scale were used to evaluate the improvement of clinical symptoms and related functional recovery 12 months after operation. There were no statistically significant differences in operation time, intraoperative blood loss and hospital stay between two groups(P>0.05). There were statistically significant differences in JOA, VAS, ASIA and Nurick scores of the all patients between 12 months after surgery and before surgery (P<0.05), and there was no significant difference between groups. There was significant difference in the incidence of C5 nerve root palsy and axial pain between two groups(P<0.05), but there was no significant difference in the complications of cerebrospinal fluid leakage between two groups (P>0.05). Total laminectomy with lateral mass screw fixation and single open-door laminoplasty in treating cervical spinal cord injury without fracture and dislocation can obtain satisfactory results in restoring nerve function, alleviating pain and improving daily behavior, but single open-door laminoplasty has the advantages of less trauma and low incidence of complications.

Complications associated with subaxial placement of pedicle screws versus lateral mass screws in the cervical spine: systematic review and meta-analysis comprising 1768 patients and 8636 screws.

Lateral mass screw (LMS) fixation for the treatment of subaxial cervical spine instability or deformity has been traditionally associated with few neurovascular complications. However, cervical pedicle screw (CPS) fixation has recently increased in popularity, especially with navigation assistance, because of the higher pullout strength of the pedicle screws. To their knowledge, the authors conducted the first meta-analysis comparing the complication rates during and/or after CPS and LMS placement for different pathologies causing cervical spine instability. A systematic literature search of PubMed and Embase from inception to January 12, 2021 was performed to identify studies reporting CPS and/or LMS-related complications. Complications were categorized into intraoperative and early postoperative (within 30days of surgery) and late postoperative (after 30days from surgery) complications. All studies that met the prespecified inclusion criteria were pooled and cumulatively analyzed. A total of 24 studies were conducted during the time frame of the search and comprising 1768 participants and 8636 subaxially placed screws met the inclusion criteria. The CPS group experienced significantly more postoperative C5 palsy (odds ratio [OR] = 3.48, 95% confidence interval [CI] = 1.27-9.53, p < 0.05). Otherwise, there were no significant differences between the LMS and CPS groups. There were no significant differences between the CPS and LMS groups in terms of neurovascular procedure-related complications other than significantly more C5 palsy in the CPS group.

Surgical management of os odontoideum: An Algerian center experience.

ABSTRACTBackground:Os odontoideum (OO) is a craniovertebral junction malformation of unknown origin. In most times, this lesion is highly unstable demanding surgical management. We present our series of OO surgical management and we discuss clinical, radiological, and management aspects of this pathology via our experience and literature opinions.Methods:This is a retrospective study of patients operated on at our department between May 2014 and May 2021 for OO. All patients were explored with plane X-rays and computed tomography (CT). In some cases, magnetic resonance imaging (MRI) was necessary. Posterior C1–C2 or C1-C3 fixation with polyaxial screws and rod fixation was used. In postoperative, the patient is asked to put Philadelphia collar for 3 months. Hospitalization periods vary between 3 and 7 days. After discharge, all our patients are followed up regularly in consultation. Control radiographs of the occipito cervical region were performed. After 3 months postoperatively, the CT scan is performed on all our patients to assess the quality of fusion. Patient's follow-up ranges from 4 months to 6 years.Results:Fifteen patients were included in this study; nine males (60%) and six females (40%); with mean age of 32.5 years old. Ten patients (67%) presented motor weakness, three patients (20%) with neck pain, one patient (6.5%) with torticollis, and one patient (6.5%) presented vertigo. No notable cervical trauma was present in six patients (40%) and in nine patients (60%), a remote history of traumatism was noted. All cases of our series presented mobile OO. Normal thickness of the C2 pedicle was noted in nine patients (60%). In two patients (13%), there was hypoplasia of one pedicle and in four patients (27%) both pedicles. MRI showed direct signs of spinal cord aggression: simple compression, myelomalacia, strangulation, or hypotrophy. C1 lateral mass screw fixation was performed in all patients; and according to C2 morphology: nine patients underwent C1-C2 pedicular fixation, in one patient, bilateral crossing C2 laminar screws technique, in three patients, we skipped C2 to perform a C1-C3 articular fixation, and in two patients, C1-C2-C3 fixations were performed. All patients improved clinically. In one patient, we noted an infection resulting in bad wound healing this infection was successfully treated with no complications. In the patient with bilateral crossing C2 laminar screws technique, CT control objectified 4 mm exceeding of one screw; the patient was reoperated and the screw was slightly pulled back. No other complications were noted.Conclusion:Congenital origin of OO is always evoked. C1-C2 fixation according to Goel and Harms technique with grafting proved its safety, providing high fixation quality with the acceptable biodynamic outcome. Once treated, the prognostic of OO is in general good, and improvement is observed in most patients with few complications.

Morphometric Anatomy of the Posterior Aspect of the Atlas and the Vertebral Artery Groove in Relation to Lateral Mass Screw Placement.

Atlantoaxial instability is an important disorder that causes serious symptoms such as difficulties in walking, limited neck mobility, sensory deficits, etc. Atlantal lateral mass screw fixation is a surgical technique that has gained important recognition and popularity. Because accurate drilling area for screw placement is of utmost importance for a successful surgery, we aimed to investigate morphometry of especially the posterior part of C1. One hundred and fifty-eight human adult C1 dried vertebrae were obtained. Measurements were performed directly on dry atlas vertebrae, and all parameters were measured by using a digital caliper accurate to 0.01 mm for linear measurements. The mean distance between the tip of the posterior arch and the medial inner edge of the groove was found to be 10.59 ± 2.26 and 10.49 ± 2.20 mm on the right and left, respectively. The mean distance between the tip of the posterior arch and the anterolateral outer edge of the groove was 21.27 ± 2.28 mm (right: 20.96 ± 2.22 mm; left: 21.32 ± 2.27 mm). The mean height of the screw entry zone on the right and left sides, respectively, were 3.86 ± 0.81 and 3.84 ± 0.77 mm. The mean width of the screw entry zone on both sides was 13.15 ± 1.17 and 13.25 ± 1.3 mm. Our result provided the literature with a detailed database for the morphometry of C1, especially in relation to the vertebral artery groove. We believe that the data in the present study can help surgeons to adopt a more accurate approach in terms of accurate lateral mass screw placement in atlantoaxial instability.

Wright's Technique with the Addition of Visualized Axial Cortical Windows in Odontoid Fractures.

This study sought to investigate and evaluate a modified axial translaminar screw fixation for treating odontoid fractures. We performed a retrospective study at Wenzhou Medical University Affiliated Second Hospital between March 2016 and June 2018. We retrospectively collected and analyzed the medical records of 23 cases with odontoid fractures. All patients were identified as type II odontoid fractures without neurological deficiency and serious diseases following the classification of Anderson. The average age, gender ratio, and body mass index (BMI) were 54.3 ± 11.1 years, 12 men to 11 women, and 22.6 ± 2.4 kg/m2, respectively. Patients in this study accepted screw fixation using our modified axial translaminar screw fixation combined with atlas pedicle or lateral mass screw fixation. Within the technique, a small cortical “window” was dug in the middle of the axial contralateral lamina, such that the screws in the lamina were visualized to prevent incorrectly implanting the posterior spinal canal through the visualized “window.” A total of 46 bone screws were accurately inserted into the axial lamina without using fluoroscopy. The length of all translaminar screws ranged between 26 and 30 mm, while the diameter was 3.5 mm. During the follow‐up survey, the visual analog scale (VAS) and neck disability index (NDI) were measured. We provide a simple modification of Wright's elegant technique with the addition of “visualized windows” at the middle of the axial lamina. In all patients, screws were inserted accurately without bony breach and the screw angle was 56.1 ± 3.0°. Mean operative time was 102 ± 28 min with an average blood loss of 50 ± 25 mL. Postoperative hemoglobin and mean length of hospital stay were 12.0 ± 1.4 g/dL and 10.4 ± 3.4 days, respectively. The average follow‐up time of all cases was 14.7 months and no internal fixation displacement, loosening, or breakage was found. All patients with odontoid fractures reported being satisfied with the treatment during the recheck period and good clinical outcomes were observed. At 1, 6, and 12 months, NDI and VAS showed that the symptoms of neck pain and limitations of functional disability improved significantly during follow‐up. Our results suggest that the modified translaminar screw fixation technique can efficiently treat Anderson type II odontoid fracture, followed by the benefits of less soft tissue dissection, simple operation, no fluoroscopy, and accurate placement of screws.

Surgical Treatment of Multilevel Degenerative Cervical Myelopathy: Open-Door Laminoplasty and Fixation via Unilateral Approach. A Feasibility Study

Objective We compared open-door laminoplasty via a unilateral approach and additional unilateral lateral mass screw fixation (uLP) with laminectomy and bilateral lateral mass screw fixation (LC) in the surgical treatment of multilevel degenerative cervical myelopathy (mDCM). Methods A retrospective cohort analysis of 46 prospectively enrolled patients (23 uLP and 23 LC). The minimum follow-up was 1 year. Neck and arm pains were evaluated with visual analog scales and disability with the Neck Disability Index (NDI). Myelopathy was rated with the modified Japanese Orthopaedic Association (mJOA) score. Cervical sagittal parameters were measured on plain and functional X-ray films with a specific software. The statistical significance was set at p < 0.05. Fusion was defined as <2 degrees of intersegmental motion on flexion/extension radiographs. Results The two groups were similar in age and comorbidities. The mean operation time and the mean hospital stay were shorter in the uLP group ( p = 0.015). The intraoperative blood loss did not exceed 200 mL in both groups. At follow-up, the groups showed comparable clinical outcome data. The sagittal profile did not deteriorate in either group. Fusion rates were 67% in the uLP group and 92% in the LC group. No infections occurred in either group. In the LC group, one patient developed a transient C5 palsy. Revision surgery was required for a malpositioned screw (LC) and for one implant failure (uLP). Conclusion Laminoplasty and unilateral fixation via a unilateral approach achieved comparable clinical and radiologic results with laminectomy and bilateral fixation, despite a lower fusion rate. However, the surgical traumatization was less.

Relationship of Change in Cervical Curvature after Laminectomy with Lateral Mass Screw Fixation to Spinal Cord Shift and Clinical Efficacy

Although laminectomy with lateral mass screw fixation (LCSF) is an effective surgical treatment for cervical spondylotic myelopathy (CSM), loss of cervical curvature may result. This study aimed to investigate the effect of cervical curvature on spinal cord drift distance and clinical efficacy. We retrospectively analyzed 78 consecutive CSM patients with normal cervical curvature who underwent LCSF. Cervical curvature was measured according to Borden's method 6 months after surgery. Study patients were divided into two groups: group A, reduced cervical curvature (cervical lordosis depth 0-7mm; n = 42); and group B, normal cervical curvature (cervical lordosis depth 7-17mm; n = 36). Spinal cord drift distance, laminectomy width, neurologic functional recovery, axial symptom (AS) severity, and incidence of C5 palsy were measured and compared. Cervical lordosis depth was 5.1 ± 1.2 mm in group A and 12.3 ± 2.4 mm in group B (p < 0.05). Laminectomy width was 21.5 ± 2.6 mm in group A and 21.9 ± 2.8 mm in group B (p > 0.05). Spinal cord drift distance was significantly shorter in group A (1.9 ± 0.4 vs. 2.6 ± 0.7 mm; p < 0.05). The Japanese Orthopaedic Association (JOA) score significantly increased after surgery in both groups (p < 0.05). Neurologic recovery rate did not differ between the two groups (61.5 vs. 62.7%; p > 0.05). AS severity was significantly higher in group A (p < 0.05). C5 palsy occurred in three group A patients (7.1%) and four group B patients (11.1%), but the difference was not significant (p > 0.05). After LCSF, 53.8% of the patients developed loss of cervical curvature. A smaller cervical curvature resulted in a shorter spinal cord drift distance. Loss of cervical curvature was related to AS severity but not improvement of neurologic function or incidence of C5 palsy.

Relationship between cervical curvature and spinal cord drift distance after laminectomy via lateral mass screw fixation and its effect on clinical efficacy.

Background:Laminectomy with lateral mass screw fixation (LCS) is considered an effective surgical procedure for cervical spondylotic myelopathy. However, varying degrees of loss of the cervical curvature were noted in some patients postoperatively. The aim of this study was to observe the relationship between cervical curvature and spinal drift distance after LCS and to determine its effect on neurological function, axial symptoms, and C5 palsy.Methods:A total of 117 consecutive cervical spondylotic myelopathy patients with normal cervical curvature underwent LCS from April 2015 to May 2017 in our institution. Of these patients, 90 patients who accepted to undergo an integrated follow-up were enrolled in this study. The patients were divided into 3 groups based on their postoperative cervical curvature. In group A (28 patients), the cervical curvature became straight postoperatively (0°≤cervical spine angle≤5°); in group B (36 patients), the cervical curvature decreased (5°<cervical spine angle≤16.5°); and in group C (26 patients), the cervical curvature remained normal (cervical spine angle>16.5°). Spinal drift distance, neurological recovery, axial symptoms, and C5 palsy in the patients were recorded and analyzed.Results:Postoperative measurements showed that there was no significant difference in laminectomy width between the groups (P > .05). The cervical spine angle was 2.7° ± 0.5° in group A, 11.2° ± 2.6° in group B, and 20.8° ± 4.1° in group C (P < .05), while the spinal drift distance was 1.2 ± 0.2 mm, 1.8 ± 0.4 mm, and 3.0 ± 0.5 mm, respectively (P < .05). The postoperative Japanese Orthopedic Association score was significantly increased in all groups (P < .05), and there was no significant difference between the groups at different time points (P > .05). However, significant differences were noted between the groups in axial symptoms (P < .05), which were analyzed via the visual analog scale score. The occurrence of C5 palsy in groups A, B, and C was 7.1% (2/28), 8.3% (3/36), and 11.5% (3/26), respectively (P > .05).Conclusion:In LCS, the cervical curvature should be maintained at the normal angle to obtain a good spinal cord drift distance and a lower incidence of axial symptoms.

Classification of unilateral cervical locked facet with or without lateral mass-facet fractures and a retrospective observational study of 55 cases

This study describes a morphology-based unilateral cervical facet interlocking classification in an attempt to clarify the injury mechanism, instability, neurological deficits, radiological features, and determine optimum management strategies for these injuries. A total of 55 patients with unilateral cervical locked facet (UCLF) involving C3 to C7 were identified between January 1, 2012 and December 1, 2019. The injuries were classified into three types, and they were further divided into six subtypes using three-dimensional computed tomography. The injury mechanism, clinical features, neurological deficits, and imaging characteristics were analyzed, and the appropriate treatment strategies for UCLF were discussed. UCLFs were divided into the following six subtypes: UCLF without lateral mass-facet fracture (type I) in nine cases, with superior articular process fracture (type II A) in 22, with inferior articular process fracture (type II B) in seven, both superior and inferior articular process fractures (type II C) in four, with lateral mass splitting fracture (type III A) in three, and with lateral mass comminution fractures (type III B) in ten. A total of 22 (40.0%) of the 55 patients presented with radiculopathy, and 23 patients (41.8%) had spinal cord injuries. The subtype analyses showed high rates of radiculopathy in types II A (68.2%) and II C (75.0%), as well as significant spinal cord injury in types I (77.8%) and III (61.5%). Destruction of the facet capsule was observed in all patients, but the injury of disc, ligamentous complex, and vertebra had a significant difference among the types or subtypes. The instability parameters of the axial rotation angle, segmental kyphosis, and sagittal displacement showed significant differences in various types of UCLF. Closed reduction by preoperative and intraoperative general anesthesia traction was achieved in 27 patients (49.1%), and successful rate of closed reduction in type I (22.2%) was significantly lower than that in type II (51.5%) and type III (61.5%). A total of 35 of 55 patients underwent a single anterior fixation and fusion, 10 patients were treated with posterior pedicle and (or) lateral mass fixation, and combined surgery was performed in ten patients. Ten patients (18.2%) with a poor outcome were observed after first surgery. Among them, 3 patients treated with a single anterior surgery had persistent or aggravated radiculopathy and posterior approach surgery with ipsilateral facet resection, foramen enlargement, and pedicle and (or) lateral mass screw fixation was performed immediately, 5 patients treated with a short-segment posterior surgery showed mild late kyphosis deformity, and 2 patients with vertebral malalignment were encountered after anterior single-level fusion during the follow-up. This retrospective study indicated that UCLF is a rotationally unstable cervical spine injury. The classification proposed in this study will contribute to understanding the injury mechanism, radiological characteristics, and neurological deficits in various types of UCLF, which will help the surgeons to evaluate the preoperative closed reduction and guide the selection of surgical approach and fusion segment.

15. Supplemental fixation of lateral mass screws: a strategy to improve fixation strength

<h3>BACKGROUND CONTEXT</h3> Elderly patients are increasingly meeting the indications for spinal fusion and are more likely to have suboptimal bone quality. Patients with suboptimal bone quality who have undergone posterior cervical fusion have increased risk of fixation failure of up to 5.4% and may require stronger forms of fixation. Adding supplemental fixation to lateral mass screws (LMS) can increase fixation as measured by pullout strength. <h3>PURPOSE</h3> This work addresses the question: can supplemental screw fixation of lateral mass screws improve pullout strength? <h3>STUDY DESIGN/SETTING</h3> Biomechanical cadaveric study. <h3>PATIENT SAMPLE</h3> Fifteen C3-C6 vertebral bodies and 15 additional motion segments (C3-C4 or C5-C6) (age: 49-67). <h3>OUTCOME MEASURES</h3> Lateral mass screw construct peak pullout strength. <h3>METHODS</h3> All specimens were CT scanned with a phantom to obtain bone mineral density (BMD). The individual vertebral bodies and the cranial body of the motion segments were implanted with bilateral lateral mass screws. Supplemental fixation was added on one side of the vertebral body using two 2.4mm diameter unicortical screws (length 8-12mm). One side of the cranial vertebral body of the motion segments was supplemented with a single 2.4mm diameter transfacet tricortical screw (length 12-16mm). Screw constructs were subjected to posterior pullout coincident with the axis of the lateral mass screw at a rate of 5mm/min until failure. <h3>RESULTS</h3> A paired comparison was made of the peak pullout force of the LMS alone and LMS with supplemental fixation. Analysis was also made comparing BMD and pullout force.In the vertebral bodies with two supplemental unicortical screws, pullout force was significantly higher in the supplemented screw side. The average pullout force was 48.2% higher with supplemental screws (865±213N vs 637±206N; p=0.0038). There was moderate correlation between pullout force and bone mineral density for both the supplemented and LMS alone (correlation coefficients of 0.34 and 0.45 respectively). In the motion segments, peak pullout force was significantly higher in the side supplemented with a tricortical transfacet screw. The pullout force was 25.9% higher with supplemental transfacet screw fixation (1055±521N vs 912±508N; p=0.047). The pullout strength of the LMS with transfacet fixation was highly correlated with BMD (correlation coefficient of 0.71) while the LMS pullout strength was moderately correlated with BMD (correlation coefficient of 0.64). <h3>CONCLUSIONS</h3> Our data confirms the hypotheses that the pullout strength of C3-C6 LMS fixation using LMS supplemented with two unicortical screws or LMS supplemented with one-tricortical transfacet screw is superior to LMS fixation alone. <h3>FDA DEVICE/DRUG STATUS</h3> Cervical Fusion System (Approved for this indication)

Spinous Process Screw Fixation: A Salvage Technique in Subaxial Cervical Spinal Instrumentation

We sought to evaluate the feasibility and efficacy of spinous process screws in subaxial cervical fixation. A retrospective study was conducted on 7 patients receiving posterior cervical instrumentation for subaxial fracture dislocation or atlantoaxial dislocation from 2014 to 2015. In addition, a biomechanical test was performed on 7 fresh-frozen cadaveric spine samples (from the occiput to C7) from healthy human subjects with no history of spinal trauma. And lastly, the potential trajectories of cervical spinous process screws of 100 adults were measured through axial computed tomography in order to establish the general rule for applicability of this technique. Rigid fixation and solid fusion were achieved in all 7 patients included in the study. Biomechanical test results revealed no significant difference between bilateral lateral mass screw fixation and the hybrid lateral mass and spinous process screw fixation constructs. Measurement of the potential trajectory suggested that spinous process screw fixation was a viable technique in the subaxial cervical spine in the general population. The spinous process screw fixation technique in the subaxial cervical spine is a viable and effective salvage option for patients in whom conventional posterior fixations were not sufficient and salvage, supplementary techniques were required.

Versatile Usage of the Modified Lateral Mass Screw as an Alternative to Cervical Pedicle Screw Fixation.

Posterior subaxial cervical screw fixation is commonly performed using the cervical pedicle screws (CPS) and lateral mass screws (LMS); however, their compatibility is low. Modified lateral mass screws (mLMS, also called paravertebral foramen screw) fixation was introduced as a salvage technique for LMS fixation and has features of both LMS and CPS techniques. In the present study, the use of mLMS as an alternative to CPS was analyzed based on clinical results. Seventy-eight screws (38 CPSs and 40 mLMSs) were inserted into 12 patients. The misplacement of the screws was evaluated by computed tomography (CT). The failure of instrumentation and instability were evaluated using plain radiographs. The total number of CPS misplacements was 3 (10.5%); however, neurologic complications were not observed. mLMSs were used in the middle segments of the fusion in 10 patients and 2 patients had mLMS fixation for single-level fusion. An additional bridging implant was not required for connecting both CPSs and mLMSs. Instability was not observed during the observation period (4-51 months). Complete fusion was seen in 10 patients. The alternative mLMS fixation can decrease the risk of screw misplacement compared with CPS fixation alone and achieves adequate stability leading to fusion.

O0005. Revision Craniovertebral Junction Surgery by Lateral Mass Plate and Screw Fixation

O0005. Revision Craniovertebral Junction Surgery by Lateral Mass Plate and Screw Fixation

Lateral Mass Screw Fixation in Sub-Axial Cervical Spine Combined with Decompression Laminectomy in Multi-Level Cervical Spondylotic Myelopathy ; Safety and Clinical Outcome

Lateral Mass Screw Fixation in Sub-Axial Cervical Spine Combined with Decompression Laminectomy in Multi-Level Cervical Spondylotic Myelopathy ; Safety and Clinical Outcome

Clinical and Radiological Evaluation of Cervical Spondylotic Myelopathy Operated With Posterior Decompression and Lateral Mass Fixation- a Retrospective Review with Minimum Two Years Follow-Up

Objective: There is controversy in surgical management of cervical spondylotic myelopathy (CSM); a few group encourage only laminectomy or laminoplasty while the others emphasize on lateral mass fixation along with laminectomy. Cervical lordosis is an important factor for maintaining posture neck and preventing postoperative axial neck pain. Literature has reported that cervical lordosis less than -20 degrees is often responsible for neck pain. The purpose of this study was to evaluate clinical outcome and radiological parameters after posterior cervical laminectomy and fixation in CSM. Material and Methods: This retrospective study included 37 patients operated with posterior cervical decompression and lateral mass screw fixation with minimum two-year follow-up. All patients were operated for CSM. All were operated by a single surgeon and followed up at six weeks, twelve weeks, six months, one year and yearly afterwards. Clinical outcome and radiological parameters were analyzed for clinical improvement [European Myelopathy Score (EMS)] and cervical lordotic angle. Results: Average age 68±8.3 years. The cervical lordotic angle of -23.02±4.19 degrees was maintained in patients operated with lateral mass screw fixations along with laminectomy at final follow-up. The EMS and VAS score showed significant improvement postoperatively from 15.7 to 13.6 (p&lt;0.05) and 8.1 to 1.5 (p&lt;0.05), respectively. Three patients had postoperative C5 palsy that recovered completely within three months. Two patients expired within a few months after surgery due to acute myocardial infarction and respiratory arrest, respectively. There were three patients who had postoperative C5 palsy, which recovered completely within three months postoperatively. There was no permanent postoperative neurological deficit noticed in the series. Conclusion: Posterior cervical lateral mass screw fixation for CSM gives satisfactory clinical outcome and maintains cervical lordosis. Lateral mass fixation with

Correlation between different instrumentation variants and the degree of destabilization in treating cervical spondylotic spinal canal stenosis by unilateral hemilaminectomy with bilateral decompression: a biomechanical investigation

PurposeUnilateral hemilaminectomy with bilateral decompression (BDZ) was proposed as an alternative decompressive procedure in cervical spondylotic myelopathy (CSM). Despite promising clinical results, the destabilizing effect is yet unknown. We therefore performed a biomechanical study to investigate whether lateral mass screw fixation should follow BDZ.MethodsSix human C2–C7 cervical specimens were tested under various conditions: native, unilateral hemilaminectomy with bilateral decompression without/with fixation (BDZ/BDF), unilateral hemilaminectomy with bilateral decompression and unilateral foraminotomy without/with fixation (UFZ/UFF), unilateral hemilaminectomy with bilateral decompression and bilateral foraminotomy without/with fixation (BFZ/BFF), and laminectomy without/with fixation (LAZ/LAF). Instrumention was applied from C3–C6. For each condition, the three-dimensional kinematics of the cervical specimen were measured in three main loading directions with an ultrasonic motion analysis system. ANOVA was used to determine differences between the specific segment conditions to assess the parameter’s range of motion (ROM) and neutral zone (NZ).ResultsFor flexion–extension, lateral bending and axial rotation, ROM of BDZ, UFZ, BFZ and LAZ remained at the level of the native condition (p > 0.74), whereas fixation reduced ROM significantly (p < 0.01). Between BDF, UFF, BFF and LAF, no significant differences in reduction in ROM were seen (p > 0.49). Results for NZ were equivalent to ROM in flexion–extension and lateral bending. For axial rotation, NZ remained almost constant on the native level for all tested conditions.ConclusionBilateral decompression via a hemilaminectomy, even if combined with foraminotomy, could be a less invasive treatment option for multilevel CSM in patients with lordotic cervical alignment and absence of segmental instability.

Combined Anterior-Posterior Fusion Versus Posterior Alone Fusion for Cervical Myelopathy in Athetoid-Cerebral Palsy.

Study Design:Retrospective comparative study.Objectives:Although some studies have discussed the use of lateral mass screws (LMSs) in patients with cerebral palsy (CP), it is unclear whether posterior LMS fixation alone is a suitable method. We aimed to compare the clinical, radiological, and surgical outcomes of 2 surgical modalities, namely, combined anterior-posterior (A-P) instrumented fusion and posterior fusion alone, in athetoid-type CP patients with cervical myelopathy (CM).Methods:We analyzed 63 patients with athetoid-CP and CM who underwent posterior fusion only with LMS (group A, 35 patients) and A-P fusion (group B, 28 patients). The primary outcome was the 1- and 3-year fusion rates for the surgical segments. The secondary outcomes included the clinical outcomes based on pain intensity determined using the visual analog scale score, neck disability index, and 17-point Japanese Orthopedic Association score, radiological, and surgical outcomes.Results:Fusion was achieved at 3 years postoperatively in 22 of 35 patients (63%) in group A and in 26 of 28 patients (93%) in group B (P = 0.02). The posterior neck pain intensity was also significantly lower in group B than in group A 2 and 3 years postoperatively (P = 0.02 and 0.01, respectively). The incidence of screw loosening and implant-related problems was higher in group A (60%) than in group B (21%) (P = 0.01). The other clinical and radiological parameters were similar between the groups.Conclusions:For athetoid CP-induced CM, combined A-P fusion would result in superior clinical and radiological outcomes compared to posterior fusion alone.

Simple Technique to Place the Lateral Mass Screws in the Revision Surgery after Cervical Laminoplasty for Ossification of the Posterior Longitudinal Ligament.

A lateral mass screw (LMS) is one of the standard anchor screws in posterior cervical fixation. Although the advantage of cervical LMS is that it is easier and safer to place than pedicle screw, it is sometimes difficult for surgeons to confirm the exact point for screw entry and accurate angle in cases of revision surgery. When LMS fixation is performed as revision surgery after cervical laminoplasty or laminectomy, it might be complicated to secure safe placement of the LMSs. We present a simple but practical technique involving a caliper and angle device for revision surgery after cervical laminoplasty for ossification of the posterior longitudinal ligament. In this technique, the distance between the bilateral entry points is ascertained using preoperative CT. Insertion of the screw is guided using the angle device set to 25 degrees. The technique presented here is easy and allows accurate placement of the LMSs in the posterior cervical spine, and is practical even for revision surgery.

Atlantoaxial osteoarthritis: a well-established entity that remains frequently overlooked

Painful atlantoaxial (C1-2) osteoarthritis (AAOA) has been described over 40 years ago. The condition may cause severe pain symptoms and disability related to the unilateral suboccipital pain and, in some cases, occipital neuralgia. One of the greatest challenges with AAOA is making the diagnosis. Diagnosis is commonly missed or delayed when headaches are treated in isolation or when pain is attributed to subaxial spondylosis. Here we present an illustrative case involving a 67-year-old male presenting with classic painful AAOA. After failing conservative treatments, he was evaluated with morphologic, radiological studies and a diagnostic injection. He was successfully treated with bilateral, navigation guided C1 lateral mass and C2 pedicle screw fixation and fusion. To conclude, when there is clinical suspicion for painful AAOA, providers have numerous diagnostic modalities, including newer hybrid techniques, that can be used to solidify the diagnosis. When conservative efforts fail, C1-2 fusion is an effective and enduring treatment for most patients.

Lateral Mass Screw Fixation in the Cervical Spine: Introducing a New Technique.

Study DesignThis was designed as a randomized double blind study to compare the classical Magerl technique of insertion of lateral mass screws with the authors’ technique. The observations regarding length, outcome, and radiology was done by a group blinded to the technique used.PurposeThe present study was designed with the objective of identifying the optimal technique for introducing the lateral mass screws that uses the maximum possible dimension of the lateral mass.Overview of LiteratureLateral mass screw fixation is a common surgery that is performed in the cervical spine. Various modifications for the procedure have been described, such as changes in the entry point, angulation of the screws, and modifications in the exit point. These do not allow the insertion of longer screws that can give more purchase on the bone.MethodsFrom January 1, 2009 to December 31, 2018, 176 patients who were scheduled to undergo lateral mass screw fixation were enrolled. They were randomized into two groups; we inserted lateral mass screws using our new technique for one group and by using the classical Magerl technique for the other group. Intraoperative measurements were used to assess the bone-screw interface length. Postoperative radiography and postoperative computed tomography were performed to assess the trajectory of the screws.ResultsTotal 88 patients were included in the study group, including 68 men. The control group included 65 men. The most common indication for surgery was cervical spondylotic myelopathy. The average bi-cortical length that was measured intraoperatively was 19.9 mm in the study group and 16.3 mm in the control group. This was significantly different from the average lengths of screws in the control group.ConclusionsThe trajectory that involves an entry point as close as possible to the posterior inferior medial angle of the lateral mass cuboid and traverses a distance of about 20 mm to obtain a bi-cortical purchase in the diagonally opposite angle may provide a much better and firmer bony purchase in the lateral mass than conventional points of entry and trajectories.