C2 Body Research Articles

Posterior fixation for paediatric and adolescent unstable hangman's fracture: evolution to C1 sparing techniques.

The aim was to study surgical outcomes in hangman's fractures in paediatric and adolescent patients and to demonstrate evolution in posterior surgery from C1-C2-C3 fusion to C1 sparing techniques. Patients (aged ≤ 18 years) operated at a tertiary level centre between September 2011 to February 2018 with more than 1 year of follow-up were included. Neurological status, type of fracture, operating time, blood loss, follow-up, and complications were assessed. Nine patients were included, with mean age mean of 16.45 years, with a mean follow-up of 42.78 months. Six patients having neurological deficit showed improvement. Two patients, one having undergone C1-C3 lateral mass screw rod fixation (LMSF) and other had C2 pedicle screw with C3 LMSF, developed kyphosis for which fixation was further extended caudally. One patient with an old hangman's fracture with reabsorbed axis pedicle underwent C2 body screw along with C3-C4 pedicle screw rod fixation and C2 pedicle reconstruction. All patients showed evidence of postoperative fusion. Hangman's fractures in young patients can be successfully managed via posterior fixation. In our centre, we have evolved in the direction of motion preservation at C1 C2 joint, along with 3 column stable fixation of the C2 pedicle. C2 pedicle reformation has allowed motion preserving surgery in complex fracture types. Extension of construct till C4 in selected cases is important to prevent postoperative kyphosis.

Reciprocal change of occipitocervical parameters after anterior cervical discectomy and fusion

To evaluate the reciprocal changes in occipitocervical parameters according to the recovery of cervical lordosis (CL) after anterior cervical discectomy and fusion (ACDF) in patients with sagittal imbalance. Sixty-five cases that underwent ACDF were followed. They were divided according to the recovery of the CL: Group 1 (ΔCL > 5°, 30 cases) and Group 2 (ΔCL < 5°, 35 cases). The following parameters were measured: occiput-cervical inclination (OCI), CL, occiput-C2 angle (OC2A), distance between external occipital protuberance and spinous process of C2 (OC2D), distance between spinous processes of C2 and C7 (C27D), and shortest distance between the plumb line of C2 body and posterosuperior corner of C7 (C27SVA). Overall, all parameters changed significantly after ACDF. Preoperative CL and preoperative C27D showed a correlation with ΔCL. ΔCL was negatively correlated with ΔC27D and ΔC27SVA. In Group 1, CL increased from − 2.60 ± 1.88° to 11.57 ± 1.83°, OC2A decreased from 23.96 ± 2.05° to 19.87 ± 1.36°, OC2D increased from 82.96 ± 1.48 mm to 86.50 ± 1.81 mm, C27D decreased from 95.61 ± 2.66 mm to 87.01 ± 2.50 mm, and C27SVA decreased from 24.14 ± 2.20 mm to 17.06 ± 2.14 mm. In Group 2, only OCI decreased significantly after ACDF. ACDF can increase CL postoperatively in patients with cervical sagittal imbalance. Patients with significant CL recovery after ACDF showed a reciprocal change in occipitocervical parameters. (OC2A, OC2D).

Normal range of clivoaxial angle in adults using flexion and extension cervical magnetic resonance imaging scans.

An abnormally decreased clivoaxial angle (CXA) is used during the clinical evaluation for corrective skull base surgery. Published normal ranges of CXA using x-ray, computed tomography, or magnetic resonance imaging (MRI) vary dramatically, especially with neck flexion or extension. The aim of this study was to use high-resolution MRI to determine the normal range of CXA in various neck positions using a reproducible measurement technique. The CXA was measured in 10 healthy volunteers on sagittal T2 SPACE c-spine MRI in supine and prone positions and with the neck both neck and extended. CXA is strictly defined as the angle between a line along the inferior third of the dorsal clival cortex and a line from the superior/posterior cortex of the dens to the posterior/inferior corner of the C2 body. Statistical analysis was performed in all positions and included mean CXA, range, standard deviation (SD), inter-reader agreement, and group comparisons. The mean CXA overall was 156.92° (SD=4.23°; range 134-179°). The mean value for extension CXA was 169.20° (SD=5.81°), and the mean value for flexion CXA was 144.73° (SD=5.71°), the difference being statistically significant (p<0.0001) regardless of supine or prone position. Concordant correlations of reader measurements showed substantial agreement in the supine position at 0.96, with lower agreement in the prone position at 0.87. We report normal ranges for CXA in various neck positions based on 3D T2-weighted MRI, using a reproducible measurement method. There was a significant difference in the CXA values between neck extended and neck flexed positions but not between supine and prone positions.

Evolution to Pedicle Reformation Technique in Surgical Management of Hangman's Fracture

Opinions vary regarding optimal treatment of unstable hangman's fractures. Recent technological advances have allowed short segment, motion preserving fixation, even in complex cases. The aim of the study was to demonstrate C1-C2 motion-preserving short-segment fusion in hangman's fracture and the evolution of technique from pedicle realignment to pedicle reformation in complex fractures with resorbed/destroyed C2 pedicles. This was a retrospective study. Patients operated by a single surgeon at a tertiary level center from 2012 to 2018 were included. The type of fracture, operating time, and blood loss was recorded. Neurologic deficits were recorded using the American Spinal Injury Association scale with regular clinicoradiologic follow-up. Nine patients (8 male), with a mean age of 36 ± 16.9 years were included. In the initial 7 patients, C2 pedicle screw, C3-C4 lateral mass screw, and rod fixation was done. The last 2 patients were complex neglected injuries, with 1 having severe angulation and displacement and the other having spondyloptosis with C2 body placed anterior to C4 body. In both these patients, direct C2 body screw were placed and pedicle reconstruction was done. Mean follow up was 41.4 ± 29.8 months. All 5 patients with preoperative neurologic deficits had improvement in power. C1-C2 joint motion was preserved in all. All patients had bony fusion. Preservation of motion at the C1-C2 joint should be the goal in all surgically managed hangman's fracture patients. The technique of C2 pedicle reconstruction can be utilized for the same in old neglected hangman's fractures.

Predictive accuracy of estimating mandibular growth potential by regression equation using cervical vertebral bone age.

Introduction:The maturational changes both in size and shape of cervical vertebrae had been widely used not only to assess skeletal maturity but also to predict the same using regression equation. Thus, the aim of this cross-sectional study was to check the predictive accuracy of estimating mandibular growth potential in the North Indian population by regression equation of Mito et al.Materials and Methods:A total of 200 subjects divided into two groups, Group I had 100 adult subjects (18–20 years) and Group II had 100 young subjects (9–14 years) were subdivided according to the gender (50 subjects in each group). Seven linear parameters on cervical vertebral bodies of C3 and C4 were measured to derive cervical vertebral age and applied to the regression equation to estimate the mandibular growth potential in Group II. The mandibular length was measured for both the groups from Co-Gn. The mean value of the actual mandibular length in Group I was statistically evaluated against the corresponding mean value of the predicted mandibular growth potential of Group II.Results:The actual mandibular length (Group I) and calculated mandibular length obtained by adding mandibular growth potential (from regression equation) to the mandibular length of Group II did not differ significantly for both males and females. Chronological age showed a statistically significant difference and poor correlation with bone age, in Group II.Conclusion:The regression equation of Mito et al. using cervical vertebral bone age has proven to be applicable and accurate in predicting mandibular growth potential in growing young Indian individuals and can be of diagnostic and prognostic value in growth modification procedures in Orthodontics.

“Crossed C1 Lateral Mass–C2 Subfacetal Screw and Rod Construct” for Atlantoaxial Fixation in Patients with High-Riding Vertebral Artery: A Technical Note

Background: Goel–Laheri's posterior C1/C2 fixation technique is the gold standard procedure for atlantoaxial dislocation (AAD) and basilar invagination. Coexisitng vertebral artery anomalies such as high-riding vertebral arteries pose an increased risk of vertebral artery injury during instrumentation. Alternate technique for avoiding vertebral artery injury in such cases like translaminar screw fixation had been associated with a high chance for screw pull out, resulting in an unstable construct. This case report introduces a novel, cost-effective technique of atlantoaxial fixation with a “bilateral crossed C1 lateral mass-C2 subfacetal screw and rod construct” in patients with atlantoaxial subluxation with high-riding vertebral arteries.Case Presentation: A 63-year-old male presented with complaints of neck pain and difficulty in walking. On physical examination, he had features of high cervical myelopathy. Imaging revealed AAD with bilateral high-riding vertebral arteries. He was treated with “Crossed C1 lateral mass-C2 subfacetal screw and rod fixation” without evidence of vertebral artery injury or neurological deficits. Postoperatively, the patient showed significant improvement in pain and Nurick score.Conclusions: This technique has the uniqueness of providing a stable, rigid fixation of the atlantoaxial joint with screws inserted into the C2 body providing good bone purchase and at the same time avoid vertebral artery injury in high riding cases. The surgical technique is demonstrated in a detailed manner in this technical note.

Atypical Fracture of Axis With False Localising Sign

Introduction: Injuries of upper cervical spine many times associated with false localizing signs as a neurological deficit means there is a no clinic-radiological correlation. Purpose of this case report is to diagnose rare clinical presentation due to injury of pyramidal tract decussating at lower medulla. Method and Materials: A 21 years old male patient presented with traumatic quadriplegia (Frankel-A). Primary treatment was given along with immobilization of neck with collar. Routine X-ray of cervical spine was taken. X-ray was showing shear fracture of C 2 vertebra with intact dens. Crucified tong was inserted. Methyl Prednisolon injection in proper dose within 8 hours was given. (NASCIS II) CT SCAN was done to know exact fracture geometry. It was showing a fracture of C2 body in an oblique plane shearing off in one piece with the dens tilted towards right side and with subluxation of C1-C2 articular process on left side. Clinically patient improved in 24 hours in form of 4/5 power grade in all limbs except left upper limb. Left upper limb shoulder and elbow muscle power was grade 2/5 and o/5 in hand. Bladder/bowel was improved. Even though there was a weakness of left upper limb, but reflexes were preserved remarkably (Cruciate paralysis as a false localizing sign). Considering atypical unstable fracture, open indirect reduction of C-1-2 done from posteriorly and stabilization done with apofix clamps after fusion between C1-C2 posterior arches. Result: Patient had Frankel grade-A on admission. At three months follow up patient had almost full neurological recovery except finger grip power grade was 4/5. On final follow up at 12 months, neurology improved to Frankel grade-E. He had no neck pain with mild restriction of rotation. X-ray of cervical spine in flexion-extension shows stability and fusion of C1-C2 posterior elements. Conclusion: Atypical clinical presentation like cruciate paralysis as a false localizing sign should be kept in mind while dealing with fracture of upper cervical spine. As this fracture has good prognosis, proper treatment is needed. If close reduction is not achieved then open reduction and stabilization with fusion will provide early mobilization and faster neurological recovery. Keywords: Fracture; Axis; Cruciate; Paralysis.

Atypical hangman’s fracture with concomitant subaxial fracture–dislocation treated with circumferential fusion of C2–C5—a case report

Atypical hangman's fractures are coronally-oriented vertical fractures of the posterior body of C2. Though these are not uncommon injuries, there is a paucity of data investigating the management of these fractures, especially when they occur in association with subaxial fracture dislocations. A 50-year-old male suffered a cervical extension injury when he dove into a shallow swimming pool while intoxicated. Initial examination demonstrated 2/5 strength in the right deltoid and biceps and 3/5 strength in the left deltoid and biceps with no motor or sensory function distal to the C5 level. Cervical CT scan revealed a C2 atypical hangman's fracture and a C4 right-sided facet fracture with traumatic spondylolisthesis at C4/5. We performed C2-C5 anterior cervical discectomy and fusion followed by a C3-C5 posterior instrumented fusion. At the patient's two year postoperative visit, the patient has had minimal improvement in neurologic function with 4/5 strength in bilateral deltoids and biceps and 2/5 strength in right wrist extension. Radiographs show a solid arthrodesis on flexion-extension radiographs. To our knowledge, this is the first case report discussing the operative management of an atypical hangman's fracture with a concomitant subaxial fracture-dislocation. This case report adds to our current knowledge by demonstrating a novel anterior-posterior approach for treating these complicated injuries.

Temporal dynamics of rotifers' feeding guilds shaped by chlorophyll‐a, nitrate, and environmental heterogeneity in subtropical floodplain lakes

AbstractIn floodplains, rotifers are among the most abundant zooplankton organisms and play an important role in ecosystem functioning. Here, we evaluated the distribution of six feeding guilds of rotifers including filter C1 (body size: &lt;200 µm), filter C2 (body size: &gt;200 to &lt;600 µm), filter C3 (body size: &gt;600 to &lt;1000 µm), filter C4 (body size: &gt;1000 µm), suctor, and predator for 11 years. We also analyzed the relationship between guild distribution and environmental parameters (i.e., chlorophyll‐a, phosphate, nitrate, ammonia, and inorganic suspended matter). Finally, we investigated the relationship between feeding guilds heterogeneity (abundance inconsistency) and environmental heterogeneity. Sampling occurred every 3 months from 2000 to 2010 in six shallow lakes of the Upper Paraná River floodplains. Filters C1, Filter C2, and suctors were the dominant feeding guilds. Nitrate and chlorophyll‐a shaped the temporal distribution of the guilds. An intermediate value of environmental heterogeneity was correlated with greater feeding guilds heterogeneity, potentially indicating that intermediate disturbance in the environmental variables may allow for greater differences in abundance distribution between rotifer guilds in shallow floodplain lakes. Our study elucidated the role of rotifers in food resource consumption, energy transfer, and competitive relationships in response to temporal environmental heterogeneity in subtropical floodplains.

Classic but unexpected: a case of Jefferson fracture

A man was found lying dead next to a ladder, with only a laceration surrounded by an abrasion visible upon external examination. No skull fractures were palpable. A CT scan and MRI showed a Jefferson fracture of the atlas, associated to a posterior displacement of the skull, a fracture of the dens of the axis, and fractures of the bodies of C5 and C6. Jefferson fractures typically result from a blow to the apex of the skull. In such cases, forensic pathologists should suspect the existence of a Jefferson fracture, particularly when no severe injuries are visible externally.

Percutaneous, Navigated Minimally Invasive Posterior Cervical Pedicle Screw Fixation.

Cervical pedicle screws provide significant biomechanical advantage but can be technically challenging and associated with morbid exposure. Improvements in intraoperative navigation guidance and instrumentation have made feasible this biomechanically robust, but technically challenging procedure. We present our initial experience with minimally invasive (MIS) percutaneous pedicle screw fixation in the cervical atlantoaxial and subaxial spine. A retrospective review was performed on 27 cases that involved a novel MIS percutaneous cervical pedicle screw technique. Small lateral skin incisions were made bilaterally on the neck using intraoperative navigation guidance. Subsequently, navigated, percutaneous screws were placed using the Proficient Minimally Invasive System (PROMIS; Spine Wave, Shelton, CT). Computed tomography (CT)-guided navigation was used for cervical pedicle screw placement with subsequent placement of percutaneous rods. Indications for surgery included type II odontoid fractures, subaxial fracture dislocations and burst fracture, metastatic pathological burst fracture, and degenerative spondylosis with stenosis. There were 15 men and 12 women, with an average age 63.5 years. Follow-up ranged from 3 to 24 months (average = 16.7 months). One screw was revised intraoperatively. Two patients (7.7%) required reoperation, 1 patient required repositioning of a C5 pedicle screw, and 1 suffered a C7 body fracture. No nerve root injury, spinal cord injury, or vertebral artery injuries were reported. Percutaneous cervical pedicle screw fixation is a feasible and safe technique when performed with CT-guided intraoperative navigation techniques. Cervical pedicle screw fixation provides a biomechanically superior construct in comparison with a lateral mass technique. In addition, the lack of paraspinal muscle disruption preserves important stabilizers of the posterior ligamentous complex and may reduce wound-healing issues in high-risk cases (eg, trauma patients). Although the current role for percutaneous instrumentation is relatively narrow, the advancement of MIS posterior cervical techniques may provide expanded opportunities in the future.

Comparison of Cervical Vertebral Body Volume in Class II Vertical and Class II Horizontal Cases With Class I Cases Using 3D-DVT

The branch of orthodontics has had an interest in the cervical vertebrae wherein cervical spine is used as a reference structure for natural head position, so skeletal age was evaluated by studying variations in the cervical vertebral morphologies. Among all evaluations, very limited data is available wherein comparison between cervical vertebral body volumes between the different malocclusions has been done. This study aimed to compare the differences in the volumes of cervical vertebral bodies of C2, C3, and C4 between skeletal class I and class II malocclusions of both horizontal and vertical growth patterns. In class I the volume was significantly lesser as compared to class II. It was seen that there was statistically no significant difference in the volume between the horizontal and vertical growers. It can be concluded from this study that cervical vertebral body volume has no effect on growth pattern. However, variations in cervical vertebral body volume are seen with different malocclusions.

Surgical outcomes of traumatic C2 body fractures: a retrospective analysis.

C2 vertebral body fractures are relatively rare fractures with no defined management protocol and outcomes. The aim of the study was to evaluate the clinical and radiological outcomes of C2 body fractures. The study was conducted at the Department of Neurosurgery, Nizam's Iinstitute of Medical Sciences, Hyderabad, India, following clearance from the Institutional Ethical Committee. The data of all patients with traumatic C2 body fracture who were managed at our Department between January 2008 and January 2019 were retrieved from the database. Functional status of the patients was assessed by Neck Disability Index while pain was assessed by VAS at follow-up after at least 6 months. Fusion and regional kyphotic angles (O-C2 and C2-C7) were assessed for radiological outcome. There were a total of 16 patients with isolated C2 body fractures in the defined time period. The male (N.=11): female (N.=5) distribution was 2.2:1. Ten patients had road traffic accidents while the remaining 6 had history of fall from height. Only 3 patients presented with neurological deficits. Benzel type 3 fracture pattern distribution was the most common fracture pattern (type 1=1, type 2=5, type 3=9). Of these, 10 were operated and 6 were managed conservatively. The VAS and NDI values improved significantly in all at follow-up when compared to values at presentation (P=0.001). Time to return to work was significantly shorter in those treated with surgical intervention (mean: 2.9±0.87) (P=0.001). Fusion was achieved in all the patients in both groups. Mean O-C2 angle at follow-up was 21.13±10.1. Mean O-C2 angle was significantly decreased in non-surgical group at follow-up (P=0.039) but no significant reduction was observed in surgical group. The management of C2 body fractures needs to be individualized, reserving surgical management for fractures requiring fragment retrival or restitution of alignment if facets were fractured.

The mandible-C2 angle: a new radiographic assessment of occipitocervical alignment

BACKGROUND CONTEXTOccipitocervical fusion is a rare and often challenging surgical procedure. Significant morbidity can result if care is not taken to achieve physiologic alignment. This is especially true for patients needing occipitocervical fusion in the setting of trauma where preoperative alignment is unknown. PURPOSETo assess the radiographic angles normally subtended between the C2 body and the mandible ramus, in a series of patients with neutral physiologic alignment and no pathology, and to assess its validity as a possible intraoperative radiographic tool to determine a neutral craniocervical alignment. DESIGNValidation and reliability study of radiographic parameters. PATIENT SAMPLEHundred lateral, neutral, cervical radiographs from patients with “normal” radiographic findings. OUTCOME MEASURESRadiographic parameters of occipital-cervical alignment with assessment of reliability and correlation in data. METHODSOne hundred neutral lateral cervical spine radiographs in the upright position of patients with no complaints or known pathology were obtained from two medical clinics between December of 2014 and January of 2017. Three physicians, at different levels of spine surgery training, took measurements of radiographic parameters. The new technique used four different angles measured between the C2-body/dens complex and the mandibular ramus (anterior/posterior C2 body and anterior/posterior mandible lines angles), and compared these with the Occipito-C2 angle, which is a validated assessment of occipitocervical alignment. Statistical analysis was performed to assess correlation in data and measure reproducibility. RESULTSBetween the three reviewers, the mean±standard deviation were 18.0°±6.5° for Occipito-C2 angle (O-C2A), −4.2°±5.4° for anterior C2-body/anterior mandible line angle (AB/AM), −4.2°±5.9° for anterior C2-body/posterior mandible line angle (AB/PM), 5.1°±5.8° for posterior C2 body/anterior mandible line angle (PB/AM) and 5.6°±6.2° for posterior C2 body/ posterior mandible line angle (PB/PM). Overall the measurements obtained were correlative with an appropriate range for the standard deviation. Mean intraclass correlation coefficient were 0.889 for O-C2A, 0.795 for AB/AM, 0.859 for AB/PM, 0.876 for PB/AM, and 0.750 for PB/PM, showing high interobserver reliability for all the radiographic measures. Across the five techniques, 87%–92% of measurements fell within 10° of the median, 76%–83% fell within 7.5°, and 55%–66% within 5°. CONCLUSIONSThe mandible-C2 angle offers a reproducible alternative to the validated O-C2A technique for determining appropriate intraoperative occipitocervical alignment, which may be especially useful when preoperative radiographic alignment is unknown, such as occurs with trauma patients, with the goal of decreasing alignment-related complications in the setting of occipitocervical stabilization.

Management of C2 Body Giant Cell Tumor by Innovatively Fashioned Iliac Crest Graft and Modified Cervical Mesh Cage Used as Plate

Locally aggressive vertebral body tumors of the axis must be treated with wide local excision for best outcome. Reconstruction of the load-bearing vertebra needs to be done after tumor resection in such a manner so as to give stable, long-term fusion in this young population. We describe the management strategy of a 25-year-old acutely quadriplegic patient, with respiratory distress, with a C2 giant cell tumor. The use of a novel iliac crest graft modification used for C2 reconstruction along with a modified mesh cage used as an anterior plate has been reported. The patient had a good outcome at 18 months' follow-up, with neurologic improvement and a solid fusion. Iliac crest autograft is inexpensive and easy to harvest and can be considered as a C2 prosthesis, especially in a resource-constrained setting. Modified iliac crest graft can be used for load transmission from C1 lateral mass to C3 body, and the mesh cage can be modified according to need as a plate with good results in an emergency.

SAT-LB64 Teriparatide and Its Bone Healing Power

Introduction:Teriparatide, a parathyroid hormone analog, is an important anabolic agent approved by the U.S. Food and Drug Administration to increase bone mineral density in osteoporotic patients. Parathyroid hormone (PTH) regulates calcium, phosphate, and active vitamin-D metabolites.The amino terminal peptide fragments of PTH has been known to increase bone mass and are being used in clinical practice for osteoporosis management (1).Current literature shows the efficacy of teriparatide in increasing bone density of lumbar spine and femoral neck, and decreasing the risk of vertebral and non-vertebral fractures both in postmenopausal women and men. It is also known to prevent fractures in patients with osteoporosis and promote healing of fractures (2).Case Description:A 79-year-old Hispanic female with history of osteopenia and major lumbar spine wedge compression fractures presented to our clinic for consultation. She was on ibandronate for the past four months and was having symptoms of pill esophagitis. Her last bone mineral density done on August 2017 revealed T-score of -2.5 at the lumbar spine, -1.5 at the left femoral neck, and 3.3% bone loss on the left femoral head. Rather than being started on teriparatide, zoledronic acid, or denosumab, she continued ibandronate along with calcium and vitamin D. Two months after the initial consultation, she sustained a traumatic fracture of the posterior arch and body of C2 bilaterally following a motor vehicle accident. There were discussions about starting anabolic treatment, as serial imaging did not show any significant improvement in the healing process despite the use of a collar. Two months after sustaining C2 fracture, she was started on teriparatide. Repeat cervical spine x-ray three months later showed complete healing of the C2 fracture.Discussion:There are a limited number of cases reported in regards to teriparatide induced healing of non-osteoporotic fractures (3). Our case is one of the very few reported to have shown complete radiographic and clinical healing of a traumatic, non-osteoporotic fracture after use of teriparatide for 12 weeks.

A Modified Posterior Approach for Decompression of a Multiloculated Atlanto-axial Cyst With Myelopathy.

Case report. To describe a modified posterior approach for decompression and excision of a multiloculated atlanto-axial cyst. Atlanto-axial cyst with myelopathy is rare. A direct decompression through anterior approach or an indirect decompression through posterior approach has been proposed. We report a rare multiloculated large C1-C2 cyst extending down to C3 body with myelopathy that created a dilemma in choice of approach. A modified posterior approach was adopted for decompression. A 72-year-old lady, known case of Rheumatoid arthritis, presented with cervical myelopathy which was rapidly progressive since 2 months being her to wheel chair bound. She had clumsiness of gait and bilateral grip weakness. Both upper and lower extremities had nonfunctional power (medical research council scale grade 2). Deep tendon reflexes were exaggerated. Sensation was reduced in trunk and both extremities. Magnetic resonance imaging and computed tomography scan showed a large multiloculated cyst compressing spinal cord. Here author used modified posterior approach from the right side to access the cyst. The C2 ganglion excision, vertebral artery isolation, and resection of the pars allowed an approach similar to transforaminal decompression in the lumbar spine. A large antero-lateral epidural part of the cyst was excised. The retro-dental cyst was decompressed by puncturing cyst. Biopsy confirmed a synovial cyst. The patient showed rapid neurological recovery after surgery. Postoperative magnetic resonance imaging at 3 months showed complete resolution of cyst. At 2-year follow-up, there was a complete neurological recovery with residual spasticity. A customized posterior approach allowed near total excision of a rare multiloculated large C1-2 cyst extending to the C3 body. This allowed visualisation anterior to the spinal cord without undue retraction that saved an additional anterior decompression. 5.

Anterior decompression through transoral axis slide and rotation osteotomy for salvage of failed posterior occipitocervical fusion: a novel technique note.

Atlantoaxial dislocation could be caused by odontoid fractures or Os odontoideum. The previous surgical techniques in treatment of atlantoaxial dislocation were based on arch remove decompression or anterior atlantoaxial release and atlantoaxial (occipital-cervical) screw fixation-based reduction and fusion. However, for some clinical situations, all of above techniques cannot be applied. In this study, a patient with atlantoaxial dislocation caused by Os odontoideum treated by posterior occipitocervical fusion 20 years ago and failed. We design a novel anterior decompression through transoral axis slide and rotation osteotomy for salvage of this failed posterior occipitocervical fusion case. The C2 body and odontoid process was ventrally slide and rotation at good position after operation as well as the position of plate and screws, the spinal canal was increased significantly after operation too. We suggest this anterior decompression through transoral "C2 slide and rotation" technique is good choice for salvage of failed posterior occipitocervical fusion and some irreducible atlantoaxial dislocation because of the anterior bony fusion, it could direct decompress the spinal cord anteriorly, avoid the odontoid resection, and is feasible and safe technique.

Artificial Intelligence for Automatic Measurement of Sagittal Vertical Axis Using ResUNet Framework.

We present an automated method for measuring the sagittal vertical axis (SVA) from lateral radiography of whole spine using a convolutional neural network for keypoint detection (ResUNet) with our improved localization method. The algorithm is robust to various clinical conditions, such as degenerative changes or deformities. The ResUNet was trained and evaluated on 990 standing lateral radiographs taken at Chang Gung Memorial Hospital, Linkou and performs SVA measurement with median absolute error of 1.183 ± 0.166 mm. The 5-mm detection rate of the C7 body and the sacrum are 91% and 87%, respectively. The SVA calculation takes approximately 0.2 s per image. The intra-class correlation coefficient of the SVA estimates between the algorithm and physicians of different years of experience ranges from 0.946 to 0.993, indicating an excellent consistency. The superior performance of the proposed method and its high consistency with physicians proved its usefulness for automatic measurement of SVA in clinical settings.

Tailored Posterior-Only Approach for C2 Vertebral Body Lesions: Our Surgical Experience in 10 Patients

C2 vertebral body (axis) lesions are often approached anteriorly and combined with posterior stabilization of the craniovertebral junction (CVJ). The anterior approach has its limitations. A posterolateral corridor is an alternative access to the C2 body lesions, and this alone may suffice in selected cases. We describe our experience with C2 body lesions, dealt primarily through a posterior approach, and propose an algorithm in the management of such cases. Ten patients with axis lesions were operated through a midline posterior approach followed by posterior stabilization of the CVJ in the same sitting. Their preoperative and follow-up clinico-radiologic details were reviewed. The lesions included aneurysmal bone cysts (n= 2), fibrous dysplasia (n= 2), chordoma (n= 2), Ewing sarcoma (n= 1), metastases (n= 1), post-traumatic malunion (n= 1), and post-inflammatory deformity (n= 1). All patients presented with worsening neck pain. Five also had spastic quadriparesis. There were no perioperative complications. All showed clinical improvement at follow-up. Only 2 patients (chordoma: n= 1; aneurysmal bone cyst: n= 1) required an additional anterior procedure. Adequate debulking or total excision of lesion, neural decompression, and stabilization of the CVJ for axis body lesions can be achieved through a single midline posterior approach in most cases. If required, an anterior approach may be later added depending on the final histopathology.