Atlantoaxial Research Articles

Posterior intra-articular distraction with cage placement to treat congenital atlantoaxial dislocation associated with basilar invagination.

Congenital atlantoaxial dislocation (AAD) associated with basilar invagination (BI) is a complex congenital malalignment at the craniovertebral junction. The olisthesis, atlantoaxial facet joint arthropathy, and the contraction of the anterior soft tissue make the treatment challenging. Our video demonstrates the surgical technique for posterior intra-articular distraction with cage placement to treat congenital atlantoaxial dislocation associated with basilar invagination.The video can be found here: https://youtu.be/7EQqW96HhN8

Occipitoatlantoaxial Malformation in a Dog Treated with a Custom-Made Implant

AbstractBackground Occipitoatlantoaxial malformation (OAAM) is reported rarely in dogs and few treatment options are described. The congenital condition is thought to be associated with a proatlas re-segmentation failure resulting in malformation and malalignment of the craniovertebral junction which can result in C1 to 5 myelopathic signs.Methods Customized three-dimensional printed locking plate with trajectory screw implantation points for the stabilization of the atlantoaxial joint in a dog with OAAM. The dog was evaluated at time points 0, 2, 6 and 9 months to determine clinical outcome, degree of fusion, implant positioning and subsidence.Results New bone formation was noted 9 months after surgery, but complete fusion remained absent, although no implant failure occurred. Clinically, the dog made a good recovery and was able to exercise normally 9 months after surgery. The only residual deficit was a subtle left-sided cervical torticollis.Clinical Significance This report illustrates a management option and outcome of a dog treated with OAAM. Collaboration between clinicians and engineers provides a new dimension of care for patients with vertebral malformations.

Anterior retropharyngeal cage distraction with atlantoaxial plate-screw fixation for basilar invagination with atlantoaxial dislocation

The unilateral submandibular anterior retropharyngeal approach in properly selected patients offers the possibility to expose both atlantoaxial joints adequately, abrade the endplates, and graft the joint spaces. The supine position in extension permits the use of wedge-shaped cages, which reduce the invagination and correct the dislocation. Adequate bone stock is available to rigidly fix the joints using an anterior plate-screw construct without any risk to the vertebral arteries. The approach preserves the posterior tension band and the C2 root. The technique is quick, simple, and safe, and results in solid fusion of the joints over time.The video can be found here: https://youtu.be/tT6j3Czy6tc

Mobilization of the high-riding vertebral artery for C2 screw insertion.

The basic surgical steps in the Goel technique of atlantoaxial fixation involve exposure of the atlantoaxial articulation, denuding of the articular cartilage, stuffing of bone graft pieces within the articular cavity, and subsequent instrumentation.“High-riding” vertebral artery in relationship to the pedicle-facet of C2 has been widely recognized to be a factor that makes insertion of the C2 pedicle-facet screw difficult or impossible. In this video, a technique of exposure and mobilization of the high-riding vertebral artery to permit safe C2 screw insertion is shown. An alternative option in the presence of such a high-riding vertebral artery is to use either C2 laminar or inferior facetal screw insertion.The video can be found here: https://youtu.be/LjxxINmzph0

An observation on risk of infection in treatment of craniovertebral junction disorders by transoral approach operation

To study the changes of bacterial flora after a series of preoperative oral disinfection and the postoperative recovery of patients with craniovertebral junction disorders who were treated with transoral approach operations. And to provide a theoretical basis for the prevention of postoperative complications such as infection. The clinical data of 20 cases with craniovertebral junction disorders and treated with transoral approach operations between October 2009 and May 2010 were analyzed. There were 8 males and 12 females, aged 2-66 years (median, 34.5 years). According to the classification of American Spinal Injury Association (ASIA)，there were 4 cases of grade B, 8 of grade C, 6 of grade D, and 2 of grade E. The Japanese Orthopedic Association (JOA) score was 10.3±3.0. The mucosa samples of the posterior pharyngeal wall were sent for bacteria culture. These samples were collected by sterile cotton swabs at four crucial points including 3 days before operation/before gargling (T1), 3 days after continuous gargling by chlorhexidine acetate/after anesthesia intubation on the day of operation (T2), after intraoperative cleaning and washing of the mouth (T3), and after intraoperative iodophor immersion for 5-10 minutes (T4). The microflora was stained by means of smear and further counted after an investigation by microscope. The ASIA classification and the JOA scores were applied to evaluate the postoperative nerve function of the patients. A regular reexamination of cervical vertebra with X-ray film, CT, and MRI was conducted after operation to evaluate the reduction of atlantoaxial dislocation, internal fixation position, bone graft fusion, inflammatory lesion, and tumor resection in the craniovertebral junction. After a series of oral disinfection, the mucosa of the posterior pharyngeal wall of all the patients was in a sterile state, which was considered as type Ⅰ incision. All these 20 patients were treated with successful operations, without any intraoperative injury in vertebral artery and spinal cord, or any postoperative complications such as plate loosening, incision infection, or intracranial infection. All the patients were followed up 3-23 months, with an average of 5.15 months. The symptoms such as neck pain, limb numbness and weakness, neural symptoms, etc. were improved to different degrees after operation. The JOA score was improved to 13.4±1.9 at 3 months after operation, showing significant difference when compared with preoperative score ( t=8.677, P=0.000); and the atlantoaxial joints had been fused. At last follow-up, the ASIA grades were improved when compared with those before operation. It is safe and effective to cut the posterior pharyngeal muscle layer and implant internal fixation by means of transoral approach in the treatment of craniovertebral junction disorders.

Development and growth of the craniocervical junction with special reference to topographical relationship between the occipital basion, the anterior arch of atlas, and the odontoid process of axis: A study using human fetuses.

The embryonic occipital bone and odontoid process of the axis are attached and connected by the notochord, but become separated in later development and growth. With special attention to the process of separation, we examined sagittal sections of the craniocervical junction in 18 human fetuses at 8-16 weeks and 22 fetuses at 31-37 weeks. At 8-9 weeks, the anterior arch of atlas was always seen overriding the occipital basal part. The odontoid process was close to the occipital with or without a transient joint cavity until 16 weeks. Near term, the top of the odontoid process was usually higher than the anterior arch, but the former was sometimes (7 of 22) at a level almost equal to or lower than the latter. The apical ligament was evident in a few specimens (5 of 22). A distance between the occipital basion and odontoid process was sometimes less than 1.5 mm (8 of 22) or less than half the thickness of the arch (10 of 22). A transient joint cavity between the basion and odontoid process was often (10 of 22). In three fetuses near term, the atlanto-occipital joint cavity was continuous with the median atlanto-axial joint cavity, and the anterior arch was overriding the occipital basal part. Therefore, rather than stage or age, individual differences were evident in the topographical relationship between the three bony elements at the craniocervical junction. An understanding of the embryology and normal development will aid in the correct interpretation of radiologic images of the pediatric cervical spine.

Implied Evidence of the Functional Role of the Rectus Capitis Posterior Muscles.

Osteopathic physicians often target the rectus capitis posterior minor (RCPm) and rectus capitis posterior major (RCPM) muscles when using muscle energy or soft tissue cervical techniques to treat patients with head and neck pain. The RCPm and RCPM muscles are located deep within the posterior occipitoatlantal and atlantoaxial interspaces, respectively. To characterize the functional role of RCPm and RCPM muscles by comparing electromyographic (EMG) activation patterns of these muscles with EMG activation patterns of specific flexor and extensor muscles of the head and neck, the sternocleidomastoid (SCM), and the splenius capitis (SC) muscles, respectively. Asymptomatic participants were recruited from the Michigan State University College of Osteopathic Medicine student body. Disposable 25-gauge, bipolar fine-wire intramuscular electrodes were used to collect EMG data from the right and left RCPm and RCPM muscles. Surface electrodes were used to collect EMG data from the right and left SCM and SC muscles. Data were collected as participants performed 4 cycles of flexion and extension with an external 4-lb force applied to the back of the head and the forehead. In RCPM muscles, EMG activity was significantly greater (P<.003) during flexion and extension of the head and neck when an external force was applied to the back of the head. EMG activity in SCM muscles was significantly greater (P<.0001) during flexion and extension of the head and neck when an external force was applied to the forehead. The authors observed that EMG activity in SC muscles was significantly greater (P<.015) during flexion and extension of the head and neck when an external force was applied to the back of the head. No significant difference was found in EMG activity in RCPm muscles (P<.834) during flexion and extension of the head and neck, regardless of whether the external force was applied to the back of the head or the forehead. The EMG activation patterns of the RCPm muscles suggest that their functional role may be to stabilize the occipitoatlantal joint by helping maintain congruency of the joint surfaces. In contrast, the EMG activation patterns of the RCPM muscles suggest that their functional role may be to contribute to extension of the head, primarily at the occipitoatlantal and the atlantoaxial joints.

RESEARCH ON THE STRATEGY OF REDUCTION OPERATION OF BASILAR INVAGINATION COMBINED WITH ATLANTOAXIAL DISLOCATION

Background: The complicated basilar invagination and atlantoaxial dislocation (BI-AAD) can cause a variety of neurological symptoms. Active treatment should be given. The main method of surgical treatment is to relieve the compression of the ventral bone of the brain stem and to fix the unstable spinal segments for fusion. At present, more surgical methods choose modified posterior cervical reduction and internal fixation fusion. Objective: The clinician has preliminarily designed an internal occipital fixation system capable of restoring both horizontal and vertical AADs, and proposed a new compression and distraction reduction (CDR) technique. The feasibility and effectiveness of posterior AAD reduction surgery using CDR techniques for different types of patients were studied in this paper. Methods: First, according to the CT scan sequence images of the congenital BI-AAD patient’s cervical vertebra, the software Materialize Mimics 13.1 was imported to reconstruct 3D geometric model of cervical spine (C0-C7). Then the geometric topology model was carried out in Geomagic2012 software, and surrounding soft tissue was established using SpaceClaim 14.0. The 3D finite element model (FEM) of cervical vertebra for congenital BI-AAD patients was obtained by assigning material attributes, setting contacts and mesh in ANSYS 14.0. To simulate the physiological activities of the spine under two conditions of forward flexion and backward extension, preoperative verification was carried out with the maximum displacement parameter. According to the postoperative CT data of the patient, the position and degree of freedom (DOF) of the occipitocervical internal fixation system were determined. The FEM of the occipitocervical internal fixation system was established by dividing unit grid in ANSYS. Using multiple loading step of statics analysis method, the CDR technology of posterior AAD reduction surgery was simulated. When the atlantoaxial horizontal and vertical reductions were satisfactory, the displacement data were obtained and verified using the post-operative data. Results: The cervical spine (C0-C7) FEM of congenital BI-AAD patients was established. For some lateral atlantoaxial articulation abnormal ossification II, we simulated the CDR technique for the AAD reduction surgery and proposed using the vertical traction instead of vertical reduction. Conclusion: This study confirms the feasibility and effectiveness of posterior AAD reduction surgery using CDR techniques and proposes the different reduction optimization scheme for the patients with lateral atlantoaxial articulation abnormal ossification II of congenital BI-AAD. The results of this study provide a biomechanical theoretical basis for improving the reliability of simple posterior reduction surgery and optimizing the surgical treatment of BI-AAD.

Intraoperative Use of Cone-Beam Computed Tomography in the Treatment of Atlantoaxial Rotatory Subluxation

Atlantoaxial rotatory subluxation (AARS) is a rare pathological condition of the upper cervical spine. It can be caused by multiple mechanisms, including minor neck manipulations. Children are more prone owing to the weaker periarticular soft tissue and a steeper slant of the C1 facet plane against the vertical axis of the dens. If AARS does not resolve spontaneously, a normal position of the atlantoaxial joint must be achieved by reduction and stabilization. A 15-year-old girl had presented with a painful torticollis that had already been present for 4 weeks after trimaxillary jaw correction for skeletal class II malocclusion. A computed tomography (CT) scan of the cervical spine showed AARS Field and Hawkins classification type I. We first attempted 1 week of conservative treatment with a soft collar and the prescription of a muscular relaxant. However, because the AARS persisted, we performed transoral closed reduction with the patient under general anesthesia, as previously described. During the procedure, we used intraoperative cone-beam CT to evaluate the degree of reduction. After obtaining complete reduction, immobilization with a halo-vest was applied. Complete reduction of the AARS was achieved with closed intraoral reduction. We used intraoperative cone-beam CT to confirm complete reduction. We found cone-beam CT to be a very useful tool.

Biomechanical study of C1 posterior arch crossing screw and C2 lamina screw fixations for atlantoaxial joint instability

BackgroundThe biomechanics of C1 posterior arch screw and C2 vertebral lamina screw techniques has not been well studied, and the biomechanical performance of the constructs cannot be explained only by cadaver testing.MethodsFrom computed tomography images, a nonlinear intact three-dimensional C1-2 finite element model was developed and validated. And on this basis, models for the odontoid fractures and the three posterior internal fixation techniques were developed. The range of motion (ROM) and stress distribution of the implants were analyzed and compared under flexion, extension, lateral bending, and axial rotation.ResultsAll three kinds of fixation techniques completely restricted the range of motion (ROM) at the C1-2 operative level. The C1-2 pedicle screw fixation technique showed lower and stable stress peak on implants. The C1 posterior arch screw + C2 pedicle screw and C1 pedicle screw + C2 lamina screw fixation techniques showed higher stress peaks on implants in extension, lateral bending, and axial rotation.ConclusionsAs asymmetrical fixations, C1 posterior arch screw + C2 pedicle screw and C1 pedicle screw + C2 lamina screw fixations may offer better stability in lateral bending and axial rotation, but symmetrical fixation C1-2 pedicle screw can put the implants in a position of mechanical advantage.

Retro-odontoid pseudotumor: a poorly recognized alteration of the craniocervical junction.

Retro-odontoid pseudotumor (ROP) is a rare disease that affects the atlantoaxial joint and, in general, is associated with local biomechanical alterations that may or may not cause instability. Descriptive study of the literature available in databases MEDLINE/PubMed, LILACS, and Scopus. The research was conducted in April 2019. ROP is, possibly, a syndromic designation that encompasses a significant variety of diseases of the atlantoaxial joint. There are different pathophysiological mechanisms implicated in its genesis. The patients, almost in their entirety, present with severe myelopathy, and most of them are treated surgically, with the posterior decompression being the most commonly used method, with or without arthrodesis. Evolution is usually favorable. The ROP is still poorly recognized as a differential diagnosis between the diseases of the cranial-cervical junction. The information available in the literature analyzed was based mainly on the study of reports or case series; therefore, it is insufficient to define conducts with a high level of scientific evidence.

Study of positioning of fetal conus medullaris by detecting atlanto-axial intervertebral space with three-dimensional ultrasound

Objective To explore the imaging rate and diagnostic rate of positioning the fetal conus medullaris by three-dimensional ultrasound method to detect atlantoaxial intervertebral space, comparing it with the traditional two-dimensional and three-dimensional ultrasound methods. Methods Consecutively 318 singleton fetuses received routine ultrasound screening during the second trimester were enrolled from November 2017 to December 2018 in Shenzhen Luohu People′s Hospital and Shenzhen People′s Hospital. These fetuses included 276 normal cases and 42 abnormal cases. The abnormal group contained 11 cases tethered cords fetuses(tethered cords group) and 31 cases non-tethered fetuses(non-tethered group). A new ultrasound method named detecting atlanto-axial intervertebral space with three-dimensional ultrasound and traditional two-dimensional and three-dimensional ultrasound methods were used to acquire and store the images. The positions of the fetal conus medullaris were analyzed blindly and recorded by three experienced physicians using three different methods with off-line software. Results ①The χ2 test comparing multiple sample rates was used to compare the imaging acquisition success rate of fetal conus medullaris by three ultrasound methods. The test level was adjusted to be α′=0.05/4=0.0125, the results showed that there were no statistically significant differences between the three methods in the normal group (χ2=7.39, P=0.025) and the abnormal group (χ2=5.32, P=0.070). ②The χ2 test comparing multiple sample rates was used to compare the diagnostic accuracy of fetal conus medullaris position in normal group by three methods, it showed there was no significant difference in the correct rate of conus medullaris position in the normal group (χ2=2.52, P=0.284). ③The χ2 test comparing multiple sample rates was used to compare the diagnostic accuracy of the fetal conus medullaris in tethered cord group and non-tethered group using 3 methods, the difference was not statistically significant in tethered cord group (χ2=1.22, P=0.543), while the difference was statistically significant in non-tethered group(χ2=9.69, P=0.008). Conclusions The method of detecting atlanto-axial intervertebral space with three-dimensional ultrasound has a high imaging rate and diagnostic accuracy in positioning the fetal conus medullaris. Positioning of fetal conus medullaris by detecting atlanto-axial intervertebral space with three-dimensional ultrasound is better than traditional two-dimensional and three-dimensional ultrasound in the abnormal non-tethered fetuses, which can provide more valuable information for prenatal diagnosis consultation and prenatal and postnatal care. Key words: Ultrasonography; Atlanto-axial intervertebral space; Fetal conus medullaris; Tethered cord

Navigation-Assisted Posterior Open Reduction and Internal Fixation in a C-CLAMP Fashion for an Isolated C1 Fracture.

C1 fractures with an intact transverse ligament are usually treated conservatively. Patients who present with a progressive diastasis of bone fragments and a progressive articular subluxation mainly attributed to progressive lengthening of the transverse ligament (TAL) fibers can be treated with a C1 “C-clamp” fusion.A 75-year-old male who sustained a motor vehicle accident was neurologically intact. A computed tomography (CT) imaging demonstrated a Jefferson's type-C1 fracture with a slight lateral displacement of the C1 left lateral mass (LM) and a rotatory subluxation on the right. MRI showed an intact TAL and demonstrated an isolated rupture of the left alar ligament. Conservative treatment was chosen. Radiographic follow-up showed, at 3 months, progressive lateral mass displacement, most likely due to elongation of the TAL fibers; this was also associated with a persistent mechanical neck pain. For this reason, we performed a posterior reduction and internal fixation in a C-clamp fashion by placement of C1 lateral mass screws and posterior compression sparing the C1–2 joint. Using navigation, a 3.5-mm screw was inserted into the LM bilaterally. The screw heads were then connected with a rod and compression was applied before tightening. Postoperative CT scan demonstrated a satisfying reduction and further imaging will be made during the follow-up. The patient had a considerable relief of neck pain. Simple lateral mass fixation with C-clamp technique is a reasonable option in case of isolated C1 fractures in patients who have failed conservative management while preserving the range of motion (ROM) at the atlanto–axial joint. The link to the video can be found at: https://youtu.be/x8bsVwzCt_M .

Posterior atlantoaxial facet joint reduction, fixation and fusion as revision surgery for failed suboccipital decompression in patients with basilar invagination and atlantoaxial dislocation: Operative nuances, challenges and outcomes

ObjectiveTo report the technical nuances and clinical outcomes of posterior atlantoaxial facet joint reduction, fixation and fusion (AFRF) technique as a revision procedure for BI and AAD patients with failed suboccipital decompression and large occipital bone defect. Patients and methodsWe reviewed 32 patients with BI and AAD who were misdiagnosed as a simple Chiari malformation and received a suboccipital decompression surgery before admission. All patients underwent AFRF as a revision surgery. The separating, fusing, opacifying and false-coloring-volume rendering (SFOF-VR) technique was used to identify the course of the VA. Clinical and radiological outcomes were assessed after revision surgeries. ResultsClinical symptoms improved in all patients. The postoperative atlantodens interval, Wackenheim line and clivus-canal angle significantly improved (all P < 0.01). Intraoperative dural tear and cerebrospinal fluid leakage occurred in 3 patients and were managed by suture repair and lumbar drain. Abnormal VA was identified in 7 patients and no VA injury occurred with the aid of SFOF-VR technique. The average follow-up was 19.1 months and atlantoaxial bone fusion was confirmed in 31 patients. ConclusionFor BI and AAD patients with failed suboccipital decompression, revision surgery is challenging. Occipitocervical fixation and posterior midline bone grafting are rather difficult due to the large occipital bone defect. The current study demonstrated that the posterior AFRF is a simple, safe and highly effective technique in revision surgery for such cases. For VA variations, the SFOF-VR technique is an effective tool to delineate the course VA.

Clinical and Radiological Assessment of Fluoroscopy Guided Injection of Atlantoaxial Joint in Rheumatoid Arthritis Patients

Abstract Background: Rheumatoid spondylitis is a feature of long-lasting Rheumatoid Arthritis (RA), it presented by neck pain, headache and sleep disturbance. Atlantoaxial Joint (AAJ) is the commonest joint which affected among the cervical spine in patients with RA. When it is involved, it can be associated with dangerous complications. Aim of Study: This study aimed to evaluate the efficacy of intra-articular steroid injection of inflamed AAJ in RA patients, on neck pain, headache and sleep quality as well as the pre and post injection MRI assessment. Patients and Methods: Sixty rheumatoid arthritis patients with inflamed AAJ were recruited to the study. Group 1 (AAJ injected group, n=30), received intraarticular atlantoaxial steroid injection, guided by fluoroscopy and Group 2 (control group, n=30), received systemic steroids. Both groups were assessed with: Visual Analogue Scale (VAS) for nocturnal neck pain, Headache and Pittsburgh Sleep Quality Index (PSQI) for sleep disturbances. Contrast enhanced MRI before and after intervention were done for all patients. Results: The injected AAJ group had significant improve-ment of nocturnal neck pain, headache and sleep disturbance during the three months’ interval follow-up, in comparison to the control group. The injected AAJ group had a statistically significant improvement in the MRI synovial enhancement, inflammatory pannus, fibrosis and bone marrow edema in comparison to control group. Conclusion: Intra-articular steroid injection of atlantoaxial joint is considered as an efficient therapeutic option in acute inflamed atlantoaxial joint of RA patients regarding clinical and radiological findings.

Craniovertebral junction fixation in children less than 5years.

Whilst rigid fixation for craniovertebral instability is the gold standard, in very young, small children conventional management may have to be modified. We present a single-centre experience of craniocervical fixation in children under 5years. A retrospective review of cases that had undergone atlantoaxial (AA) or occipitocervical (OC) fixation aged under 5years. Fusion was assessed using computerised tomography or flexion extension X-rays. Twenty-six children (median age 2.3, range 0.8-4.9years, 19 under the age of 3) underwent OC (n = 19) or AA (n = 7) fusion between 1999 and 2016. Pathology comprised 17 congenital, five trauma, two tumour and two post-infection cases. Twenty-one patients underwent sublaminar cable fixation with calvarial, autologous bone graft and halo-body orthosis immobilisation. An occipital plate and rods to sublaminar wire construct were used in four cases. A rigid instrumented fixation with occipital plate and C2 pedicle screws was utilised in one case. Follow-up was for a median of 2.8years (range 0.03-16.3years). Initial fusion rate was 91%, reaching 100% following two re-operations. Ninety-two per cent of patients were neurologically stable or improved following surgery. Twenty-one patients had a good overall outcome. Two patients had post-operative neurological deteriorations, and four died due to non-procedure related causes. Pin site morbidity secondary to halo use occurred in five cases. High fusion rates with good outcomes are achievable using semi-rigid fixation in the under 5-year-olds. Full thickness, autologous calvarial bone graft secured with wire cables and halo external orthosis offers a safe and effective alternative technique when traditional screw instrumentation is not feasible. These slides can be retrieved under Electronic Supplementary Material.

C2 Lateral Mass Vertebrae Anthropometry for Evaluating C2 Straight Lateral Mass Screw Fixation

Background: The cervical vertebra is an important vertebra as there are blood vessels in its surroundings from the brain to the entire vertebrae. Cervical injury has the most fatal consequences when it occurs as high as C1-C2. If instability occurs in the C1-C2 vertebrae and atlantoaxial joints, the procedure of surgical techniques include cervical arthrodesis or spinal fusion. C2 straight lateral mass fixation is one technique that can be used for fixation in patients with spinal cord compression and anomalous vertebral artery by inserting shorter screws in the lateral mass of the C2 vertebrae from the posterior direction. There have been not many references similar to the present study of anatomy to discover the screw characteristics needed in this technique. Aim: This study aimed to identify the length of the lateral mass in the C2 vertebra for the purposes of the C2 straight lateral mass screw fixation technique. Method: This research was an observational descriptive study with cross sectional design that observed the results of cervical CT-Scan. Observation was made using the RadiAnt DICOM Viewer application and measurements were based on a sagittal cross section. The length was measured from the posterior parallel to the posterior longitudinal ligament (PLL). The initial mean was measured on the right and left side; afterwards, the final mean is the total mean of both sides. Result: From 10 samples, there were mean long lateral masses of C2 vertebrae on the right side of 13.511 ± 1.081 millimeters, the left side of 13.444 ± 1.396 millimeters, and the final mean of 13.48 ± 1,216 millimeters. It was rounded to an average of 13.5 ± 1.2 millimeters. Discussion: The line parallel to the posterior longitudinal ligament (PLL) is more posterior than the line parallel to the foramen transversum wall which causes the measured length to be shorter. This is useful for the C2 straight lateral mass screw technique as it avoids the possibility of lesions in the vertebral artery. Conclusion: The average lateral mass length in the population of Surabaya is 13.5 ± 1.2 millimeters.

Change in rates of primary atlantoaxial spinal fusion surgeries in the United States (1993-2015).

The objective of this study was to investigate revision burden and associated demographic and economic data for atlantoaxial (AA) fusion procedures in the US. Patient data from the National Inpatient Sample (NIS) database for primary AA fusion were obtained from 1993 to 2015, and for revision AA fusion from 2006 to 2014 using ICD-9 procedure codes. Data from 2006 to 2014 were used in comparisons between primary and revision surgeries. National procedure rates, hospital costs/charges, length of stay (LOS), routine discharge, and mortality rates were investigated. Between 1993 and 2014, 52,011 patients underwent primary AA fusion. Over this period, there was a 111% increase in annual number of primary surgeries performed. An estimated 1372 patients underwent revision AA fusion between 2006 and 2014, and over this time period there was a 6% decrease in the number of revisions performed annually. The 65-84 year-old age group increased as a proportion of primary AA fusions in the US from 35.9% of all AA fusions in 1997 to 44.2% in 2015, an increase of 23%. The mean hospital cost for primary AA surgery increased 32% between 2006 and 2015, while the mean cost for revision AA surgery increased by 35% between 2006 and 2014. Between 2006 and 2014, the mean hospital charge for primary AA surgery increased by 67%; the mean charge for revision surgery over that same period increased by 57%. Between 2006 and 2014, the mean age for primary AA fusions was 60 years, while the mean age for revision AA fusions was 52 years. The mean LOS for both procedures decreased over the study period, with primary AA fusion decreasing by 31% and revision AA fusion decreasing by 24%. Revision burden decreased by 21% between 2006 and 2014 (mean 4.9%, range 3.2%-6.4%). The inpatient mortality rate for primary AA surgery decreased from 5.3% in 1993 to 2.2% in 2014. The number of primary AA fusions between 2006 and 2014 increased 22%, while the number of revision procedures has decreased 6% over the same period. The revision burden decreased by 21%. The inpatient mortality rate decreased 62% (1993-2014) to 2.2%. The increased primary fusion rate, decreased revision burden, and decreased inpatient mortality determined in this study may suggest an improvement in the safety and success of primary AA fusion.

Alternative technique of C1-2-3 stabilization-sectioning of muscles attached to C2 spinous process and C2-3 fixation.

Aim:An alternative technique of C1-2-3 fixation is described that blocks the critical anteroposterior odontoid process movements and retains rotatory movement at the atlantoaxial joint. The technique involves sharp section of the muscles attached to the C2 spinous process and C2-3 transarticular interfacetal screw fixation.Materials and Methods:We successfully used this technique of fixation in 14 cases wherein in similar case situation; we earlier advocated inclusion of C1 in the fixation construct. Eleven patients had multisegmental spinal degeneration, 1 patient had Hirayama disease, and 2 patients had ossified posterior longitudinal ligament.Results and Technical Advantages:The procedure avoids manipulating C1 vertebra and excludes it from the fixation process, disables movement of C2 vertebra but retains rotation movements of the atlantoaxial joint that are executed by the muscles attached to the transverse process of atlas. The net effect is that the anteroposterior odontoid process movements that threaten the cervicomedullary neural structures are blocked and the critical rotatory atlantoaxial movements are retained.Conclusions:The discussed technique can be useful for cases undergoing multisegmental fixation that includes atlantoaxial joint.

Strategies in the management of atlantoaxial tuberculosis: Midterm radiological and functional outcomes of seven patients

Strategies in the management of atlantoaxial tuberculosis: Midterm radiological and functional outcomes of seven patients