C1-C2 Fixation Research Articles

Outcomes Following Arthrodesis for Atlanto-Axial Osteoarthritis.

Retrospective analysis. We set out to evaluate the radiographic and patient-reported outcomes following C1-C2 arthrodesis for atlantoaxial osteoarthritis (AAOA) using modern instrumentation and techniques. Few studies have evaluated outcomes following C1-C2 arthrodesis for AAOA using modern surgical fixation techniques. Retrospective analysis of all patients following C1-C2 arthrodesis with recalcitrant AAOA from a single center, single surgeon from 2002 to 2012. Preoperative, immediate and final follow-up postoperative radiographic images were evaluated. Patient-reported outcomes scores were assessed preoperative, 1-year, and final postoperative follow-up. We found a total of 14 patients (13 female, 1 male) with average follow-up of 2.96 ± 2.26 years and mean age at surgery of 71.8 ± 9.3 years old. The most common construct was posterior C1-C2 bilateral screw-rod construct (SRC) (n = 9), and there were 3 patients with transarticular screw (TAS) constructs, and 2 patients with hybrid fixation (unilateral SRC and contralateral TAS). Mean change from baseline to final follow-up for Numeric Pain Rating Scale (NRS) was -4.7 ± 2.1, and Neck Disability Index (NDI) was -21.0 ± 13.6, with 11 (78.6%) patients demonstrated a substantial clinical benefit (change in NDI ≥ 10). There were no differences from baseline to all follow-up time points for SF-12 Physical and Mental Component Scores. All patients had evidence of solid C1-C2 arthrodesis and stable fixation at final follow-up, with no significant change in subaxial sagittal alignment. There were no perioperative or postoperative complications. We report one of the largest series evaluating patient-reported outcomes in patients following arthrodesis for AAOA using modern C1-C2 fixation techniques. Our study found C1-C2 arthrodesis for AAOA to be safe and effective, with a significant improvement in patient-reported pain and neck disability and most patients reporting substantial clinical benefit. 4.

Management of Type II Odontoid Fractures: Experience from Latin American Spine Centers

To analyze characteristics of type II odontoid fracture (TII-OF), including clinical and radiographic factors, that influence surgical planning in 8 Latin American centers. Retrospective chart review was performed of 88 patients with TII-OF between 2004 and 2015 from 8 Latin American centers. Parameters studied included 1) demographic data and causes of TII-OF, 2) clinical and neurologic presentation, 3) characteristics of fracture (degree of odontoid displacement, displacement of odontoid relative to C2 body, anatomy of fracture line, distance between fragments, presence of comminution, contact area between odontoid and C2 body), 4) type of treatment, and 5) clinical and radiographic outcome. Bone fusion was assessed using computed tomography. Mean patient age was 45.33 years ± 23.54; 78.4% of patients were male. Surgery was the primary treatment in 65 patients (73.8%), with an anterior approach in 64.6%. Surgery was usually preferred in patients with posterior or horizontal oblique fracture lines, local pain, and a smaller bone contact surface between the odontoid and the body of C2. A posterior approach was chosen when distance between the fractured bone fragments was >2 mm or after failed conservative or anterior odontoid screw treatment in a symptomatic patient. The treatment of choice for TII-OF in 8 Latin American trauma centers was surgery through an anterior approach using screw fixation. Posterior segmental C1-C2 fixation was indicated when distance between bone fragments was >2 mm and in symptomatic patients with nonunion.

Comparison of outcomes after atlantoaxial fusion with C1 lateral mass-C2 pedicle screws and C1-C2 transarticular screws.

To compare the clinical and radiological outcomes of posterior atlantoaxial fixation and fusion using C1 lateral mass-C2 pedicle screws (screw-rod constructs, SRC) with C1-C2 transarticular screws (TAS). A retrospective review was conducted of 105 patients with atlantoaxial instability who underwent posterior C1-C2 fixation and fusion by SRC group (60 pt) and TAS group (45 pt). The follow-up period was minimum 2years. Clinical outcomes measurements included the Numeric Rating Scale (NRS) for pain assessment, the Neck Disability Index (NDI), the Japanese Orthopedic Association (JOA) score and the American Spinal Injury Association (ASIA) impairment scale for the functional and neurological outcomes that were assessed. Radiological outcomes were assessed by evaluating the fusion rate and proper screws position. Both outcomes were evaluated in the early postoperative period, 3, 6, 12 and 24months after surgery. Operative time, estimated blood loss, complications and length of stay were also reviewed. The majority of cases were caused by trauma and presented with axial neck pain. The improvement of NRS, NDI, JOA score and ASIA impairment scale were not different between the two groups. Proper screw position and fusion rate were also observed similarly between the two groups. Estimated blood loss was lesser and operative time was shorter in TAS group than SRC group (p=0.047, p=0.001, respectively). Operative complications and the length of hospital stay were also not different between the two groups. Both SRC and TAS produced excellent outcomes for atlantoaxial stabilization. But the volume of bleeding and operation time tended to be better in TAS group compared to SRC group.

Surgical Treatment of Occipitocervical Dislocation with Atlas Assimilation and Klippel-Feil Syndrome Using Occipitalized C1 Lateral Mass and C2 Fixation and Reduction Technique

To introduce and assess a surgical treatment of occipitocervical (OC) dislocation with atlas assimilation and Klippel-Feil syndrome (KFS) using occipitalized C1 lateral mass and C2 fixation and reduction technique. From January 2007 to August 2013, 58 symptomatic patients with OC dislocation and KFS of C2-3 congenital fusion and atlas assimilation were surgically treated in our institution via this technique. After opening the C1-2 facet joints via a posterior approach, OC reduction was conducted by intraoperative manipulation and C1 lateral mass and C2 pedicle screw and rod fixation. The instrument position, fusion status, and clinical outcome were analyzed. The average follow-up was 36 months (range, 18-52 months). Radiologically, effective reduction was achieved in 56 patients (96.6%) and <50% reduction in 2 (3.4%) who had additional transoral decompression. Neurologic improvement and solid bone fusion were achieved in all patients. The clinical symptoms improved for all patients, with the averaged Japanese Orthopedic Association myelopathy scores increasing from 11.5 to 15.6 (P < 0.01). In patients with OC dislocation and KFS of C2-3 fusion and atlas assimilation, posterior manipulative reduction combined with occipitalized C1 lateral mass and C2 fixation provides a reliable and effective treatment.

Six Different Vertebral Artery Configurations, in Three Subjects Commanding Different Approaches for C1-C2 Distraction and Fixation in Cases of CVJ Anomaly: A Case Series

Introduction There are various choices to fix up Atlanto-Axial dislocation (AAD) and Basilar invagination (BI), it may be Posterior only, Anterior only or Combined. Many surgeons refrain from “posterior only” approach of C1-C2 distraction (as described by Atul Goel and Lahiri) because of the fear of Vertebral artery (VA) injury and it's poorly understood course between C1, C2, and Occipital condyles. We describe details of preoperative work and subsequently adopted, customized surgical plans, as per VA configuration to distract &amp; fix the C1-C2 joint to achieve reduction in AAD and BI without harming the Vertebral artery. This case series covers most of the variations of VA around C1-C2 for learning purpose. After seeing this work up, many surgeons may allay their anxieties and take up this single stage corrective measure to achieve correction of deformities in cases of AAD &amp; BI. In the due course author will also explain different variations of Vertebral artery not only in different individuals, but also in same subject on either sides. We describe the adaptive surgical methods taken based on these data to avoid injury to VA, and still achieve a firm distraction and fixation at C1-C2 with this single stage. The technique can thus be extrapolated in various other cases of AAD and BI with hardly any exception. Material and Methods Three serial patients with an established diagnosis of Atlanto-axial dislocation and Basilar invagination are described. All three were evaluated with 3-D MPR CT with vertebral artery angiography (CTA-VA), and MRI at Cervico-medullary junction (MRI-CMJ). The VA in one subject was going through pedicle on one side and in another subject, it was going around the C1-C2 facet joint, while in another case it was entirely intra-spinal. The radiological evaluation was done in both pre and post operative period to describe anomalies of CVJ, different courses of VA and vectors thus used for potential instrumentation. Postoperative scans were used to see adequacy of fixation. Results There was a clear evidence of highly variable course in VA of all three subjects. There were different courses in right and left VAs as well, commanding different choices of instrumentation on both sides in a single individual. All patients achieved reduction of AAD &amp; BI and there was no injury to the vascular structure in question. They all improved in clinical signs and symptoms in the due course. Conclusion Authors conclude that it's mandatory to subject all patients to CT angiography in an order to view the Vertebral artery course wrt C1-C2 facets, which is not only variable in different individuals but also, on both sides in same individual, hence even in a single patient we may need different instrumentation to achieve the same goal. The authors also conclude that instrumentation at C1-C2 without CTA-VA is not only dangerous but can be fatal as well, hence instrumentation done without the above mentioned study should be considered a mandatory practice in the safest interest of patients and to achieve optimum and customized instrumentation.

New entry point for C2 screw, in posterior C1-C2 fixation (Goel-Harm’s technique) significantly reducing the possibility of vertebral artery injury

Objective: To reduce the chance of vertebral artery injury in posterior C1 lateral mass and C2 pedicle/pars screw–rod fixation (Goel–Harms technique ).Method: 49 patients, 30 males and 19 females, 12years - 82 years, underwent posterior C1–C2 fixation from February 2007 till June2013. A new entry point for the posterior C2 screw, 3mm below the midpoint of the C1–C2 joint which is directed medially and downwards into the C2 body , probably avoids the vertebral artery. As the screw now bypasses the pedicle/ pars , the chance of injuring the vertebral artery is probably reduced.Results: No case of intra-operative vertebral artery injury.Conclusion: The new technique of C2 screw fixation allows rigid immobilization of the C1–C2 joint without significant risk of vertebral artery injury.

Proatlas segmentation anomalies: Surgical management of five cases and review of the literature.

Objective:Proatlas segementation anomalies are due to defective re-segmentation of the proatlas sclerotome. These anomalies of the craniovertebral junction are rare and have multiple presentations. The aim of this study is to report this author's personal experience in managing five of these patients with different radiological findings necessitating different surgical strategies and to provide a brief review of the relevant literature.Materials and Methods:Five patients, all in the second decade of life were treated between 2010 and 2013. There were three males and two females. All the patients presented with spastic quadriparesis and/or cerebellar signs. Patients underwent plain radiographs, MRI and CT of the craniovertebral junction. CT of the cranioveretebral junction was the key to the diagnosis of this anomaly. Postoperatively, patients were assessed with plain radiographs and CT in all patients and MRI in one.Results:Two patients underwent craniovertebral realignment with occipitocervical fixation, two patients underwent C1-C2 fixation using Goel-Harms technique and one patient underwent craniovertebral realignment with C1-C2 fixation using spacers in the atlanatoaxial joint and foramen magnum decompression. All patients improved during follow up.Conclusions:Proatlas segmentation defects are rare anomalies of the craniovertebral junction. Routine use of thin section CT of the craniovertebral junction and an awareness of this entity and its multivarious presentations are necessary for clinicians dealing with abnormalities of the craniovertebral junction.

Transoral Decompression and Posterior Stabilization in Fixed Anterior Pathology of the Craniocervical Junction

Introduction Management of the anterior compressive pathology of the craniovertebral junction (CVJ) is complex and demanding. We review our experience with the transoral surgical decompression of fixed anterior CVJ lesions, with particular attention to the decision making and to the indication for a consecutive stabilization. Patients and Methods Retrospective study (2000–2013) of 47 consecutive patients (14 males and 13 females). Mean age was 59.2 years (range, 32–82 years). Encountered lesions were rheumatoid arthritis with pannus (29, 9 of which with associated cranial settling), ankylosing spondylitis (four), tumors (seven: six extradural chordomas/chondrosarcomas and one metastasis), odontoid fractures with hypoporosis, and rotational instability (seven). Patients presented with a variety of following symptoms: high cervical pain (82%), varying degrees of quadriparesis (64%), lower cranial nerve deficits (23%), and central cord syndrome with neurogenic bladder (14%). All patients underwent one-stage transoral decompression and consecutive posterior atlantoaxial or occipitocervical stabilization. Clinical evaluation was made pre- and postoperatively using the Ranawat score. Follow-up period ranged between 6 and 48 months (average, 22 months). Results According to the Ranawat score, we had 21 grade I patients, in 20 of which pain was eradicated, 10 grade II patients, 8 of which passed to grade I, 11 grade IIIA patients, of which 6 passed to grade I and 5 to grade II, and 5 grade IIIB patients of which 4 passed to grade IIIA. In seven patients, the transarticular screws crossed the anterior cortex of the atlas, without clinical manifestations. In five patients, complete reduction of the C1–C2 rotation was not possible, because of the chronic nature of the defect. Surgical morbidity occurred in five cases (three dural tears and two occipital wound infections). There were two perioperative deaths ([a] dural rupture, pneumoencephaly, meningitis, and massive pulmonary embolism, [b] pulmonary infection, and cardiorespiratory arrest). Conclusion Successful and stable decompression of the CVJ requires extensive preoperative evaluation, appropriate tailoring, and adequate expertise. The transarticular C1–C2 fixation is a safe and effective stabilization method when the atlanto-occipital joints remain competent. Complications appear mostly in patients with rotational deformity of the C1–C2 complex. Patients with clinical and radiological findings of myelopathy improve less even if surgery is successful.

C2 Subfacetal Body Screw in Posterior Atlantoaxial Fixation (Goel–Harm Technique) to Avoid the Vertebral Artery

Introduction Axis (C2) pedicle/pars screw fixation has a definite risk of injury to the vertebral artery. An alternative trajectory 3 mm below the midpoint of the C2 facet surface, directed, downwards and medially into the C2 body, bypasses the vertebral artery altogether, and still offers adequate bone stock for rigid fixation of the C2 vertebra. Material and Methods Overall, 65 patients, 40 males and 25 females, aged 12 to 82 years, underwent posterior C1–C2 fixation from February 2007 to June 2014. Reducible atlantoaxial instability due to trauma (35), rheumatoid arthritis (20), and infection (tuberculosis) (10), magnetic resonance imaging (MRI), dynamic lateral X-rays of craniovertebral junction (CVJ), 3D CT scan of the craniovertebral region along with dynamic study and CT angiography. The entry point for the C2 screw was 2 to 3 mm below the midpoint of superior facet of the C2 which is also the midpoint C1–C2 joint and directed 10–to 15 degrees medially and downwards into the body of the axis. The same 3-mm drill bit was used incrementally till a depth of 5 mm and, 3.5 mm and 18 to 24mm length self-tapping screw with polyaxial head was used in most cases. Results No case of intraoperative vertebral artery injury. No patient required per operative blood transfusion. Follow-up visits were scheduled at 2, 6 to 8 weeks, and 3 months. Dynamic X-ray imaging was done in all patients at 6 to 8 weeks before discontinuing the collar and after 3 months since the operation. All patients followed up for 3 months. Telephonic follow-up of 30 patients was available for 24 months, 12 patients for 6 months, and remaining 7 patients have not reported and are not contactable after the 3 month visit. One postoperative mortality due to myocardial infarction on 7th day. Seven patients complained of occipital numbness and paresthesia which was not disturbing and responded to reassurance and supportive medication (pregabalin). Two patients had superficial wound infection which responded to appropriate antibiotics. There was no case of implant failure or loss of rigidity of fixation up to 3 months. Conclusion The new entry point offers rigid fixation and avoids the vertebral artery altogether nullifying the chance of arterial injury. Divergent screws (bridge vs. tension band construct) have a greater pull out strength. The new technique of C2 screw fixation allows rigid immobilization of the C1–C2 joint without any risk of vertebral artery injury.

Trends in Epidemiology and Management of Traumatic Type II Odontoid Fracture: Experience in Latin America

Introduction Odontoid fractures (OF) are frequent in the trauma population, and there is no universally accepted single method of management. The objective of this study was to evaluate the epidemiology and management of type II OF in Latin America treated either with rigid cervical orthosis or surgery. Patients and Methods A total of 83 patients treated conservatively or by surgery were enrolled in this retrospective study. Medical charts, imaging studies, and outcomes of patients were analyzed in the pretreatment period and at the last medical evaluation. The fractures were assessed using conventional radiographs, three-dimensional computed tomographic (3D-CT) scans, and magnetic resonance images. Fracture gaps, the direction and the degree of displacement of the odontoid process, the fracture line anatomy, the degrees of atlantoaxial instability, the comminuted fracture, and the surface contact area were analyzed. The decision for operative or nonoperative treatment was based on anesthesia risk, and patient's choice of the nonoperative treatment. The nonoperative management generally consisted of a rigid cervical orthosis for 3 months. The type of surgery to be performed was chosen by the surgeon. The solid bony union was defined as the presence of bony bridges and the definite continuity of cortical bone. Fibrous union was considered present when no degree of motion was evident in dynamic radiographs despite persistent cortical bone discontinuity within a fracture gap on 3D CT scans. Nonunion was defined as a definite fracture gap with abnormal motion of the fractured dens on dynamic radiographs and on a 3D CT scan. Results A total of 83 patients were included in this study. The patients were 78.3% men, the mean age = 44.98 ( ± 23.20 years) years. Traffic accidents (66.3%) were the most common cause of trauma. The main symptom was pain (85.5%) in the posterior cervical region. The median time elapsed from accident to surgery was 7 days (P25: 2/P75: 27.5). Median follow-up was 23.66 ( ± 25.43 months) months. Conservative treatment with cervical orthosis, for example, Miami J collar or halo-vest was used in 20.5% of the cases. Odontoid screw technics (57.6%) were the most common surgical treatment adopted as primary surgical treatment. Symptomatic nonunion was observed in two cases with conservative treatment and three cases after odontoid screw fixation. All the patients were referred to posterior C1–C2 fixation. The posterior fixation tended to be used after conservative failed therapy, after nonunion anterior screw surgery, and in fractures with greater displacement. The most common radiological feature was no displacement of the odontoid process in relation to the body of C2, horizontal fracture line, gap fracture &lt; 2 mm, no subluxation across each C1–C2 facet joint and no comminuted fracture. Conclusion The patients treated nonoperatively with a rigid collar may have an overall favorable outcome compared with surgical treatment. A well-designed prospective study is needed to better elucidate optimal treatment algorithms from both an outcomes and cost-effectiveness perspective.

Traumatic occipitocervical and atlantoaxial dislocation with clivus fracture in a child. Case report

Abstract Background Craniovertebral junction lesions in the paediatric population are associated with a low survival rate, which has declined in recent years. Neurological disability is a major concern due to the high economical cost it represents. Paediatric patients are more susceptible to this lesion because of hyperextension capacity, flat articulation, and increased ligamentous laxity. Survival after these kinds of injuries has been more often reported in adults, but are limited in the paediatric population. Clinical case A case of an 8-year-old male is reported with occipitocervical and atlantoaxial dislocation associated with clivus fracture, brain oedema, and post-traumatic subarachnoid haemorrhage. A halo vest system was placed with no traction. One month after the trauma the patient was surgically treated with C1 and C2 trans-articular screws, occipitocervical fixation with plate and screws, and C1–C2 fixation with tricortical bone graft and wires without complication. He has now returned to school and is self-sufficient. Conclusions With better pre-hospital medical care and with improved surgical techniques the mortality rate has declined in this kind of lesion.

Subaxial sagittal alignment after atlantoaxial fixation techniques.

A retrospective clinical case series. To evaluate the association between C1-C2 fixation angle and postoperative C2-C7 alignment in the sagittal plane after C1 lateral mass screw with C2 pedicle screw fixation (C1-LMS) or Magerl with wiring technique. Various techniques for posterior correction and fusion, such as the Magerl procedure with posterior wiring and C1-LMS procedures, are used for treating atlantoaxial instability. However, only few studies investigating the relationship between postoperative C1-C2 angle and C2-C7 sagittal alignment change after C1-C2 fixation have been reported. We retrospectively followed up 42 patients who underwent the C1-LMS (22 patients) or Magerl with wiring procedure (20 patients) to treat C1-C2 instability for >2 years. The atlantodental interval, space available for the spinal cord, and O-C1, C1-C2, C2-C3, and C2-C7 angles were measured. Significant reduction in atlantodental interval and increase in space available for the spinal cord were observed in both groups. Although the preoperative C1-C2 angles were similar, the angle at the final follow-up was higher in the Magerl with wiring group than in the C1-LMS group (P<0.01). The C1-C2 fixation and postoperative C2-C7 angles were negatively correlated in both groups (C1-LMS group, r=-0.55, P<0.01; Magerl with wiring, r=-0.62, P<0.01). Increased lordotic change in the C1-C2 angle was associated with increased kyphotic changes in the C2-C7 angle after both procedures. The C1-LMS procedure effectively controlled C1-C2 sagittal alignment during surgery. To decrease the risk of postoperative subaxial kyphotic changes, the C1-C2 fixation angle should be carefully determined.

Placement of C1 Pedicle Screws Using Minimal Exposure: Radiographic, Clinical, and Literature Validation.

Traditional C1-2 fixation involves placement of C1 lateral mass screws. Evolving techniques have led to the placement of C1 pedicle screws to avoid exposure of the C1-C2 joint capsule. Our minimal dissection technique utilizes anatomical landmarks with isolated exposure of C2 and the inferior posterior arch of C1. We evaluate this procedure clinically and radiographically through a technical report. Consecutive cases of cranial-vertebral junction surgery were reviewed for one fellowship trained spinal surgeon from 2008-2014. Information regarding sex, age, indication for surgery, private or public hospital, intra-operative complications, post-operative neurological deterioration, death, and failure of fusion was extracted. Measurement of pre-operative axial and sagittal CT scans were performed for C1 pedicle width and C1 posterior arch height respectively. 64 patients underwent posterior cranio-vertebral junction fixation surgery. 40 of these patients underwent occipital-cervical fusion procedures. 7/9 (77.8%) C1 instrumentation cases were from trauma with the remaining two (22.2%) from oncologic lesions. The average blood loss among isolated C1-C2 fixation was 160cc. 1/9 patients (11.1%) suffered pedicle breech requiring sub-laminar wiring at the C1 level. On radiographic measurement, the average height of the C1 posterior arch was noted at 4.3mm (range 3.8mm to 5.7mm). The average width of the C1 pedicle measured at 5.3mm (range 2.8 to 8.7mm). The patient with C1 pedicle screw failure had a pedicle width of 2.78mm on pre-operative axial CT imaging. Our study directly adds to the literature with level four evidence supporting a minimal dissection of C1 arch in the placement of C1 pedicle screws with both radiographic and clinical validation. Justification of this technique avoids C2 nerve root manipulation or sacrifice, reduces bleeding associated with the venous plexus, and leaves the third segment of the vertebral artery unexplored. Pre-operative review of imaging is critical in the placement of C1-C2 instrumentation.

Retro-odontoid cystic mass treated by laminectomy and C1-C2 fixation.

Retro-odontoid cysts associated with chronic atlantoaxial subluxation are extremely rare. This article describes a case of retro-odontoid cystic mass associated with chronic atlantoaxial subluxation and its management with posterior C1 and partial C2 laminectomy and C1-C2 pedicle screw fixation without resection of the retro-odontoid cyst. A 64-year-old woman experienced a sudden onset of neck pain, hand and foot paresthesia. Atlantoaxial instability associated with a retro-odontoid cystic mass was found in the imaging. The patient underwent posterior C1 and partial C2 laminectomy and C1-C2 pedicle screws fixation without resection of the retro-odontoid cyst. During the 24 months followup period, the cyst disappeared completely and the patient remained symptom free and returned to independent daily living. These findings suggest that posterior laminectomy and fixation without resection of the retro-odontoid cyst is relatively simple and safe and the results are satisfactory.

C1 posterior arch screw as an auxiliary anchor in posterior reconstruction for atlantoaxial dislocation associated with type II odontoid fracture: a case report and review of the literature.

AbtractIntroductionAlthough pedicle or lateral mass screws are usually chosen to fix atlantoaxial (C1-C2) instability, there is an increased risk for vertebral artery (VA) injury when used in patients with bone or arterial anomalies or osteoporotic bone. Here we report the C1 posterior arch screw as a new technique for upper cervical fixation.Case descriptionA 90-year-old man complained of upper cervical pain after falling in his house. The initial computed tomography (CT) scan showed C1-C2 posterior dislocation with a type II odontoid fracture. The patient underwent C2 fracture reduction and posterior C1-C2 fixation. On the right side of C1, because lateral mass screw placement could cause injury to the dominant VA considering a risk in oldest-old osteoporotic patients, a posterior arch screw was chosen instead as an auxiliary anchor. An intralaminar screw was placed on the right side of C2 because a high-riding VA was observed. A lateral mass screw and a pars interarticularis screw were placed on the left side of C1 and C2, respectively. Ten months later, the odontoid fracture had healed, with normal anatomical alignment. Although the patient experienced slight weakness when spreading his bilateral fingers, his overall condition was good.Discussion and evaluationWe have presented a novel technique using C1 posterior arch screws for the fixation of a C1-C2 dislocation. Such a screw is an alternative to the C1 lateral mass screw in patients who are at risk for a VA injury because of anomalous bone and arterial structures or poor bone quality.ConclusionsAlthough there have been few comparable studies, and the long-term outcome is unknown, fixation with a posterior arch screw could be a beneficial choice for surgeries involving the upper cervical region.

Atlantoaxial anterior transarticular screw fixation: a case series and reappraisal of the technique

Background contextAtlantoaxial instability is commonly treated with C1–C2 fixation performed via posterior approaches. Although anterior transarticular screw (ATS) fixation, performed with a classic retropharyngeal approach, was described more than 10 years ago, the published literature still lacks a comprehensive analysis of the procedure and a real case series. PurposeWe report a series of patients treated with atlantoaxial ATS, describing the surgical procedure in detail and discussing advantages and disadvantages of the technique. Study designThe study design includes case series and technical report. MethodsWe prospectively enrolled 15 patients affected by atlantoaxial instability secondary to trauma, degenerative diseases, or inflammatory diseases. Anterior transarticular screw fixation was performed with anteroposterior open-mouth and lateral intraoperative radiographs. All patients were evaluated radiologically at follow-up to identify bone fusion. ResultsAnterior transarticular screw was performed successfully in 14 patients without complications. The procedure was aborted in a case of vertebral invagination, and one case required revision surgery owing to C2 articular bone fracture. Solid C1–C2 fusion was achieved in all cases (at 10- to 21-week follow-up) except in an elderly patient affected by severe osteoporosis. No complications occurred. ConclusionsAlthough the procedure is still not widely known, ATS allows the effective and safe treatment of C1–C2 instability even in patients with systemic comorbidities. It offers several advantages over posterior approaches.

Clinically relevant complications related to posterior atlanto-axial fixation in atlanto-axial instability and their management

BackgroundThe Magerl transarticular technique and the Harms–Goel C1 lateral mass-C2 isthmic screw technique are the two most commonly used surgical procedures to achieve fusion at C1–C2 level for atlanto-axial instability. Despite recent technological advances with an increased safety, several complications may still occur, including vascular lesions, neurological injuries, pain at the harvested bone graft site, infections, and metallic device failure. MethodsWe retrospectively analyzed all patients (n=42 cases) undergoing a Harms–Goel C1–C2 fixation surgery with polyaxial C1 lateral mass screws and C2 isthmic screws at two different institutions between 2003 and 2012 and report clinical and radiological complications. One patient was lost to follow-up. The mean follow-up of the remaining 41 patients was 18.7 months (range 12–90). A clinically relevant complication was defined as a complication determining the onset of a new neurological deficit or requiring the need for a revision surgery. ResultsA total of 14 complications occurred in 10 patients (24.4% of 41 patients). Greater occipital nerve neuralgia was evident in 4 patients (9.8%). All but one completely resolved at the end of the follow-up. Persistent neck pain was reported by 3 patients (7.3%), hypoesthesia by 1 patient (2.4%), and anesthesia in the C2 area on both sides in 1 patient (2.4%). Furthermore, a superficial, a deep, and a combined superficial and deep wound infection occurred in 1 patient each (2.4%). One patient (2.4%) had pain at the iliac bone graft donor site for several weeks with spontaneous resolution. A posterior progressive intestinal herniation through the iliac scar was seen in 1 case (2.4%), which required surgical repair. No vascular damages occurred. Altogether, 5/41 patients (12.2%) had a clinically relevant complication including 4 patients necessitating a revision surgery at the C1–C2 level (9.8%). ConclusionsAtlanto-axial fixation surgery remains a challenging procedure because of the proximity of important neurovascular structures. Nevertheless, on the basis of our current experience, the C1 lateral mass-C2 isthmic screw technique appears to be safe with a low incidence of clinically relevant complications. Postoperative C2 neuralgia, as the most frequent problem, is due to surgical manipulation during preparation of the C1 screw entry point.

Atlanto-axial dislocation complicating a type II odontoid fracture. Reduction and final fixation

A case of traumatic posterolateral C1-C2 dislocation associated with odontoid fracture is reported. This is a rare case of traumatic posterolateral C1-C2 dislocation associated with odontoid fracture. Its management is discussed. A traumatic dislocation of atlanto-axial joint associated with an odontoid fracture remains a rare injury. No case of posterior dislocation has been reported so far in the literature with this type of management. The case is of a 25 year-old-man with a primary atlanto-axial posterolateral dislocation associated with a type II displaced odontoid fracture without any neurological complication. The patient underwent gentle traction during 24hours with a halo frame. An incomplete reduction was achieved. Two days later, a complete reduction was obtained thanks to a preoperative manual traction maintained by a Mayfield (R) modified skull clamp. Anterior C1-C2 fixation was performed according to Vaccaro's technique. The patient wore a cervical collar and underwent physiotherapy during three months. To our best knowledge, this case represents the first traumatic atlanto-axial dislocation associated with an odontoid fracture which was treated through retropaharyngeal approach. This had been rendered possible thanks to the final reduction maneuver in extension.

Occipitocervical collision after C1–C2 fusion

A 54-year-old woman presented with a 10-year history of neck pain. On medical history, she suffered from rheumatoid arthritis for several years. Plain X-ray imaging showed increased atlantodental interval as 9 mm (Fig. 1). Postoperative X-ray study shows that C1–C2 fixation was done using bilateral C1 lateral mass, left C2 intralaminar, and right C2 pedicle screws. Her neck pain disappeared immediately after surgery. However, the distance between occiput and posterior C1 arch was decreased compared with preoperative X-ray imaging because C1–C2 fixation was done in distracted position and oversized iliac bone graft was placed between the C1 and C2 posterior arch (Fig. 2). Twenty-seven months later, she revisited the outpatient clinic because of severe occipital headache

Comparison of Fatigue Strength of C2 Pedicle Screws, C2 Pars Screws, and a Hybrid Construct in C1–C2 Fixation

A biomechanical study comparing the fatigue strength of different types of C2 fixation in a C1-C2 construct. To determine the pullout strength of a C2 pedicle screw and C2 pars screw after cyclical testing and differentiate differences in stiffness pre- and post-cyclical loading of 3 different C1-C2 fixations. Some surgeons use a short C2 pars screw in a C1-C2 construct, because it is less technically demanding and/or when the vertebral artery is high riding. Difference in construct stiffness between use of bilateral C2 pedicle screws, bilateral C2 pars screws, or a hybrid construct is unknown. Biomechanical testing was performed on 15 specimens. A bicortical C1 lateral mass screw was used in combination with 1 of 3 methods of C2 fixation: (1) bilateral long C2 pedicle screws (LL), (2) bilateral 14-mm C2 pars screws (SS), and (3) unilateral long C2 pedicle screw with a contralateral 14-mm C2 pars screw (LS). Each construct was subject to 16,000 cycles to simulate the immediate postoperative period. Changes in motion in flexion-extension, lateral bending, and axial rotation were calculated. This was followed by pullout testing. The ability to limit range of motion significantly decreased after cyclical testing in flexion-extension, lateral bending, and axial rotation for all 3 groups. After loading, the LL and LS groups had less percentage of increase in motion in flexion-extension and lateral bending than the SS group. Overall, the average pullout strength of a pedicle screw was 92% stronger than a pars screw. C2 pedicle screws have twice the pullout strength of C2 pars screws after cyclical loading. In cases in which the anatomy limits placement of bilateral C2 pedicle screws, a construct using a unilateral C2 pedicle screw with a contralateral short pars screw is a viable option and compares favorably with a bilateral C2 pedicle screw construct. N/A.