Posterior atlanto-axial fusion with the Olerud Cervical Fixation System for odontoid fractures and C1-C2 instability in rheumatoid arthritis

Potential intraoperative factors of screw-related complications following posterior transarticular C1-C2 fixation: a systematic review and meta-analysis

PURPOSE

This study aimed to evaluate the impact of several factors, including patients' intraoperative position, intraoperative visualization technique, fixation method, and type of screws and their parameters, on the frequency of intraoperative screw-associated complications in posterior transarticular C1-C2 fixation.

METHODS

A systematic review of the PubMed database between January 1986 and March 2018 was performed. The key inclusion criteria comprised detailed descriptions of the surgical technique and post-operative screw-associated complications.

RESULTS

The initial search resulted in 1041 abstracts, and a total of 54 abstracts were included in the present study. The overall number of operated patients was 2306. In this group, 4439 screws were inserted. The rate of screw-associated complications during the different time periods was estimated upon meta-analysis. Statistical analysis of the screw malposition rate, vertebral artery injury rate, screw breakage rate based on patients' intraoperative position, intraoperative visualization technique, fixation method, and type of implants and their parameters was also performed.

CONCLUSIONS

The factors that help reduce the rate of screw-associated complications include the intraoperative application of biplanar fluoroscopy or neuronavigation system, the use of 4 mm or thicker lag screws, and screw insertion through contraincisions using cannulated ported instruments. On the other hand, the potential risk factors of screw-associated complications include inadequate intraoperative head fixation using skeletal traction, uniplanar fluoroscopy-guided screw insertion, screw insertion using the posterior midline approach, and the use of 3.5 mm or thinner full-threaded screws. These slides can be retrieved under Electronic Supplementary Material.

Biomechanical Assessment of Stabilization of Simulated Type II Odontoid Fracture with Case Study

STUDY DESIGN

Researchers created a proper type II dens fracture (DF) and quantified a novel current posterior fixation technique with spacers at C1-C2. A clinical case study supplements this biomechanical analysis.

PURPOSE

Researchers explored their hypothesis that spacers combined with posterior instrumentation (PI) reduce range of motion significantly, possibly leading to better fusion outcomes.

OVERVIEW OF LITERATURE

Literature shows that the atlantoaxial joint is unique in allowing segmental rotary motion, enabling head turning. With no intervertebral discs at these joints, multiple ligaments bind the axis to the skull base and to the atlas; an intact odontoid (dens) enhances stability. The most common traumatic injury at these strong ligaments is a type II odontoid fracture.

METHODS

Each of seven specimens (C0-C3) was tested on a custom-built six-degrees-of-freedom spine simulator with constructs of intact state, type II DF, C1-C2 PI, PI with joint capsulotomy (PIJC), PI with spacers (PIS) at C1-C2, and spacers alone (SA). A bending moment of 2.0 Nm (1.5°/sec) was applied in flexion-extension (FE), lateral bending (LB), and axial rotation (AR). One-way analysis of variance with repeated measures was performed.

RESULTS

DF increased motion to 320%, 429%, and 120% versus intact (FE, LB, and AR, respectively). PI significantly reduced motion to 41%, 21%, and 8%. PIJC showed negligible changes from PI. PIS reduced motion to 16%, 14%, and 3%. SA decreased motion to 64%, 24%, and 54%. Reduced motion facilitated solid fusion in an 89-year-old female patient within 1 year.

CONCLUSIONS

Type II odontoid fractures can lead to acute or chronic instability. Current fixation techniques use C1-C2 PI or an anterior dens screw. Addition of spacers alongside PI led to increased biomechanical rigidity over intact motion and may offer an alternative to established surgical fixation techniques.

Erosion in the occipital bone caused by the fixation instrument used for posterior atlantoaxial fusion -report of 4 cases

Introduction

Conventionally, posterior C1-C2 fusion has been performed using a sublaminar wiring technique with a structural bone graft. Subsequent advent of newer fixation devices, such as the C1 lateral mass screw and C1 hook, has achieved more solid fixation with improved surgical outcome; however, in these fixation systems, the protruding end of the metal implant above the level of the atlas may result in a complication due to contact with the surrounding structures.

Case description

Two men and two women whose ages at the time of surgery ranged from 14 to 72 years. A supralaminar hook was used as a fixation device for C1 in two cases, whereas a lateral mass screw (Tan’s method) and an atlas claw hook were employed for one each of the remaining 2 cases. We retrospectively reviewed the clinical features and postoperative course of these patients using the clinical records. Moreover, we measured the protruding height of the instrument above the atlas as well as the Redlund-Johnell (R-J) value on postoperative radiographs. All patients complained of crepitus and/or pain on neck extension. Erosion in the occipital bone was detected on multiplanar reconstruction computed tomography (MPR-CT), whereas plain radiographs failed to reveal the bony change. In those cases, protruding instruments used for C1 fixation contacted the occipital bone resulting in an erosive change at the impingement point. We removed the implant in all four cases after confirmation of solid bony union.

Discussion and evaluation

Two of the four patients complained of occipital crepitus alone without pain. The management options for this condition may be controversial; however, progression of bony erosion may result in perforation of the occipital bone. This may possibly be associated with the serious complication of cerebrospinal fluid leakage. Considering this potential sequela, we removed the implants from all our reported cases after confirmation of solid bony union.

Conclusions

We treated four cases that developed erosion in the occipital bone after posterior spinal instrumentation was performed for upper cervical lesions including C1. MPR-CT was useful in detecting the erosive changes in the occipital bone.

Systematic review on surgical and nonsurgical treatment of type II odontoid fractures in the elderly

Odontoid fractures type II according to Anderson and d'Alonzo are not uncommon in the elderly patients. Still, due to the paucity of evidence the published treatment guidelines are far from equivocal. This systematic review focuses on the published results of type II odontoid fracture treatment in the elderly with regard to survival, nonunion, and complications. After a systematic literature research 38 publications were included. A cumulative analysis of 1284 published cases found greater survival if elderly patients with odontoid fractures type II received surgical treatment (RR = 0.64). With regard to nonunion in 669 published cases primary posterior fusion had the best fusion results. The systematic literature review came to the following conclusions. (1) Surgical stabilisation of odontoid fractures type II improves survival in patients between 65 and 85 years of age compared to nonsurgical treatment. (2) Posterior atlantoaxial fusion for odontoid fractures type II in the elderly has the greatest bony union rate. (3) Odontoid nonunion is not associated with worse clinical or functional results in the elderly. (4) The complication rate of nonsurgical treatment is similar to the complication rate of surgical treatment of odontoid fractures type II in the elderly.

Bilateral C1-C2 transarticular screw and C1 laminar hook fixation and bone graft fusion for reducible atlantoaxial dislocation: a seven-year analysis of outcome

BACKGROUND

Bilateral C1-2 transarticular screw and C1 laminar hook fixation was developed on the basis of transarticular screws fixation. The modified technique has showed a better biomechanical stability than established techniques in previous study. However, long-term (minimum follow-up 7 years) outcomes of patients with reducible atlantoaxial dislocation who underwent this modified fixation technique have not still been reported.

METHODS

A retrospective study was conducted to evaluate the outcome of 36 patients who underwent this modified technique. Myelopathy was assessed using the Ranawat myelopathy score and Myelopathy Disability Index. Pain scores were assessed using Visual Analogue Scale. Radiological imaging was assessed and the following data were extracted: the atlantodental intervals, the space available for cord, presence of spinal cord signal change on T2 weighted image, C1-C2 angle, C2-C7 angle and fusion rates.

FINDINGS

All patients achieved a minimum seven-year follow up. 95% patients with neck and suboccipital pain improved after surgery; in their Visual Analogue pain scores, there was a greater than 50% improvement in their VAS scores with a drop of 5 points on the VAS (P<0.05). 92% of patients improved in the Ranawat myelopathy grade; the Myelopathy Disability Index assessment showed a preoperative mean score of 35.62 with postoperative mean 12.75(P<0.05). There was not any significant atlantoaxial instability at each follow-up time. The space available for cord increased in all patients. Postoperative sagittal kyphosis of the subaxial spine was not observed. After six months after surgery, bone grafts of all patients were fused. No complications related to surgery were found in the period of follow-up.

CONCLUSIONS

The long-term outcomes of this case series demonstrate that under the condition of thorough preoperative preparations, bilateral C1-C2 transarticular screw and C1 laminar hook fixation and bone graft fusion is a reliable posterior atlantoaxial fusion technique for reducible atlantoaxial dislocation.

Is inclusion of the occiput necessary in fusion for C1-2 instability in rheumatoid arthritis?

OBJECT

The atlantoaxial joint is the location most and earliest affected in patients with rheumatoid arthritis (RA). In longstanding disease, ligamentous and osseous destruction can progress and involve all cervical segments. If surgical intervention is necessary, some prefer, to be safe, undertaking fusion to the occiput, whereas others advocate 1-level fusion of C1-2. Sparing the occiput (Oc)-C1 segment would allow retention of a considerable amount of physiological range of motion and seems beneficial against subaxial overload. Previous clinical studies on this topic have provided only nonspecific data after short-term follow-up, rendering a segment-sparing approach questionable. The purpose of the present investigation was to assess long-term progression of inflammatory or degenerative destruction in the Oc-C1 segment after isolated C1-2 fusion for RA.

METHODS

In a series of 113 consecutive patients with RA-related destruction restricted to the craniocervical junction, 14 individuals underwent Oc-C2 fusion and 99 underwent surgery exclusively at the C1-2 level. After a mean follow-up period of 9.4 years (range 4.9-14.7 years), 46 patients were available for clinical and radiographic examination, including CT imaging.

RESULTS

None of the 46 patients needed additional surgery to extend the fusion to the occiput. Despite marked deterioration in the subaxial cervical spine, in general there were little or no changes in the atlantooccipital region. All but one patient presented with bony fusion of the fixed C1-2 level at follow-up.

CONCLUSIONS

The results of this investigation suggest that if the Oc-C1 joint is free of osseous destructions on conventional radiographs and free of abnormalities on MRI scans at the time of surgery (for transarticular fixation and fusion of C1-2), there is a very low risk for relevant destruction in the following 5-14 years. Thus, no prophylactic oligosegmental approach, but rather a segment-sparing monosegmental approach, is preferred, even in patients with high inflammatory levels.

C1-2 transarticular screws combined with C1 laminar hooks fixation: a modified posterior atlantoaxial fixation technique and outcome in 72 patients

PURPOSE

To retrospectively evaluate the outcome of C1-2 transarticular screws combined with C1 laminar hooks fixation.

METHODS

All patients underwent atlantoaxial fixation during a 5-year period. The surgical technique and treatment procedures were intensively reviewed and clinical symptoms, neurological function and imaging appearance were retrospectively evaluated.

RESULTS

The clinical and radiology follow-up indicated a stable arthrodesis and clinical relief from symptoms for all patients. All patients with neurological defects improved an average of 1.33 grade at their most recent clinical assessment, P < 0.05; their average admission ASIA motor score, pin prick score and light touch score improved to an average follow-up ASIA score of 99.80 (99.83 ± 0.38), 111.83 (111.83 ± 0.45), and 111.89 (111.89 ± 0.32), respectively. No neurovascular impairment and case of implant failure were observed.

CONCLUSIONS

The C1-2 transarticular screws combined with C1 laminar hooks fixation is a reliable technique for atlantoaxial instability.

Transarticular screw and C1 hook fixation for os odontoideum with atlantoaxial dislocation

OBJECTIVE

To introduce a fixation device composed of C1-2 transarticular (TA) screws and C1 hooks and explore its indication and clinical outcome for os odontoideum with atlantoaxial dislocation (AAD).

METHODS

From January 2004 to December 2008, 12 patients with os odontoideum (5 men and 7 women, average age 37.7 years [range 14-62 years]) were treated in the authors' hospital. All patients had AAD with local symptoms, and 10 had myelopathy. All patients underwent a posterior atlantoaxial fixation with C1-2 TA screws and C1 hooks. Clinical and radiographic analyses were performed at 3, 6, and 12 months postoperatively and annually thereafter.

RESULTS

The follow-up period was 12-66 months (average follow-up period 35.5 months). No neurologic or vascular complications occurred in these cases, and the device was placed well with no loosening or breakage. Plain radiographs and three-dimensional reconstruction of computed tomography (CT) images revealed solid bony fusion with a good alignment of C1 and C2 at 3 months postoperatively. No hardware failure, pseudarthrosis, or instability was noted during the follow-up period. All patients had relief of pain within 3 months, and neurologic symptoms were substantially improved.

CONCLUSIONS

When appropriate patients are selected, C1-2 TA screws combined with C1 hooks can be used to treat os odontoideum with AAD effectively with a relatively simple procedure resulting in excellent biomechanical strength and high bone fusion rate. Preoperative planning is crucial for the management of os odontoideum with AAD.

Bilateral atlantoaxial transarticular screws and atlas laminar hooks fixation for pediatric atlantoaxial instability

STUDY DESIGN

An atlantoaxial fixation using bilateral C1-C2 transarticular screws and C1 laminar hooks was used in 5 pediatric patients, who were then followed up for 12 to 17 months to evaluate the technique.

OBJECTIVE

To describe a modified posterior C1-C2 fixation technique and preliminary clinical and radiographic results in 5 pediatric patients.

SUMMARY OF BACKGROUND DATA

Conventional posterior atlantoaxial fixations, such as Gallie and Brooks techniques, are frequently associated with high rates of pseudarthrosis and implant failure. The C1-C2 transarticular screw fixation has been shown to be effective in treatment of pediatric atlantoaxial instability, as well as adult atlantoaxial instability; however, this 2-point fixation merely stabilizes the atlantoaxial motion segment laterally. A 3-point fixation, composed with bilateral C1-C2 transarticular screws and C1 laminar hooks, has been developed.

METHODS

Five patients with atlantoaxial instability, including 4 males and 1 female, aged 6 to 17 (average 10) years, underwent atlantoaxial fixation using bilateral C1-C2 transarticular screws and C1 laminar hooks during a 2-year period. The surgical technique and treatment procedures were intensively reviewed, and clinical symptoms and imaging appearance were retrospectively evaluated.

RESULTS

Clinical follow-ups were obtained for an average of 14.4 (range: 12-17) months. The clinical and radiologic follow-up indicated a stable arthrodesis and offered clinical relief from symptoms for all patients. No neural or vascular impairment related to this technique was observed.

CONCLUSION

Fixation of the atlantoaxial articulation using bilateral C1-C2 transarticular screws and C1 laminar hooks appears to be a reliable technique for treatment of pediatric atlantoaxial instability.

Surgical treatment of unstable type II odontoid fractures in skeletally mature individuals

STUDY DESIGN

Systematic review of literature.

OBJECTIVE

To determine the optimal indications and methods of surgical treatment for unstable type II odontoid fractures in skeletally mature individuals.

SUMMARY OF BACKGROUND DATA

Odontoid fractures are a frequently encountered injury pattern in the cervical spine. The surgical treatment of type II odontoid fractures varies among spinal surgeons. The optimal surgical indications and treatment for type II odontoid fractures remains unclear.

METHODS

Five primary research questions, based on safety and efficacy, were determined by consensus of a panel of spine trauma surgeons consisting of fellowship trained orthopedic and neurologic surgeons. A comprehensive review of the literature was performed using MeSH search terms in MEDLINE, PubMed, EMBASE, CINAHL, and the Cochrane Database of Systematic reviews. The quality of literature was rated as high, moderate, low, or very low. Using the GRADE evidence-based review system, the primary questions were answered using the literature review and expert opinion. These treatment recommendations were then rated as either strong or weak based on the quality of evidence and clinical expertise.

RESULTS

The initial search resulted in over 1300 results. After initial application of all inclusion and exclusion criteria, 458 abstracts were reviewed from which 22 manuscripts were found to meet all criteria. These were obtained, reviewed, and used to create an evidentiary table. All articles were of either low or very low quality.

CONCLUSION

There is no moderate or high quality literature on the surgical management of acute type II odontoid fractures. Optimal indications for either anterior or posterior treatment of fractures are described but with no comparative data. A single anterior odontoid screw is the recommended technique for anterior treatment. Posterior internal fixation (C1-C2 transarticular screw, C1-C2 segmental fixation) is the recommended technique for posterior treatment. In equivocally indicated instances, anterior or posterior treatment can be safely used with good outcome. In this scenario, surgical management decision should be influenced by surgeon and patient preference as well as cost considerations.

The lasso technique for posterior C1-C2 fusion

OBJECTIVE

Posterior atlantoaxial arthrodesis requires placement of a bone graft in a properly prepared environment that includes decorticated bony surfaces, compressive forces between graft and native bone, and limited motion. To achieve posterior atlantoaxial arthrodesis, various cable-and-graft constructs have been used, all of which require an intact posterior arch of C1. For patients who lack an intact arch owing to congenital, iatrogenic, or traumatic causes, we have devised the "lasso technique," which uses the remnants of the posterior arch of C1 for placement of the graft to achieve fusion isolated to C1-C2 or to be part of an occipitocervical construct.

METHODS

A retrospective record review was conducted of all patients who underwent the lasso technique. Clinical and radiographic history, perioperative course, and time to fusion were recorded. We describe the technique in detail.

RESULTS

During the last 13 years, we have used this technique successfully in five female and four male patients. The absent or incompetent posterior arch was a congenital defect in one patient, a result of prior surgical removal in four patients, and caused by fracture associated with prior failed fusion attempts in four other patients. All patients experienced successful fusion after an average of 6.8 months.

CONCLUSION

Securing a bone graft in the absence of an intact C1 lamina is a challenge when a patient presents with atlantoaxial instability. We have devised the lasso technique to secure an interpositional C1-C2 graft using the remnants of the posterior atlantal arch. Although this technique has been required relatively infrequently, we have found it to be valuable and effective in our practice.

CT analysis of the axis for transarticular screw fixation of rheumatoid atlantoaxial instability

OBJECTIVE

To investigate the morphological characteristics of the axis of rheumatoid arthritis (RA) patients with atlantoaxial instability and to determine, by means of sagittal reconstructed computed tomography (CT), the suitability for atlantoaxial transarticular screw fixation.

DESIGN AND PATIENTS

Twenty-seven patients, who had undergone reconstructed cervical spine CT scanning preoperatively and posterior atlantoaxial arthrodesis for atlantoaxial instability, were identified from a database for inclusion in this study. The isthmus height and internal height of the lateral mass of the axis were measured using digital imaging software.

RESULTS

The mean isthmus height and internal height of the lateral mass of the axis in RA patients (n=14) were significantly lower than in non-RA patients (n=13) (P<0.01). A high-riding vertebral artery (VA) was present in 54% (15 joints, 9 patients) of the 28 atlantoaxial joints in the RA group and in 12% (3 joints, 2 patients) of the 26 atlantoaxial joints in the non-RA group (P<0.01).

CONCLUSIONS

In RA patients, the axis showed more extensive thinning of the isthmus and lateral mass than in non-RA patients. A precise preoperative evaluation of screw trajectory using reconstruction CT imaging may be useful in atlantoaxial transarticular fixation, particularly for RA patients with atlantoaxial instability.

Die rheumatisch bedingte Instabilität der oberen Halswirbelsäule

Rheumatic manifestation at the cervical spine occurs in more than 50% of all cases in the natural course of this disease. The first cervical manifestation takes place in the upper cervical spine. The initial involvement of the C1/C2 segment leads to atlantodental subluxation. Progressive destruction can result in vertical instability, which is characterized by cranial subluxation of the odontoid process with the danger of resulting stenosis and cervical myelopathy. The goal of diagnosis has to be the early recognition of these changes to establish an effective treatment protocol. Persistent pain, neurological deficits, and progressive radiological signs for instability are indications for operative stabilizing procedures. These procedures avoid progressive destruction and improve the prognosis regarding pain decrease, regression of neurological deficits, and life expectancy.