Does isolated atlantoaxial fusion result in better clinical outcome compared to occipitocervical fusion?

Advances in surgical treatment for atlantoaxial instability focusing on rheumatoid arthritis: Analysis of a series of 67 patients

AIM

An estimated 88% of rheumatoid arthritis (RA) patients experience various degrees of cervical spine involvement. The excessive movement of the atlantoaxial joint, which connects the occiput to the upper cervical spine, results in atlantoaxial instability (AAI). AAI stabilization is usually achieved by C1 lateral mass-to-C2 pedicle screw-rod fixation (LC1-PC2 fixation), which is technically challenging in RA patients who often show destructive changes in anatomical structures. This study aimed to analyze the clinical results and operative experiences of C1-C2 surgery, with emphasis on the advancement of image-guided surgery and augmented reality (AR) assisted navigation.

METHODS

We presented our two decades of experience in the surgical management of AAI from April 2004 to November 2022.

RESULTS

We have performed surgery on 67 patients with AAI, including 21 traumatic odontoid fractures, 20 degenerative osteoarthritis, 11 inflammatory diseases of RA, 5 congenital anomalies of the os odontoideum, 2 unknown etiologies, 2 movement disorders, 2 previous implant failures, 2 osteomyelitis, 1 ankylosing spondylitis, and 1 tumor. Beginning in 2007, we performed LC1-PC2 fixation under C-arm fluoroscopy. As part of the progress in spinal surgery, since 2011 we used surgical navigation from presurgical planning to intraoperative navigation, using the preoperative computed tomography (CT) -based image-guided BrainLab navigation system. In 2021, we began using intraoperative CT scan and microscope-based AR navigation.

CONCLUSION

The technical complexities of C1-C2 surgery can be mitigated by CT-based image-guided surgery and microscope-based AR navigation, to improve accuracy in screw placement and overall clinical outcomes, particularly in RA patients with AAI.

Radiographic measurements for the prediction of dysphagia after occipitocervical fusion: a systematic review

BACKGROUND

Occipitocervical fusion (OCF) is a procedure performed for multiple upper cervical pathologies. A common postprocedural complication of OCF is dysphagia, which has been linked to the narrowing of the pharyngeal space due to fixation in a hyper-flexed angle. Postoperative dysphagia is linked to reduced quality of life, prolonged hospital stay, aspiration pneumonia, and increased mortality. This has led to investigations of the association between sagittal radiographic angles and dysphagia following OCF.

METHODS

A systematic review of the literature was performed to explore the current evidence regarding cervical sagittal radiographic measurements and dysphagia following OCF. A search strategy was carried out using the PubMed, Embase, and Web of Science databases from their dates of inception until August 2022. Only original English-language studies were considered. Moreover, studies had to include the correlation between dysphagia and at least one radiographic measurement in the sagittal plane.

RESULTS

The search and subsequent selection process yielded eight studies that were included in the final review, totaling 329 patients in whom dysphagia had been assessed and graded. The dysphagia score by Bazaz et al. (Spine 27, 22:2453-2458, 2002) was used most often. The pooled incidence of dysphagia, in the early postoperative period, was estimated at 26.4%. At long-term follow-up (range: 17-72 months), about one-third of patients experienced resolution of symptoms, which resulted in a long-term post-OCF dysphagia incidence of 16.5%. Across the studies included, six different radiographic parameters were used to derive several measures which were repeatedly and significantly associated with the occurrence of dysphagia.

CONCLUSIONS

The high incidence of postoperative dysphagia following OCF warrants close monitoring of patients, especially in the short-term postoperative period. These patients may be assessed through standardized tools where the one by Bazaz et al. was the most commonly used. Moreover, there are several radiographic measurements that can be used to predict the occurrence of dysphagia. These findings may serve as a basis for strategies to prevent the occurrence of dysphagia after OCF.

Anatomical Parameters for Occipital Condyle Screws: An Analysis of 500 Condyles Using CT Scans

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

To establish occipital condyle dimensions (length, width, height), as well as the medialization angle necessary for safe occipital condyle screw placement in occipitocervical fixation.

METHODS

Between 1/2014-6/2014, patients who presented to a single level 1 academic trauma center emergency room and received computed tomography (CT) imaging of the cervical spine as part of routine clinical care were identified. After excluding patients with cervical fractures, neoplastic disease, or infection, 500 condyles representing 250 patients were analyzed. Condyle length, height, and width (all reported in millimeters [mm]) were evaluated on the sagittal, coronal, and axial series, respectively. Medialization angle (reported in degrees) was evaluated on the axial series of CT imaging. Measurements were compared by sex and age.

RESULTS

The average condyle length, width, and height were 18.6 millimeters (mm) (range, 14.5-23.0 mm), 10.5 mm (range, 7.4-13.8 mm), and 11.3 mm (7.1-15.3 mm), respectively. Additionally, the average occipital condyle medialization angle was 23° (range, 14-32°). Occipital condyles of men were significantly longer, wider, and taller (all comparisons, p < 0.05). The medialization angle was significantly steeper for women than men (p < 0.05). No measurement differences were appreciated by age.

CONCLUSION

Our findings are similar to previous studies in the field; however, length appears slightly shorter. Further, measurement differences were appreciated by sex but not age. Thus, our measurement findings emphasize the importance of preoperative planning utilizing individual patient anatomy to ensure safe placement of occipital condyle screws for optimal outcomes.

Robot-assisted atlantoaxial fixation: illustrative cases

BACKGROUND

Placing screws in the high cervical spine can be challenging because of the vital anatomical structures located in that region. Precision and accuracy with screw placement is needed. The use of robotics in the cervical spine has been described before; however, here the authors describe the use of a new robotic setup.

OBSERVATIONS

The authors describe 2 cases of robot-assisted placement of C2 pars screws and C1–2 transarticular screws. The operative plans for each patient were as follows: placement of C2 pars screws with C2–4 fusion for hangman’s fracture and placement of C1–2 transarticular screws for degenerative disease. Intraoperative computed tomography (CT) was used to plan and navigate the screws. Postoperative CT showed excellent placement of hardware. Both patients presented for initial postoperative clinic visits with no recurrence of prior symptoms.

LESSONS

Intraoperative robotic assistance with instrumentation of the high cervical spine, particularly C2 pars and C1–2 transarticular screws, may ensure proper screw placement and help avoid injury.

Feasibility of 3.5mm C2 pedicle screws in children: Part II, a computerized tomography analysis

BACKGROUND

There have been no studies with large sample sizes on growth of the pedicle of C2 in children. In the present study we measured the pedicle of C2 through computed tomography (CT) imaging in children aged less than 14 years and evaluated the suitability of the 3.5-mm screw for the pedicle in such children.

METHODS

The study was conducted on CT morphometric images of 420 children in our hospital between June 2018 and June 2020. The width (D1), length (D2), height (D3), inclination angle (α), and tail angle (β) of the C2 pedicle were measured. One-way analysis of variance and Student's t test were used for statistical analyses. The least-square method was used to analyze the curve fitting the trend of anatomical change in the pedicle. The largest degree of goodness of fit determined the best-fitting curve.

RESULTS

The size of the pedicle of C2 increased with age. The median ranges of D1, D2, D3, α, and β were 3.312-5.431 mm, 11.732-23.645 mm, 3.597-8.038 mm, 32.583°-36.640°, and 24.867°-31.567°, respectively. The curves fitting the trends of D1 and D3 were power functions, whereas D2 was fitted by a logarithmic curve. However, no curve fitted α or β.

CONCLUSION

A 3.5-mm screw can be placed in the pedicle of C2 in children aged more than one year. The growth and development trend of this pedicle can provide an anatomical reference for deciding on posterior cervical surgery and for selecting and designing pedicle screws for children.

Occipitocervical Revision Surgery Using the Bicortical Screw and Plate System for Failed Craniovertebral Junction Stabilization

Background

To evaluate the clinical efficacy and safety of the modified technique utilizing the occipital bicortical screws and plate system in occipitocervical revision surgery.

Methods

Between October 2010 and May 2018, 12 consecutive patients were retrospectively evaluated. All patients had posterior occipitocervical resurgery utilizing modified technique of bicortical screws and occipital plate. The measurements of extracranial occiput on midline were conducted on computed tomography (CT) scans. The thickness of the occipital bone at the location of external occipital protuberance and below 15 mm were evaluated, respectively. For the procedure, the trajectory was drilled perpendicular to the external occipital protuberance for the specified depth with a depth‐limited drilling, 2 mm away from the internal bone plate, then the trajectory was deepened at intervals of 1 mm each time until reaching the internal bone plate. Meanwhile, a probe was used to explore all the walls of the trajectory. Bicortical screws were inserted to the occipital plate and the depth of penetration was less than 2 mm from the internal bone plate. Clinical efficacy and radiographic evaluation were followed up.

Results

The thickest point was the external occipital protuberance, which was 15.49 ± 1.47 mm and decreased gradually on the midline to 13.41 ± 1.60 mm at below 15 mm. Twelve cases (mean age 41.17 years; range, 24–62 years), including five males and seven females, were followed up for 24.08 months (14–32 months). The interval time was 40.42 months (3–156 months) after the initial operation. At the final follow‐up, JOA score increased from 8.58 ± 2.53 before surgery to 12.67 ± 1.84 (P < 0.05) and VAS score improved from 6.17 ± 1.21 to 2.08 ± 1.32 (P < 0.05). Besides, clinical symptoms were relieved in all patients after revision surgery. All patients had rigid internal fixations with bone fusion and no major complications occurred.

Conclusions

Posterior occipitocervical plate‐screw system with bicortical screws had the advantages of safety, simple and promising efficacy without excessive tissue release or intraspinal manipulation, proving that it's valuable as a modified technique for occipitocervical revision surgery.

The relationship between radiologic parameters and transverse atlantal ligament injury obtained from MRI scans in patients with an isolated atlas burst fracture: A retrospective observational study

The treatment of an atlas burst fracture depends on whether transverse atlantal ligament (TAL) injury is present. We compared the radiologic parameters associated with the presence of a TAL injury as detected using magnetic resonance imaging (MRI), and verified whether the lateral mass displacement (LMD) criteria currently used to diagnose TAL injuries in atlas burst fractures are reliable or need revision.Thirty patients who presented with isolated atlas burst fractures were included in this retrospective observational study. We measured radiologic parameters, including LMD, atlanto-dental interval, basion-dens interval, internal lateral mass displacement, and external lateral mass displacement, in each patient at the time of initial presentation. The presence of TAL injury was evaluated using MRI. We compared the radiologic parameters and characteristics of patients who presented with TAL injury. We also determined the sensitivity and specificity of an LMD test to accurately diagnose TAL injury based on MRI. Finally, we compared the radiologic parameters according to the presence of surgical treatment and patient union status.Twenty patients presented with an intact TAL, while 10 patients had a TAL injury on MRI. LMD was significantly higher in patients with TAL injury (9.61 vs 3.73 mm, P < .001). In multivariable logistic regression analysis, LMD was also significantly higher in patients with TAL injury. The sensitivity and specificity of LMD for diagnosing TAL injury based on MRI in patients with isolated C1 fractures were 90% and 100%, respectively. The incidence of an LMD greater than 8.1 mm was statistically higher in patients than in those without TAL injury (90% vs 0%, P < .001).Nine patients underwent surgery for isolated atlas burst fractures, and 21 did not. LMD (9.56 vs 4.03 mm, P < .001) and fracture gap (7.96 vs 4.01 mm, P < .001) were significantly higher in patients who underwent surgery.Among the various radiologic parameters, LMD closely correlated with the presence of TAL injury, as patients with an LMD greater than 8.1 mm were more likely to have a TAL injury in the case of atlas burst fractures. LMD is a good method for predicting the presence of TAL injury if MRI is not available.

Complications of occipitocervical fixation: retrospective review of 128 patients with 5-year mean follow-up

PURPOSE

Occipitocervical fusion is necessary for many pathologies of the craniocervical junction. The anatomy of the region is unique, and fusion can cause significant morbidity. This retrospective review aims to investigate the complication rates and outcomes of occipitocervical fixation.

MATERIAL AND METHODS

This is a retrospective review of 128 patients with occipitocervical fixation operated between 1994 and 2020. The average follow-up is 63 months.

RESULTS

The indications of occipitocervical fixation were basilar invagination (53 patients; 41.4%), trauma (25 patients; 19.5%), tumor (23 patients; 18%), instability due to rheumatoid arthritis (13 patients; 10.2%), cervical deformity (7 patients; 5.5%) and os odontoideum (7 patients; 5.5%). There were six early postoperative (1st month) deaths. We observed complications in 67 patients (52%). Most common complication was implant-related (32%), followed by wound problems (23.4%), systemic and other complications (11.7%), neurologic complications (6.2%). Implants are removed in 31 patients (24%) for different reasons: deep wound infection (7), local pain and restriction of head movements (21), respiratory distress and swallowing problems (2), screw fracture and local pain (1).

CONCLUSIONS

Occipitocervical fixation has quite large number of complications and significantly restricts head movements. With the advent of our biomechanical concepts, indications should be limited, and shorter cervical fixations should be preferred.

LEVEL OF EVIDENCE

Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Staged Repositioning in Endoscopic Endonasal Odontoidectomy Maximizes Decompression While Allowing Preservation of the C1 Anterior Arch: A Technical Note

BACKGROUND

Preservation of the anterior arch of C1 in endoscopic endonasal odontoidectomy has been proposed as an alternative to complete C1 arch resections, potentially affording less destabilization of the craniocervical junction. Nonetheless, this approach may limit the decompression achieved. In this case, intraoperative repositioning allowed maximal decompression while preserving the anterior arch of C1.

METHODS

A 79-year-old woman presented with suboccipital pain caused by an expansile and compressive mass centered on the dens. Notably, the mass occluded both vertebral arteries resulting in small cerebellar strokes. An endoscopic endonasal approach for diagnosis and decompression was performed followed by posterior fixation.

RESULTS

Given the significant compression, the patient was initially positioned in slight cervical extension. After rhinopharyngeal flap harvest, the top half of the anterior arch of C1 was resected, maintaining its structural integrity. The odontoidectomy was completed flush to the superior border of the reduced C1 arch. After an intraoperative computed tomography (CT) scan, performed in a neutral position, the patient was then repositioned with cervical flexion. This maneuver presented the residual odontoid above the C1 arch, but, given the partial removal of the dens, it did not result in any change in neuromonitoring. Further odontoid resection was then completed and follow-up CT scan revealed maximal dens removal, extending below the C1 anterior arch in neutral position.

CONCLUSIONS

In cases of odontoid/atlantoaxial pathology causing significant neural compression, staged intraoperative repositioning can safely maximize the odontoidectomy, while affording preservation of the structural integrity of the anterior arch of C1.

Atlantoaxial Stabilization by Posterior C1 and C2 Screw-Rod Fixation for Various Pathologies: Case Series and Comprehensive Review of Literature

We retrospectively analyzed atlantoaxial dislocation (AAD) of various pathologies, namely, rheumatoid arthritis (RA), os odontoideum, and trauma. Various techniques were discussed in relation to C1-C2 stabilization. The study aims to share our clinical experience in a series of six cases of C1-C2 instability that underwent posterior C1-C2 fusion, with free hand technique and limited fluoroscopy. The clinicoradiological presentation for each patient is described. We reviewed different literatures related to our case vividly and focused on the basic neuroanatomy involved in the atlantoaxial joint. All patients of AAD had evidence of severe canal compromise and chronic compressive spinal cord changes. In our study, the patients age ranged from 28 to 52 years. The study included four males and two females. Out of six patients of AAD, three had history of trauma, two had os odontoideum, and one had chronic inflammatory condition (RA). From our case series, we concluded that the Goel-Harms technique is the most versatile and surgeon friendly technique for C1-C2 fixation. Early recognition and surgical intervention of atlantoaxial joint instability is essential to prevent catastrophic neurological complications.

Postoperative complication rates and hazards-model survival analysis of revision surgery following occipitocervical and atlanto-axial fusion

Background

Methods

Results

Conclusions