Unilateral C-1 posterior arch screws and C-2 laminar screws combined with a 1-side C1–2 pedicle screw system as salvage fixation for atlantoaxial instability

OBJECT Atlantoaxial instability often requires surgery, and the current methods for fixation pose some risk to vascular and neurological tissues. Thus, new effective and safer methods are needed for salvage operations. This study sought to assess unilateral C-1 posterior arch screws (PASs) and C-2 laminar screws (LSs) combined with 1-side C1–2 pedicle screws (PSs) for posterior C1–2 fixation using biomechanical testing with bilateral C1–2 PSs in a cadaveric model. METHODS Six fresh ligamentous human cervical spines were evaluated for their biomechanics. The cadaveric specimens were tested in their intact condition, stabilization after injury, and after injury at 1.5 Nm of pure moment in 6 directions. The 3 groups tested were bilateral C1–2 PSs (Group A); left side C1–2 PSs with an ipsilateral C-1 PAS + C-2 laminar screw (Group B); and left side C1–2 PSs with a contralateral C-1 PAS + C-2 LS (Group C). During the testing, angular motion was measured using a motion capture platform. Data were recorded, and statistical analyses were performed. RESULTS Biomechanical testing showed that there was no significant difference among the stabilities of these fixation systems in flexion-extension and rotation control. In left lateral bending, the bilateral C1–2 PS group decreased flexibility by 71.9% compared with the intact condition, the unilateral C1–2 PS and ipsilateral PAS+LS group decreased flexibility by 77.6%, and the unilateral C1–2 PS and contralateral PAS+LS group by 70.0%. Each method significantly decreased C1–2 movements in right lateral bending compared with the intact condition, and the bilateral C1–2 PS system was more stable than the C1–2 PS and contralateral PAS+LS system (p = 0.036). CONCLUSIONS A unilateral C-1 PAS + C-2 LS combined with 1-side C-1 PSs provided the same acute stability as the PS, and no statistically significant difference in acute stability was found between the 2 screw techniques. These methods may constitute an alternative method for posterior atlantoaxial fixation.

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Biomechanical comparison of a C1 posterior arch clamp with C1 lateral mass screws in constructs for C1-C2 fusion

Proceedings of the Institution of Mechanical Engineers Part H Journal of Engineering in Medicine ◽

10.1177/09544119211032479 ◽

2021 ◽

pp. 095441192110324

Author(s):

Timothy L Lasswell ◽

John B Medley ◽

Jack P Callaghan ◽

Duane S Cronin ◽

Colin D McKinnon ◽

...

Keyword(s):

Axial Rotation ◽

Atlantoaxial Instability ◽

Posterior Arch ◽

Lateral Mass ◽

Lateral Bending ◽

Intact State ◽

Significant Difference ◽

Flexion Extension ◽

Translaminar Screw ◽

Fresh Frozen

The aim of this experimental study was to assess the biomechanical performance of a novel C1 posterior arch (C1PA) clamp compared with C1 lateral mass (C1LM) screws in constructs used to treat atlantoaxial instability. These constructs had either C2 pedicle (C2P) screws or C2 translaminar (C2TL) screws. Eight fresh-frozen human cadaveric ligamentous spine specimens (C0-C3) were tested under six conditions: the intact state, the destabilized state after a simulated odontoid fracture, and when instrumented with four constructs (C1LM-C2P, C1LM-C2TL, C1PA-C2P, C1PA-C2TL). Each specimen was tested in a spinal loading simulator that separately applied axial rotation, flexion-extension and lateral bending. In each test condition, displacement controlled angular motion was applied in both directions at a speed of 2 deg/s until a resulting moment of 1.5 Nm was achieved. The measured ranges of motion (ROM) of the C1-C2 segments were compared for each test condition using nonparametric Friedman tests. The destabilized state had significantly more C1-C2 motion ( p < 0.05) than the intact state in all cases, and all constructs greatly reduced this motion. C2 pedicle screw constructs that used the C1PA clamp had significantly less C1-C2 motion ( p < 0.05) than those with C1LM screws in flexion-extension as well as axial rotation and no statistically significant difference was detected in lateral bending. C2 translaminar screw constructs that used the C1PA clamp had significantly less C1-C2 motion ( p < 0.05) than those with C1LM screws in flexion-extension and no statistically significant difference was detected in axial rotation or in lateral bending. Data from the current study suggested that constructs using the novel C1PA clamp would provide as good, or improved, biomechanical stability to the C1-C2 segment compared with constructs using C1LM screws.

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Atlantoaxial fixation using C1 posterior arch screws: feasibility study, morphometric data, and biomechanical analysis

Journal of Neurosurgery Spine ◽

10.3171/2018.8.spine18160 ◽

2019 ◽

Vol 30 (3) ◽

pp. 314-322 ◽

Cited By ~ 1

Author(s):

Gilbert Cadena ◽

Huy T. Duong ◽

Jonathan J. Liu ◽

Kee D. Kim

Keyword(s):

Biomechanical Testing ◽

Axial Rotation ◽

Biomechanical Analysis ◽

Posterior Arch ◽

Lateral Mass ◽

Morphometric Data ◽

Lateral Bending ◽

Freehand Technique ◽

Flexion Extension ◽

Low Incidence

OBJECTIVEC1–2 is a highly mobile complex that presents unique surgical challenges to achieving biomechanical rigidity and fusion. Posterior wiring methods have been largely replaced with segmental constructs using the C1 lateral mass, C1 pedicle, C2 pars, and C2 pedicle. Modifications to reduce surgical morbidity led to the development of C2 laminar screws. The C1 posterior arch has been utilized mostly as a salvage technique, but recent data indicate that this method provides significant rigidity in flexion-extension and axial rotation. The authors performed biomechanical testing of a C1 posterior arch screw (PAS)/C2 pars screw construct, collected morphometric data from a population of 150 CT scans, and performed a feasibility study of a freehand C1 PAS technique in 45 cadaveric specimens.METHODSCervical spine CT scans from 150 patients were analyzed to determine the average C1 posterior tubercle thickness and size of C1 posterior arches. Eight cadavers were used to compare biomechanical stability of intact specimens, C1 lateral mass/C2 pars screw, and C1 PAS/C2 pars screw constructs. Paired comparisons were made using repeated-measures ANOVA and Holm-Sidak tests. Forty-five cadaveric specimens were used to demonstrate the feasibility and safety of the C1 PAS freehand technique.RESULTSMorphometric data showed the average craniocaudal thickness of the C1 posterior tubercle was 12.3 ± 1.94 mm. Eight percent (12/150) of cases showed thin posterior tubercles or midline defects. Average posterior arch thickness was 6.1 ± 1.1 mm and right and left average posterior arch length was 28.7 mm ± 2.53 mm and 28.9 ± 2.29 mm, respectively. Biomechanical testing demonstrated C1 lateral mass/C2 pars and C1 PAS/C2 pars constructs significantly reduced motion in flexion-extension and axial rotation compared with intact specimens (p < 0.05). The C1 lateral mass/C2 pars screw construct provided significant rigidity in lateral bending (p < 0.05). There was no statistically significant difference between the two constructs in flexion-extension, lateral bending, or axial rotation. Of the C1 posterior arches, 91.3% were successfully cannulated using a freehand technique with a low incidence of cortical breach (4.4%).CONCLUSIONSThis biomechanical analysis indicates equivalent stability of the C1 PAS/C2 pars screw construct compared with a traditional C1 lateral mass/C2 pars screw construct. Both provide significant rigidity in flexion-extension and axial rotation. Feasibility testing in 45 cadaveric specimens indicates a high degree of accuracy with low incidence of cortical breach. These findings are supported by a separate radiographic morphometric analysis.

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Cervical pedicle screws fixation treatment the atlantoaxial instability of axis burst fractures

10.21203/rs.2.23830/v1 ◽

2020 ◽

Author(s):

Denglu Yan ◽

Zaiheng Zhang ◽

Zhi Zhang

Keyword(s):

Clinical Outcomes ◽

Pedicle Screws ◽

Atlantoaxial Instability ◽

Burst Fractures ◽

Significant Difference ◽

Flexion Extension ◽

Fixation Treatment ◽

Cervical Pedicle ◽

Cervical Pedicle Screws

Abstract BackgroundAlthough the cervical pedicle screws and rods were used for atlantoaxial instable, the axis fractures still a challenge for spine surgeon.ObjectiveThis study was to evaluated the clinical outcomes of axis burst fractures had C1C3 pedicles screws fixation treatment.MethodsFrom June 2014 to July 2018, 45 patients with axis fractures were enrolled in this study; 23 patients was odontoid underwent C1C2 pedicles screws fixation, and 21 patients was odontoid combine body fractures had C1C3 pedicles screws fixation. The clinical outcomes of pain relief (visual analog scale, VAS), functional disability (neck disability index, NDI) were recorded at baseline and at the final follow-up.ResultsThe pain index and NDI were all significantly improved when compared to pretreatment (P < 0.01). The VAS and ND were no significant difference between two groups (P > 0.05). All patients, suffered from severe mechanical upper cervical neck pain at pre-operative, were pain free post-operation. Pre-operative neurological examination was normal in all patients, and remained the same after surgery. All cases showed normal neurological function at the final follow-up. No vascular or neurological complication was noted. The fracture healing and the bony union of the fixed segments were revealed in all cases on CT views. Implant failure and instability were not seen on lateral flexion/extension radiographs of the cervical spine.ConclusionsCervical pedicle screws fixation was effective and safe procedures in the treatment of traumatic spondylolisthesis of axial fractures. The atlantoaxial instable of axis burst fractures can be managed with C1-C3 pedicles screws fixation.

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Biomechanical evaluation of lumbar pedicle screws in spondylolytic vertebrae: comparison of fixation strength between the traditional trajectory and a cortical bone trajectory

Journal of Neurosurgery Spine ◽

10.3171/2015.11.spine15926 ◽

2016 ◽

Vol 24 (6) ◽

pp. 910-915 ◽

Cited By ~ 19

Author(s):

Keitaro Matsukawa ◽

Yoshiyuki Yato ◽

Hideaki Imabayashi ◽

Naobumi Hosogane ◽

Takashi Asazuma ◽

...

Keyword(s):

Cortical Bone ◽

Pedicle Screws ◽

Axial Rotation ◽

Fixation Strength ◽

Isthmic Spondylolisthesis ◽

Pullout Strength ◽

Lateral Bending ◽

Cortical Bone Trajectory ◽

Significant Difference ◽

Flexion Extension

OBJECTIVE In the management of isthmic spondylolisthesis, the pedicle screw system is widely accepted surgical strategy; however, there are few reports on the biomechanical behavior of pedicle screws in spondylolytic vertebrae. The purpose of the present study was to compare fixation strength between pedicle screws inserted through the traditional trajectory (TT) and those inserted through a cortical bone trajectory (CBT) in spondylolytic vertebrae by computational simulation. METHODS Finite element models of spondylolytic and normal vertebrae were created from CT scans of 17 patients with adult isthmic spondylolisthesis (mean age 54.6 years, 10 men and 7 women). Each vertebral model was implanted with pedicle screws using TT and CBT techniques and compared between two groups. First, fixation strength of a single screw was evaluated by measuring axial pullout strength. Next, vertebral fixation strength of a paired-screw construct was examined by applying forces simulating flexion, extension, lateral bending, and axial rotation to vertebrae. RESULTS Fixation strengths of TT screws showed a nonsignificant difference between the spondylolytic and the normal vertebrae (p = 0.31–0.81). Fixation strength of CBT screws in the spondylolytic vertebrae demonstrated a statistically significant decrease in pullout strength (21.4%, p < 0.01), flexion (44.1%, p < 0.01), extension (40.9%, p < 0.01), lateral bending (38.3%, p < 0.01), and axial rotation (28.1%, p < 0.05) compared with those in the normal vertebrae. In the spondylolytic vertebrae, no statistically significant difference was observed for pullout strength between TT and CBT (p = 0.90); however, the CBT construct showed lower vertebral fixation strength in flexion (39.0%, p < 0.01), extension (35.6%, p < 0.01), lateral bending (50.7%, p < 0.01), and axial rotation (59.3%, p < 0.01) compared with the TT construct. CONCLUSIONS CBT screws are less optimal for stabilizing the spondylolytic vertebra due to their lower fixation strength compared with TT screws.

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Biomechanical evaluation of lateral lumbar interbody fusion with secondary augmentation

Journal of Neurosurgery Spine ◽

10.3171/2016.4.spine151386 ◽

2016 ◽

Vol 25 (6) ◽

pp. 720-726 ◽

Cited By ~ 14

Author(s):

Marco T. Reis ◽

Phillip M. Reyes ◽

Idris Altun ◽

Anna G. U. S. Newcomb ◽

Vaneet Singh ◽

...

Keyword(s):

Interbody Fusion ◽

Pedicle Screws ◽

Axial Rotation ◽

Lumbar Interbody Fusion ◽

Lateral Bending ◽

Lateral Lumbar Interbody Fusion ◽

Significant Difference ◽

Flexion Extension ◽

Supplemental Fixation ◽

The Stability

OBJECTIVE Lateral lumbar interbody fusion (LLIF) has emerged as a popular method for lumbar fusion. In this study the authors aimed to quantify the biomechanical stability of an interbody implant inserted using the LLIF approach with and without various supplemental fixation methods, including an interspinous plate (IP). METHODS Seven human cadaveric L2–5 specimens were tested intact and in 6 instrumented conditions. The interbody implant was intended to be used with supplemental fixation. In this study, however, the interbody was also tested without supplemental fixation for a relative comparison of these conditions. The instrumented conditions were as follows: 1) interbody implant without supplemental fixation (LLIF construct); and interbody implant with supplemental fixation performed using 2) unilateral pedicle screws (UPS) and rod (LLIF + UPS construct); 3) bilateral pedicle screws (BPS) and rods (LLIF + BPS construct); 4) lateral screws and lateral plate (LP) (LLIF + LP construct); 5) interbody LP and IP (LLIF + LP + IP construct); and 6) IP (LLIF + IP construct). Nondestructive, nonconstraining torque (7.5 Nm maximum) induced flexion, extension, lateral bending, and axial rotation, whereas 3D specimen range of motion (ROM) was determined optoelectronically. RESULTS The LLIF construct reduced ROM by 67% in flexion, 52% in extension, 51% in lateral bending, and 44% in axial rotation relative to intact specimens (p < 0.001). Adding BPS to the LLIF construct caused ROM to decrease by 91% in flexion, 82% in extension and lateral bending, and 74% in axial rotation compared with intact specimens (p < 0.001), providing the greatest stability among the constructs. Adding UPS to the LLIF construct imparted approximately one-half the stability provided by LLIF + BPS constructs, demonstrating significantly smaller ROM than the LLIF construct in all directions (flexion, p = 0.037; extension, p < 0.001; lateral bending, p = 0.012) except axial rotation (p = 0.07). Compared with the LLIF construct, the LLIF + LP had a significant reduction in lateral bending (p = 0.012), a moderate reduction in axial rotation (p = 0.18), and almost no benefit to stability in flexion-extension (p = 0.86). The LLIF + LP + IP construct provided stability comparable to that of the LLIF + BPS. The LLIF + IP construct provided a significant decrease in ROM compared with that of the LLIF construct alone in flexion and extension (p = 0.002), but not in lateral bending (p = 0.80) and axial rotation (p = 0.24). No significant difference was seen in flexion, extension, or axial rotation between LLIF + BPS and LLIF + IP constructs. CONCLUSIONS The LLIF construct that was tested significantly decreased ROM in all directions of loading, which indicated a measure of inherent stability. The LP significantly improved the stability of the LLIF construct in lateral bending only. Adding an IP device to the LLIF construct significantly improves stability in sagittal plane rotation. The LLIF + LP + IP construct demonstrated stability comparable to that of the gold standard 360° fixation (LLIF + BPS).

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Biomechanics of C-7 transfacet screw fixation

Journal of Neurosurgery Spine ◽

10.3171/2009.3.spine08785 ◽

2009 ◽

Vol 11 (3) ◽

pp. 338-343 ◽

Cited By ~ 6

Author(s):

Eric M. Horn ◽

Phillip M. Reyes ◽

Seungwon Baek ◽

Mehmet Senoglu ◽

Nicholas Theodore ◽

...

Keyword(s):

Pedicle Screw ◽

Normal Condition ◽

Small Diameter ◽

Pedicle Screws ◽

Axial Rotation ◽

Lateral Bending ◽

Screw Insertion ◽

Loading Mode ◽

Significant Difference ◽

Flexion Extension

Object The small diameter of the pedicle can make C-7 pedicle screw insertion dangerous. Although transfacet screws have been studied biomechanically when used in pinning joints, they have not been well studied when used as part of a C7–T1 screw/rod construct. The authors therefore compared C7–T1 fixation using a C-7 transfacet screw/T-1 pedicle screw construct with a construct composed of pedicle screws at both levels. Methods Each rigid posterior screw/rod construct was placed in 7 human cadaveric C6–T2 specimens (14 total). Specimens were tested in normal condition, after 2-column instability, and once fixated. Nondestructive, nonconstraining pure moments (maximum 1.5 Nm) were applied to induce flexion, extension, lateral bending, and axial rotation while recording 3D motion optoelectronically. The entire construct was then loaded to failure by dorsal linear force. Results There was no significant difference in angular range of motion between the 2 instrumented groups during any loading mode (p > 0.11, nonpaired t-tests). Both constructs reduced motion to < 2° in any direction and allowed significantly less motion than in the normal condition. The C-7 facet screw/T-1 pedicle screw construct allowed a small but significantly greater lax zone than the pedicle screw/rod construct during lateral bending, and it failed under significantly less load than the pedicle screw/rod construct (p < 0.001). Conclusions When C-7 transfacet screws are connected to T-1 pedicle screws, they provide equivalent stability of constructs formed by pedicle screws at both levels. Although less resistant to failure, the transfacet screw construct should be a viable alternative in patients with healthy bone.

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Is a cross-connector beneficial for single level traditional or cortical bone trajectory pedicle screw instrumentation?

PLoS ONE ◽

10.1371/journal.pone.0253076 ◽

2021 ◽

Vol 16 (6) ◽

pp. e0253076

Author(s):

Frédéric Cornaz ◽

Jonas Widmer ◽

Marie-Rosa Fasser ◽

Jess Gerrit Snedeker ◽

Keitaro Matsukawa ◽

...

Keyword(s):

Cortical Bone ◽

Pedicle Screws ◽

Axial Rotation ◽

Lateral Bending ◽

Cortical Bone Trajectory ◽

Single Level ◽

Significant Difference ◽

Flexion Extension ◽

Human Cadavers ◽

Minimal Reduction

The cortical bone trajectory (CBT) has been introduced with the aim of better screw hold, however, screw-rod constructs with this trajectory might provide less rigidity in lateral bending (LB) and axial rotation (AR) compared to the constructs with the traditional trajectory (TT). Therefore, the addition of a horizontal cross-connector could be beneficial in counteracting this possible inferiority. The aim of this study was to compare the primary rigidity of TT with CBT screw-rod constructs and to quantify the effect of cross-connector-augmentation in both. Spines of four human cadavers (T9 –L5) were cropped into 15 functional spine units (FSU). Eight FSUs were instrumented with TT and seven FSUs with CBT pedicle screws. The segments were tested in six loading directions in three configurations: uninstrumented, instrumented with and without cross-connector. The motion between the cranial and caudal vertebra was recorded. The range of motion (ROM) between the CBT and the TT group did not differ significantly in either configuration. Cross-connector -augmentation did reduce the ROM in AR (16.3%, 0.27°, p = 0.02), LB (2.9%, 0.07°, p = 0.03) and flexion-extension FE (2.3%, 0.04°, p = 0.02) for the TT group and in AR (20.6%, 0.31°, p = 0.01) for the CBT-group. The primary rigidity of TT and CBT single level screw-rod constructs did not show significant difference. The minimal reduction of ROM due to cross-connector-augmentation seems clinically not relevant. Based on the findings of these study there is no increased necessity to use a cross-connector in a CBT-construct.

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The Anatomical and Biomechanical Superiority of Novel Posterior En Bloc Elevation Cervical Laminoplasty

Surgical Innovation ◽

10.1177/1553350620984650 ◽

2021 ◽

pp. 155335062098465

Author(s):

Dong-Lai Wang ◽

Guo-Qing Zhu ◽

An-Quan Huang ◽

Hong Zhang ◽

Chuan Feng ◽

...

Keyword(s):

Biomechanical Testing ◽

Cervical Laminoplasty ◽

Open Door ◽

Lateral Bending ◽

En Bloc ◽

Cross Sectional ◽

Expansion Pattern ◽

Intact Condition ◽

Axial Symptoms ◽

The Common

Objectives. In this study, we performed a novel type of posterior en bloc elevation cervical laminoplasty (PEEL) to keep the integrity of the posterior structure, aiming to reduce axial symptoms complicated by a conventional cervical laminoplasty procedure. Methods. Twelve human cervical cadaveric spines (C2-T1) were sequentially tested in the following order: intact condition, open-door laminoplasty (ODL) through bilateral intermuscular approach (mini-invasive ODL), PEEL, and laminectomy (LN). After bilateral transecting at the junction of lamina and lateral mass through the tubular retraction system, the PEEL procedure symmetrically elevated all the posterior structure which was further stabilized with bone grafts and titanium plates. Computed tomography (CT) scan and biomechanical testing were performed after each condition. Results. Both mini-invasive ODL and PEEL procedures were accomplished with 2 small incisions on each side. Two types of laminoplasties could enlarge the spinal canal significantly both in cross-sectional area and anteroposterior diameter comparing with intact condition. The PEEL procedure demonstrated a significantly higher enlargement rate on a canal area and a symmetrical expansion pattern. Compared with intact condition, mini-invasive ODL performed from C3-C7 demonstrated significantly decreased motion in all testing directions except the flexion range of motion (ROM); the PEEL procedure showed mild and insignificant decrease on ROM in all directions. Laminectomy resulted in a statistically significant increase in all directions except the lateral bending ROM. Conclusions. Posterior en bloc elevation cervical laminoplasty can enlarge the canal more effectively and preserve better ROM after operation than the ODL procedure. Although technically challenging, the PEEL procedure probably would decrease the common complications associated with ODL laminoplasty.

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Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

Global Spine Journal ◽

10.1177/21925682211006061 ◽

2021 ◽

pp. 219256822110060

Author(s):

Jun-Xin Chen ◽

Yun-He Li ◽

Jian Wen ◽

Zhen Li ◽

Bin-Sheng Yu ◽

...

Keyword(s):

Intervertebral Disc ◽

Degrees Of Freedom ◽

Mechanical Stability ◽

Biomechanical Testing ◽

Bending Stiffness ◽

Biomechanical Study ◽

Torsional Stiffness ◽

P Value ◽

Lateral Bending ◽

Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

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Use of a titanium mesh cage for posterior atlantoaxial arthrodesis

Journal of Neurosurgery Spine ◽

10.3171/spi.2002.96.1.0127 ◽

2002 ◽

Vol 96 (1) ◽

pp. 127-130 ◽

Cited By ~ 4

Author(s):

Morio Matsumoto ◽

Kazuhiro Chiba ◽

Takashi Tsuji ◽

Hirofumi Maruiwa ◽

Yoshiaki Toyama ◽

...

Keyword(s):

Donor Site ◽

Atlantoaxial Instability ◽

Os Odontoideum ◽

Posterior Arch ◽

Rigid Fixation ◽

Titanium Mesh ◽

Content Type ◽

Atlantoaxial Fixation ◽

Mesh Cage ◽

Atlantoaxial Arthrodesis

✓ The authors placed titanium mesh cages to achieve posterior atlantoaxial fixation in five patients with atlantoaxial instability caused by rheumatoid arthritis or os odontoideum. A mesh cage packed with autologous cancellous bone was placed between the C-1 posterior arch and the C-2 lamina and was tightly connected with titanium wires. Combined with the use of transarticular screws, this procedure provided very rigid fixation. Solid fusion was achieved in all patients without major complications. The advantages of this method include more stable fixation, better control of the atlantoaxial fixation angle, and reduced donor-site morbidity compared with a conventional atlantoaxial arthrodesis in which an autologous iliac crest graft is used.

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