"Direct vision" operation of posterior atlantoaxial transpedicular screw fixation for unstable atlantoaxial fractures: A retrospective study

Accurate Placement and Revisions for Cervical Pedicle Screws Placed With or Without Navigation: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

To evaluate the accuracy of placement for cervical pedicle screws with and without the use of spinal navigation.

METHODS

A structured search was conducted in electronic databases without any language or date restrictions. Eligible studies reported the proportion of accurately placed cervical pedicle screws measured on intraoperative or postoperative 3D imaging, and reported whether intraoperative navigation was used during screw placement. Randomized Studies (MINORS) criteria were used to evaluate the methodological quality of how accuracy was assessed for cervical pedicle screws.

RESULTS

After screening and critical appraisal, 4697 cervical pedicle screws from 18 studies were included in the meta-analysis. The pooled proportion for cervical pedicle screws with a breach up to 2 mm was 94% for navigated screws and did not differ from the pooled proportion for non-navigated screws (96%). The pooled proportion for cervical pedicle screws placed completely in the pedicle was 76% for navigated screws and did not differ from the pooled proportion for non-navigated screws (82%). Intraoperative screw reposition rates and screw revision rates as a result of postoperative imaging also did not differ between navigated and non-navigated screw placement.

CONCLUSIONS

This systematic review and meta-analysis found that the use of spinal navigation systems does not significantly improve the accuracy of placement of cervical pedicle screws compared to screws placed without navigation. Future studies evaluating intraoperative navigation for cervical pedicle screw placement should focus on the learning curve, postoperative complications, and the complexity of surgical cases.

Efficacy and Safety of Goel-Harms Technique in Upper Cervical Spine Surgery: A Systematic Review and Meta-Analysis

OBJECTIVE

The main purpose of this systematic review and meta-analysis was to estimate the incidence of implant-associated complications and fusion rates for the Goel-Harms technique (GHT) and to show potential factors affecting the complications and nonunion development.

METHODS

A systematic search of the PubMed database according to PRISMA guidance was performed. The main inclusion criteria comprised description of fusion rate and/or implant-associated complications rate.

RESULTS

This systematic review included 86 articles focused on the results of surgery in 4208 patients. The rate of screw-related complications was as follows: 1) vertebral artery (VA) injury, 2.8%; 2) screw malposition in the direction of the VA, 5.8%; and 3) C2 nerve root irritation, 6.1%. The nonunion rate was 4.2%. Transpedicular screw insertion to the C1 and C2 vertebrae were the safest regarding VA injury and correlated with lower blood loss. For C1-C2 fusion, there was no statistical difference for the different bone graft localization. C2 nerve root irritation rate did not depend on screw insertion technique. The use of a freehand technique did not correlate with a high rate of screw-related complications.

CONCLUSIONS

The Goel-Harms technique is a promising method of C1-C2 fusion, with a relatively low nonunion and VA injury rate. It can be performed safely without C-arm or navigation system assistance. Transpedicular screw insertion trajectories to the C1 and C2 vertebrae were safest regarding VA injury and blood loss volume. Further comparative studies of various C1-C2 stabilization methods with a high level of significance should be carried out to identify the optimal approach.

Spiral CT measurement for atlantoaxial pedicle screw trajectory and its clinical application

OBJECTIVE

This study aimed to focus on the atlantoaxial pedicle screw placement and evaluate the effects of anatomical data and degree of surgical exposure of the atlantoaxial pedicle screw trajectory determined using spiral CT on the reference sites for pedicle screw insertion and various parameters in clinical application.

METHOD

The data of CT scan of cervical spine from individuals treated in our hospital were selected. Various anatomical parameters of the atlantoaxial pedicle screw trajectory were measured through multiplanar reconstruction (MPR) technology. Anatomical data and degree of surgical exposure of the atlantoaxial pedicle screw trajectory were obtained through spiral CT. Vernier calipers with least count of 0.01 mm was selected and the least count of the protractor was 0.2°. Prism 8.0 was adopted for graphical data analysis. The anatomical data of atlas of the local population were established. The measurement technique for pedicle screw trajectory and the method for pedicle screw insertion were mastered.

RESULTS

The results indicated that the intraoperative blood loss was between 30-280 ml with no case of excessive blood loss. Follow-up studies 10-18 months after the operations indicated stability of upper cervical spine without adverse conditions. The width of the pedicle screw was 13-24 mm, and the maximal inclination angle of the horizontal for the insertion was 17-21°.

CONCLUSION

The atlantoaxial pedicle screw placement was an effective surgical treatment for stabilizing the upper cervical spine. The measurement data of the atlantoaxial pedicle screw path was obtained through spiral CT and the surgical placement of pedicle screw was guided through individual data. Postoperative CT scan was adopted to evaluate the accuracy of pedicle screw placement, record the occurrence of secondary injuries, improve the stability of clinical applications, and reduce the risks for patients.

Clinical Outcomes of Atlantoaxial Dislocation Combined with Osteoporosis Using Posterior Atlantoaxial Rod, Screw Fixation, and Posterior Interfacet Fusion: A Retrospective Study of 21 Cases

Background

Surgical procedures on atlantoaxial dislocation combined with osteoporosis remain controversial. This study was established to assess the mid-term clinical outcomes of atlantoaxial dislocation combined with osteoporosis using posterior atlantoaxial rod, screw fixation and posterior interfacet fusion.

Material/Methods

From January 2017 to January 2020, 21 patients (4 males and 17 females) with coexisting atlantoaxial dislocation and osteoporosis who underwent posterior atlantoaxial rod and screw fixation were included in our study with an average age of 64±8.1 years (range, 57–74 years). The subjective and objective symptoms, together with the neurological function of the patients were measured. Radiography and magnetic resonance imaging (MRI) were performed, Japanese Orthopaedic Association (JOA) score for spinal cord function and VAS score for pain recovery was assessed.

Results

JOA and visual analog scale (VAS) score were significantly improved at 14±5.9 month follow-up compared with pretreatment values. Complete or almost complete anatomical reduction was observed in all 21 patients. All patients had good bony fusion at the final follow-up. No screw-loosening or atlantoaxial redislocation occurred in 21 cases. The only complication was mild numbness in the C2 innervation area of the posterior occipital region in 6 cases, which had no effect on life.

Conclusions

The results suggested that posterior atlantoaxial rod, screw fixation system, and posterior interfacet fusion could achieve satisfactory initial results for the treatment of atlantoaxial dislocation combined with osteoporosis.

Accuracy and safety of C2 pedicle or pars screw placement: a systematic review and meta-analysis

Study design

Systematic review and meta-analysis.

Aim

The purpose of this study was to compare the safety and accuracy of the C2 pedicle versus C2 pars screws placement and free-hand technique versus navigation for upper cervical fusion patients.

Methods

Databases searched included PubMed, Scopus, Web of Science, and Cochrane Library to identify all papers published up to April 2020 that have evaluated C2 pedicle/pars screws placement accuracy. Two authors individually screened the literature according to the inclusion and exclusion criteria. The accuracy rates associated with C2 pedicle/pars were extracted. The pooled accuracy rate estimated was performed by the CMA software. A funnel plot based on accuracy rate estimate was used to evaluate publication bias.

Results

From 1123 potentially relevant studies, 142 full-text publications were screened. We analyzed data from 79 studies involving 4431 patients with 6026 C2 pedicle or pars screw placement. We used the Newcastle-Ottawa Scale (NOS) to evaluate the quality of studies included in this review. Overall, funnel plot and Begg’s test did not indicate obvious publication bias. The pooled analysis reveals that the accuracy rates were 93.8% for C2 pedicle screw free-hand, 93.7% for pars screw free-hand, 92.2% for navigated C2 pedicle screw, and 86.2% for navigated C2 pars screw (all, P value < 0.001). No statistically significant differences were observed between the accuracy of placement C2 pedicle versus C2 pars screws with the free-hand technique and the free-hand C2 pedicle group versus the navigated C2 pedicle group (all, P value > 0.05).

Conclusion

Overall, there was no difference in the safety and accuracy between the free-hand and navigated techniques. Further well-conducted studies with detailed stratification are needed to complement our findings.

Design a novel integrated screw for minimally invasive atlantoaxial anterior transarticular screw fixation: a finite element analysis

PURPOSE

To design a new type of screw for minimally invasive atlantoaxial anterior transarticular screw (AATS) fixation with a diameter that is significantly thicker than that of traditional screws, threaded structures at both ends, and a porous metal structure in the middle. The use of a porous metal structure can effectively promote bone fusion and compensate for the disadvantages of traditional AATSs in terms of insufficient fixation strength and difficulty of bone fusion. The biomechanical stability of this screw was verified through finite element analysis. This instrument may provide a new surgical option for the treatment of atlantoaxial disorders.

METHODS

According to the surgical procedure, the new type of AATS was placed in a three-dimensional atlantoaxial model to determine the setting of relevant parameters such as the diameter, length, and thread to porous metal ratio of the structure. According to the results of measurement, the feasibility and safety of the new AATS were verified, and a representative finite element model of the upper cervical vertebrae was chosen to establish, and the validity of the model was verified. Then, finite element-based biomechanical analysis was performed using three models, i.e., atlantoaxial posterior pedicle screw fixation, traditional atlantoaxial AATS fixation, and atlantoaxial AATS fixation with the new type of screw, and the biomechanical effectiveness of the novel AATS was verified.

RESULTS

By measuring the atlantoaxial parameters, the atlantoaxial CT data of the representative 30-year-old normal adult male were selected to create a personalized 3D printing AATS screw. In this case, the design parameters of the new screw were determined as follows: diameter, 6 mm; length of the head thread structure, 10 mm; length of the middle porous metal structure, 8 mm (a middle porous structure containing an annular cylinder ); length of the tail thread structure, 8 mm; and total length, 26 mm. Applying the same load conditions to the atlantoaxial complex along different directions in the established finite element models of the three types of atlantoaxial fusion modes, the immediate stability of the new AATS is similar with Atlantoaxial posterior pedicle screw fixation.They are both superior to traditional atlantoaxial anterior screw fixation.The maximum local stress on the screw head in the atlantoaxial anterior surgery was less than those of traditional atlantoaxial anterior surgery.

CONCLUSIONS

By measuring relevant atlantoaxial data, we found that screws with a larger diameter can be used in AATS surgery, and the new AATS can make full use of the atlantoaxial lateral mass space and increase the stability of fixation. The finite element analysis and verification revealed that the biomechanical stability of the new AATS was superior to the AATS used in traditional atlantoaxial AATS fixation. The porous metal structure of the new AATS may promote fusion between atlantoaxial joints and allow more effective bone fusion in the minimally invasive anterior approach surgery.