Atlantoaxial instability (AAI) is surgically a complex entity due to its proximity to vital neurovascular structures. C1-C2 fusion has been an established standard in its treatment for a considerable time now. Here, we have outlined the most common techniques for C2 screw fixation in practice at present such as C2 pedicle, C2 pars, C2 translaminar, C2 subfacetal, C2-C3 transfacetal, and C2 inferior facet screw. We have discussed in detail the technical as well as biomechanical aspects of each technique of C2 screw fixation in AAI and explored the intricacies of each technique.

While osteoarthritis is a common degenerative disease, ankle osteoarthritis is a subdivision that has received little attention. Two effective ways to treat osteoarthritis of the ankle are total ankle replacement (TAR) and ankle arthrodesis (AAD). Whether TAR or AAD is more beneficial for treatment is controversial. The purpose of this meta-analysis was to compare the efficiency (clinical outcome and patient satisfaction) and safety (complications and survival) of these two procedures. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was performed as a guideline for this study. Three electronic databases, PubMed, Web of Science, and Cochrane Library, were searched up to May 2019, with no language restrictions. Prospective or retrospective comparative studies were identified. The outcomes included clinical outcome, patient satisfaction, complications, and survival. Review Manager (Revman) 5.3 software was used to conduct the data analysis. We only selected literature from the past 5 years (no earlier than 2015). Seven comparative studies were included. There were six cohort studies and one cross-sectional study. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of cohort studies, and The Agency for Healthcare Research and Quality (AHRQ) checklist was chosen to assess the quality of cross-sectional studies. No significant difference was observed for efficiency and safety. Clinical outcome was included in five studies with four different scoring systems. Two of them used the American Orthopaedic Foot & Ankle Society (AOFAS) questionnaire scores to assess the two procedures (mean difference, -4.26; 95% confidence interval [CI], -11.37-2.85; P = 0.24; I2 = 1%). Patient satisfaction (risk ratio [RR], 0.96; 95% CI, 0.65-1.40; P = 0.82; I2 = 54%), complications (RR, 1.15; 95% CI, 0.16-8.21; P = 0.89; I2 = 84%), and survival (RR, 1.91; 95% CI, 0.33-11.08; P = 0.47; I2 = 90%) showed no significant difference between the TAR group and the AAD group. This meta-analysis showed no statistically significant difference between TAR and AAD in clinical outcome, patient satisfaction, complications, and survival. This revealed that TAR and AAD could appear to have similar results in these aspects. Therefore, the present results are not sufficient to conclude which of these two methods is better. Further studies are needed to obtain more clues.