A prospective clinical study for pedicle screw placement with augmented reality surgical navigation including intraoperative 3D imaging in a hybrid operating room was performed in 20 patients of whom 13 had scoliosis. The screw placement accuracy was 94.1% with an average navigation time of 5.4 minutes per screw placement.

The 16s rRNA gene of Gallionella ferruginea was amplified by polymerase chain reaction and sequenced by direct double-stranded sequencing. The phylogenetic analysis placed G. ferruginea in the pgroup of the Proteobacteria, with 90-0 % similarity to Nitrosolobus multiformis and 88.6 Yo to Rhodocyclus purpureus. The published phenotypic characteristics of G. ferruginea were compiled and supplemented with growth experiments using ferrous iron, thiosulphate and sulphide as electron donor, and nitrate as nitrogen source. G. ferruginea is a Gram-negative, curved bacterium with one polar flagellum. It grows auto-and mixotrophically with CO,, glucose, fructose and sucrose as carbon sources, ferrous iron as an electron donor and ammonium or nitrate as nitrogen sources. Two G. ferruginea specific oligonucleotide probes are suggested. An iron-oxidizing bacterium without stalk-forming ability, but with the same growth pattern as G. ferruginea, was identified as G. ferruginea by comparison of highly variable parts of the 16s rRNA gene. This indicates that the stalk is not essential for growth.

This study aimed to compare screw placement accuracy and clinical aspects between Augmented Reality Surgical Navigation (ARSN) and free-hand (FH) technique. Twenty patients underwent spine surgery with screw placement using ARSN and were matched retrospectively to a cohort of 20 FH technique cases for comparison. All ARSN and FH cases were performed by the same surgeon. Matching was based on clinical diagnosis and similar proportions of screws placed in the thoracic and lumbosacral vertebrae in both groups. Accuracy of screw placement was assessed on postoperative scans according to the Gertzbein scale and grades 0 and 1 were considered accurate. Procedure time, blood loss and length of hospital stay, were collected as secondary endpoints. A total of 262 and 288 screws were assessed in the ARSN and FH groups, respectively. The share of clinically accurate screws was significantly higher in the ARSN vs FH group (93.9% vs 89.6%, p < 0.05). The proportion of screws placed without a cortical breach was twice as high in the ARSN group compared to the FH group (63.4% vs 30.6%, p < 0.0001). No statistical difference was observed for the secondary endpoints between both groups. This matched-control study demonstrated that ARSN provided higher screw placement accuracy compared to free-hand.Compared to conventional free-hand (FH) surgical technique, computer-assisted navigation using intraoperative 3D imaging has been shown to improve screw placement accuracy and reduce complications due to screw misplacements 1 . Moreover, improved accuracy has also been shown in more challenging conditions, such as scoliosis surgery, where it may be of even greater importance 2 . Consequently, navigation also reduces the frequency of postoperative revision surgery compared to FH surgery 3 .Although several studies have compared intraoperative image guidance to free-hand (FH) technique, the evidence in favor of navigation is still limited. In a recent systematic review, Chan et al., found only four studies comparing computed tomography (CT) guidance with free-hand methods head-to-head, including one small (10 patients in each group, 169 screws in total) randomized study 4 . Overall, the reviewers found only moderate level evidence showing that CT guidance has lower breach rates than FH, while screw-related complication rates were conflicting at 0% in CT navigation compared with 0%-1.7% in FH groups 5 . In a more recent retrospective study comparing O-arm navigation to FH, Wang et al. demonstrated higher pedicle screw accuracy and lower total

OBJECTIVE Surgery for chronic subdural hematoma (CSDH) is one of the most common neurosurgical procedures. The benefit of postoperative passive subdural drainage compared with no drains has been established, but other drainage techniques are common, and their effectiveness compared with passive subdural drains remains unknown. METHODS In Scandinavian population-based cohorts the authors conducted a consecutive, parallel cohort study to compare different drainage techniques. The techniques used were continuous irrigation and drainage (CID cohort, n = 166), passive subdural drainage (PD cohort, n = 330), and active subgaleal drainage (AD cohort, n = 764). The primary end point was recurrence in need of reoperation within 6 months of index surgery. Secondary end points were complications, perioperative mortality, and overall survival. The analyses were based on direct regional comparison (i.e., surgical strategy). RESULTS Recurrence in need of surgery was observed in 18 patients (10.8%) in the CID cohort, in 66 patients (20.0%) in the PD cohort, and in 85 patients (11.1%) in the AD cohort (p < 0.001). Complications were more common in the CID cohort (14.5%) compared with the PD (7.3%) and AD (8.1%) cohorts (p = 0.019). Perioperative mortality rates were similar between cohorts (p = 0.621). There were some differences in baseline and treatment characteristics possibly interfering with the above-mentioned results. However, after adjusting for differences in baseline and treatment characteristics in a regression model, the drainage techniques were still significantly associated with clinical outcome (p < 0.001 for recurrence, p = 0.017 for complications). CONCLUSIONS Compared with the AD cohort, more recurrences were observed in the PD cohort and more complications in the CID cohort, also after adjustment for differences at baseline. Although the authors cannot exclude unmeasured confounding factors when comparing centers, AD appears superior to the more common PD. Clinical trial registration no.: NCT01930617 (clinicaltrials.gov).