Percutaneous screw fixation of the iliosacral joint: optimal screw pathways are frequently not completely intraosseous

INTRODUCTION In iliosacral screw fixation, the dimensions of solely intraosseous (secure) pathways, perpendicular to the ilio-sacral articulation (optimal) with corresponding entry (EP) and aiming points (AP) on lateral fluoroscopic projections, and the factors (demographic, anatomic) influencing these have not yet been described. METHODS In 100 CTs of normal pelvises, the height and width of the secure and optimal pathways were measured on axial and coronal views bilaterally (total measurements: n=200). Corresponding EP and AP were defined as either the location of the screw head or tip at the crossing of lateral innominate bones' cortices (EP) and sacral midlines (AP) within the centre of the pathway, respectively. EP and AP were transferred to the sagittal pelvic view using a coordinate system with the zero-point in the centre of the posterior cortex of the S1 vertebral body (x-axis parallel to upper S1 endplate). Distances are expressed in relation to the anteroposterior distance of the S1 upper endplate (in %). The influence of demographic (age, gender, side) and/or anatomic (PIA=pelvic incidence angle; TCA=transversal curvature angle, PID-Index=pelvic incidence distance-index; USW=unilateral sacral width-index) parameters on pathway dimensions and positions of EP and AP were assessed (multivariate analysis). RESULTS The width, height or both factors of the pathways were at least 7mm or more in 32% and 53% or 20%, respectively. The EP was on average 14±24% behind the centre of the posterior S1 cortex and 41±14% below it. The AP was on average 53±7% in the front of the centre of the posterior S1 cortex and 11±7% above it. PIA influenced the width, TCA, PID-Index the height of the pathways. PIA, PID-Index, and USW-Index significantly influenced EP and AP. Age, gender, and TCA significantly influenced EP. CONCLUSION Secure and optimal placement of screws of at least 7mm in diameter will be unfeasible in the majority of patients. Thoughtful preoperative planning of screw placement on CT scans is advisable to identify secure pathways with an optimal direction. For this purpose, the presented methodology of determining and transferring EPs and APs of corresponding pathways to the sagittal pelvic view using a coordinate system may be useful.

A clinically applicable laser-based image-guided system for laparoscopic liver procedures

PURPOSE Laser range scanners (LRS) allow performing a surface scan without physical contact with the organ, yielding higher registration accuracy for image-guided surgery (IGS) systems. However, the use of LRS-based registration in laparoscopic liver surgery is still limited because current solutions are composed of expensive and bulky equipment which can hardly be integrated in a surgical scenario. METHODS In this work, we present a novel LRS-based IGS system for laparoscopic liver procedures. A triangulation process is formulated to compute the 3D coordinates of laser points by using the existing IGS system tracking devices. This allows the use of a compact and cost-effective LRS and therefore facilitates the integration into the laparoscopic setup. The 3D laser points are then reconstructed into a surface to register to the preoperative liver model using a multi-level registration process. RESULTS Experimental results show that the proposed system provides submillimeter scanning precision and accuracy comparable to those reported in the literature. Further quantitative analysis shows that the proposed system is able to achieve a patient-to-image registration accuracy, described as target registration error, of [Formula: see text]. CONCLUSIONS We believe that the presented approach will lead to a faster integration of LRS-based registration techniques in the surgical environment. Further studies will focus on optimizing scanning time and on the respiratory motion compensation.

Internal bacterial colonization of implants: association with peri-implant bone loss

OBJECTIVES The aim of the present longitudinal study was to investigate bacterial colonization of the internal implant cavity and to evaluate a possible association with peri-implant bone loss. METHODS A total of 264 paper point samples were harvested from the intra-implant cavity of 66 implants in 26 patients immediately following implant insertion and after 3, 4, and 12 months. Samples were evaluated for Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythia as well as total bacterial counts by real-time PCR. Bone loss was evaluated on standardized radiographs up to 25 months after implant insertion. For the statistical analysis of the data, mixed effects models were fitted. RESULTS There was an increase in the frequency of detection as well as in the mean counts of the selected bacteria over time. The evaluation of the target bacteria revealed a significant association of Pr. intermedia at 4 and 12 months with peri-implant bone loss at 25 months (4 months: P = 0.009; 12 months: P = 0.021). CONCLUSIONS The present study could demonstrate a progressive colonization by periodontopathogenic bacteria in the internal cavities of two-piece implants. The results suggest that internal colonization with Pr. intermedia was associated with peri-implant bone loss.

A Novel Ultrasound-Based Registration for Image-Guided Laparoscopic Liver Ablation.

BACKGROUND Patient-to-image registration is a core process of image-guided surgery (IGS) systems. We present a novel registration approach for application in laparoscopic liver surgery, which reconstructs in real time an intraoperative volume of the underlying intrahepatic vessels through an ultrasound (US) sweep process. METHODS An existing IGS system for an open liver procedure was adapted, with suitable instrument tracking for laparoscopic equipment. Registration accuracy was evaluated on a realistic phantom by computing the target registration error (TRE) for 5 intrahepatic tumors. The registration work flow was evaluated by computing the time required for performing the registration. Additionally, a scheme for intraoperative accuracy assessment by visual overlay of the US image with preoperative image data was evaluated. RESULTS The proposed registration method achieved an average TRE of 7.2 mm in the left lobe and 9.7 mm in the right lobe. The average time required for performing the registration was 12 minutes. A positive correlation was found between the intraoperative accuracy assessment and the obtained TREs. CONCLUSIONS The registration accuracy of the proposed method is adequate for laparoscopic intrahepatic tumor targeting. The presented approach is feasible and fast and may, therefore, not be disruptive to the current surgical work flow.

Characterization of fetal antigen 1/delta-like 1 homologue expressing cells in the rat nigrostriatal system: effects of a unilateral 6-hydroxydopamine lesion.

Fetal antigen 1/delta-like 1 homologue (FA1/dlk1) belongs to the epidermal growth factor superfamily and is considered to be a non-canonical ligand for the Notch receptor. Interactions between Notch and its ligands are crucial for the development of various tissues. Moreover, FA1/dlk1 has been suggested as a potential supplementary marker of dopaminergic neurons. The present study aimed at investigating the distribution of FA1/dlk1-immunoreactive (-ir) cells in the early postnatal and adult midbrain as well as in the nigrostriatal system of 6-hydroxydopamine (6-OHDA)-lesioned hemiparkinsonian adult rats. FA1/dlk1-ir cells were predominantly distributed in the substantia nigra (SN) pars compacta (SNc) and in the ventral tegmental area. Interestingly, the expression of FA1/dlk1 significantly increased in tyrosine hydroxylase (TH)-ir cells during early postnatal development. Co-localization and tracing studies demonstrated that FA1/dlk1-ir cells in the SNc were nigrostriatal dopaminergic neurons, and unilateral 6-OHDA lesions resulted in loss of both FA1/dlk1-ir and TH-ir cells in the SNc. Surprisingly, increased numbers of FA1/dlk1-ir cells (by 70%) were detected in dopamine-depleted striata as compared to unlesioned controls. The higher number of FA1/dlk1-ir cells was likely not due to neurogenesis as colocalization studies for proliferation markers were negative. This suggests that FA1/dlk1 was up-regulated in intrinsic cells in response to the 6-OHDA-mediated loss of FA1/dlk1-expressing SNc dopaminergic neurons and/or due to the stab wound. Our findings hint to a significant role of FA1/dlk1 in the SNc during early postnatal development. The differential expression of FA1/dlk1 in the SNc and the striatum of dopamine-depleted rats could indicate a potential involvement of FA1/dlk1 in the cellular response to the degenerative processes.

Design and Implementation of a Laparoscope Calibration Method for Augmented Reality Navigation

Intraoperative laparoscopic calibration remains a challenging task. In this work we present a new method and instrumentation for intraoperative camera calibration. Contrary to conventional calibration methods, the proposed technique allows intraoperative laparoscope calibration from single perspective observations, resulting in a standardized scheme for calibrating in a clinical scenario. Results show an average displacement error of 0.52 ± 0.19 mm, indicating sufficient accuracy for clinical use. Additionally, the proposed method is validated clinically by performing a calibration during the surgery.

Intraoperative image-guided navigation system: development and applicability in 65 patients undergoing liver surgery

Background Image-guided systems have recently been introduced for their application in liver surgery.We aimed to identify and propose suitable indications for image-guided navigation systems in the domain of open oncologic liver surgery and,more specifically, in the setting of liver resection with and without microwave ablation. Method Retrospective analysis was conducted in patients undergoing liver resection with and without microwave ablation using an intraoperative image-guided stereotactic system during three stages of technological development (accuracy: 8.4 ± 4.4 mm in phase I and 8.4 ± 6.5 mm in phase II versus 4.5 ± 3.6 mm in phase III). It was evaluated, in which indications image-guided surgery was used according to the different stages of technical development. Results Between 2009 and 2013, 65 patients underwent image-guided surgical treatment, resection alone (n=38), ablation alone (n =11), or a combination thereof (n =16). With increasing accuracy of the system, image guidance was progressively used for atypical resections and combined microwave ablation and resection instead of formal liver resection (p<0.0001). Conclusion Clinical application of image guidance is feasible, while its efficacy is subject to accuracy. The concept of image guidance has been shown to be increasingly efficient for selected indications in liver surgery. While accuracy of available technology is increasing pertaining to technological advancements, more and more previously untreatable scenarios such as multiple small, bilobar lesions and so-called vanishing lesions come within reach.

Cerebral Microembolization During Aortic Valve Replacement Using Minimally Invasive or Conventional Extracorporeal Circulation: A Randomized Trial.

To compare intraoperative cerebral microembolic load between minimally invasive extracorporeal circulation (MiECC) and conventional extracorporeal circulation (CECC) during isolated surgical aortic valve replacement (SAVR), we conducted a randomized trial in patients undergoing primary elective SAVR at a tertiary referral hospital. The primary outcome was the procedural phase-related rate of high-intensity transient signals (HITS) on transcranial Doppler ultrasound. HITS rate was used as a surrogate of cerebral microembolism in pre-defined procedural phases in SAVR using MiECC or CECC with (+F) or without (-F) an oxygenator with integrated arterial filter. Forty-eight patients were randomized in a 1:1 ratio to MiECC or CECC. Due to intraprocedural Doppler signal loss (n = 3), 45 patients were included in final analysis. MiECC perfusion regimen showed a significantly increased HITS rate compared to CECC (by a factor of 1.75; 95% confidence interval, 1.19-2.56). This was due to different HITS rates in procedural phases from aortic cross-clamping until declamping [phase 4] (P = 0.01), and from aortic declamping until stop of extracorporeal perfusion [phase 5] (P = 0.05). Post hoc analysis revealed that MiECC-F generated a higher HITS rate than CECC+F (P = 0.005), CECC-F (P = 0.05) in phase 4, and CECC-F (P = 0.03) in phase 5, respectively. In open-heart surgery, MiECC is not superior to CECC with regard to gaseous cerebral microembolism. When using MiECC for SAVR, the use of oxygenators with integrated arterial line filter appears highly advisable. Only with this precaution, MiECC confers a cerebral microembolic load comparable to CECC during this type of open heart surgery.

Sexual Activity Without Condoms and Risk of HIV Transmission in Serodifferent Couples When the HIV-Positive Partner Is Using Suppressive Antiretroviral Therapy

Importance A key factor in assessing the effectiveness and cost-effectiveness of antiretroviral therapy (ART) as a prevention strategy is the absolute risk of HIV transmission through condomless sex with suppressed HIV-1 RNA viral load for both anal and vaginal sex. Objective To evaluate the rate of within-couple HIV transmission (heterosexual and men who have sex with men [MSM]) during periods of sex without condoms and when the HIV-positive partner had HIV-1 RNA load less than 200 copies/mL. Design, Setting, and Participants The prospective, observational PARTNER (Partners of People on ART-A New Evaluation of the Risks) study was conducted at 75 clinical sites in 14 European countries and enrolled 1166 HIV serodifferent couples (HIV-positive partner taking suppressive ART) who reported condomless sex (September 2010 to May 2014). Eligibility criteria for inclusion of couple-years of follow-up were condomless sex and HIV-1 RNA load less than 200 copies/mL. Anonymized phylogenetic analysis compared couples' HIV-1 polymerase and envelope sequences if an HIV-negative partner became infected to determine phylogenetically linked transmissions. Exposures Condomless sexual activity with an HIV-positive partner taking virally suppressive ART. Main Outcomes and Measures Risk of within-couple HIV transmission to the HIV-negative partner. Results Among 1166 enrolled couples, 888 (mean age, 42 years [IQR, 35-48]; 548 heterosexual [61.7%] and 340 MSM [38.3%]) provided 1238 eligible couple-years of follow-up (median follow-up, 1.3 years [IQR, 0.8-2.0]). At baseline, couples reported condomless sex for a median of 2 years (IQR, 0.5-6.3). Condomless sex with other partners was reported by 108 HIV-negative MSM (33%) and 21 heterosexuals (4%). During follow-up, couples reported condomless sex a median of 37 times per year (IQR, 15-71), with MSM couples reporting approximately 22 000 condomless sex acts and heterosexuals approximately 36 000. Although 11 HIV-negative partners became HIV-positive (10 MSM; 1 heterosexual; 8 reported condomless sex with other partners), no phylogenetically linked transmissions occurred over eligible couple-years of follow-up, giving a rate of within-couple HIV transmission of zero, with an upper 95% confidence limit of 0.30/100 couple-years of follow-up. The upper 95% confidence limit for condomless anal sex was 0.71 per 100 couple-years of follow-up. Conclusions and Relevance Among serodifferent heterosexual and MSM couples in which the HIV-positive partner was using suppressive ART and who reported condomless sex, during median follow-up of 1.3 years per couple, there were no documented cases of within-couple HIV transmission (upper 95% confidence limit, 0.30/100 couple-years of follow-up). Additional longer-term follow-up is necessary to provide more precise estimates of risk.