Surgical navigation for guidewire placement from intraoperative fluoroscopy in orthopaedic surgery.

Objective. Surgical guidewires are commonly used in placing fixation implants to stabilize fractures. Accurate positioning of these instruments is challenged by difficulties in 3D reckoning from 2D fluoroscopy. This work aims to enhance the accuracy and reduce exposure times by providing 3D navigation for guidewire placement from as little as two fluoroscopic images.Approach. Our approach combines machine learning-based segmentation with the geometric model of the imager to determine the 3D poses of guidewires. Instrument tips are encoded as individual keypoints, and the segmentation masks are processed to estimate the trajectory. Correspondence between detections in multiple views is established using the pre-calibrated system geometry, and the corresponding features are backprojected to obtain the 3D pose. Guidewire 3D directions were computed using both an analytical and an optimization-based method. The complete approach was evaluated in cadaveric specimens with respect to potential confounding effects from the imaging geometry and radiographic scene clutter due to other instruments.Main results. The detection network identified the guidewire tips within 2.2 mm and guidewire directions within 1.1°, in 2D detector coordinates. Feature correspondence rejected false detections, particularly in images with other instruments, to achieve 83% precision and 90% recall. Estimating the 3D direction via numerical optimization showed added robustness to guidewires aligned with the gantry rotation plane. Guidewire tips and directions were localized in 3D world coordinates with a median accuracy of 1.8 mm and 2.7°, respectively.Significance. The paper reports a new method for automatic 2D detection and 3D localization of guidewires from pairs of fluoroscopic images. Localized guidewires can be virtually overlaid on the patient's pre-operative 3D scan during the intervention. Accurate pose determination for multiple guidewires from two images offers to reduce radiation dose by minimizing the need for repeated imaging and provides quantitative feedback prior to implant placement.

Spontaneous healing of acute ACL ruptures: rate, prognostic factors and short-term outcome.

INTRODUCTION: Anterior cruciate ligament (ACL) reconstruction is considered the first line treatment in ACL rupture. However, some patients return to high intensity sport activities and show a normal knee function without ACL reconstruction. Therefore, aim of this study was to evaluate the rate and prognostic factors of spontaneous healing in patients with ACL rupture and the short-term functional outcome. METHODS: The rate, prognostic factors and short-term functional results of spontaneous healing in patients with ACL rupture were evaluated in 381 patients. Morphology of ACL rupture and extent of posterior tibial slope (PTS) were classified by MR- and x-ray imaging. In patients with normal knee stability in anesthesia examination and healed ACL during the arthroscopy 6 weeks after trauma ACL reconstruction was canceled. IKDC -, Tegner Activity Score, KT 1000 testing and radiological characteristics were collected 12 months postoperatively in these patients. RESULTS: 14.17% of the patients with ACL rupture showed a spontaneous healing after 6 weeks. Femoral ACL-rupture (p < 0.02) with integrity of ligament stump > 50% (p < 0.001), without bundle separation (p < 0.001) and decreased PTS (p < 0.001) was found significantly more often in patients with a spontaneous healed ACL. The average IKDC score was high at 84,63 in patients with healed ACL at 1 year follow-up, but KT 1000 testing was inferior compared to non-injured side. CONCLUSION: Spontaneous healing of a ruptured ACL happened in 14% of the patients. Especially in low-demand patients with femoral single bundle lesions without increased posterior tibial slope delayed ACL surgery should be considered to await the possibility for potential spontaneous ACL healing.

Clinical and radiological comparison between partial and complete resection of the anterior cruciate ligament in patients with mucoid degeneration of the anterior cruciate ligament: a controlled clinical trial.

INTRODUCTION: The pathology of a mucoid degeneration of the anterior cruciate ligament (MDACL) has been mentioned in several publications but due to its rare incidence it is not a well-known pathology. Partial or complete resection of the ACL is the option of choice after failed non-surgical treatment. However, the success rate of both surgical techniques and the subsequent risk of an ACL instability is not known. The purpose of this study was to compare the clinical and radiological outcome between partial resection and complete resection of the ACL in patients with MDACL. MATERIALS AND METHODS: Patients with MDACL verified by MRI and persistent knee pain were treated by partial (Group I) or complete resection (Group II) of the ACL and were included in a controlled clinical trial after unsuccessful conservative treatment for at least 6 months. Demographic, clinical and radiological data including the thickness of ACL, ACL/intercondylar ratio, patient's age at the time of surgery, the presenting symptoms, range of motion and ligament stability assessed by the ACL ligament score (Lachman test) were collected. In addition, Tegner activity score and Lysholm score were evaluated preoperatively and at final follow-up after a minimum of 12 months. RESULTS: At final follow-up with a mean of 16.8 ± 8.8 months (range 12-41; Group I: 18.3 ± 9.7 vs. Group II: 15.3 ± 8.0; ns), all patients were pain free. Postoperatively, positive Lachman tests were noted in all patients (100%) in Group II (n = 5 patients with grade II and n = 5 patients with grade III). In Group I, 8 patients (80%) showed a negative Lachman test (grade I) and 2 patients (20%) a slightly elongated Lachman test with a firm stop (grade II). The mean knee flexion at follow-up examination was 132° ± 7° (range 120°-140°; Group I: 129° ± 9° vs. Group II: 135° ± 4°; ns). In pairwise comparison, flexion angle increased significantly in both groups (Group I: p = 0.0124 and Group II: p < 0.001). Pairwise comparison of thickness of the ACL and ACL/intercondylar ratio prior to and post-surgery in Group I showed non-significant differences. CONCLUSION: Both arthroscopic debridement and complete resection of the ACL lead to improvement of clinical and radiological findings in isolated MDACL. However, complete resection of the ACL will result in higher instability. Therefore, partial resection might be the better treatment option, especially in young patients with MDACL.

3D-2D image registration in the presence of soft-tissue deformation in image-guided transbronchial interventions.

Purpose. Target localization in pulmonary interventions (e.g. transbronchial biopsy of a lung nodule) is challenged by deformable motion and may benefit from fluoroscopic overlay of the target to provide accurate guidance. We present and evaluate a 3D-2D image registration method for fluoroscopic overlay in the presence of tissue deformation using a multi-resolution/multi-scale (MRMS) framework with an objective function that drives registration primarily by soft-tissue image gradients.Methods. The MRMS method registers 3D cone-beam CT to 2D fluoroscopy without gating of respiratory phase by coarse-to-fine resampling and global-to-local rescaling about target regions-of-interest. A variation of the gradient orientation (GO) similarity metric (denotedGO') was developed to downweight bone gradients and drive registration via soft-tissue gradients. Performance was evaluated in terms of projection distance error at isocenter (PDEiso). Phantom studies determined nominal algorithm parameters and capture range. Preclinical studies used a freshly deceased, ventilated porcine specimen to evaluate performance in the presence of real tissue deformation and a broad range of 3D-2D image mismatch.Results. Nominal algorithm parameters were identified that provided robust performance over a broad range of motion (0-20 mm), including an adaptive parameter selection technique to accommodate unknown mismatch in respiratory phase. TheGO'metric yielded median PDEiso= 1.2 mm, compared to 6.2 mm for conventionalGO.Preclinical studies with real lung deformation demonstrated median PDEiso= 1.3 mm with MRMS +GO'registration, compared to 2.2 mm with a conventional transform. Runtime was 26 s and can be reduced to 2.5 s given a prior registration within ∼5 mm as initialization.Conclusions. MRMS registration via soft-tissue gradients achieved accurate fluoroscopic overlay in the presence of deformable lung motion. By driving registration via soft-tissue image gradients, the method avoided false local minima presented by bones and was robust to a wide range of motion magnitude.

Sandwich Technique for Large Osteochondral Lesions of the Knee.

OBJECTIVE: To evaluate whether a sandwich technique procedure for large osteochondral lesions (OCL) of the medial femur condyle reduces clinical symptoms and improves activity level as well as to assess repair tissue integration on MRI over 2 years. DESIGN: Twenty-one patients (median age: 29 years, 18-44 years) who received matrix-associated autologous chondrocyte transplantation (MACT) combined with cancellous bone grafting at the medial femur condyle in a 1-step procedure were prospectively included. Patients were evaluated before surgery (baseline) as well as 3, 6, 12, and 24 months postoperatively, including clinical evaluation, Lysholm score, Tegner Activity Rating Scale, and MRI with Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score and a modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). RESULTS: Seventeen patients were available for the 24-month (final) follow-up (4 dropouts). Lysholm significantly improved from 48 preoperatively stepwise to 95 at final follow-up (P < 0.05). Tegner improvement from 2.5 at baseline to 4.0 at final follow-up was not significant (P = 1.0). MOCART score improved significantly and stepwise from 65 at 3 months to 90 at 24 months (P < 0.05). Total WORMS improved from 14.5 at surgery to 7.0 after 24 months (P < 0.05). Body mass index and defect size at surgery correlated with total WORMS at final follow-up (P < 0.05) but did not correlate with clinical scores or defect filling. CONCLUSION: MACT combined with cancellous bone grafting at the medial femoral condyle reduces symptoms continuously over 2 years. A 1-step procedure may reduce perioperative morbidity. However, despite improvements, patients' activity levels remain low, even 2 years after surgery.

Evaluation of the antiseptic activity of 5% alcoholic povidone-iodine solution using four different modes of application: a randomized open-label study.

BACKGROUND: Before some invasive procedures, such as injections, surgical incision or intravascular catheter insertions, alcoholic antiseptics (e.g., alcoholic povidone-iodine (PVP-I)) are widely used to prevent infection. AIM: This randomized, open-label study investigated the impact of mode of application (which includes both application technique and volume) on the antiseptic activity of 5% alcoholic PVP-I solution. METHODS: Alcoholic PVP-I was administered to the backs of healthy adults using four modes of application: (A) concentric circle method, 3 mL; (B) concentric circle method, 10 mL; (C) back-and-forth friction method, 3 mL; (D) back-and-forth friction method, 10 mL. PRIMARY ENDPOINT: antiseptic activity of alcoholic PVP-I, assessed via change from baseline in log10/cm2 colony-forming units (cfu) count for total aerobic and facultative anaerobic bacteria. Safety was monitored. FINDINGS: A total of 113 healthy participants were screened; 32 were randomized. Alcoholic PVP-I showed significant antiseptic activity with all modes of application (P<0.001 for each), providing an overall mean decrease from baseline in cfu count of >3 log10/cm2 (P<0.001). Significantly greater efficacy was seen with back-and-forth friction (modes C and D) versus concentric circles (modes A and B): covariate adjusted change in log10/cm2 cfu count 0.22; 90% confidence intervals: 0.07, 0.37 (P=0.017). No safety issues were observed. CONCLUSIONS: Alcoholic PVP-I demonstrated high antiseptic activity for all modes of application. Greater efficacy was achieved with back-and-forth friction versus concentric circles, showing that application technique may influence antiseptic activity; these findings suggest that when comparing the efficacy of antiseptic substances (e.g., alcoholic PVP-I and alcoholic chlorhexidine), comparable application techniques should be used.

Cross-feeding between intestinal pathobionts promotes their overgrowth during undernutrition.

Child undernutrition is a global health issue associated with a high burden of infectious disease. Undernourished children display an overabundance of intestinal pathogens and pathobionts, and these bacteria induce enteric dysfunction in undernourished mice; however, the cause of their overgrowth remains poorly defined. Here, we show that disease-inducing human isolates of Enterobacteriaceae and Bacteroidales spp. are capable of multi-species symbiotic cross-feeding, resulting in synergistic growth of a mixed community in vitro. Growth synergy occurs uniquely under malnourished conditions limited in protein and iron: in this context, Bacteroidales spp. liberate diet- and mucin-derived sugars and Enterobacteriaceae spp. enhance the bioavailability of iron. Analysis of human microbiota datasets reveals that Bacteroidaceae and Enterobacteriaceae are strongly correlated in undernourished children, but not in adequately nourished children, consistent with a diet-dependent growth synergy in the human gut. Together these data suggest that dietary cross-feeding fuels the overgrowth of pathobionts in undernutrition.

Does the anterolateral ligament protect the anterior cruciate ligament in the most common injury mechanisms? A human knee model study.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction still has a risk of re-rupture and persisting rotational instability. Thus, extra-articular structures such as the anterolateral ligament (ALL) are increasingly treated. The ALL however prevents the internal rotation of the tibia and it must be doubted that the ALL protects the ACL in other common injury mechanisms which primarily include tibial external rotation. In this study we aimed to evaluate which extra-articular structures support the ACL in excessive tibial internal and external rotation using a knee finite element (FE) model. METHODS: Internal and external rotations of the tibia were applied to an FE model with anatomical ACL, posterior cruciate ligament (PCL), lateral collateral ligament (LCL), medial collateral ligament (MCL) and intact medial and lateral meniscus. Three additional anatomic structures (anterolateral ligament, popliteal tendon and posterior oblique ligament) were added to the FE model separately and then all together. The force histories within all structures were measured and determined for each case. RESULTS: The ACL was the most loaded ligament both in tibial internal and external rotation. The ALL was the main stabilizer of the tibial internal rotation (46%) and prevented the tibial external rotation by only 3%. High forces were only observed in the LCL with tibial external rotation. The ALL reduced the load on the ACL in tibial internal rotation by 21%, in tibial external rotation only by 2%. The POL reduced the load on the ACL by 8%, the PLT by 6% in tibial internal rotation. In tibial external rotation the POL and PLT did not reduce the load on the ACL by more than 1%. CONCLUSION: The ALL protects the ACL in injury mechanisms with tibial internal rotation but not in mechanisms with tibial external rotation. In injury mechanisms with tibial external rotation other structures that support the ACL need to be considered.

Fluoroscopic Guidance of a Surgical Robot: Pre-clinical Evaluation in Pelvic Guidewire Placement.

Purpose: A method and prototype for a fluoroscopically-guided surgical robot is reported for assisting pelvic fracture fixation. The approach extends the compatibility of existing guidance methods with C-arms that are in mainstream use (without prior geometric calibration) using an online calibration of the C-arm geometry automated via registration to patient anatomy. We report the first preclinical studies of this method in cadaver for evaluation of geometric accuracy. Methods: The robot is placed over the patient within the imaging field-of-view and radiographs are acquired as the robot rotates an attached instrument. The radiographs are then used to perform an online geometric calibration via 3D-2D image registration, which solves for the intrinsic and extrinsic parameters of the C-arm imaging system with respect to the patient. The solved projective geometry is then be used to register the robot to the patient and drive the robot to planned trajectories. This method is applied to a robotic system consisting of a drill guide instrument for guidewire placement and evaluated in experiments using a cadaver specimen. Results: Robotic drill guide alignment to trajectories defined in the cadaver pelvis were accurate within 2 mm and 1° (on average) using the calibration-free approach. Conformance of trajectories within bone corridors was confirmed in cadaver by extrapolating the aligned drill guide trajectory into the cadaver pelvis. Conclusion: This study demonstrates the accuracy of image-guided robotic positioning without prior calibration of the C-arm gantry, facilitating the use of surgical robots with simpler imaging devices that cannot establish or maintain an offline calibration. Future work includes testing of the system in a clinical setting with trained orthopaedic surgeons and residents.

Fracture reduction planning and guidance in orthopaedic trauma surgery via multi-body image registration.

PURPOSES: Surgical reduction of pelvic fracture is a challenging procedure, and accurate restoration of natural morphology is essential to obtaining positive functional outcome. The procedure often requires extensive preoperative planning, long fluoroscopic exposure time, and trial-and-error to achieve accurate reduction. We report a multi-body registration framework for reduction planning using preoperative CT and intraoperative guidance using routine 2D fluoroscopy that could help address such challenges. METHOD: The framework starts with semi-automatic segmentation of fractured bone fragments in preoperative CT using continuous max-flow. For reduction planning, a multi-to-one registration is performed to register bone fragments to an adaptive template that adjusts to patient-specific bone shapes and poses. The framework further registers bone fragments to intraoperative fluoroscopy to provide 2D fluoroscopy guidance and/or 3D navigation relative to the reduction plan. The framework was investigated in three studies: (1) a simulation study of 40 CT images simulating three fracture categories (unilateral two-body, unilateral three-body, and bilateral two-body); (2) a proof-of-concept cadaver study to mimic clinical scenario; and (3) a retrospective clinical study investigating feasibility in three cases of increasing severity and accuracy requirement. RESULTS: Segmentation of simulated pelvic fracture demonstrated Dice coefficient of 0.92±0.06. Reduction planning using the adaptive template achieved 2-3 mm and 2-3° error for the three fracture categories, significantly better than planning based on mirroring of contralateral anatomy. 3D-2D registration yielded ~2 mm and 0.5° accuracy, providing accurate guidance with respect to the preoperative reduction plan. The cadaver study and retrospective clinical study demonstrated comparable accuracy: ~0.90 Dice coefficient in segmentation, ~3 mm accuracy in reduction planning, and ~2 mm accuracy in 3D-2D registration. CONCLUSION: The registration framework demonstrated planning and guidance accuracy within clinical requirements in both simulation and clinical feasibility studies for a broad range of fracture-dislocation patterns. Using routinely acquired preoperative CT and intraoperative fluoroscopy, the framework could improve the accuracy of pelvic fracture reduction, reduce radiation dose, and could integrate well with common clinical workflow without the need for additional navigation systems.

Platelet-rich plasma (PRP) as therapy for cartilage, tendon and muscle damage - German working group position statement.

PURPOSE: Platelet rich plasma (PRP) is widely used in orthopaedics, but is still heavily debated. Therefore, a survey among the German "Working Group for Clinical Tissue Regeneration" of the German Society of Orthopaedics and Traumatology was conducted to achieve a consensus about the current therapeutical potential of PRP. METHODS: A first survey (n = 65 experts, all orthopaedic/trauma surgeons) was conducted (n = 13 questions). Following, a second round (n = 40 experts) was conducted with 31 questions to achieve consensus in 5 categories: three most common indications, PRP application, future research areas. RESULTS: Therapeutic PRP application was regarded as useful (89%), possibly even more important in the future (90%). Most common indications were tendon pathologies (77%), osteoarthritis (OA) (68%), muscle injuries (57%) and cartilage damage (51%). Consensus was reached in 16/31 statements. The application of PRP for early knee OA (Kellgren-Lawrence grade II) was regarded as potentially useful, as well as for acute and chronic tendinopathies. For chronic lesions (cartilage, tendons), multiple injections (2-4) were seen preferable to singular injections. However, no sufficient data exists on the time interval between the injections. Standardization of PRP preparation, application, frequency, as well as determining the range of indication is strongly recommended. CONCLUSIONS: There is a need of further standardization of the PRP preparation methods, indication and application protocols for knee OA and other indications, which must be further evaluated in basic science studies and randomized controlled clinical trials. LEVEL OF EVIDENCE: Consensus of expert opinion, Level V.

A multiplanet system of super-Earths orbiting the brightest red dwarf star GJ 887.

The closet exoplanets to the Sun provide opportunities for detailed characterization of planets outside the Solar System. We report the discovery, using radial velocity measurements, of a compact multiplanet system of super-Earth exoplanets orbiting the nearby red dwarf star GJ 887. The two planets have orbital periods of 9.3 and 21.8 days. Assuming an Earth-like albedo, the equilibrium temperature of the 21.8-day planet is ~350 kelvin. The planets are interior to, but close to the inner edge of, the liquid-water habitable zone. We also detect an unconfirmed signal with a period of ~50 days, which could correspond to a third super-Earth in a more temperate orbit. Our observations show that GJ 887 has photometric variability below 500 parts per million, which is unusually quiet for a red dwarf.

C-arm orbits for metal artifact avoidance (MAA) in cone-beam CT.

Metal artifacts present a challenge to cone-beam CT (CBCT) image-guided surgery, obscuring visualization of metal instruments and adjacent anatomy-often in the very region of interest pertinent to the imaging/surgical tasks. We present a method to reduce the influence of metal artifacts by prospectively defining an image acquisition protocol-viz., the C-arm source-detector orbit-that mitigates metal-induced biases in the projection data. The metal artifact avoidance (MAA) method is compatible with simple mobile C-arms, does not require exact prior information on the patient or metal implants, and is consistent with 3D filtered backprojection (FBP), more advanced (e.g. polyenergetic) model-based image reconstruction (MBIR), and metal artifact reduction (MAR) post-processing methods. The MAA method consists of: (i) coarse localization of metal objects in the field-of-view (FOV) via two or more low-dose scout projection views and segmentation (e.g. a simple U-Net) in coarse backprojection; (ii) model-based prediction of metal-induced x-ray spectral shift for all source-detector vertices accessible by the imaging system (e.g. gantry rotation and tilt angles); and (iii) identification of a circular or non-circular orbit that reduces the variation in spectral shift. The method was developed, tested, and evaluated in a series of studies presenting increasing levels of complexity and realism, including digital simulations, phantom experiment, and cadaver experiment in the context of image-guided spine surgery (pedicle screw implants). The MAA method accurately predicted tilted circular and non-circular orbits that reduced the magnitude of metal artifacts in CBCT reconstructions. Realistic distributions of metal instrumentation were successfully localized (0.71 median Dice coefficient) from 2-6 low-dose scout views even in complex anatomical scenes. The MAA-predicted tilted circular orbits reduced root-mean-square error (RMSE) in 3D image reconstructions by 46%-70% and 'blooming' artifacts (apparent width of the screw shaft) by 20-45%. Non-circular orbits defined by MAA achieved a further ∼46% reduction in RMSE compared to the best (tilted) circular orbit. The MAA method presents a practical means to predict C-arm orbits that minimize spectral bias from metal instrumentation. Resulting orbits-either simple tilted circular orbits or more complex non-circular orbits that can be executed with a motorized multi-axis C-arm-exhibited substantial reduction of metal artifacts in raw CBCT reconstructions by virtue of higher fidelity projection data, which are in turn compatible with subsequent MAR post-processing and/or polyenergetic MBIR to further reduce artifacts.

Multi-body 3D-2D registration for image-guided reduction of pelvic dislocation in orthopaedic trauma surgery.

Surgical reduction of pelvic dislocation is a challenging procedure with poor long-term prognosis if reduction does not accurately restore natural morphology. The procedure often requires long fluoroscopic exposure times and trial-and-error to achieve accurate reduction. We report a method to automatically compute the target pose of dislocated bones in preoperative CT and provide 3D guidance of reduction using routine 2D fluoroscopy. A pelvic statistical shape model (SSM) and a statistical pose model (SPM) were formed from an atlas of 40 pelvic CT images. Multi-body bone segmentation was achieved by mapping the SSM to a preoperative CT via an active shape model. The target reduction pose for the dislocated bone is estimated by fitting the poses of undislocated bones to the SPM. Intraoperatively, multiple bones are registered to fluoroscopy images via 3D-2D registration to obtain 3D pose estimates from 2D images. The method was examined in three studies: (1) a simulation study of 40 CT images simulating a range of dislocation patterns; (2) a pelvic phantom study with controlled dislocation of the left innominate bone; (3) a clinical case study investigating feasibility in images acquired during pelvic reduction surgery. Experiments investigated the accuracy of registration as a function of initialization error (capture range), image quality (radiation dose and image noise), and field of view (FOV) size. The simulation study achieved target pose estimation with translational error of median 2.3 mm (1.4 mm interquartile range, IQR) and rotational error of 2.1° (1.3° IQR). 3D-2D registration yielded 0.3 mm (0.2 mm IQR) in-plane and 0.3 mm (0.2 mm IQR) out-of-plane translational error, with in-plane capture range of ±50 mm and out-of-plane capture range of ±120 mm. The phantom study demonstrated 3D-2D target registration error of 2.5 mm (1.5 mm IQR), and the method was robust over a large dose range, down to 5 [Formula: see text]Gy/frame (an order of magnitude lower than the nominal fluoroscopic dose). The clinical feasibility study demonstrated accurate registration with both preoperative and intraoperative radiographs, yielding 3.1 mm (1.0 mm IQR) projection distance error with robust performance for FOV ranging from 340 × 340 mm2 to 170 × 170 mm2 (at the image plane). The method demonstrated accurate estimation of the target reduction pose in simulation, phantom, and a clinical feasibility study for a broad range of dislocation patterns, initialization error, dose levels, and FOV size. The system provides a novel means of guidance and assessment of pelvic reduction from routinely acquired preoperative CT and intraoperative fluoroscopy. The method has the potential to reduce radiation dose by minimizing trial-and-error and to improve outcomes by guiding more accurate reduction of joint dislocations.

No association of complement mannose-binding lectin deficiency with cardiovascular disease in patients with Systemic Lupus Erythematosus.

Cardiovascular (CV) morbidity is the major cause of death in patients with Systemic Lupus Erythematosus (SLE). Previous studies on mannose-binding lectin (MBL) gene polymorphisms in SLE patients suggest that low levels of complement MBL are associated with cardiovascular disease (CVD). However, as large studies on MBL deficiency based on resulting MBL plasma concentrations are lacking, the aim of our study was to analyze the association of MBL concentrations with CVD in SLE patients. Plasma MBL levels SLE patients included in the Swiss SLE Cohort Study were quantified by ELISA. Five different CV organ manifestations were documented. Of 373 included patients (85.5% female) 62 patients had at least one CV manifestation. Patients with MBL deficiency (levels below 500 ng/ml or 1000 ng/ml) had no significantly increased frequency of CVD (19.4% vs. 15.2%, P = 0.3 or 17.7% vs. 15.7%, P = 0.7). After adjustment for traditional CV risk factors, MBL levels and positive antiphospholipid serology (APL+) a significant association of CVD with age, hypertension, disease duration and APL+ was demonstrated. In our study of a large cohort of patients with SLE, we could not confirm previous studies suggesting MBL deficiency to be associated with an increased risk for CVD.

Image-Guided Robotic K-Wire Placement for Orthopaedic Trauma Surgery.

Purpose: We report the initial development of an image-based solution for robotic assistance of pelvic fracture fixation. The approach uses intraoperative radiographs, preoperative CT, and an end effector of known design to align the robot with target trajectories in CT. The method extends previous work to solve the robot-to-patient registration from a single radiographic view (without C-arm rotation) and addresses the workflow challenges associated with integrating robotic assistance in orthopaedic trauma surgery in a form that could be broadly applicable to isocentric or non-isocentric C-arms. Methods: The proposed method uses 3D-2D known-component registration to localize a robot end effector with respect to the patient by: (1) exploiting the extended size and complex features of pelvic anatomy to register the patient; and (2) capturing multiple end effector poses using precise robotic manipulation. These transformations, along with an offline hand-eye calibration of the end effector, are used to calculate target robot poses that align the end effector with planned trajectories in the patient CT. Geometric accuracy of the registrations was independently evaluated for the patient and the robot in phantom studies. Results: The resulting translational difference between the ground truth and patient registrations of a pelvis phantom using a single (AP) view was 1.3 mm, compared to 0.4 mm using dual (AP+Lat) views. Registration of the robot in air (i.e., no background anatomy) with five unique end effector poses achieved mean translational difference ~1.4 mm for K-wire placement in the pelvis, comparable to tracker-based margins of error (commonly ~2 mm). Conclusions: The proposed approach is feasible based on the accuracy of the patient and robot registrations and is a preliminary step in developing an image-guided robotic guidance system that more naturally fits the workflow of fluoroscopically guided orthopaedic trauma surgery. Future work will involve end-to-end development of the proposed guidance system and assessment of the system with delivery of K-wires in cadaver studies.

Dyspnea in amyotrophic lateral sclerosis: The Dyspnea-ALS-Scale (DALS-15) essentially contributes to the diagnosis of respiratory impairment.

BACKGROUND: Dyspnea is a cardinal but often underestimated symptom in amyotrophic lateral sclerosis (ALS). The newly developed Dyspnea-ALS-Scale (DALS-15) is highly relevant for therapeutic decisions because dyspnea is a separate criterion to consider noninvasive ventilation (NIV) in ALS. In comparison to the limited effects of neuroprotective compounds, NIV has the greatest impact on survival and improves quality of life. OBJECTIVE: To investigate whether dyspnea corresponds to parameters of respiratory status mainly used in clinical neurological practice. We also investigated if the DALS-15 could help identify patients for consideration of NIV in whom neither spirometry nor blood gas parameters indicate the need for NIV (forced vital capacity (FVC) < 50% or probable <75%, pCO2 ≥45  mmHg). METHODS: Seventy ALS patients with dyspnea according to the DALS-15 obtained blood gas analysis and spirometry (FVC in sitting and supine positions). The supine decline in FVC was calculated. RESULTS: There was no linear relationship between dyspnea and spirometry as well as blood gases. 83% of our patients had an upright FVC still greater than 50% and no daytime hypercapnia. CONCLUSIONS: Our study clearly shows that dyspnea can occur independently of objective indicators of respiratory impairment like spirometry or blood gases. Hence, the DALS-15 covers another aspect of respiratory impairment than these tests and refers to the subjective component of respiratory impairment. It detects dyspnea in a considerable proportion of patients in whom NIV should thus be considered although their spirometric and blood gas results do not point towards NIV. The DALS-15 therefore may help to improve the stratification of patients with respiratory impairment for more efficient symptom management and timely coordination of care.

Atlas-based automatic planning and 3D-2D fluoroscopic guidance in pelvic trauma surgery.

Percutaneous screw fixation in pelvic trauma surgery is a challenging procedure that often requires long fluoroscopic exposure times and trial-and-error insertion attempts along narrow bone corridors of the pelvis. We report a method to automatically plan surgical trajectories using preoperative CT and assist device placement by augmenting the fluoroscopic scene with planned trajectories. A pelvic shape atlas was formed from 40 CT images and used to construct a statistical shape model (SSM). Each member of the atlas included expert definition of volumetric regions representing safe trajectory within bone corridors for fixating 10 common fracture patterns. Patient-specific planning is obtained by mapping the SSM to the (un-segmented) patient CT via active shape model (ASM) registration and free-form deformation (FFD), and the resulting transformation is used to transfer the atlas trajectory volumes to the patient CT. Fluoroscopic images acquired during K-wire placement are in turn augmented with projection of the planned trajectories via 3D-2D registration. Registration performance was evaluated via leave-one-out cross-validation over the 40-member atlas, computing the root mean square error (RMSE) in pelvic surface alignment (volumetric registration error), the positive predicted value (PPV) of volumetric trajectories within bone corridors (safety of the automatically planned trajectories), and the distance between trajectories within the planned volume and the bone cortex (absence of breach). A cadaver study was conducted in which K-wires were placed under fluoroscopic guidance to validate 3D-2D registration accuracy and evaluate the potential utility of augmented fluoroscopy with planned trajectories. The leave-one-out cross-validation achieved surface RMSE of 2.2 ± 0.3 mm after ASM registration and 1.8 ± 0.2 mm after FFD refinement. Automatically determined surgical plans conformed within bone corridors with PPV > 90% and centerline trajectory within 3-5 mm of the bone cortex. 3D-2D registration in the cadaver study achieved 0.3 ± 0.8 mm accuracy (in-plane translation) and <4° accuracy (in-plane rotation). Fluoroscopic images augmented with planning data exhibited >90% conformance of volumetric planning data overlay within bone, and all centerline trajectories were within safe corridors. The approach yields a method for both automatic planning of pelvic fracture fixation and augmentation of fluoroscopy for improved surgical precision and safety. The method does not require segmentation of the patient CT, operates without additional hardware (e.g. tracking systems), and is consistent with common workflow in fluoroscopically guided procedures. The approach has the potential to reduce operating time and radiation dose by minimizing trial-and-error attempts in percutaneous screw placement.

Visualizing the dynamics of soil aggregation as affected by arbuscular mycorrhizal fungi.

Stable soils provide valuable ecosystem services and mechanical soil stability is enhanced by the presence of arbuscular mycorrhizal fungi (AMF). Soil aggregation, which is the major driver of mechanical soil stability, is often treated as a static phenomenon, even though aggregate turnover is continually ongoing. In fact, some breakdown of macroaggregates is necessary to allow new aggregate formation and inclusion of new organic matter into microaggregates. We determined how aggregate turnover times were affected by AMF by tracking movement of rare earth elements (REE), applied as their immobile oxides, between aggregate size classes, and using X-ray fluorescence microscopy to spatially localize REEs in a sample of aggregates. Here we show that AMF increased large macroaggregate formation and slowed down disintegration of large and small macroaggregates. Microaggregate turnover was increased in the presence of AMF. Internal aggregate organization suggested that although formation of microaggregates by accretion of soil to particulate organic matter is common, it is not the only mechanism in operation.

A candidate super-Earth planet orbiting near the snow line of Barnard's star.

Barnard's star is a red dwarf, and has the largest proper motion (apparent motion across the sky) of all known stars. At a distance of 1.8 parsecs1, it is the closest single star to the Sun; only the three stars in the α Centauri system are closer. Barnard's star is also among the least magnetically active red dwarfs known2,3 and has an estimated age older than the Solar System. Its properties make it a prime target for planetary searches; various techniques with different sensitivity limits have been used previously, including radial-velocity imaging4-6, astrometry7,8 and direct imaging9, but all ultimately led to negative or null results. Here we combine numerous measurements from high-precision radial-velocity instruments, revealing the presence of a low-amplitude periodic signal with a period of 233 days. Independent photometric and spectroscopic monitoring, as well as an analysis of instrumental systematic effects, suggest that this signal is best explained as arising from a planetary companion. The candidate planet around Barnard's star is a cold super-Earth, with a minimum mass of 3.2 times that of Earth, orbiting near its snow line (the minimum distance from the star at which volatile compounds could condense). The combination of all radial-velocity datasets spanning 20 years of measurements additionally reveals a long-term modulation that could arise from a stellar magnetic-activity cycle or from a more distant planetary object. Because of its proximity to the Sun, the candidate planet has a maximum angular separation of 220 milliarcseconds from Barnard's star, making it an excellent target for direct imaging and astrometric observations in the future.