From mild to gangrenous cholecystitis, laparoscopic cholecystectomy is safe 24 hours a day.

OBJECTIVES: Laparoscopic cholecystectomy (LC) at night remains controversial. Prior studies have not controlled for disease severity. We analyzed outcomes of LC performed day vs. night while controlling for the Parkland Grading Scale for Cholecystitis (PGS). METHODS: Analysis of the AAST multicenter evaluation of cholecystitis database was performed. Exclusion criteria included non-operative cases, open operations, and missing PGS. Cases were divided based on operation start time. PGS was used to control for disease severity. Outcomes included operative time, use of bailout techniques and complications. RESULTS: Of 759 procedures identified, 16% were nighttime LC. No differences in demographics, comorbidities, physiologic variables and PGS were noted. Operative time (108.6 min vs 105.6), bailout techniques (8.3% vs 7.4%) and complications (9.9% vs 11.3%) were similar between groups. CONCLUSION: Regardless of severity, laparoscopic cholecystectomy is safe 24-h a day. Operations performed at night have a similar complication profile to those performed during the day.

The Conventional Gait Model's sensitivity to lower-limb marker placement.

Clinical gait analysis supports treatment decisions for patients with motor disorders. Measurement reproducibility is affected by extrinsic errors such as marker misplacement-considered the main factor in gait analysis variability. However, how marker placement affects output kinematics is not completely understood. The present study aimed to evaluate the Conventional Gait Model's sensitivity to marker placement. Using a dataset of kinematics for 20 children, eight lower-limb markers were virtually displaced by 10 mm in all four planes, and all the displacement combinations were recalculated. Root-mean-square deviation angles were calculated for each simulation with respect to the original kinematics. The marker movements with the greatest impact were for the femoral and tibial wands together with the lateral femoral epicondyle marker when displaced in the anterior-posterior axis. When displaced alone, the femoral wand was responsible for a deviation of 7.3° (± 1.8°) in hip rotation. Transversal plane measurements were affected most, with around 40% of simulations resulting in an effect greater than the acceptable limit of 5°. This study also provided insight into which markers need to be placed very carefully to obtain more reliable gait data.

Uncertainty analysis and sensitivity of scapulothoracic joint angles to kinematic model parameters.

The purposes of this study were to determine the influence of kinematic model parameter variability on scapulothoracic angle estimates, and to define which parameters of the kinematic model have the largest effect on scapulothoracic angle estimates. Nominal subject-specific kinematic models of nine participants were implemented. Fifteen parameters of the nominal models relative to the clavicle length, ellipsoid, sternoclavicular and acromioclavicular joint centers, and contact point location were altered from - 1 to 1 cm. Then, scapulothoracic angles were computed during four movements using multibody kinematic optimizations for nominal and altered models. The percentage of scapulothoracic angle variance explained by each parameter of the kinematic model was computed using Effective Algorithm for Computing Global Sensitivity Indices. When altering simultaneously the 15 parameters of the kinematic model, scapulothoracic angles varied up to 50°. For all movements and degrees of freedom, the clavicle length significantly explained the largest part of scapulothoracic angle variance (up to 25%, p < 0.01). In conclusion, kinematic model parameters need to be estimated accurately to avoid any bias in scapulothoracic angle estimates especially in a clinical context. The present sensitivity analysis may also be used as a benchmark for future works focusing on improving shoulder kinematic models. The curves represent mean scapulothoracic angles computed with the nominal model and their variability when kinematic model parameters are altered. The colormap graphs represent the percentage of scapulothoracic angle variance explained by each parameter of the kinematic model.

Subject-specific model-derived kinematics of the shoulder based on skin markers during arm abduction up to 180° - assessment of 4 gleno-humeral joint models.

Accuracy of shoulder kinematics predicted by multi-body kinematics optimisation depend on the joint models used. This study assesses the influence of four different subject-specific gleno-humeral joint models within multi-body kinematics optimisation: a 6-degree-of-freedom joint (i.e. single-body kinematics optimisation), a sphere-on-sphere joint (with two spheres of different radii) and a spherical joint with or without penalised translation. To drive these models, the 3D coordinates of 12 skin markers of 6 subjects performing static arm abduction poses up to 180° were used. The reference data was obtained using biplane X-rays from which 3D bone reconstructions were generated: scapula and humerus were 3D reconstructed by fitting a template model made of geometrical primitives on the two bones' X-rays. Without any motion capture system, the recording of the skin markers was performed at the very same time than the X-rays with radiopaque markers. The gleno-humeral displacements and angles, and scapula-thoracic angles were computed. The gleno-humeral sphere-on-sphere joint provided slightly better results than the spherical joint with or without penalised translation, but considerably better gleno-humeral displacements than the 6-DoF joint. Considering that it can easily be personalised from medical images, this sphere-on-sphere model seems promising for shoulder multi-body kinematics optimisation.

The effect of ankle and hindfoot malalignment on foot mechanics in patients suffering from post-traumatic ankle osteoarthritis.

BACKGROUND: Ankle and hindfoot malalignment is a common finding in patients suffering from post-traumatic ankle osteoarthritis. However, no studies have addressed the effect of concomitant foot deformities on intrinsic foot kinematics and kinetics. Therefore, the objective of this study was to investigate the effect of ankle and hindfoot malalignment on the kinematics and kinetics of multiple joints in the foot and ankle complex in patients suffering from post-traumatic ankle osteoarthritis. METHODS: Twenty-nine subjects with post-traumatic ankle osteoarthritis participated in this study. Standardized weight-bearing radiographs were obtained preoperatively to categorize patients as having cavus, planus or neutral ankle and hindfoot alignment, based on 4 X-ray measurements. All patients underwent standard gait assessment. A 4-segment foot model was used to estimate intrinsic foot joint kinematics and kinetics during gait. Statistical parametric mapping was used to compare foot kinematics and kinetics between groups. FINDINGS: There were 3 key findings regarding overall foot function in the 3 groups of post-traumatic ankle osteoarthritis: (i) altered frontal and transverse plane inter-segmental angles and moments of the Shank-Calcaneus and Calcaneus-Midfoot joints in the cavus compared to the planus group; (ii) in cavus OA group, Midfoot-Metatarsus joint abduction sought to compensate the varus inclination of the ankle joint; (iii) there were no significant differences in inter-segmental angles and moments between the planus and neutral OA groups. INTERPRETATION: Future studies should integrate assessment of concomitant foot and ankle deformities in post-traumatic ankle osteoarthritis, to provide additional insight into associated mechanical deficits and compensation mechanisms during gait.

Trauma video review utilization: A survey of practice in the United States.

INTRODUCTION: Trauma video review (TVR) for quality improvement and education in the United States has been described for nearly three decades. The most recent information on this practice indicated a declining prevalence. We hypothesized that TVR utilization has increased since most recent estimates. METHODS: We conducted a survey of TVR practices at level I and level II US trauma centers. We distributed an electronic survey covering past, current, and future TVR utilization to the Eastern Association for the Surgery of Trauma membership. RESULTS: 45.0% of US level I and level II trauma centers completed surveys. 71/249 centers (28.5%) had active TVR programs. The use of TVR did not differ between level I and level II centers (28.8% vs. 27.8%, p = 0.87). Respondents using TVR were overwhelmingly positive about its perception (median score 8, [IQR 6-9]; 10 = 'best') at their institutions. CONCLUSIONS: TVR use at Level I centers has increased over the past decade. Increased TVR utilization may form the basis for multicenter studies comparing processes of care during trauma resuscitation.

Emergency Department Versus Operating Suite Intubation in Operative Trauma Patients: Does Location Matter?

BACKGROUND: Decreasing the time from patient arrival to definitive surgical care in injured patients requiring an operation improves outcomes. We sought to study the effect of intubation location (emergency department versus operating suite) on time to definitive surgical care. We hypothesized that patients requiring emergency surgical interventions intubated in the emergency department would have shorter times to definitive care when compared to patients intubated in the operating suite. METHODS: All injured patients with a preoperative emergency department dwell time of less than 30 min and undergoing emergency operative procedures with the trauma surgery service at an urban Level I center (2010-2017) were analyzed. Demographics, clinical variables, and outcomes were assessed in relation to emergency department intubation versus operating suite intubation. The primary study endpoint was time to initiation of definitive surgical care, defined as the total elapsed time from emergency department arrival until operating room incision time. To investigate the relationship between clinical variables and time, multivariable regression was performed. RESULTS: In total, 241 patients were included. In total, 138 patients were intubated in the emergency department and 103 patients were intubated in the operative suite. There was no difference between patients intubated in the emergency department and those intubated in the operating room with respect to age, gender, injury mechanism, initial heart rate or systolic blood pressure. Emergency department patients were more likely to sustain post-intubation, traumatic cardiopulmonary arrest (8.0 vs. 0.9%; p = 0.014). No statistical difference in total elapsed time from arrival to definitive surgical care was appreciated between study groups (41 vs. 43 min; p = 0.064). After controlling for clinical variables, emergency department intubation was not associated with time to definitive care (p = 0.386) in the multiple variable regression analysis. CONCLUSION: When emergency department and operative suite intubation patients were compared, emergency department intubation did not decrease total elapsed time until definitive surgery but was associated with post-intubation, traumatic cardiopulmonary arrest.

[Quality and safety policy implementation for a new radiotherapy device]. / Mise en place d'une politique de qualité et de sécurité lors de l'installation d'un nouvel équipement dans un service de radiothérapie.

Modern radiotherapy techniques (intensity-modulated radiotherapy, volumetric-modulated arctherapy, image-guided radiotherapy) or stereotactic radiotherapy are in expansion in most French cancer centres. The arrival of such techniques requires updates of existing equipment or implementation of new radiotherapy devices with adapted options. With the arrival of these new devices, there is a need to develop a quality and safety policy. This is necessary to ease the process from the setup to the first treated patient. The quality and safety policy is maintained to ensure the quality assurance of the radiotherapy equipment. We conducted a review of the literature on the quality and safety policy in the French legal framework that can be proposed when implementing a new radiotherapy device.

Technical considerations in lateral extra-articular reconstruction coupled with anterior cruciate ligament reconstruction: A simulation study evaluating the influence of surgical parameters on control of knee stability.

BACKGROUND: Surgical parameters such as the selection of tibial and femoral attachment site, graft tension, and knee flexion angle at the time of fixation may influence the control of knee stability after lateral extra-articular reconstruction. This study aimed to determine how sensitive is the control of knee rotation and translation, during simulated pivot-shift scenarios, to these four surgery settings. METHODS: A computer model was used to simulate 625 lateral extra-articular reconstructions based upon five different variations of each of the following parameters: femoral and tibial attachment sites, knee flexion angle and graft tension at the time of fixation. For each simulated surgery, the lateral extra-articular reconstruction external rotation moment at the knee joint center was computed during simulated pivot-shift scenarios. The sensitivity of the control of knee rotation and translation to a given surgery setting was assessed by calculating the coefficient of variation of the lateral extra-articular reconstruction external rotation moment. FINDINGS: Graft tension had minimal influence on the control of knee rotation and translation with less than 2.4% of variation across the scenarios tested. Control of knee rotation and translation was the least affected by the femoral attachment site if the knee was close to full extension at the time of graft fixation. The choice of the tibial attachment site was crucial when the femoral fixation was proximal and posterior to the femoral epicondyle since 15 to 67% of variation was observed in the control of knee rotation and translation. INTERPRETATION: Femoral and tibial attachment sites as well as knee flexion angle at the time of fixation should be considered by surgeons when performing lateral extra-articular reconstruction. Variation in graft tension between the ranges 20-40 N has minimal influence on the control of knee rotation and translation.

Spin transfer torque driven higher-order propagating spin waves in nano-contact magnetic tunnel junctions.

Short wavelength exchange-dominated propagating spin waves will enable magnonic devices to operate at higher frequencies and higher data transmission rates. While giant magnetoresistance (GMR)-based magnetic nanocontacts are efficient injectors of propagating spin waves, the generated wavelengths are 2.6 times the nano-contact diameter, and the electrical signal strength remains too weak for applications. Here we demonstrate nano-contact-based spin wave generation in magnetic tunnel junctions and observe large-frequency steps consistent with the hitherto ignored possibility of second- and third-order propagating spin waves with wavelengths of 120 and 74 nm, i.e., much smaller than the 150-nm nanocontact. Mutual synchronization is also observed on all three propagating modes. These higher-order propagating spin waves will enable magnonic devices to operate at much higher frequencies and greatly increase their transmission rates and spin wave propagating lengths, both proportional to the much higher group velocity.

Knee medial and lateral contact forces in a musculoskeletal model with subject-specific contact point trajectories.

Contact point (CP) trajectory is a crucial parameter in estimating medial/lateral tibio-femoral contact forces from the musculoskeletal (MSK) models. The objective of the present study was to develop a method to incorporate the subject-specific CP trajectories into the MSK model. Ten healthy subjects performed 45 s treadmill gait trials. The subject-specific CP trajectories were constructed on the tibia and femur as a function of extension-flexion using low-dose bi-plane X-ray images during a quasi-static squat. At each extension-flexion position, the tibia and femur CPs were superimposed in the three directions on the medial side, and in the anterior-posterior and proximal-distal directions on the lateral side to form the five kinematic constraints of the knee joint. The Lagrange multipliers associated to these constraints directly yielded the medial/lateral contact forces. The results from the personalized CP trajectory model were compared against the linear CP trajectory and sphere-on-plane CP trajectory models which were adapted from the commonly used MSK models. Changing the CP trajectory had a remarkable impact on the knee kinematics and changed the medial and lateral contact forces by 1.03 BW and 0.65 BW respectively, in certain subjects. The direction and magnitude of the medial/lateral contact force were highly variable among the subjects and the medial-lateral shift of the CPs alone could not determine the increase/decrease pattern of the contact forces. The suggested kinematic constraints are adaptable to the CP trajectories derived from a variety of joint models and those experimentally measured from the 3D imaging techniques.

Alterations of musculoskeletal models for a more accurate estimation of lower limb joint contact forces during normal gait: A systematic review.

Musculoskeletal modelling is a methodology used to investigate joint contact forces during a movement. High accuracy in the estimation of the hip or knee joint contact forces can be obtained with subject-specific models. However, construction of subject-specific models remains time consuming and expensive. The purpose of this systematic review of the literature was to identify what alterations can be made on generic (i.e. literature-based, without any subject-specific measurement other than body size and weight) musculoskeletal models to obtain a better estimation of the joint contact forces. The impact of these alterations on the accuracy of the estimated joint contact forces were appraised. The systematic search yielded to 141 articles and 24 papers were included in the review. Different strategies of alterations were found: skeletal and joint model (e.g. number of degrees of freedom, knee alignment), muscle model (e.g. Hill-type muscle parameters, level of muscular redundancy), and optimisation problem (e.g. objective function, design variables, constraints). All these alterations had an impact on joint contact force accuracy, so demonstrating the potential for improving the model predictions without necessarily involving costly and time consuming medical images. However, due to discrepancies in the reported evidence about this impact and despite a high quality of the reviewed studies, it was not possible to highlight any trend defining which alteration had the largest impact.

Tibio-femoral joint contact in healthy and osteoarthritic knees during quasi-static squat: A bi-planar X-ray analysis.

The aim of this study was to quantify the tibio-femoral contact point (CP) locations in healthy and osteoarthritic (OA) subjects during a weight-bearing squat using stand-alone biplanar X-ray images. Ten healthy and 9 severe OA subjects performed quasi-static squats. Bi-planar X-ray images were recorded at 0°, 15°, 30°, 45°, and 70° of knee flexion. A reconstruction/registration process was used to create 3D models of tibia, fibula, and femur from bi-planar X-rays and to measure their positions at each posture. A weighted centroid of proximity algorithm was used to calculate the tibio-femoral CP locations. The accuracy of the reconstruction/registration process in measuring the quasi-static kinematics and the contact parameters was evaluated in a validation study. The quasi-static kinematics data revealed that in OA knees, adduction angles were greater (p<0.01), and the femur was located more medially relative to the tibia (p<0.01). Similarly, the average CP locations on the medial and lateral tibial plateaus of the OA patients were shifted (6.5±0.7mm; p<0.01) and (9.6±3.1mm; p<0.01) medially compared to the healthy group. From 0° to 70° flexion, CPs moved 8.1±5.3mm and 8.9±5.3mm posteriorly on the medial and lateral plateaus of healthy knees; while in OA joints CPs moved 10.1±8.4mm and 3.6±2.8mm posteriorly. The average minimum tibio-femoral bone-to-bone distances of the OA joints were lower in both compartments (p<0.01). The CPs in the OA joints were located more medially and displayed a higher ratio of medial to lateral posterior translations compared to healthy joints.

A constrained extended Kalman filter for the optimal estimate of kinematics and kinetics of a sagittal symmetric exercise.

This paper presents a method for real-time estimation of the kinematics and kinetics of a human body performing a sagittal symmetric motor task, which would minimize the impact of the stereophotogrammetric soft tissue artefacts (STA). The method is based on a bi-dimensional mechanical model of the locomotor apparatus the state variables of which (joint angles, velocities and accelerations, and the segments lengths and inertial parameters) are estimated by a constrained extended Kalman filter (CEKF) that fuses input information made of both stereophotogrammetric and dynamometric measurement data. Filter gains are made to saturate in order to obtain plausible state variables and the measurement covariance matrix of the filter accounts for the expected STA maximal amplitudes. We hypothesised that the ensemble of constraints and input redundant information would allow the method to attenuate the STA propagation to the end results. The method was evaluated in ten human subjects performing a squat exercise. The CEKF estimated and measured skin marker trajectories exhibited a RMS difference lower than 4mm, thus in the range of STAs. The RMS differences between the measured ground reaction force and moment and those estimated using the proposed method (9N and 10Nm) were much lower than obtained using a classical inverse dynamics approach (22N and 30Nm). From the latter results it may be inferred that the presented method allows for a significant improvement of the accuracy with which kinematic variables and relevant time derivatives, model parameters and, therefore, intersegmental moments are estimated.

Main component of soft tissue artifact of the upper-limbs with respect to different functional, daily life and sports movements.

Soft tissue artifact (STA) is the main source of error in kinematic estimation of human movements based on skin markers. Our objective was to determine the components of marker displacements that best describe STA of the shoulder and arm (i.e. clavicle, scapula and humerus). Four participants performed arm flexion and rotation, a daily-life and a sports movement. Three pins with reflective markers were inserted into the clavicle, scapula and humerus. In addition, up to seven skin markers were stuck on each segment. STA was described with a modal approach: individual marker displacements or marker-cluster (i.e. translations, rotations, homotheties and stretches) relative to the local segment coordinate system defined by markers secured to the pins. The modes were then ranked according to the percentage of total STA energy that they explained. Both individual skin marker displacements and marker-cluster geometrical transformations were task-, location-, segment- and subject-specific. However, 85% of the total STA energy was systematically explained by the rigid transformations (i.e. translations and rotations of the marker-cluster). In conclusion, large joint dislocations and limited efficiency of least squares bone pose estimators are expected for the computation of upper limb joint kinematics from skin markers. Future developments shall consider the rigid transformations of marker-clusters in the implementation of an STA model to reduce its effects on kinematics estimation.

A simplified marker set to define the center of mass for stability analysis in dynamic situations.

The extrapolated center of mass (XCoM), a valuable tool to assess balance stability, involves defining the whole body center of mass (CoMWB). However, accurate three-dimensional estimation of the CoMWB is time consuming, a severe limitation in certain applications. In this study, twenty-four subjects (young and elderly, male and female) performed three different balance tasks: quiet standing, gait and balance recovery. Three different models, based on a segmental method, were used to estimate the three-dimensional CoMWB absolute position during these movements: a reference model based on 38 markers, a simplified 13-marker model and a single marker (sacral) model. CoMWB and XCoM estimations from the proposed simplified model came closer to the reference model than estimations from the sacral marker model. It remained accurate for dynamic tasks, where the sacral marker model proved inappropriate. The simplified model proposed here yields accurate three-dimensional estimation of both the CoMWB and the XCoM with a limited number of markers. Importantly, using this model would reduce the experimental and post-processing times for future balance studies assessing dynamic stability in humans.