Take a shot! Natural language control of intelligent robotic X-ray systems in surgery.

PURPOSE: The expanding capabilities of surgical systems bring with them increasing complexity in the interfaces that humans use to control them. Robotic C-arm X-ray imaging systems, for instance, often require manipulation of independent axes via joysticks, while higher-level control options hide inside device-specific menus. The complexity of these interfaces hinder "ready-to-hand" use of high-level functions. Natural language offers a flexible, familiar interface for surgeons to express their desired outcome rather than remembering the steps necessary to achieve it, enabling direct access to task-aware, patient-specific C-arm functionality. METHODS: We present an English language voice interface for controlling a robotic X-ray imaging system with task-aware functions for pelvic trauma surgery. Our fully integrated system uses a large language model (LLM) to convert natural spoken commands into machine-readable instructions, enabling low-level commands like "Tilt back a bit," to increase the angular tilt or patient-specific directions like, "Go to the obturator oblique view of the right ramus," based on automated image analysis. RESULTS: We evaluate our system with 212 prompts provided by an attending physician, in which the system performed satisfactory actions 97% of the time. To test the fully integrated system, we conduct a real-time study in which an attending physician placed orthopedic hardware along desired trajectories through an anthropomorphic phantom, interacting solely with an X-ray system via voice. CONCLUSION: Voice interfaces offer a convenient, flexible way for surgeons to manipulate C-arms based on desired outcomes rather than device-specific processes. As LLMs grow increasingly capable, so too will their applications in supporting higher-level interactions with surgical assistance systems.

Stand in surgeon's shoes: virtual reality cross-training to enhance teamwork in surgery.

PURPOSE: Teamwork in surgery depends on a shared mental model of success, i.e., a common understanding of objectives in the operating room. A shared model leads to increased engagement among team members and is associated with fewer complications and overall better outcomes for patients. However, clinical training typically focuses on role-specific skills, leaving individuals to acquire a shared model indirectly through on-the-job experience. METHODS: We investigate whether virtual reality (VR) cross-training, i.elet@tokeneonedotexposure to other roles, can enhance a shared mental model for non-surgeons more directly. Our study focuses on X-ray guided pelvic trauma surgery, a procedure where successful communication depends on the shared model between the surgeon and a C-arm technologist. We present a VR environment supporting both roles and evaluate a cross-training curriculum in which non-surgeons swap roles with the surgeon. RESULTS: Exposure to the surgical task resulted in higher engagement with the C-arm technologist role in VR, as measured by the mental demand and effort expended by participants ( p < 0.001 ). It also has a significant effect on non-surgeon's mental model of the overall task; novice participants' estimation of the mental demand and effort required for the surgeon's task increases after training, while their perception of overall performance decreases ( p < 0.05 ), indicating a gap in understanding based solely on observation. This phenomenon was also present for a professional C-arm technologist. CONCLUSION: Until now, VR applications for clinical training have focused on virtualizing existing curricula. We demonstrate how novel approaches which are not possible outside of a virtual environment, such as role swapping, may enhance the shared mental model of surgical teams by contextualizing each individual's role within the overall task in a time- and cost-efficient manner. As workflows grow increasingly sophisticated, we see VR curricula as being able to directly foster a shared model for success, ultimately benefiting patient outcomes through more effective teamwork in surgery.

Failure after operative repair is higher for ballistic femoral neck fractures than for closed, blunt-injury fractures: a multicenter retrospective cohort study.

Introduction: The purpose of this study was to describe the outcomes after operative repair of ballistic femoral neck fractures. To better highlight the devastating nature of these injuries, we compared a cohort of ballistic femoral neck fractures to a cohort of young, closed, blunt-injury femoral neck fractures treated with open reduction and internal fixation (ORIF). Methods: Retrospective chart review identified all patients presenting with ballistic femoral neck fractures treated at three academic trauma centers between January 2016 and December 2021, as well as patients aged ≤50 with closed, blunt-injury femoral neck fractures who received ORIF. The primary outcome was failure of ORIF, which includes the diagnosis of non-union, avascular necrosis, conversion to total hip arthroplasty, and conversion to Girdlestone procedure. Additional outcomes included deep infection, postoperative osteoarthritis, and ambulatory status at last follow-up. Results: Fourteen ballistic femoral neck fractures and 29 closed blunt injury fractures were identified. Of the ballistic fractures, 7 (50%) patients had a minimum of 1-year follow-up or met the failure criteria. Of the closed fractures, 16 (55%) patients had a minimum of 1-year follow-up or met the failure criteria. Median follow-up was 21 months. 58% of patients with ballistic fractures were active tobacco users. Five of 7 (71%) ballistic fractures failed, all of which involved non-union, whereas 8 of 16 (50%) closed fractures failed (p=0.340). No outcomes were significantly different between cohorts. Conclusion: Our results demonstrate that ballistic femoral neck fractures are associated with high rates of non-union. Large-scale multicenter studies are necessary to better determine optimal treatment techniques for these fractures. Level of evidence: Level III. Retrospective cohort study.

Psychological treatments for the management of pain after musculoskeletal injury: a systematic review and meta-analysis.

ABSTRACT: Musculoskeletal injury is a leading cause of pain and disability worldwide; 35% to 75% of people experience persistent pain for months and years after injury. Psychological treatments can reduce pain, functional impairment, and psychological distress but are not widely used after injury. This systematic review and meta-analysis (PROSPERO ID: CRD42021236807) aimed to synthesize the literature testing psychological treatments for pain after musculoskeletal injury. We searched EMBASE, MEDLINE, PubMed, PsycINFO, and CENTRAL from inception to May 2022. We extracted participant, treatment, and injury characteristics and primary (eg, pain intensity, functional impairment, depression, anxiety, and PTSD symptoms) and secondary (treatment feasibility and acceptability) outcomes. Twenty-four randomized controlled trials (N = 1966) were included. Immediately posttreatment, people who received psychological treatments (versus any control) reported lower pain intensity (standardized mean differences [SMD] = -0.25, 95% confidence interval [-0.49, -0.02]), functional impairment (SMD = -0.32 [-0.55, -0.09]), and symptoms of depression (SMD = -0.46 [-0.64, -0.29]), anxiety (SMD = -0.34 [-0.65, -0.04]), and PTSD (SMD = -0.43 [-0.70, -0.15]); at 6-month follow-up, only depression symptoms were significantly lower. Included trials varied widely in treatment and injury characteristics. The certainty of evidence was low or very low for most effects and heterogeneity moderate to substantial. Most studies had risk of bias domains judged to be high or unclear. Owing to very low certainty of results, we are unsure whether psychological therapies reduce pain and functional impairment after musculoskeletal injury; they may result in improved depression immediately posttreatment and at follow-up. More research is needed to identify treatments that result in enduring effects.

Mixed Reality Interfaces for Achieving Desired Views with Robotic X-ray Systems.

Robotic X-ray C-arm imaging systems can precisely achieve any position and orientation relative to the patient. Informing the system, however, what pose exactly corresponds to a desired view is challenging. Currently these systems are operated by the surgeon using joysticks, but this interaction paradigm is not necessarily effective because users may be unable to efficiently actuate more than a single axis of the system simultaneously. Moreover, novel robotic imaging systems, such as the Brainlab Loop-X, allow for independent source and detector movements, adding even more complexity. To address this challenge, we consider complementary interfaces for the surgeon to command robotic X-ray systems effectively. Specifically, we consider three interaction paradigms: (1) the use of a pointer to specify the principal ray of the desired view relative to the anatomy, (2) the same pointer, but combined with a mixed reality environment to synchronously render digitally reconstructed radiographs from the tool's pose, and (3) the same mixed reality environment but with a virtual X-ray source instead of the pointer. Initial human-in-the-loop evaluation with an attending trauma surgeon indicates that mixed reality interfaces for robotic X-ray system control are promising and may contribute to substantially reducing the number of X-ray images acquired solely during "fluoro hunting" for the desired view or standard plane.

An autonomous X-ray image acquisition and interpretation system for assisting percutaneous pelvic fracture fixation.

PURPOSE: Percutaneous fracture fixation involves multiple X-ray acquisitions to determine adequate tool trajectories in bony anatomy. In order to reduce time spent adjusting the X-ray imager's gantry, avoid excess acquisitions, and anticipate inadequate trajectories before penetrating bone, we propose an autonomous system for intra-operative feedback that combines robotic X-ray imaging and machine learning for automated image acquisition and interpretation, respectively. METHODS: Our approach reconstructs an appropriate trajectory in a two-image sequence, where the optimal second viewpoint is determined based on analysis of the first image. A deep neural network is responsible for detecting the tool and corridor, here a K-wire and the superior pubic ramus, respectively, in these radiographs. The reconstructed corridor and K-wire pose are compared to determine likelihood of cortical breach, and both are visualized for the clinician in a mixed reality environment that is spatially registered to the patient and delivered by an optical see-through head-mounted display. RESULTS: We assess the upper bounds on system performance through in silico evaluation across 11 CTs with fractures present, in which the corridor and K-wire are adequately reconstructed. In post hoc analysis of radiographs across 3 cadaveric specimens, our system determines the appropriate trajectory to within 2.8 ± 1.3 mm and 2.7 ± 1.8[Formula: see text]. CONCLUSION: An expert user study with an anthropomorphic phantom demonstrates how our autonomous, integrated system requires fewer images and lower movement to guide and confirm adequate placement compared to current clinical practice. Code and data are available.

Visualization in 2D/3D registration matters for assuring technology-assisted image-guided surgery.

PURPOSE: Image-guided navigation and surgical robotics are the next frontiers of minimally invasive surgery. Assuring safety in high-stakes clinical environments is critical for their deployment. 2D/3D registration is an essential, enabling algorithm for most of these systems, as it provides spatial alignment of preoperative data with intraoperative images. While these algorithms have been studied widely, there is a need for verification methods to enable human stakeholders to assess and either approve or reject registration results to ensure safe operation. METHODS: To address the verification problem from the perspective of human perception, we develop novel visualization paradigms and use a sampling method based on approximate posterior distribution to simulate registration offsets. We then conduct a user study with 22 participants to investigate how different visualization paradigms (Neutral, Attention-Guiding, Correspondence-Suggesting) affect human performance in evaluating the simulated 2D/3D registration results using 12 pelvic fluoroscopy images. RESULTS: All three visualization paradigms allow users to perform better than random guessing to differentiate between offsets of varying magnitude. The novel paradigms show better performance than the neutral paradigm when using an absolute threshold to differentiate acceptable and unacceptable registrations (highest accuracy: Correspondence-Suggesting (65.1%), highest F1 score: Attention-Guiding (65.7%)), as well as when using a paradigm-specific threshold for the same discrimination (highest accuracy: Attention-Guiding (70.4%), highest F1 score: Corresponding-Suggesting (65.0%)). CONCLUSION: This study demonstrates that visualization paradigms do affect the human-based assessment of 2D/3D registration errors. However, further exploration is needed to understand this effect better and develop more effective methods to assure accuracy. This research serves as a crucial step toward enhanced surgical autonomy and safety assurance in technology-assisted image-guided surgery.

What Factors Are Associated With Delayed Wound Closure in Open Reduction and Internal Fixation of Adult Both-bone Forearm Fractures?

BACKGROUND: Delayed wound closure is often used after open reduction and internal fixation (ORIF) of both-bone forearm fractures to reduce the risk of skin necrosis and subsequent infection caused by excessive swelling. However, no studies we are aware of have evaluated factors associated with the use of delayed wound closure after ORIF. QUESTIONS/PURPOSES: (1) What proportion of patients undergo delayed wound closure after ORIF of adult both-bone forearm fractures? (2) What factors are associated with delayed wound closure? METHODS: The medical records of all patients who underwent ORIF with plate fixation for both-bone fractures by the adult orthopaedic trauma service at our institution were considered potentially eligible for analysis. Between January 2010 and April 2022, we treated 74 patients with ORIF for both-bone forearm fractures. Patients were excluded if they had fractures that were fixed more than 2 weeks from injury (six patients), if their fracture was treated with an intramedullary nail (one patient), or if the patient experienced compartment syndrome preoperatively (one patient). No patients with Gustilo-Anderson Type IIIB and C open fractures were included. Based on these criteria, 89% (66 of 74) of the patients were eligible. No further patients were excluded for loss of follow-up because the primary endpoint was the use of delayed wound closure, which was performed at the time of ORIF. However, one further patient was excluded for having bilateral forearm fractures to ensure that each patient had a single fracture for statistical analysis. Thus, 88% (65 of 74) of patients were included in the analysis. These patients were captured by an electronic medical record search of CPT code 25575. The mean ± SD age was 34 ± 15 years and mean BMI was 28 ± 7 kg/m 2 . The mean follow-up duration was 4 ± 5 months. The primary endpoint was the use of delayed wound closure, which was determined at the time of definitive fixation if tension-free closure could not be achieved. All surgeons used a volar Henry or modified Henry approach and a dorsal subcutaneous approach to the ulna for ORIF. Univariate logistic regression was used to identify which factors might be associated with delayed wound closure. A multivariable logistic regression analysis was then performed for male gender, open fractures, age, and BMI. RESULTS: Twenty percent (13 of 65) of patients underwent delayed wound closure, 18% (12 of 65) of which occurred in patients who had high-energy injuries and 14% (nine of 65) in patients who had open fractures. Being a man (adjusted odds ratio 9.9 [95% confidence interval 1 to 87]; p = 0.04) was independently associated with delayed wound closure, after adjusting for open fractures, age, and BMI. CONCLUSION: One of five patients had delayed wound closure after ORIF of both-bone forearm fractures. Being a man was independently associated with greater odds of delayed wound closure. Surgeons should counsel all patients with these fractures about the possibility of delayed wound closure, with particular attention to men with high-energy and open fractures. Future larger-scale studies are necessary to confirm which factors are associated with the use of delayed wound closure in ORIF of both-bone fractures and its effects on fracture healing. LEVEL OF EVIDENCE: Level III, therapeutic study.

Novel Approach of Femur Shortening With Insertion of Expandable Rod to Achieve End-to-End Repair of Sciatic Nerve Laceration.

BACKGROUND: Sciatic nerve injuries are challenging for diagnosis and treatment. Particularly in proximally located high-grade injuries, neurorrhaphy often has poor outcomes. Most advocate autologous grafting and some more recently have suggested the value of knee flexion braces to facilitate end-to-end repair. OBJECTIVE: To describe a case of femur shortening to facilitate tension-free, end-to-end sciatic nerve neurorrhaphy. METHODS: The patient was a 17-year-old man who was injured by the propeller of a motor boat and suffered a series of lacerations to both lower extremities including transection of his right sciatic nerve in the proximal thigh. After extensive mobilization of the nerve, a greater than 7-cm gap was still present. The patient was treated with femur shortening to facilitate end-to-end coaptation. He subsequently had an expandable rod placed which was lengthened 1 mm per day until his leg length was symmetric. RESULTS: Within 7 months postoperatively, the patient had an advancing Tinel sign and paresthesias to the dorsum of his foot. Nine months postoperatively, he had early mobility in his plantarflexion. CONCLUSION: We present a novel method of femur shortening with insertion of an expandable rod to facilitate direct end-to-end and tension-free sciatic nerve neurorrhaphy in a proximally located injury. Furthermore, larger scale and comparative studies are warranted to further explore this and other techniques.

Quantitative Dual-Energy Imaging of Bone Marrow Edema Using Multisource Cone-Beam CT with Model-Based Decomposition.

Purpose: We investigated the feasibility of dual-energy (DE) detection of bone marrow edema (BME) using a dedicated extremity cone-beam CT (CBCT) with a unique three-source x-ray unit. The sources can be operated at different energies to enable single-scan DE acquisitions. However, they are arranged parallel to the axis of rotation, resulting in incomplete sampling and precluding the application of DE projection-domain decompositions (PDD) for beam-hardening reduction. Therefore, we propose a novel combination of a model-based "one-step" DE two-material decomposition followed by a constrained image-domain change-of-basis to obtain virtual non-calcium (VNCa) images for BME detection. Methods: DE projections were obtained using an "alternating-kV" protocol by operating the peripheral two sources of the CBCT system at low-energy (60 kV, 0.105 mAs/frame) and the central source at high-energy (100 kV, 0.028 mAs/frame), for a total of 600 frames over 216° of gantry rotation. Projections were processed with detector lag, glare and fast Monte Carlo (MC)-based iterative scatter corrections. Model-based material decomposition (MBMD) was then implemented to obtain aluminum (Al) and polyethylene (PE) volume fraction images with minimal beam-hardening. Statistical ray weights in MBMD were modified to account for regions with highly oblique sampling by the peripheral sources. To generate the VNCa maps, image-domain decomposition (IDD) constrained by the volume conservation principle (VCP) was performed to convert the Al and PE MBMD images into volume fractions of water, fat and cortical bone. Accuracy of BME detection was evaluated using physical phantom data acquired on the multi-source extremity CBCT scanner. Results: The proposed framework estimated the volume of BME with ~10% error. The MC-based scatter corrections and the modified MBMD ray weights were essential to achieve such performance - the error without MC scatter corrections was >30%, whereas the uniformity of estimated VNCa images was 3x improved using the modified weights compared to the conventional weights. Conclusions: The proposed DE decomposition framework was able to overcome challenges of high scatter and incomplete sampling to achieve BME detection on a CBCT system with axially-distributed x-ray sources.

Pelphix: Surgical Phase Recognition from X-ray Images in Percutaneous Pelvic Fixation.

Surgical phase recognition (SPR) is a crucial element in the digital transformation of the modern operating theater. While SPR based on video sources is well-established, incorporation of interventional X-ray sequences has not yet been explored. This paper presents Pelphix, a first approach to SPR for X-ray-guided percutaneous pelvic fracture fixation, which models the procedure at four levels of granularity - corridor, activity, view, and frame value - simulating the pelvic fracture fixation workflow as a Markov process to provide fully annotated training data. Using added supervision from detection of bony corridors, tools, and anatomy, we learn image representations that are fed into a transformer model to regress surgical phases at the four granularity levels. Our approach demonstrates the feasibility of X-ray-based SPR, achieving an average accuracy of 99.2% on simulated sequences and 71.7% in cadaver across all granularity levels, with up to 84% accuracy for the target corridor in real data. This work constitutes the first step toward SPR for the X-ray domain, establishing an approach to categorizing phases in X-ray-guided surgery, simulating realistic image sequences to enable machine learning model development, and demonstrating that this approach is feasible for the analysis of real procedures. As X-ray-based SPR continues to mature, it will benefit procedures in orthopedic surgery, angiography, and interventional radiology by equipping intelligent surgical systems with situational awareness in the operating room.

Fat Embolism Syndrome and in-Hospital Mortality Rates According to Patient Age: A Large Nationwide Retrospective Study.

Introduction: Fat embolism syndrome (FES) is a rare life-threatening condition that can develop after traumatic orthopedic injuries. Controversy remains concerning the epidemiology in the elderly population. Therefore, this study aims to report FES related to in-hospital mortality stratified by age. Methods: A retrospective trauma cohort study was conducted using data from the National Trauma Data Bank (NTDB) from 2007 to 2014. All FES cases were included in the study with the diagnosis of FES (ICD9 958.1). Death on arrival cases were excluded. Patients were stratified by age cohort: less than 40 (G1), 40-64 (G2), and greater than 65 (G3) years of age. The primary outcome evaluated was in-hospital mortality. Multivariable regression models were performed to adjust for potential confounders. Results: Between 2007 and 2014, 451 people from a total of 5,836,499 trauma patients in the NTDB met the inclusion criteria. The incidence rate was 8 out of 100,000. The inpatient mortality rate was 11.8% for all subjects with the highest mortality rate of 17.6% in patients over 65. Multivariable analyses demonstrated that age greater than 65 years was an independent predictor of mortality (aOR 24.16, 95% CI 3.73, 156.59, p=0.001), despite higher incidence and injury severity of FES among patients less than 40. No significant association with length of hospital stay, length of intensive unit care, or length of ventilation use was found between the groups. Subgroup analysis of the elderly population also showed a higher mortality rate for FES in femoral neck fracture patients (18%) than other femoral fractures (14%). Conclusion: In this retrospective cohort analysis, old age (≥ 65 years) was found to be an independent risk factor for in-hospital mortality among fat embolism syndrome patients. Elderly patients specifically with femoral neck fractures should be monitored for the development of FES.

Model-based three-material decomposition in dual-energy CT using the volume conservation constraint.

Objective. We develop a model-based optimization algorithm for 'one-step' dual-energy (DE) CT decomposition of three materials directly from projection measurements.Approach.Since the three-material problem is inherently undetermined, we incorporate the volume conservation principle (VCP) as a pair of equality and nonnegativity constraints into the objective function of the recently reported model-based material decomposition (MBMD). An optimization algorithm (constrained MBMD, CMBMD) is derived that utilizes voxel-wise separability to partition the volume into a VCP-constrained region solved using interior-point iterations, and an unconstrained region (air surrounding the object, where VCP is violated) solved with conventional two-material MBMD. Constrained MBMD (CMBMD) is validated in simulations and experiments in application to bone composition measurements in the presence of metal hardware using DE cone-beam CT (CBCT). A kV-switching protocol with non-coinciding low- and high-energy (LE and HE) projections was assumed. CMBMD with decomposed base materials of cortical bone, fat, and metal (titanium, Ti) is compared to MBMD with (i) fat-bone and (ii) fat-Ti bases.Main results.Three-material CMBMD exhibits a substantial reduction in metal artifacts relative to the two-material MBMD implementations. The accuracies of cortical bone volume fraction estimates are markedly improved using CMBMD, with ∼5-10× lower normalized root mean squared error in simulations with anthropomorphic knee phantoms (depending on the complexity of the metal component) and ∼2-2.5× lower in an experimental test-bench study.Significance.In conclusion, we demonstrated one-step three-material decomposition of DE CT using volume conservation as an optimization constraint. The proposed method might be applicable to DE applications such as bone marrow edema imaging (fat-bone-water decomposition) or multi-contrast imaging, especially on CT/CBCT systems that do not provide coinciding LE and HE ray paths required for conventional projection-domain DE decomposition.

The impact of visualization paradigms on the detectability of spatial misalignment in mixed reality surgical guidance.

PURPOSE: Mixed reality (MR) for image-guided surgery may enable unobtrusive solutions for precision surgery. To display preoperative treatment plans at the correct physical position, it is essential to spatially align it with the patient intra-operatively. Accurate alignment is safety critical because it will guide treatment, but cannot always be achieved for varied reasons. Effective visualization mechanisms that reveal misalignment are crucial to prevent adverse surgical outcomes to ensure safe execution. METHODS: We test the effectiveness of three MR visualization paradigms in revealing spatial misalignment: wireframe, silhouette, and heatmap, which encodes residual registration error. We conduct a user study among 12 participants and use an anthropomorphic phantom mimicking total shoulder arthroplasty. Participants wearing Microsoft HoloLens 2 are presented with 36 randomly ordered spatial (mis)alignments of a virtual glenoid model overlaid on the phantom, each rendered using one of the three methods. Users choose whether to accept or reject the spatial alignment at every trial. Upon completion, participants report their perceived difficulty while using the visualization paradigms. RESULTS: Across all visualization paradigms, the ability of participants to reliably judge the accuracy of spatial alignment was moderate (58.33%).The three visualization paradigms showed comparable performance. However, the heatmap-based visualization resulted in significantly better detectability than random chance ([Formula: see text]). Despite heatmap enabling the most accurate decisions according to our measurements, wireframe was the most liked paradigm (50 %), followed by silhouette (41.7 %) and heatmap (8.3 %). CONCLUSION: Our findings suggest that conventional mixed reality visualization paradigms are not sufficiently effective in enabling users to differentiate between accurate and inaccurate spatial alignment of virtual content to the environment.

Visualization of Fluoroscopic Imaging in Orthopedic Surgery: Head-Mounted Display vs Conventional Monitor.

Purpose. See-through head-mounted displays (HMDs) can be used to view fluoroscopic imaging during orthopedic surgical procedures. The goals of this study were to determine whether HMDs reduce procedure time, number of fluoroscopic images required, or number of head turns by the surgeon compared with standard monitors. Methods. Sixteen orthopedic surgery residents each performed fluoroscopy-guided drilling of 8 holes for placement of tibial nail distal interlocking screws in an anatomical model, with 4 holes drilled while using HMD and 4 holes drilled while using a standard monitor. Procedure time, number of fluoroscopic images needed, and number of head turns by the resident during the procedure were compared between the 2 modalities. Statistical significance was set at P < .05. Results. Mean (SD) procedure time did not differ significantly between attempts using the standard monitor (55 [37] seconds) vs the HMD (56 [31] seconds) (P = .73). Neither did mean number of fluoroscopic images differ significantly between attempts using the standard monitor vs the HMD (9 [5] images for each) (P = .84). Residents turned their heads significantly more times when using the standard monitor (9 [5] times) vs the HMD (1 [2] times) (P < .001). Conclusions. Head-mounted displays lessened the need for residents to turn their heads away from the surgical field while drilling holes for tibial nail distal interlocking screws in an anatomical model; however, there was no difference in terms of procedure time or number of fluoroscopic images needed using the HMD compared with the standard monitor.

Toward Perception-based Anticipation of Cortical Breach During K-wire Fixation of the Pelvis.

Intraoperative imaging using C-arm X-ray systems enables percutaneous management of fractures by providing real-time visualization of tool to tissue relationships. However, estimating appropriate positioning of surgical instruments, such as K-wires, relative to safe bony corridors is challenging due to the projective nature of X-ray images: tool pose in the plane containing the principal ray is difficult to assess, necessitating the acquisition of numerous views onto the anatomy. This task is especially demanding in complex anatomy, such as the superior pubic ramus of the pelvis, and results in high cognitive load and repeat attempts even in experienced trauma surgeons. A perception-based algorithm that interprets interventional radiographs during internal fixation to infer the likelihood of cortical breach - especially early on, when the wire has not been advanced - might reduce both the amount of X-rays acquired for verification and the likelihood of repeat attempts. In this manuscript, we present first steps towards developing such an algorithm. We devise a strategy for in silico collection and annotation of X-ray images suitable for detecting cortical breach of a K-wire in the superior pubic ramus, including those with visible fractures. Beginning with minimal manual annotations of correct trajectories, we randomly perturb entry and exit points and project the 3D scene using a physics-based forward model to obtain a large number of 2D X-ray images with and without cortical breach. We report baseline results for anticipating cortical breach at various K-wire insertion depths, achieving an AUROC score of 0.68 for 50% insertion. Code and data are available at github.com/benjamindkilleen/cortical-breach-detection.

Development of a fluoroscopically guided robotic assistant for instrument placement in pelvic trauma surgery.

Purpose: A method for fluoroscopic guidance of a robotic assistant is presented for instrument placement in pelvic trauma surgery. The solution uses fluoroscopic images acquired in standard clinical workflow and helps avoid repeat fluoroscopy commonly performed during implant guidance. Approach: Images acquired from a mobile C-arm are used to perform 3D-2D registration of both the patient (via patient CT) and the robot (via CAD model of a surgical instrument attached to its end effector, e.g; a drill guide), guiding the robot to target trajectories defined in the patient CT. The proposed approach avoids C-arm gantry motion, instead manipulating the robot to acquire disparate views of the instrument. Phantom and cadaver studies were performed to determine operating parameters and assess the accuracy of the proposed approach in aligning a standard drill guide instrument. Results: The proposed approach achieved average drill guide tip placement accuracy of 1.57 ± 0.47 mm and angular alignment of 0.35 ± 0.32 deg in phantom studies. The errors remained within 2 mm and 1 deg in cadaver experiments, comparable to the margins of errors provided by surgical trackers (but operating without the need for external tracking). Conclusions: By operating at a fixed fluoroscopic perspective and eliminating the need for encoded C-arm gantry movement, the proposed approach simplifies and expedites the registration of image-guided robotic assistants and can be used with simple, non-calibrated, non-encoded, and non-isocentric C-arm systems to accurately guide a robotic device in a manner that is compatible with the surgical workflow.

Exploring partial intrinsic and extrinsic symmetry in 3D medical imaging.

We present a novel methodology to detect imperfect bilateral symmetry in CT of human anatomy. In this paper, the structurally symmetric nature of the pelvic bone is explored and is used to provide interventional image augmentation for treatment of unilateral fractures in patients with traumatic injuries. The mathematical basis of our solution is based on the incorporation of attributes and characteristics that satisfy the properties of intrinsic and extrinsic symmetry and are robust to outliers. In the first step, feature points that satisfy intrinsic symmetry are automatically detected in the Möbius space defined on the CT data. These features are then pruned via a two-stage RANSAC to attain correspondences that satisfy also the extrinsic symmetry. Then, a disparity function based on Tukey's biweight robust estimator is introduced and minimized to identify a symmetry plane parametrization that yields maximum contralateral similarity. Finally, a novel regularization term is introduced to enhance similarity between bone density histograms across the partial symmetry plane, relying on the important biological observation that, even if injured, the dislocated bone segments remain within the body. Our extensive evaluations on various cases of common fracture types demonstrate the validity of the novel concepts and the accuracy of the proposed method.

Distal femur fractures have a higher mortality rate compared to hip fractures among the elderly: Insights from the National Trauma Data Bank.

INTRODUCTION: The comparison of mortality and morbidity between distal femur (DF) and hip fracture in the old age is rarely reported in the literature. We aim to analyze a nationwide database among the elderly to compare the outcomes between hip fractures and distal femur fractures in the United States. MATERIALS AND METHODS: A retrospective analysis of the National Trauma Data Bank was queried between 2007-2014 to identify distal femur (DF) and hip fracture patients greater than 65 years of age. Outcomes analyzed included in-hospital mortality, total hospital length of stay(LOS), intensive care unit length of stay(ICU-LOS), length of ventilation use and hospital discharge disposition. Multivariable regression models were performed to adjust for potential confounders. Statistical significance was established at p < 0.001. RESULTS: 26,325 (10.1%) and 233,213 (89.9%) patients reported a diagnosis of DF and hip fracture, respectively. The inpatient mortality rate was significantly higher in the distal femur fracture group (8.3% vs. 6.7%), with significantly longer LOS (7.87 vs. 6.65), ICU-LOS (1.50 vs. 0.73), and required ventilation days (0.74 vs. 0.27). Multivariable analyses demonstrated that hip fracture patients had a lower mortality (adjusted odds ratio [aOR], 0.80; 95% CI [0.76, -0.85]; p < 0.001), shorter LOS ([aOR], -0.31; 95% CI [-0.39, -0.23]; P < 0.001), and more likely to be discharged home ([aOR], 0.88; 95% CI, 0.85, 0.91; P < 0.001, compared to DF fracture patients. CONCLUSION: After adjusting for potential factors, DF fracture patients have a significantly higher mortality, longer LOS, and less likely to be discharged home compared to hip fractures among the elderly. These results may suggest clinicians and caregivers for closely monitoring of clinical conditions for these patients. LEVEL OF EVIDENCE: III.