Fracture fixation in polytraumatized patients-From an interdisciplinary early total/appropriate care to the safe definitive surgery concept.

The strategies for the timing of fracture fixation in polytrauma patients have changed with improvements in resuscitation and patient assessment. Specifically, the criteria for damage control have been formulated, and more precise parameters have been found to determine those patients who can safely undergo primary definitive fixation of major fractures. Our current recommendations are supported by objective and data-based criteria and development groups. Those were validated and compared to existing scores. This review article introduces the concept of "safe definitive surgery" and provides an update on the parameters used to clear patients for timely fixation of major fractures.

Augmented reality-based surgical navigation of pelvic screw placement: an ex-vivo experimental feasibility study.

BACKGROUND: Minimally invasive surgical treatment of pelvic trauma requires a significant level of surgical training and technical expertise. Novel imaging and navigation technologies have always driven surgical technique, and with head-mounted displays being commercially available nowadays, the assessment of such Augmented Reality (AR) devices in a specific surgical setting is appropriate. METHODS: In this ex-vivo feasibility study, an AR-based surgical navigation system was assessed in a specific clinical scenario with standard pelvic and acetabular screw pathways. The system has the following components: an optical-see-through Head Mounted Display, a specifically designed modular AR software, and surgical tool tracking using pose estimation with synthetic square markers. RESULTS: The success rate for entry point navigation was 93.8%, the overall translational deviation of drill pathways was 3.99 ± 1.77 mm, and the overall rotational deviation of drill pathways was 4.3 ± 1.8°. There was no relevant theoretic screw perforation, as shown by 88.7% Grade 0-1 and 100% Grade 0-2 rating in our pelvic screw perforation score. Regarding screw length, 103 ± 8% of the planned pathway length could be realized successfully. CONCLUSION: The novel innovative system assessed in this experimental study provided proof-of-concept for the feasibility of percutaneous screw placement in the pelvis and, thus, could easily be adapted to a specific clinical scenario. The system showed comparable performance with other computer-aided solutions while providing specific advantages such as true 3D vision without intraoperative radiation; however, it needs further improvement and must still undergo regulatory body approval. Future endeavors include intraoperative registration and optimized tool tracking.

Remote Interactive Surgery Platform (RISP): Proof of Concept for an Augmented-Reality-Based Platform for Surgical Telementoring.

The "Remote Interactive Surgery Platform" (RISP) is an augmented reality (AR)-based platform for surgical telementoring. It builds upon recent advances of mixed reality head-mounted displays (MR-HMD) and associated immersive visualization technologies to assist the surgeon during an operation. It enables an interactive, real-time collaboration with a remote consultant by sharing the operating surgeon's field of view through the Microsoft (MS) HoloLens2 (HL2). Development of the RISP started during the Medical Augmented Reality Summer School 2021 and is currently still ongoing. It currently includes features such as three-dimensional annotations, bidirectional voice communication and interactive windows to display radiographs within the sterile field. This manuscript provides an overview of the RISP and preliminary results regarding its annotation accuracy and user experience measured with ten participants.

Perspectives of Patients With Orthopedic Trauma on Fully Automated Digital Physical Activity Measurement at Home: Cross-sectional Survey Study.

BACKGROUND: The automated digital surveillance of physical activity at home after surgical procedures could facilitate the monitoring of postoperative follow-up, reduce costs, and enhance patients' satisfaction. Data on the willingness of patients with orthopedic trauma to undergo automated home surveillance postoperatively are lacking. OBJECTIVE: The aims of this study were to assess whether patients with orthopedic trauma would be generally willing to use the proposed automated digital home surveillance system and determine what advantages and disadvantages the system could bring with it. METHODS: Between June 2021 and October 2021, a survey among outpatients with orthopedic trauma who were treated at a European level 1 trauma center was conducted. The only inclusion criterion was an age of at least 16 years. The paper questionnaire first described the possibility of fully automated movement and motion detection (via cameras or sensors) at home without any action required from the patient. The questionnaire then asked for the participants' demographics and presented 6 specific questions on the study topic. RESULTS: In total, we included 201 patients whose mean age was 46.9 (SD 18.6) years. Most of the assessed patients (124/201, 61.7%) were male. Almost half of the patients (83/201, 41.3%) were aged between 30 and 55 years. The most stated occupation was a nine-to-five job (62/199, 30.8%). The majority of the participants (120/201, 59.7%) could imagine using the proposed measurement system, with no significant differences among the genders. An insignificant higher number of younger patients stated that they would use the automated surveillance system. No significant difference was seen among different occupations (P=.41). Significantly more young patients were using smartphones (P=.004) or electronic devices with a camera (P=.008). Less than half of the surveyed patients (95/201, 47.3%) stated that they were using tracking apps. The most stated advantages were fewer physician visits (110/201, 54.7%) and less effort (102/201, 50.7%), whereas the most prevalent disadvantage was the missing physician-patient contact (144/201, 71.6%). Significantly more patients with a part-time job or a nine-to-five job stated that data analysis contributes to medical progress (P=.047). CONCLUSIONS: Most of the assessed participants (120/201, 59.7%) stated that they would use the automated digital measurement system to observe their postoperative follow-up and recovery. The proposed system could be used to reduce costs and ease hospital capacity issues. In order to successfully implement such systems, patients' concerns must be addressed, and further studies on the feasibility of these systems are needed.

Satisfaction With Telemedicine in Patients With Orthopedic Trauma During the COVID-19 Lockdown: Interview Study.

BACKGROUND: Telemedicine can take many forms, from telephone-only consultations to video consultations via a smartphone or personal computer, depending on the goals of the treatment. One of the advantages of videoconferencing is the direct visual contact between patients and therapists even over long distances. Although some telemedicine models require specially designed add-on devices, others get by with off-the-shelf equipment and software and achieve similarly successful successful results. This depends, among other things, on the nature of the injury, the desired outcome of therapy, and the medical consultation. In the last decade, the science and practice of telemedicine have grown exponentially and even more so during the COVID-19 pandemic. Depending on the traumatic lesion, posttraumatic and postoperative treatment and care of patients who experience trauma may require medical or physical therapy consultations in a clinic or office. However, due to the COVID-19 lockdown, direct physical follow-up was more difficult, and therefore, telemedicine solutions were sought and implemented. OBJECTIVE: The aim of this study was to assess satisfaction with telemedical aftercare in patients with orthopedic trauma. METHODS: Between March and July 2020, a standardized interview using a standardized questionnaire-Freiburg Index of Patient Satisfaction (FIPS)-among patients with orthopedic trauma who received telemedical postsurgical or physiotherapeutic care was conducted. The FIPS is composed of 5 questions regarding treatment and 1 question on the overall treatment satisfaction. Furthermore, we assessed patients' demographics and their telemedical use. Subgroup analysis was performed for age groups (<65 years vs ≥65 years), the used device, and gender. RESULTS: In total, we assessed 25 patients with a mean age of 43 (SD 24.31) years (14 female). The majority of patients (n=19, 76%) used their smartphone for consultations. The mean overall FIPS score assessed was 2.14 (SD 0.87). The mean FIPS score for younger patients was 2.23 (SD 0.90) vs 1.91 (SD 0.82) for older patients. The vast majority of the surveyed patients (n=20, 80%) were absolutely confident with their smartphone or tablet use. CONCLUSIONS: Most patients surveyed stated a high satisfaction with the telemedical follow-up. Older patients showed a higher satisfaction rate than their younger counterparts. It seems that telemedical postsurgical or physiotherapeutic care is a viable option, especially in times of reduced contact, like the current COVID-19 pandemic. Thus, telemedicine offers the opportunity to ensure access to effective patient care, even over long distances, while maintaining patient satisfaction.

Augmented Reality-Based Rehabilitation of Gait Impairments: Case Report.

BACKGROUND: Gait and balance impairments are common in neurological diseases, including stroke, and negatively affect patients' quality of life. Improving balance and gait are among the main goals of rehabilitation. Rehabilitation is mainly performed in clinics, which lack context specificity; therefore, training in the patient's home environment is preferable. In the last decade, developed rehabilitation technologies such as virtual reality and augmented reality (AR) have enabled gait and balance training outside clinics. Here, we propose a new method for gait rehabilitation in persons who have had a stroke in which mobile AR technology and a sensor-based motion capture system are combined to provide fine-grained feedback on gait performance in real time. OBJECTIVE: The aims of this study were (1) to investigate manipulation of the gait pattern of persons who have had a stroke based on virtual augmentation during overground walking compared to walking without AR performance feedback and (2) to investigate the usability of the AR system. METHODS: We developed the ARISE (Augmented Reality for gait Impairments after StrokE) system, in which we combined a development version of HoloLens 2 smart glasses (Microsoft Corporation) with a sensor-based motion capture system. One patient with chronic minor gait impairment poststroke completed clinical gait assessments and an AR parkour course with patient-centered performance gait feedback. The movement kinematics during gait as well as the usability and safety of the system were evaluated. RESULTS: The patient changed his gait pattern during AR parkour compared to the pattern observed during the clinical gait assessments. He recognized the virtual objects and ranked the usability of the ARISE system as excellent. In addition, the patient stated that the system would complement his standard gait therapy. Except for the symptom of exhilaration, no adverse events occurred. CONCLUSIONS: This project provided the first evidence of gait adaptation during overground walking based on real-time feedback through visual and auditory augmentation. The system has potential to provide gait and balance rehabilitation outside the clinic. This initial investigation of AR rehabilitation may aid the development and investigation of new gait and balance therapies.

Camera augmented mobile C-arm (CAMC): calibration, accuracy study, and clinical applications.

Mobile C-arm is an essential tool in everyday trauma and orthopedics surgery. Minimally invasive solutions, based on X-ray imaging and coregistered external navigation created a lot of interest within the surgical community and started to replace the traditional open surgery for many procedures. These solutions usually increase the accuracy and reduce the trauma. In general, they introduce new hardware into the OR and add the line of sight constraints imposed by optical tracking systems. They thus impose radical changes to the surgical setup and overall procedure. We augment a commonly used mobile C-arm with a standard video camera and a double mirror system allowing real-time fusion of optical and X-ray images. The video camera is mounted such that its optical center virtually coincides with the C-arm's X-ray source. After a one-time calibration routine, the acquired X-ray and optical images are coregistered. This paper describes the design of such a system, quantifies its technical accuracy, and provides a qualitative proof of its efficiency through cadaver studies conducted by trauma surgeons. In particular, it studies the relevance of this system for surgical navigation within pedicle screw placement, vertebroplasty, and intramedullary nail locking procedures. The image overlay provides an intuitive interface for surgical guidance with an accuracy of < 1 mm, ideally with the use of only one single X-ray image. The new system is smoothly integrated into the clinical application with no additional hardware especially for down-the-beam instrument guidance based on the anteroposterior oblique view, where the instrument axis is aligned with the X-ray source. Throughout all experiments, the camera augmented mobile C-arm system proved to be an intuitive and robust guidance solution for selected clinical routines.

Parallax-free intra-operative X-ray image stitching.

We present a novel method to generate parallax-free panoramic X-ray images during surgery by enabling the mobile C-arm to rotate around its X-ray source center, relative to the patient's table. Rotating the mobile C-arm around its X-ray source center is impractical and sometimes impossible due to the mechanical design of mobile C-arm systems. In order to ensure that the C-arm motion is a relative pure rotation around its X-ray source center, we propose to move the table to compensate for the translational part of the motion based on C-arm pose estimation. For this we employ a visual marker pattern and a Camera Augmented Mobile C-arm system that is a standard mobile C-arm augmented by a video camera and mirror construction. We are able to produce a parallax-free panoramic X-ray image independent of the geometric configuration of imaged anatomical structures. Our method does not require a fronto-parallel setup or any overlap between the acquired X-ray images. This generated parallax-free panoramic X-ray image preserves the linear perspective projection property. It also presents a negligible difference (below 2 pixels) in the overlapping area between two consecutive individual X-ray images and has a high visual quality. This promises suitability for intra-operative clinical applications in orthopedic and trauma surgery. The experiments on phantoms and ex-vivo bone structure demonstrate both the functionality and accuracy of the method.

The virtual mirror: a new interaction paradigm for augmented reality environments.

Medical augmented reality (AR) has been widely discussed within the medical imaging as well as computer aided surgery communities. Different systems for exemplary medical applications have been proposed. Some of them produced promising results. One major issue still hindering AR technology to be regularly used in medical applications is the interaction between physician and the superimposed 3-D virtual data. Classical interaction paradigms, for instance with keyboard and mouse, to interact with visualized medical 3-D imaging data are not adequate for an AR environment. This paper introduces the concept of a tangible/controllable Virtual Mirror for medical AR applications. This concept intuitively augments the direct view of the surgeon with all desired views on volumetric medical imaging data registered with the operation site without moving around the operating table or displacing the patient. We selected two medical procedures to demonstrate and evaluate the potentials of the Virtual Mirror for the surgical workflow. Results confirm the intuitiveness of this new paradigm and its perceptive advantages for AR-based computer aided interventions.

Parallax-free long bone X-ray image stitching.

In this paper, we present a novel method to create parallax-free panoramic X-ray images of long bones during surgery by making the C-arm rotate around its X-ray source, relative to the patient's table. In order to ensure that the C-arm motion is a relative pure rotation around its X-ray source, we move the table to compensate for the translational part of the motion based on C-arm pose estimation, for which we employed a Camera Augmented Mobile C-arm system and a visual planar marker pattern. Thus, we are able to produce a parallax-free panoramic X-ray image that preserves the property of linear perspective projection. We additionally implement a method to reduce the error caused by varying intrinsic parameters of C-arm X-ray imaging. The results show that our proposed method can generate a parallax-free panoramic X-ray image, independent of the configuration of bone structures and without the requirement of a fronto-parallel setup or any overlap in the X-ray images. The resulting panoramic images have a negligible difference (below 2 pixels) in the overlap between two consecutive individual X-ray images and have a high visual quality, which promises suitability for intra-operative clinical applications in orthopedic and trauma surgery.

Long bone X-ray image stitching using Camera Augmented Mobile C-arm.

X-ray images are widely used during surgery for long bone fracture fixation. Mobile C-arms provide X-ray images which are used to determine the quality of trauma reduction, i.e. the extremity length and mechanical axis of long bones. Standard X-ray images have a narrow field of view and can not visualize the entire long bone on a single image. In this paper, we propose a novel method to generate panoramic X-ray images in real time by using the previously introduced Camera Augmented Mobile C-arm. This advanced mobile C-arm system acquires registered X-ray and optical images by construction, which facilitates the generation of panoramic X-ray images based on first stitching the optical images and then embedding the X-ray images. We additionally introduce a method to reduce the parallax effect that leads to the blurring and measurement error on panoramic X-ray images. Visual marker tracking is employed to automatically stitch the sequence of video images and to rectify images. Our proposed method is suitable for intra-operative usage generating panoramic X-ray images, which enable metric measurements, with less radiation and without requirement of fronto-parallel setup and overlapping X-ray images. The results show that the panoramic X-ray images generated by our method are accurate enough (errors less than 1%) for metric measurements and suitable for many clinical applications in trauma reduction.

Virtually extended surgical drilling device: virtual mirror for navigated spine surgery.

This paper introduces a new method for navigated spine surgery using a stereoscopic video see-through head-mounted display (HMD) and an optical tracking system. Vertebrae are segmented from volumetric CT data and visualized in-situ. A surgical drilling device is virtually extended with a mirror for intuitive planning of the drill canal, control of drill direction and insertion depth. The first designated application for the virtually extended drilling device is the preparation of canals for pedicle screw implantation in spine surgery. The objective of surgery is to install an internal fixateur for stabilization of injured vertebrae. We invited five surgeons of our partner clinic to test the system with realistic replica of lumbar vertebrae and compared the new approach with the classical, monitor-based navigation system providing three orthogonal slice views on the operation site. We measured time of procedure and scanned the drilled vertebrae with CT to verify accuracy of drilling.

A multi-view Opto-Xray imaging system: development and first application in trauma surgery.

The success of minimally invasive trauma and orthopedic surgery procedures has resulted in an increase of the use of fluoroscopic imaging. A system aiming to reduce the amount of radiation has been introduced by Navab et al. It uses an optical imaging system rigidly attached to the gantry such that the optical and X-ray imaging geometry is identical. As an extension to their solution, we developed a multi-view system which offers 3D navigation during trauma surgery and orthopedic procedures. We use an additional video camera in an orthogonal arrangement to the first video camera and a minimum of two X-ray images. Furthermore, tools such as a surgical drill are extended by optical markers and tracked with the same optical cameras. Exploiting that the cross ratio is invariant in projective geometry, we can estimate the tip of the instrument in the X-ray image without external tracking systems. This paper thus introduces the first multi-view Opto- Xray system for computer aided surgery. First tests have proven the accuracy of the calibration and the instrument tracking. Phantom and cadaver experiments were conducted for pedicle screw placement in spinal surgery. Using a postoperative CT, we evaluate the quality of the placement of the pedicle screws in 3D.

Depth perception--a major issue in medical AR: evaluation study by twenty surgeons.

The idea of in-situ visualization for surgical procedures has been widely discussed in the community. While the tracking technology offers nowadays a sufficient accuracy and visualization devices have been developed that fit seamlessly into the operational workflow [1, 3], one crucial problem remains, which has been discussed already in the first paper on medical augmented reality. Even though the data is presented at the correct place, the physician often perceives the spatial position of the visualization to be closer or further because of virtual/real overlay. This paper describes and evaluates novel visualization techniques that are designed to overcome misleading depth perception of trivially superimposed virtual images on the real view. We have invited 20 surgeons to evaluate seven different visualization techniques using a head mounted display (HMD). The evaluation has been divided into two parts. In the first part, the depth perception of each kind of visualization is evaluated quantitatively. In the second part, the visualizations are evaluated qualitatively in regard to user friendliness and intuitiveness. This evaluation with a relevant number of surgeons using a state-of-the-art system is meant to guide future research and development on medical augmented reality.

Hybrid navigation interface for orthopedic and trauma surgery.

Several visualization methods for intraoperative navigation systems were proposed in the past. In standard slice based navigation, three dimensional imaging data is visualized on a two dimensional user interface in the surgery room. Another technology is the in-situ visualization i.e. the superimposition of imaging data directly into the view of the surgeon, spatially registered with the patient. Thus, the three dimensional information is represented on a three dimensional interface. We created a hybrid navigation interface combining an augmented reality visualization system, which is based on a stereoscopic head mounted display, with a standard two dimensional navigation interface. Using an experimental setup, trauma surgeons performed a drilling task using the standard slice based navigation system, different visualization modes of an augmented reality system, and the combination of both. The integration of a standard slice based navigation interface into an augmented reality visualization overcomes the shortcomings of both systems.

Visual servoing for intraoperative positioning and repositioning of mobile C-arms.

The problem of positioning mobile C-arms, e.g. for down the beam techniques, as well as repositioning during surgical procedures currently requires time, skill and additional radiation. This paper uses a Camera-Augmented Mobile C-arm (CAMC) to speed up the procedure, simplify its execution and reduce the necessary radiation. For positioning the C-arm in down-the-beam position, the pre-operative diagnostic CT is used for defining the axis. Additional CT visible markers on patient's skin allow the CAMC's optical camera to compute the C-arm's pose and its required displacement for positioning. In the absence of electronically controlled mobile C-arms, the system provides step-by-step guidance to surgical staff until the final position is achieved. At this point, the surgeon can acquire an X-ray to ensure the correct positioning. In the case of intra-operative repositioning, no pre-operative CT is required. X-ray/Optical markers allow the visual servoing algorithm to guide the surgical staff in C-arm repositioning using CAMC's optical camera. This work paves the path for many possible applications of visual servoing in C-arm positioning and in surgical navigation. Experiments on phantom and a cadaver study demonstrate the advantages of the new methods.

C-arm-based mobile computed tomography: a comparison with established imaging on the basis of simulated treatments of talus neck fractures in a cadaveric study.

OBJECTIVE: To analyse the image quality and diagnostic effectiveness of a new C-arm-based 3D imaging method (C-arm-CT) for intraoperative evaluation of screw osteosyntheses adjacent to a peripheral joint. MATERIALS AND METHODS: Insertion of screws into four cadaveric specimens simulated the surgical treatment of talus neck fractures. Ten orthopedic surgeons and 10 radiologists evaluated X-ray, C-arm fluoroscopy, C-arm-CT and CT images. RESULTS: The best image quality was obtained with X-rays (p < 0.001), followed by C-arm fluoroscopy (2D) and CT, with the C-arm-CT (3D) being rated lowest (p < 0.001). The most correct diagnoses were obtained with CT and C-arm-CT (with no statistical difference between them), while C-arm-fluoroscopy was inferior (p < 0.001) and X-rays were the worst (p < 0.05). CONCLUSIONS: Even if the image quality of C-arm-CT is definitely inferior to that of CT, screw misplacements can be reliably detected using C-arm-CT. As compared to the current standard procedures (intraoperative fluoroscopy and postoperative radiography), C-arm-CT performed better. C-arm-CT is ideally suited to the intraoperative diagnosis of high-contrast inquiries like bone fragments and OS material, especially at the extremities. Coupling of the new 3D imaging to existing navigation systems is possible. C-arm-CT will support the further development and implementation of open and minimally invasive surgical procedures.