Aim. Bone and joint infection requires antimicrobial treatment for 6 to 12 weeks. When patients are well prepared and instructed regarding their therapy, they are more likely to have less side effects and improved compliance. Although side effects are common, this coaching is often not routinely performed when oral treatment is given. We developed a monitoring and guidance program for our outpatients who are on long term antimicrobial therapy, in which we can early signal side effects and treatment failure and coach the patients in their journey of infection treatment. Method. In our tertiary referral centre for orthopaedic infections, we started the outpatient monitoring of antimicrobial treatment (OMAT)- team for patients who will receive antimicrobial therapy for >2 weeks. Before discharge, our trained nurse gives instruction to the patient. Within 3 days after hospital discharge the patient is contacted by phone to, if necessary, clarify ambiguities in monitoring set up. During this contact, the nurse checks for side effects, addresses logistic problems regarding laboratory monitoring or future appointments and coaches patients for other questions. The patient is instructed how to recognize and who to contact in case of red flags and problems possibly related to the treatment. This is repeated after every laboratory check-up. Supervision is performed by an infectious disease specialist in close collaboration with the patient's surgeon. Results. The OMAT-team started in October 2020 and consists of 3 trained nurses and 3 ID specialist. In one year, 453 patients were proactively monitored for a mean of 11 weeks. Routinely, laboratory measurements were performed 1 week after the start of therapy and every 3–4 weeks thereafter, which resulted in 2711 contacts per year. In total, 64% of the patients reported side effects and 13% needed one or more extra laboratory measurement. This led to 40 additional outpatient consultations by the ID specialist because of complications of treatment and a switch of the antimicrobial agent in 31% of the patients. Conclusions. OMAT seems to improve the early signalling of complications regarding treatment, which is likely to improve compliance. The OMAT-team serves as a easy to access team to discuss any problem regarding antimicrobial therapy. Being proactive, the OMAT-team intervenes in an early stage of problems regarding side effects, logistics of the treatment and possible treatment failure. Future analysis of our data will show to what extend this will lead to prevention of re-hospitalization and improvement of success rate

Total knee arthroplasty (TKA) is a common procedure with good success rates. The literature shows resection accuracy plays a crucial role in device longevity. 1. Computer guidance is used by some surgeons to enhance accuracy. This study reports on a continuous series of Optetrak knee prostheses (Exactech Inc., FL, USA) implanted by three senior surgeons between October 2010 and December 2013. 324 TKA were implanted at the Joseph Ducuing Hospital, Toulouse, France (Site 1), the Cleveland Clinic, Cleveland, OH, USA (Site 2) and the Riverview Hospital, Noblesville, IN, USA (Site 3) using Exactech GPS (Blue-Ortho, Grenoble, FR), a new computer-assisted guidance system. Each centre in this study used different surgical profiles defined specifically for their surgeical preferences. Planned tibial and femoral cuts were compared to actual cuts digitised using GPS. Operating time was analyzed and post-operative leg alignment was compared to pre-operative. The mean error between planned and digitised proximal tibial cuts was 0.06°±0.89 of valgus and 0.53°±0.90 of anterior slope for Site 1, 0.18°±0.85 of varus and 0.25°±1.18 of posterior slope for Site 2, and 0.02°±0.51 of valgus and 0.60°±1.15 of anterior slope for Site 3. The mean error between planned and digitised femoral distal cuts was 0.14°±0.85 of valgus and 0.49°±0.93 of flexion for Site 1, 0.15°±0.96 of varus and 0.04°±1.54 of extension for Site 2, and 0.09°±0.54 of varus and 0.48°±1.21 of extension for Site 3. Average operating time was 29 minutes for Site 1, 39 minutes for Site 2, and 33 minutes for Site 3. Post-operative Hip-Knee-Ankle angle (HKA) varied between 172° and 184° with an average of 179° for Site 1, 177° to 183° with an average of 179° for Site 2, and 177° to 185° with an average of 180° for Site 3. Pre-operative HKA ranged from 162 to 189°. Site 1 was already reporting in the series presented at ISTA 2013. 2. Sites 2 and 3 were added later and could therefore benefit from the early feedback the analysis of site 1 cases provided. The use of the computer guidance at the new sites was associated with promising results and it did not take long to the surgeons to reach a reproducibility equivalent to the one of site 1. Average surgical time was similar in all three sites. GPS guidance added an average of 10 minutes to standard surgical times. All surgeons agreed the increased accuracy justified the additional time. Average post-operative HKA was 179°. HKA scores were within 3° of perfect alignment in 96% of the cases of Site 1, 99% of Site 2 and 97% of Site 3. According to the literature. 1. , HKA between 177° and 183° is linked with high implant survival. Participating surgeons still associated Exactech GPS with satisfactory immediate post-operative results

Introduction. Clinical outcomes for total knee arthroplasty (TKA) are especially sensitive to lower extremity alignment and implant positioning. 1. The use of computer-assisted orthopedic surgery (CAOS) can improve overall TKA accuracy. 2. This study assessed the accuracy of an image-free CAOS guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) used in TKA. Materials and methods:. A high-resolution 3D scanner (Comet L3D, Steinbichler, Plymouth, MI) was used to scan seven knee models (MITA, Medical Models, Bristol, UK) and collect pre-identified anatomical landmarks (see Figure 1) prior to using the models to simulate knee surgery. The image-free CAOS guidance system was then used to acquire the same landmarks. After adjusting the position and orientation of the cutting block to match the targets, bone resections were performed, and the knee models were re-scanned. The 3D scans made before and after the cuts were overlaid (see Figure 2) and the resection parameters calculated using the pre-identified anatomical landmark data and advanced software (XOV & XOR, RapidForm, Lakewood, CO and UG NX, Siemens PLM, Plano, TX). Data sets obtained from the 3D scanner were compared with data sets from the guidance system. Given the accuracy of the 3D scanner, its measurements were used as the baseline for assessing CAOS system error. Results:. The CAOS system bone resection measurement errors had an overall mean of less than 0.35 mm. The mean errors for joint angle measurement was less than 0.6° (see Table I). Even considering the ranges, errors were no more than 1 mm for all bone resection measurements and no more than 1° for all joint angle measurements. The low variability is also supported by small standard deviation values. Discussion/Conclusion:. To our knowledge, this is the first study to use a high-resolution 3D scanner to assess the accuracy of surgical cuts made with image-free CAOS system assistance. Determining precise landmarks using CAOS for TKA has been shown to be of critical importance. 3. For this reason, the anatomical landmarks used by the scanner and guidance system were carefully identified and prepared to ensure consistency. The study demonstrated that the evaluated image-free CAOS system was able to achieve a high level of in-vitro accuracy (small mean errors) as well as a high level of precision (small error variability) when making femoral and tibial bone resections during TKA

Beside spine and pelvis surgery, computer-assisted guidance systems are not used frequently for musculoskeletal injuries. Main reason is the dependence on a fixed reference array that must be firmly attached to all moving parts. We investigated a novel fluoroscopy-based image guidance system in orthopaedic trauma surgery that uses a different technique. This was a prospective, not randomised single centre case series at a level I trauma centre. 45 patients with 46 injuries (foot 12, shoulder 10, long bones 7, hand and wrist 7, ankle 7, spine and pelvis 4) were included. Different surgical procedures were examined following the basic principles of the AO/ASIF. Main outcome measurements were the number of trials for implant placement, total surgery time, usability via user questionnaire and system failure rate. Furthermore we wanted to test the ability of the new system to be integrated in existing surgical workflows. In all cases, the trajectory function was used, inserting a total of 56 guided implants. The trajectory was the most popular feature used by surgeons (n=43, 93.5%), followed by the length measurement tool (n=29, 63%) and the bending function (n=17, 37%). The functions could be freely activated by the performing surgeon. The system failed when used in pelvic and spinal injuries, resulting in a total failure rate of 6.5% (n=3) of all included cases. The overall usability was rated as good, scoring 84.3%. This study examined the clinical application of a fluoroscopy-based image guidance system for different musculoskeletal injuries. Its major advantage is the high integrability in the accustomed surgical workflow and its connectivity with existing technical equipment. It can hardly be compared to known navigation solutions, since instruments are not tracked and fixed reference arrays are not required. Expected advantages should be explored in randomised studies

Fractures of the femoral head are a challenging problem. The most often performed head preserving procedure worldwide is closed reduction and insertion of cannulated screws under fluoroscopic control. The use of navigation is still experimental in general trauma since rigid reference markers must be attached to all fragments. The examined system (Surgix®, Tel Aviv, Israel) is a fluoroscopy based image analysing system. It consists of a workstation and X-ray opaque markers in surgical tools. When the tool is visible in a C-arm shot a trajectory is displayed as additional layer in the image to serve as guidance for the surgeon. Forty synthetic femurs (Synbone®, Malans, Switzerland) were used and placed inside foam to simulate the soft tissue of the thigh. The models were equipped with 4.5mm radio-opaque markers at the fovea capitis femoris as target point. The aim was to bring the tip of a K-wire as close as possible to the target point entering the bone at the lateral base of the greater trochanter in a center-center position. Twenty were done under image guidance and 20 were operated the conventional way. Outcome measures included the accuracy (the distance between the tip of the wire and the target in a CT), the number of guide wire insertions, procedure duration, radiation exposure and learning curve. In the image guided group optimal guide wire placement was accomplished on first pass in 65% of the cases as compared to 5% in the conventional group (p = < 0.0001). The average number of trial and error was significantly lower in the guided group (1.7 vs. 5.8, p = < 0.0001). Consequently the average duration of the guided procedure was significantly shorter (p = 0.0008) along with radiation exposure time reduced by over 70% (p = 0.0002). The guidance system hit averaged 5.8 mm off target as compared to 5.3 mm for the freehand method (p = 0.3319). Image based guidance significantly shortened the procedure, reduced the radiation exposure and the number of trials without changing the surgeons workflow and can be used in trauma cases were reference marker based navigation is not applicable

Percutaneous fixation of scaphoid fractures has become popular in recent years, mainly due to its reduced complexity compared to open surgical approaches. Fluoroscopy is currently used as guidance for this percutaneous approach, however, as a projective imaging modality, it provides only a 2D view of the complex 3D anatomy of the wrist during surgery, and exposes both patient and physician to harmful X-ray radiation. To avoid these drawbacks, 3D ultrasound has been suggested to provide imaging for guidance as a widely available, real-time, radiation-free and low-cost modality. However, the blurred, disconnected, weak and noisy bone responses render interpretation of the US data difficult so far. In this work, we present the integration of 3D ultrasound with a statistical wrist model to allow development of an improved ultrasound-based guidance procedure. For enhancement of bone responses in ultrasound, a phase symmetry based approach is used to exploit the symmetry of the ultrasound signal around the expected bone location. We propose an improved estimation of the local phase symmetry by using the local spectrum variation of the ultrasound image. The statistical wrist model is developed through a group-wise registration based framework in order to capture the major modes of shape and pose variations across 30 subjects at different wrist positions. Finally, the statistical wrist model is registered to the enhanced ultrasound bone surfaces using a probabilistic registration approach. Feasibility experiments are performed using two volunteer wrists, and the results are promising and warrant further development and validation to enable ultrasound guided percutaneous scaphoid fracture reduction

Background. Total Shoulder Arthroplasty (TSA) has been shown to improve the function and pain of patients with severe degeneration. Recently, TSA has been of interest for younger patients with higher post-operative expectations; however, they are treated using traditional surgical approaches and techniques, which, although amenable to the elderly population, may not achieve acceptable results with this new demographic. Specifically, to achieve sufficient visualization, traditional TSA uses the highly invasive deltopectoral approach that detaches the subscapularis, which can significantly limit post-operative healing and function. To address these concerns, we have developed a novel surgical approach, and guidance and instrumentation system (for short-stemmed/stemless TSA) that minimize muscle disruption and aim to optimize implantation accuracy. Development. Surgical Approach: A muscle splitting approach with a reduced incision size (∼6–8cm) was developed that markedly reduces muscle disruption, thus potentially improving healing and function. The split was placed between the infraspinatus and teres-minor (Fig.1) as this further reduces damage, provides an obvious dissection plane, and improves access to the retroverted articular surfaces. This approach, however, precludes the use of standard bone preparation methods/instruments that require clear visualization and en-face articular access. Therefore, a novel guidance technique and instrumentation paradigm was developed. Minimally Invasive Surgical Guidance: 3D printed Patient Specific Guides (PSGs) have been developed for TSA; however, these are designed for traditional, highly invasive approaches providing unobstructed access to each articular surface separately. As the proposed approach does not offer this access, a novel PSG with two opposing contoured surfaces has been developed that can be inserted between the humeral and scapular articular surfaces and use the rotator cuff's passive tension to self-locate (Fig.2). During computer-aided pre-operative planning/PSG design, the two bones are placed into an optimized relative pose and the PSG is constructed between and around them. This ensures that when the physical PSG is inserted intra-operatively, the bones are locked into the preoperatively planned pose. New Instrumentation Paradigm: With the constraints of this minimally invasive approach, a new paradigm for bone preparation/instrumentation was required which did not rely on en-face access. This new paradigm involves the ability to simultaneously create glenoid and humeral guide axes – the latter of which can guide humeral bone preparation and be a working channel for tools – by driving a short k-wire into the glenoid by passing through the humerus starting laterally (Fig.3). By preoperatively defining the pose produced by the inserted PSG as one that collinearly aligns the bones’ guide axes, the PSG and an attached c-arm drill guide facilitate this new lateral drilling technique. Subsequently, bone preparation is conducted using novel instruments (e.g. reamers and drills for creating holes radial to driver axis) powered using a trans-humeral driver and guided by the glenoid k-wire or humeral tunnel. Conclusion. To meet the expectations of increasingly younger TSA patients, advancements in procedural invasiveness and implantation accuracy are needed. This need was addressed by developing a novel, fully integrated surgical approach, PSG system, and instrumentation paradigm, the initial in-vitro results of which have demonstrated acceptable accuracy while significantly reducing invasiveness

Clinical outcomes for total knee arthroplasty (TKA) are especially sensitive to lower extremity alignment and implant positioning. The use of computer-assisted orthopedic surgery (CAOS) can improve overall TKA accuracy. This study assessed the accuracy of an image-free CAOS guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) used in TKA. A high-precision 3D scanner (Comet L3D, Steinbichler, Plymouth, MI) was used to scan seven knee models (MITA, Medical Models, Bristol, UK) and collect pre-identified anatomical landmarks prior to using the models to simulate knee surgery. The Exactech GPS was then used to acquire the same landmarks. After adjusting the Exactech GPS cutting block to match the targets, bone resections were performed, and the knee models were re-scanned. The 3D scans made before and after the cuts were overlaid and the resection parameters calculated using the pre-identified anatomical landmark data and advanced software (XOV & XOR, RapidForm, Lakewood, CO and UG NX, Siemens PLM, Plano, TX). Data sets obtained from the 3D scanner were compared with data sets from the guidance system. Given the accuracy of the 3D scanner, its measurements were used as the baseline for assessing CAOS system error. The CAOS system bone resection measurement errors had an overall mean of less than 0.35 mm. The mean errors for joint angle measurement was less than 0.6°. Even considering the ranges, errors were no more than 1 mm for all bone resection measurements and no more than 1° for all joint angle measurements. The low variability is also supported by small SD values. To our knowledge, this is the first study to use a high-resolution 3D scanner to assess the accuracy of surgical cuts made with image-free CAOS system assistance. Determining precise landmarks using CAOS for TKA has been shown to be of critical importance. For this reason, the anatomical landmarks used by the scanner and guidance system were carefully identified and prepared to ensure consistency. The study demonstrated that the evaluated image-free CAOS system was able to achieve a high level of in-vitro accuracy (small mean errors) as well as a high level of precision (small error variability) when making femoral and tibial bone resections during TKA

Introduction. Clinical outcomes for total knee arthroplasty (TKA) are especially sensitive to lower extremity alignment and implant positioning. 1. The use of computer-assisted orthopaedic surgery (CAOS) can improve overall TKA accuracy. 2. This study assessed the accuracy of an image-free CAOS guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) in both a synthetic leg with a normal mechanical axis and legs with abnormal mechanical axis. Materials and methods. A high-resolution 3D scanner (Comet L3D, Steinbichler, Plymouth, MI) was used to scan varus-deformed (n=12), neutral (n=12), and valgus-deformed (n=4) knee inserts (Mita M-00566, M-00598, M-00567; respectively, Medical Models, Bristol, UK) and collect pre-identified anatomical landmarks prior to using the models to simulate knee surgery. The image-free CAOS guidance system was then used to acquire the same landmarks. After adjusting the position and orientation of the cutting block to match the targets, bone resections were performed, and the knee models were re-scanned. The 3D scans made before and after the cuts were overlaid and the resection parameters calculated using the pre-identified anatomical landmark data and advanced software (UG NX, Siemens PLM, Plano, TX). Data sets obtained from the 3D scanner (see Figure 1A) were compared with data sets from the guidance system (see Figure 1B). Given the accuracy of the 3D scanner (<50μm), its measurements were used as the baseline for assessing CAOS system error. Results. Table I shows errors in bone resection thickness orientation measurement errors as well as CAOS system confidence intervals (CI) for both the tibia and femur, depending on deformity type. Regardless of knee deformity and other parameters, the mean error of the CAOS system was systematically less than 0.5 mm for bone resection measurements and 1° for joint angle measurements. The 95% CI were in the range of −1.54 to 0.67mm for bone resection measurements and −0.64° to 1.67° for joint angle measurements. No statistical differences were detected between different deformity groups in the Error Indexes for both the tibia and femur. Discussion. This study represents an extension of a previous evaluation of the same CAOS system, where only a limited number of neutral models (n=6) were investigated. The current study was performed to reassess the accuracy and precision of the CAOS system using the same methodology with a larger number of knee models (n=28) exhibiting different types of deformities affecting the mechanical axis. In conclusion, this study demonstrates a high level of in-vitro accuracy for the CAOS system, regardless of leg-alignment deformity type. The mean error of the CAOS system, characterized as the difference between the measured and checked values, was systematically less than 0.5 mm for bone resection measurements and 1° for joint angle measurements

Introduction. From pre-operative planning to final implant cementation, total knee arthroplasty (TKA) can be defined by a succession of individual steps, each presenting potential errors that can result in devices being implanted outside the desired range of alignment. Our study used an image-free computer-assisted orthopedic surgery (CAOS) guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) to evaluate alignment discrepancies occurring during different steps of a typical TKA procedure. Materials and methods:. A surgical profile was established to define resection parameters and steps for proximal tibial and distal femoral cuts (see Figure 1A) to be made on seven synthetic knee models (MITA, Medical Models, Bristol, UK). First, the guidance system was used to acquire pre-identified landmarks. Next, a cutting block was adjusted to match the resection targets and then fixed to the bone using locking pins. Bone cuts were performed and then checked. Data was collected from the guidance system at three steps: (1) cutting block adjusted but not pinned to bone (see Figure 1B), (2) cutting block adjusted and pinned to bone (see Figure 1C), and (3) after checking cuts (see Figure 1D). These data were then compared to the resection target parameters to assess potential discrepancies. Results:. Discrepancies for all cuts were minimal, as the differences in bone resection thickness and angular measurement were less than 1 mm and 1°, respectively (see Table I). For each parameter, the mean value was close to nominal, demonstrating a well-centered distribution. This being said, there was a consistent derivative of the distal femoral parameters in extension (up to 0.9°), resulting in lower than expected amount of distal femur resection (up to 0.9 mm). Discussion/Conclusion:. In general, discrepancies at each step seemed random, and there was no apparent accumulation trend except for the flexion/extension of the distal femoral cut. There was a slight discrepancy in extension during the pinning of the block, possibly due to the offset weight of the tracker acting on the adjustable instrumentation. There was also a consistent discrepancy in extension during the cut, likely resulting from the saw skiving during cuts. Such a discrepancy can result in a slightly tighter joint in extension than expected. The guidance system did not exhibit substantial alignment discrepancies during procedure steps, reflecting its robustness

Introduction. Accurate component placement in total hip arthroplasty (THA) improves post-operative stability and reduces wear and aseptic loosening. Methods for achieving accurate stem placement have not been as extensively studied as cup placement. Objectives. The purpose of this study is to determine how consistently femoral stem version can be corrected to an ideal of 15 +/− 5 degrees using robotic guidance. Furthermore, the study aims to identify other factors related to approach and patient demographics, which may influence the degree of correction obtained. Methods. 175 consecutive patients who underwent MAKO robotic guidance THA were included in the study with a mean age of 57.9 years and a mean body mass index (BMI) of 30.41kg/m2. 48% of the population was male and 74% of the procedures were performed through an anterior approach. The absolute difference between 15 degrees of anteversion and native femoral version as well as 15 degrees of anteversion and femoral stem version was calculated for each patient. A smaller absolute value post-operatively reflects a closer femoral stem version to a target of 15 degrees. Results. The mean native femoral version was 6.39+/−9.14 degrees. The mean stem version was 9.23+/−8.57 degrees. With respect to achieving a target version of 15 degrees the mean absolute difference between native version and 15 degrees was 10.46+/−6.94 degrees and mean absolute difference between the stem version and 15 degrees was 8.37+/−6.03 degrees. This difference was statistically significant. 69% of patients were able to have their native femoral version corrected to a target of 15 degrees. Conclusions. Robotic guidance in THA was effective in correcting native femoral version towards a target of 15 degrees. This is can be achieved using both the anterior and posterior approach and is not affected by BMI

Fluoroscopic C-arms are operated by medical radiography technologists (RTs) in Canadian operating rooms (ORs). While they do receive formal, accredited training, most of it is theoretical, rather than hands-on. During their first encounters in the OR, new RTs can experience difficulty achieving the radiographic views required by surgeons, often needing several scout X-rays during C-arm positioning. Furthermore, ambiguous language by surgeons often inadequately conveys their request. The result is often frustration, unnecessary radiation exposure, and added OR time. The purpose of this study was to evaluate the value of artificial X-rays in improving C-arm positioning performance, with inexperienced C-arm users. We developed an Artificial X-ray Imaging System (AXIS) that generates Digitally Reconstructed Radiographs (DRRs), or artificial X-ray images, based on the relative position of a C-arm and manikin. 30 participants were enrolled in the user study and performed four activities: an introduction session, an AXIS-guided evaluation, a non-AXIS-guided evaluation, and a questionnaire. The main goal of the study was to assess C-arm positioning performance with and without AXIS guidance. For each evaluation, the participants had to replicate a set of target X-ray images by taking real radiographs of the manikin with the C-arm. During the AXIS evaluation, artificial X-rays were generated at 2 Hz for guidance, while in the non-AXIS evaluation, the participants had to acquire real scout X-rays to guide them toward the correct view. For each imaging task the number of real X-rays and time required per task was recorded, and the C-arm's pose was tracked and compared to the target pose to determine positioning accuracy; these were averaged for each participant and condition. Hypothesis testing on the means and paired t-tests were carried out using a significance level of α=0.05. On average, users took significantly fewer real scout X-ray images (53% fewer (2.8 vs 6.0), p<0.001) when guided by AXIS. Lateral distance accuracy was improved by 10% for final C- arm positions and by 26% for the most accurate intermediate C-arm positions when guided by AXIS (p<0.05). There was no significant difference in average task time or angular accuracies between the AXIS and non-AXIS evaluations. Overall, we are encouraged by these findings and plan to further develop this system with the goal of deploying it both for training and intraoperative uses

Background. Robotics assisted surgery are tools that provide successful biomechanical reconstruction of the hip. We compare the accuracy of cup placement in the safe zones described by Lewinnek et al. and Callanan et al., leg length discrepancy (LLD) and global offset (GO) measurement in total hip arthroplasty (THA) using five diferent image guided techniques performed by six diferent surgeons. Methods. Between June 2008 and April 2014, 2330 THRs were performed by six different surgeons. Ninety-three (4.69%) patients underwent robotic-assisted THA anterior approach, 135 (6.8%) had robotic-assisted THA posterior approach, 942 (47.5%) patients underwent fluoroscopic guided THA anterior approach, 708 (35.7%) had THA without guidance using posterior approach, 43 (2.1%) patients underwent navigation-guided anterior approach and 59 (2.9%) patients underwent radiographic-guided posterior approach THAs (Figure 1). Results. One Thousand, nine hundred-eigthy patients met the inclusion and exclusion criteria. Robotic guidance groups had a significantly greater percentage of hips in the Lewinnek's and Callanan's safe zone (p < 0.005). Between robotic guidance groups, the group with posterior approach has more cups placed in the Lewinnek's and Callanan's safe zone (p < 0.005). The frequency of hips within the Lewinnek's safe zone was significantly greater in the navigation guided group, compared to the other groups except robotic guided (p < 0.05) (Figure 2). Sixty-four (3.2%) of our cases were with LLD greater than or equal to 10mm, five of those cases were (8.5%) in the group treated with x-ray guidance (p < 0.05) (Figure 3). The mean GOD for the overall cohort was 4.0mm ± 0.4mm (p < 0.0001) (Figure 3). Mean ages of patients in the treatment groups were significantly different (p < 0.0001). Conclusion. Robotic assisted surgery was more consistent than the other techniques in placing the acetabular cup into the Lewinnek and Callanan safe zone. In general, we can conclude that the useof the robot in hip arthroplasty surgery is more accurate fulfilling the goals needed to actual hip arthroplasty. We know new technologies will be developed

Introduction. Lewinnek et al described a safe zone of acetabular component placement in Total Hip Arthroplasty (THA) to reduce complications. Callanan et al proposed a modified safe zone with a reduced range of acetabular inclination of 30–45 degrees to eliminate the steeper or more inclinated cups 2. This study compares the accuracy of cup placement in the safe zones described by Lewinnek et al and Callanan et al, leg length discrepancy (LLD) and global offset (GO) measurement in THA using five different surgical techniques performed by six different surgeons. Methods. Between June 2008 and April 2014, 2330 THRs were performed by six different surgeons. Post-operative radiographic images were retrospectively reviewed and measured using TraumaCad® software to determine cup placement, LLD, and GOD. Results. One thousand, nine hundred-eighty patients met the inclusion and exclusion criteria. Ninety-three (4.69%) patients underwent robotic-assisted THA anterior approach, 135 (6.8%) had robotic-assisted THA posterior approach, 942 (47.5%) patients underwent fluoroscopic guided THA anterior approach, 708 (35.7%) had THA without guidance using posterior approach, 43 (2.1%) patients underwent navigation-guided anterior approach and 59 (2.9%) patients underwent radiographic-guided posterior approach THAs. Robotic guidance groups had a significantly greater percentage of hips in the Lewinnek's and Callanan's safe zone (p < 0.005). Between robotic guidance groups, the group with posterior approach has more cups placed in the Lewinnek's and Callanan's safe zone (p < 0.005). The frequency of hips within the Lewinnek's safe zone was significantly greater in the navigation guided group, compared to the other groups except robotic guided (p < 0.05). Sixty-four (3.2%) of our cases were with LLD greater than or equal to 10mm, five of those cases were (8.5%) in the group treated with x-ray guidance. (p < 0.05). The mean GOD for the overall cohort was 4.0mm ± 0.4mm (p < 0.0001). Mean ages of patients in the treatment groups were significantly different (p < 0.0001). Conclusion. Robotic assisted surgery was more consistent than the other techniques in placing the acetabular cup into the Lewinnek and Callanan safe zone. The use of robotic assistance in hip arthroplasty surgery is more accurate fulfilling the goals needed to actual hip arthroplasty. Long term follow-up is required to determine clinical impact of increased accuracy

Total hip replacement in Germany has been performed in 227293 cases in 2015 and tendency is increasing. Although it is a standard intervention, freehand positioning of cup protheses has frequently poor accuracy. Image-based and image-free navigation systems improve the accuracy but most of them provide target positions as alphanumeric values on large-size screens beneath the patient site. In this case the surgeon always has to move his head frequently to change his eye-focus between incision and display to capture the target values. Already published studies using e.g. IPod-based displays or LED ring displays, show the chance for improvement by alternative approaches. Therefore, we propose a novel solution for an instrument-mounted small display in order to visualise intuitive instructions for instrument guidance directly in the viewing area of the surgeon. For this purpose a solution consisting of a MicroView OLED display with integrated Arduino microcontroller, equipped with a Bluetooth interface as well as a battery has been developed. We have used an optical tracking system and our custom-designed navigation software to track surgical instruments equipped with reference bodies to acquire the input for the mini-display. The first implementation of the display is adapted to total hip replacement and focuses on assistance while reaming the acetabulum. In this case the reamer has to be centred to the middle point of the acetabular rim circle and its rotation axis must be aligned to the acetabular centre axis by Hakki. By means of these references the actual deviations between instrument and target pose are calculated and indicated. The display contains a cross-hair indicator for current position, two bubble level bars for angular deviation and a square in square indicator for depth control. All display parts are furnished with an adaptive variable scale. Highest possible resolution is 0.5 degrees angular, 1 millimeter for position and depth resolution is set to 2 mm. Compared to existing approaches for instrument-mounted displays, the small display of our solution offers high flexibility to adjust the mounting position such that it is best visible for the surgeon while not constraining instrument handling. Despite the small size, the proposed visualisation symbols provide all information for instrument positioning in an intuitive way

Introduction. From pre-operative planning to final implant cementation, total knee arthroplasty (TKA) preparation is a succession of many individual steps, each presenting potential sources of error that can result in devices being implanted outside the targeted range of alignment. This study assessed alignment discrepancy occurring during different TKA steps using an image-free computer-assisted orthopaedic surgery (CAOS) guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) in normal and abnormal mechanical axis. Materials and methods. We used a commercially available artificial leg (MITA trainer leg M-00058, Medical Models, Bristol, UK) able to receive (neutral / varus / valgus) knee inserts simulating the proximal tibia and distal femur. A pre-surgical profile was established to define resection parameters for the proximal tibial and distal femoral cuts (Figure 1A). Data from the guidance system were collected at three separate steps: (1) cutting block adjusted but not pinned to the bone (Figure 1B), (2) cutting block adjusted and pinned to the bone (Figure 1C), and (3) after the cuts were checked (Figure 1D). These data were then compared to the resection target parameters to track potential dispersions occurring during the process. Due to the amount of data (i.e., four studied resection parameters per bone, three operative steps, and three knee model types), the authors introduced an “error index”, which was a unitless indication of overall error magnitude obtained by averaging the absolute values of all linear and angular measurement errors. Due to knee model dimensions (∼55 mm), the authors equally considered linear and angular measurement values (i.e., 1 mm equivalent to 1°). Results. Regardless of resection parameter or bone deformity type, all linear or angular error distributions were symmetrical around the neutral value, which implies no obvious skew in terms of error direction. The type of knee model deformity had almost no effect on overall error magnitudes throughout all surgical steps (Figure 2). Discussion. Few studies present possible causes for errors when using CAOS for TKA. Notably, Bathis et al. evaluated cutting errors as the difference between the primary cutting block position and the resulting resection plane. As a result, errors due to a malpositioning of the guide jig itself were not described. 1. In general, the authors found the dispersions at each step to seemingly be random. For both the tibia and the femur, a significant increase in the error index from the adjusted to the attached step (p<0.001 and p=0.005; respectively) was observed, meaning the pinning of the cutting block to the bone is a key step. Also, observing the relationship between linear and angular parameters was relevant. For example, for the femur, a cut in extension was highly correlated with lower than expected distal femoral resection (Pearson correlation factor of 0.783 and 0.913 at the checked step for the medial and lateral distal femoral resections; respectively, p<0.001). Regardless of the presence and type of deformity, the evaluated image-free computer-assisted guidance system did not exhibit substantial alignment dispersions during any step of the procedure

The internal fixation of scaphoid bone fractures remains technically difficult due to the size of the bone and its three- dimensional shape. Early rigid fixation, e.g with a screw, has been shown to support good functional outcome. In terms of stability of the fracture, biomechanical studies have shown a superior result with central screw placement in the scaphoid in comparison with an eccentric position, which can lead to delayed or non-union. Image-based navigation could be helpful for these cases. The main limitation of reference-based navigation systems is their dependence on fixed markers like used in modern navigation systems. Therefore it is limited in treatment of small bone fractures. In former experimental studies 20 artificial hand specimens were randomised into two groups and blinded with polyurethane foam: 10 were treated conventionally and 10 were image guided. For trajectory guidance a reduction of duration of surgery, radiation exposure and perforation rate compared to the conventional technique could be found. Accuracy was not improved by the new technique. The purpose of this study was to identify the possible advantages of the new guidance technique in a clinical setting. In this prospective, non-randomised case series we tested the feasibility of the system into the accommodated surgical workflow. There was no control group. Three cases of scaphoid fractures were included. All of the patients were treated with a cannulated screw following K-wire placement via the percutaneous volar approach described. In addition, length measurements and screw sizes were determined using special features of the system. The performing surgeon and two attending assistant doctors (one assisting the surgical procedure, one handling the guidance system) had to rate the system following each procedure via a user questionnaire. They had to rate the system's integration in the workflow and its contribution to the success of the surgical procedure in percentages (0 %: totally unsuccessful; 100 %: perfect integration and excellent contribution). All of the clinical procedures were performed by the same surgeon. The surgeons rated the system's contribution and integration as very good (91 and 94 % of 100 %). No adverse event occurred. An average of 1.3 trials ± 0.6 (1; 2) was required to place the K-wire in the fractured scaphoid bone. The dose-area product was 19 cGycm2 ± 3 (16; 22). The mean incision until suture time was 36.7 min ± 5.7 (30; 40). For clinical cases, the system was integrated and rated as very helpful by users. The system is simple and can be easily integrated into the surgical workflow. Therefore it should be evaluated further in prospective clinical series

Introduction. An emerging consensus in the surgical specialties is that skill acquisition should be more emphasized during surgical training. 1. This study was an attempt to evaluate the effects of repetitive practices using an image-free computer-assisted orthopaedic surgery (CAOS) guidance system (Exactech GPS, Blue-Ortho, Grenoble, FR) on both technical and cognitive skills. Materials and methods. A senior knee replacement surgeon with limited previous experience with the CAOS system performed a series of consecutive simulated knee surgeries using a commercially available artificial leg (MITA trainer leg M-00058, Medical Models, Bristol, UK). In order to assess the effects repetitive practice has on technical skills, we evaluated two indexes:. Error index: A unitless indication of overall error magnitude obtained by averaging the absolute values of all linear and angular measurement differences between targeted and checked cuts. Time index: An indication of the time required to acquire landmarks, adjust the custom blocks, and make cuts. In order to assess the effect repetitive practice has on cognitive skills, we evaluated the number of times the surgeon elected to deviate from pre-surgical planning or re-acquire landmarks. We evaluated these parameters for three chronological and consecutive groups of simulated surgeries: Group A (knee models #1 to #10), Group B (knee models #11 to #20), and Group C (knee models #21 to #28). Results. Regardless of the number of operations, tibial and femoral cuts were associated with a low error index (ranging from 0.45 to 0.71 for all three groups), suggesting the continuous guidance offered by the CAOS system provided an opportunity to correct discrepancies from the plan during surgery (Figure 1A). The variability of surgical time at key steps substantially reduced from Group A to Group C (Figure 1B). Finally, the surgeon elected to re-perform femoral landmark acquisitions 8 times for Group A, 4 times for Group B, and 0 times for Group C. Discussion. The authors attempted to delineate the effects of repetitive practices on skills using a CAOS system. The overall perception was the number of sequential practice surgeries had no significant effect on surgical accuracy. The significant decrease in the time index (43%) during the course of the practice surgeries is in line with recent studies regarding the learning curve associated with navigation for knee arthroplasty. 2. Compared to the initial planning, the only modifications in surgical steps were related to re-acquiring femoral landmarks. As with any image-free system, the present CAOS system relies on precise landmark acquisition. To achieve this goal, the system under consideration presents an interactive software enabling landmark visualization (Figure 2) allowing immediate feedback loop. Despite the obvious limitation of being conducted on synthetic bones, this study enabled a senior surgeon to perfect his technical and cognitive skills, potentially leading to increases in efficiency and efficacy in the intense environment of the operating room

To evaluate a innovate one stage procedure of the PJI knee treatment using computed assisted guidance. Our objectives; to increase the functional results by optimizing the anatomical joint reconstruction and to verifie if CAS help to simplifie and standardize these complex surgeries. It's a prospective, single surgeon study. Since septembre 2011, 41 patients treated for chronic knee PJI in a one stage revision (one of them had a ipsilateral chronic knee arthritis). For all of them, a computed assisted guidance, the ExactechGPS® system was used. This system offers the possibility to define specific profiles to performe primary TKA surgeries. A personnalized profile of revision was created. All surgeries were performed with the same protocole; independently of the type of germ, with no use of tourniquet, no drainage by performing the same debridement procedure step by step and by using the same knee components. 27 males, 14 female with 26 PJI of primary TKA, one infected unicompartimental prosthesis and 15 PJI of first revised TKA has been treated. The average age was 71 years old (55–87). The time of surgery was on average 135 mn (120 – 195 mn). The average time of hospitalization was 10 days (7–16). The average follow up was 20,9 months (6–47 months). The ROM were on average 114,7% (90°–130°), None post operative HKA outliers were reported. 3 patients presented a failure of the PJI treatment (one after a local open traumatism, one diabetic patient, one after a early revision for mechanical complication). None specific CAS complications and no failure of the CAS procedures are reported. As surgeon, CAS simplified the management of the bone loss after debridement and the control of the differents parameters (HKA, external femoral rotation, ligamentary balancing, lign joint…) by a real time feedback. we changed our practise by using more constraint condylar component instead hinge prostheses. With a rate of success of 92,7% at this follow up, the one stage option appears to be valided. Using CAS is a safe option with no specific complication. It increases the quality of the ROM, a earlier functional recovery and a better middle term clinical result. Both combined, It should be a optimal medicoeconomical solution. compared revision using mechanical ancillary

Acetabular component positioning is highly correlated with total hip arthroplasty (THA) outcomes. Multiple reports however indicate that less than 50% of acetabular cups are placed within surgeon-desired ranges for abduction and anteversion angles when using conventional cup positioning techniques. Issues with improper placement include instability-dislocation, impingement and impact on range of motion, polyethylene wear, leg length discrepancy, and gait mechanics. Accuracy in placement of the acetabular component is complicated by the need to estimate cup impactor angles to create desired cup position. A low cost approach to THA using Image-based Ultrasonic Guidance (IUG) (Orthosensor, Sunrise, FL) coupled to existing surgical tools is presented. IUG utilises acoustic measurement techniques for achieving optimal component positioning and leg length. A precisely machined Hip Test Fixture (HTF) has been built to simulate the anatomical pelvis, acetabular cup, and femur to validate system accuracy. The IUG was affixed to the HTF to demonstrate placement of the cup during THA. The HTF was loaded onto a 27-inch Graphic User Interface (GUI) providing three-dimensional CAD data of the HTF. Registration points included the Iliac Crest and 10 points around the acetabular cup. These points were mapped to the CAD data by the GUI. The HTF was set to 45° of abduction and 0° of version to begin testing. Abduction and version were measured over a +15° range in 1-degree increments while leg length and offset were measured over a +5mm range in 2mm increments. A high-resolution coordinate measurement machine (FaroArm EDGE) verified the accuracy and margin of error for inclination, version, leg length and offset at each increment. The HTF provided a precise means for evaluating IUG system accuracy of simulated THA in a controlled environment. Acceptable margins of error were reported on the HTF: mean error for version was 0.36° (SD 0.02°; 0.25° to 0.38°); mean error for inclination was 1.04° (SD 0.52°; 0.48° to 1.66°); mean error for leg length and offset were respectively 0.36mm (SD 0.86mm; −0.65 to 1.55mm) and 0.41mm (SD 0.28; 0.05 to 0.80mm). IUG provides a means for achieving acceptable precision and accuracy in component placement during THA as evaluated with the HTF. Further study is however necessary to correlate accuracy of IUG with clinical utility and short-term clinical outcomes