Surgical navigation systems enable surgeons to carry out surgical interventions more accurately and less invasively, by tracking the surgical instruments inside human body with respect to the target anatomy. Currently, optical tracking (OPT) is the gold standard in surgical instrument tracking because of its sub-millimeter accuracy, but is constrained by direct line of sight (LOS) between camera sensors and active or passive markers. Electromagnetic tracking (EMT) is an alternative without the requirement of LOS, but subject to environmental ferromagnetic distortion. An intuitive idea is to integrate respective strengths of them to overcome respective weakness and we aim to develop a tightly-coupled method emphasising the interactive coupled sensor fusion from magnetic and optical tracking data. In order to get real-time position and orientation of surgical instruments in the surgical field, we developed a new tracking system, which is aiming to overcome the constraints of line-of-sight and paired-point interference in surgical environment. The primary contribution of this study is that the LOS and point correspondence problems can be mitigated using the initial measurements of EMT, and in turn the OPT result can provide initial value for non-linear iterative solver of EMT sensing module. We developed an integrated optical and electromagnetic tracker comprised of custom multiple infrared cameras, optical marker, field generator and sensing coils, because the current commercial optical or magnetic tracker typically consists of unchangeable lower level proprietary hardware and firmware. For the instrument-affixed markers, the relative pose between passive optical markers and magnetic coils is calibrated. The pose of magnetic sensing coils calculated by electromagnetic sensing module, can speed up the extraction of fiducial points and the point correspondences due to the reduced search space. Moreover, the magnetic tracking can compensate the missing information when the optical markers are temporarily occluded. For magnetic sensing subsystem comprised of 3-axis transmitters and 3-axis receiving coils, the objective function for nonlinear pose estimator is given by the summation of the square difference between the measured sensing data and theoretical data from the dipole model. Non-linear optimisation is computational intensive and requires initial pose estimation value. Traditionally, the initial value is calculated by equation-based algorithm, which is sensitive to noise. Instead, we get the initial value from the measurement of optical tracking subsystem. The real-time integrated tracking system was validated to have tracking errors about 0.87mm. The proposed interactive and tightly coupled sensor-fusion of magnetic-optical tracking method is efficient and applicable for both general surgeries as well as intracorporeal surgeries

Aims

This study aimed to assess the carbon footprint associated with total hip arthroplasty (THA) in a UK hospital setting, considering various components within the operating theatre. The primary objective was to identify actionable areas for reducing carbon emissions and promoting sustainable orthopaedic practices.

Retained polymethylmethacrylate (PMMA) debris in surgical instrument trays is a rare, but disquieting situation for the arthroplasty surgeon. Although retained debris could be considered to be sterile after autoclaving, there is no peer-reviewed literature to support this assumption. This uncertainty and subsequent fear of contamination from this bioburden often leads to operating room personnel turning over entire surgical tables and opening new surgical instruments, which consumes time and burdens a hospital's sterilization infrastructure. Consequently, the purpose of the current study was to determine if retained, heavily contaminated PMMA in surgical trays could be effectively sterilized through clinically utilized autoclave protocols. MSSA (Xen36, Perkin Elmer) biofilm was grown on identically sized PMMA (Palacos R) coupons for 72-hour duration. Following incubation, coupons were exposed to three commonly used sterilization protocols. Cobalt-Chrome (CC) coupons were included in the same tray, replicating instruments in proximity to retained PMMA. Autoclave protocols included: 1.) Single Instrument Flash protocol: Pre-vac, 270° F, 10 min exposure, 1 min drying, 2.) One Tray OR protocol: Pre-vac, 270° F, 4 min exposure, 1 min drying, and 3.) Standard Post-Operative protocol: Pre-vac, 270° F, 10 min exposure, 60 min drying. Control coupons did not undergo autoclaving. Coupons were then sonicated for 30 minutes in tryptic soy broth and plated to count CFUs. Experiments were performed in quadruplicate. Control coupons showed significant contamination with CFU counts in the range of 10. 6. CFU/mL. CFU counts of zero across all autoclaved PMMA and CC coupons revealed that each protocol was effective in completely eradicating culturable S. aureus, confirming clinical efficacy on orthopaedic cement sterilized in surgical trays. Our findings demonstrate that heavily contaminated PMMA and exposed metal in surgical trays can be effectively sterilized through several autoclaving protocols. Clinicians should feel confident in the efficacy of autoclave protocols in removing bacteria and its associated biofilm from othopaedic materials

An overview about 3D printing technology in orthopaedic applications will be given based on examples. The process from early prototypes to certified implants coming from serial production will be demonstrated also considering relevant surrounding conditions. Today's focus is mostly on orthopaedic implants, but there is a high potential for new implant-related surgical instrument solutions taking into account up-coming clinical demands and user needs accessible by actual 3D printing technologies

Introduction. Ilizarov fixators are reliant on tensioned fine wires for stability. The tension in the wires is generated using specific tensioning devices. Loss of wire tension over time may lead of loss a stability and complications. A series of in vitro experiments were undertaken to explore wire tensioner accuracy, the impact of fixation bolt torque and initial tension on loss of tension in ilizarov constructs under static and dynamic loads. Materials & Methods. Medical grade materials were applied to a synthetic bone analogue using surgical instruments in all experiments. Bolt torque was fixed at 6, 10 or 14 Nm using a torque limiting wrench. Wire tension was assessed using a strain measurement bridge. Wires were tensioned to 90, 110 and 130kg as measured by a commercial dynamometric tensioner. Static and dynamic testing was undertaken using an instron testing machine. Cyclical loads from 50–750N were applied for 5000 cycles. Results. Actual wire tension was approximately 15% less than indicated by the tensioner device. Using fixation bolt torques of 10Nm and 14Nm achieved final wire tensions of around 60% and 80% of that applied at 90 and 130kg of applied tension. Static load testing demonstrated self stiffening to similar levels in all pre-tensions. Dynamic testing demonstrated significant loss of tension, most of which occured in the first 3 cycles, inversely proportional to the tension initially applied. Conclusions. These experiments provides insight into the effect of initially applied wire tension on Illizarov mechanical performance. It is important surgeons understand how the different ways that these devices are applied affects mechanical performance. Further research examining what factors affect performance across different manufacturers equipment would therefore be relevant, alongside the development of novel fixation methods to reduce wire slippage and the further development of equipment for clinical use

Abstract. Background. Ultrasonic cutting of bone boasts many advantages over alternatively powered surgical instruments, including but not limited to: elimination of swarf, reduced reaction forces, increased precision in cutting and reduced adjacent soft tissue damage, reduced post-operative complications such as bleeding and bone fracture, reduced healing time, reduced intra-operative noise and ease of handling. Despite ultrasonic cutting devices being well established in oral and maxillofacial surgery, applications in orthopaedic surgery are more niche and are not as well understood. The aim of this study was to investigate the cutting speed (mm/s) and cutting forces (N) of orthopaedic surgeons using a custom-designed state of the art ultrasonic cutting tool to cut fresh human bone samples. Methods. A setup based on the Robot Operating System (ROS) and AprilTag was designed to track and to record the real time position of the ultrasonic cutting tool in space. Synchronised load cell axial force readings of three separate orthopaedic surgeons during ultrasonic cutting were recorded. Each surgeon was asked to find a comfortable position that reflects as close as possible their clinical handling of a cutting instrument used in surgery, and to perform two cuts in each of three samples of human cortical bone. Bone samples were obtained following ethical approval from an institutional review board (ethics approval number: SR1342) and prior informed consent was obtained from all patients. Bone samples were extracted from the femoral neck region of three hip osteoarthritis patients. During cutting, surgeons were allowed a total cutting time of one minute and cutting was conducted using an ultrasonic tool with frequency of a 35kHz (35.7 µm peak to peak displacement amplitude) under constant irrigation using a MINIPULS® 3 Peristaltic pump (38 revolutions per minute) using Phosphate-Buffered Saline (PBS) at 25°C. From the recorded data, the average instantaneous cutting velocity was calculated and the maximum cutting force was identified. Results. All surgeons assumed a back-and-forth cutting motion, variation in the applied cutting force was observed. The average vertical cutting speed, axial cutting force and cutting depth across all surgeons and all samples was 1.64 mm/s, 1.91 N and 0.73 mm, respectively. While increasing the axial cutting force resulted in a deeper cut, overloading of the ultrasound transducer occurred when the tool advanced too quickly into the bone tissue during cutting. The exact force threshold, or the optimal speed at which the surgeon can maintain a constant force during cutting, requires further investigation. Conclusions. In this study, all surgeons cut using a back-and-forth cutting motion, with variation in the applied cutting force which may ultimately inform which clinical applications in orthopaedic engineering are most suitable for this technology. Applying too much force caused overloading of the ultrasound transducer, which is a limitation with the current cutting tool. The results from this study may facilitate the eventual uptake of ultrasonic cutting tools for application in orthopaedic surgery. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Demographic changes will increase the number of surgical procedures in the next years. Therefore, quality assurance of clinical processes, such as the reprocessing of surgical instruments as well as intraoperative workflows will be of increasing importance to ensure patient safety. Surgical procedures are often complex and may involve risks for the patient. For fixation of screws, e.g. in case of pedicle screws, osteosynthesis plates or revision joint replacement surgery implants, the application of defined torques may be crucial in order to achieve optimal therapeutic results and minimal complication rates. In many cases a subjective rating of the surgeon is necessary as no adequate instrumentation is available. With the same subjective feeling, hammering or screwing in are performed to implant e.g. the acetabular component in THA. Our actual work is dedicated to the implementation of a functional prototypes of sensor- integrated instruments for specific types of intervention (especially in traumatology) and the evaluation of the sensor integrated surgical instruments in combination with RFID technology for smart process optimisation in the operating room as well as for reprocessing of surgical instruments and surgical management in combination with a knowledge-based planning, control and documentation system. Complementary (preferably wireless) sensors such for instrument identification, tracking or more complex measurements such as forces, torques, temperature or impacts during surgery as well as during reprocessing of reusable instruments could enable computer network based quality assurance in a much broader and comprehensive manner. Within the framework of the OR.NET initiative we follow the approach to integrate wireless sensors for measurement of temperature, force-torque as well as inertial sensors for orientation and impact control, depending on the specific type of application for monitoring of workflows during surgery as well as during reprocessing of reusable instruments and devices. The integration of smart surgical instruments into an open networked operating room based on the open communication standard IEEE 11073 knowledge-based workflow system, can help to improve the process and quality management

Abstract. Objectives. Accurate orientation of the acetabular component during a total hip replacement is critical for optimising patient function, increasing the longevity of components, and reducing the risk of complications. This study aimed to determine the validity of a novel VR platform (AescularVR) in assessing acetabular component orientation in a simulated model used in surgical training. Methods. The AescularVR platform was developed using the HTC Vive® VR system hardware, including wireless trackers attached to the surgical instruments and pelvic sawbone. Following calibration, data on the relative position of both trackers are used to determine the acetabular cup orientation (version and inclination). The acetabular cup was manually implanted across a range of orientations representative of those expected intra-operatively. Simultaneous readings from the Vicon® optical motion capture system were used as the ‘gold standard’ for comparison. Correlation and agreement between these two methods was determined using Bland-Altman plots, Pearson's correlation co-efficient, and linear regression modelling. Results. A total of 55 separate orientation readings were obtained. The mean average difference in acetabular cup version and inclination between the Vicon and VR systems was 3.4° (95% CI: −3–9.9°), and −0.005° (95% CI: −4.5–4.5°) respectively. Strong positive correlations were demonstrated between the Vicon and VR systems in both acetabular cup version (Pearson's R = 0.92, 99% CI: 0.84–0.96, p<0.001), and inclination (Pearson's R = 0.94, 99% CI: 0.88–0.97, p<0.001). Using linear regression modelling, the adjusted R. 2. for acetabular version was 0.84, and 0.88 for acetabular inclination. Conclusion. The results of this study indicate that the AescularVR platform is highly accurate and reliable in determining acetabular component orientation in a simulated environment. The AescularVR platform is an adaptable tracking system, which may be modified for use in a range of simulated surgical training and educational purposes, particularly in orthopaedic surgery. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Nowadays 80% of patients with bone sarcomas can benefit from limb salvage. Their disease-free life expectancy is not jeopardised by conservative surgery as long as safe margins are obtained. For this reason, the oncological result relies on the accuracy of pre-operative and per-operative surgical measurements. Pre-operative evaluation of tumours is now quite accurate with digital margins (computed tomography, MNR, digital angiography). However, surgeons are still using centimeters or conventional radiographs with their own technical limitations for per-operative evaluation. A more accurate technique is needed. The system is composed of three components: 1) a color, graphic computer workstation with software to calculate and present the location of the surgical instrument on a three-dimensional, reconstructed bone image, 2) a complete set of hand-held instruments containing infrared emitters, 3) an infrared receiver linked to the work station. This measuring system enables determination of the position and incidence of a surgical instrument in real time during surgery, with an accuracy of less than one mm. The system requires four steps: 1) recording data with C.T., N.M.R. or angiography, 2) creating a three-dimensional image displayed on the computer screen for preoperative simulation of a virtual operation, 3) recording the very important anatomical points of the patient and optimal incidences of the surgical instruments, 4) preoperative location of surgical instruments and control of their location on bone. This system is very useful for resection of bone tumours when the conventional location is uncertain (innonimate bone, rib), when very sharp accuracy is needed to preserve the growth plate of the distal femur in young children, and to avoid medullary damage in a spinal tumour. The frameless stereotactic device is also very accurate in the reconstructive phase of limb salvage. After an internal hemipelvectomy, the device permits localisation of the acetabular prosthesis in the precise location before resection. In our practice, the accuracy of the video guiding system is always within two mm as compared to conventional measurements usually between one or two cm for long bones and three to five cm for innominate bone. The use of a video guidance system is very beneficial for limb salvage surgery for pelvic bone tumours

Nowadays 80% of patients with bone sarcomas can benefit from limb salvage. Their disease-free life expectancy is not jeopardised by conservative surgery as long as safe margins are obtained. For this reason, the oncological result relies on the accuracy of pre-operative and per-operative surgical measurements. Pre-operative evaluation of tumours is now quite accurate with digital margins (computed tomography, MNR, digital angiography). However, surgeons are still using centimeters or conventional radiographs with their own technical limitations for per-operative evaluation. A more accurate technique is needed. The system is composed of three components: 1) a color, graphic computer workstation with software to calculate and present the location of the surgical instrument on a three-dimensional, reconstructed bone image, 2) a complete set of hand-held instruments containing infrared emitters, 3) an infrared receiver linked to the work station. This measuring system enables determination of the position and incidence of a surgical instrument in real time during surgery, with an accuracy of less than one mm. The system requires four steps: 1) recording data with C.T., N.M.R. or angiography, 2) creating a three-dimensional image displayed on the computer screen for preoperative simulation of a virtual operation, 3) recording the very important anatomical points of the patient and optimal incidences of the surgical instruments, 4) preoperative location of surgical instruments and control of their location on bone. This system is very useful for resection of bone tumours when the conventional location is uncertain (innonimate bone, rib), when very sharp accuracy is needed to preserve the growth plate of the distal femur in young children, and to avoid medullary damage in a spinal tumour. The frameless stereotactic device is also very accurate in the reconstructive phase of limb salvage. After an internal hemipelvectomy, the device permits localisation of the acetabular prosthesis in the precise location before resection. In our practice, the accuracy of the video guiding system is always within two mm as compared to conventional measurements usually between one or two cm for long bones and three to five cm for innominate bone. The use of a video guidance system is very beneficial for limb salvage surgery for pelvic bone tumours

In orthopaedic trauma surgery, X-ray fluoroscopy is frequently employed to monitor fracture reduction and to guide surgical procedures where implants are inserted to fix the fractures. Fluoro-navigation is the application of real-time navigation on intraoperatively acquired fluoroscopic images to achieve the same goals. The theoretical advantages of fluoro-navigation are:. Minimising exposure to X-ray on surgeons, operating room personells and patients,. Accurate positioning of implants,. Expanding the application of minimally invasive surgery,. Shortening the operation time. Fluoro-navigation is particular indicated in orthopaedic trauma as the fracture fragments are mobile and the orientations are not fixed before surgery. At this time, many procedures that require intraoperative fluoroscopic control can now be done with fluoro-navigation. These procedures include:. Fixation of femoral neck fractures with percutaneous cannulated screws,. Intramedullary locked nails for long bone fractures,. Intramedullary fixation of trochanteric fractures. Percutaneous fixation of sacro-iliac fractures dislocations. Percutaneous fixation of iliac wing fractures. Percutaneous fixation of acetabulum fractures. Insertion of Ilizarov tension wires for complex articular fractures. Many percutaneous fixation procedures that need fluoroscopic controls. Since 2001, we have been using fluoro-navigation orthopaedic trauma surgery. 535 different procedures of operative treatment of fractures were carried out. These operative procedures included. Operation, amount, success rate:. Femoral neck fractures, 65, 100%, Gamma nailing, 172, 100%, Femoral locked nails, 77, 98.5%, Tibial locked nails, 53, 100%, Sacro-iliac screws, 45, 95.1%, Pelvic acetabular fractures, 29, 96.1%, Ilizarov tension wires, 13, 100%, Percutaneous screws, 18, 100%, Distal locking without X-ray, 15, 100%, 3-D Navigation, 48 92.7%. Our clinical experience has confirmed the advantages and the extended applications of this technique benefited many of our patients by enhancing minimally invasive technique in orthopaedic trauma surgery, better implant position and significantly decreasing the radiation of the fluoroscopy (p< 0.05). We have modified the operative procedures in order to adapt better with the fluoro-navigation procedures. We also worked with the industrial partners to design specific instruments as well as modified the existing surgical instruments to facilitate the fluoro-navigation procedures. Most of the failure were due to poor quality fluoro-images, unstable operating system and poorly adapted surgical instruments in the early phase of the applications. Further improvement is expected in the system on the hardware and software for quicker image acquisition with improved quality, accurate and precise registration, increase interactivities and adaptation of surgical instruments as well as implants. There is a great need for the development of dedicated surgical instruments for orthopaedic trauma sugary in line with the further improvement of the navigation system. With the establishment of image libraries for implants and skeleton, further minimising the need for standard fluoroscopy will be possible. The combination of 3-D fluoroscopy and the navigation will improve percutaneous fixation of articular fractures. At the time, it is only possible to navigate the images obtained during the operation after fracture reduction or manipulation is completed. The possibility to navigate on each individual fracture fragment will extend the technique even more to real-time fracture reduction. The fluoro-navigation system will also play an important role in surgical training as well as assessment in the virtual surgical environment. We also developed specific training models for fluoro-navigation for preoperative training and practice of standard procedures. This will help to promote further application of fluoro-navigation in orthopaedic trauma. The recognition of its clinical significance will help to stimulate more research and thus encourages industries to devote more resources in the development of fluoro-navigation for orthopaedic trauma

INTRODUCTION. Due to increasing interest into taper corrosion observed primarily in hip arthroplasty devices with modular tapers, efforts towards characterizing the corrosion byproducts are prevalent in the literature [1–4]. As a result of this motivation, several studies postulate cellular induced corrosion due to the presence of remarkable features in the regions near taper junction regions and articulating surfaces [3–5]. Observations made on explanted devices from a retrieval database as well as laboratory tests have led to the alternative proposal of electrocautery-electrosurgery damage as the cause of these features. These surgical instruments are commonly used for hemostasis or different degrees of tissue dissection. METHODS. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to evaluate the features observed on retrieved devices. Retrieved devices consisted of OXINIUM and cobalt-chromium-molybdenum (CoCrMo) femoral implants, a Titanium-alloy hip stem, and a CoCrMo metal-on-metal femoral head. Electrocautery-electrosurgery damage was created using a SurgiStat II (Valleylab, Colorado) onto various components (CoCrMo, OXINIUM femoral heads as well as Ti-6Al-4V and CoCrMo alloy test stem constructs). Test components were evaluated using the same methods as the retrieved devices. RESULTS. Remarkable features were present on retrieved devices (Figure 1) which were similar to previous studies (3–5). The appearance of these features could be described as crater-like, pitted, scratched, molten or splattered material, and ruffled. These features were present on articulating and non-articulating regions as well as near taper junctions. Testing performed on samples using the SurgiStat II, created features that were similar in appearance (Figure 1). Additionally, material transfer that included an iron peak based on EDS in addition to the cobalt and chromium (present due to native material) was detected in the regions of contact (Figure 2). CONCLUSIONS. It was possible to re-create damage features similar to those previously characterized as remarkable features created by cellular-induced corrosion [3–5]. It is theorized that the high-voltage based electrocautery (commonly Bovie) or high-frequency based electrosurgical devices can result in localized degradation/alteration of oxides and passive regions of commonly used orthopaedic alloys. These surgical instruments, specifically the cutting electrodes, are frequently made of stainless steels which can result in iron transfer during contact with the device. During the surgical use of the electrocautery-electrosurgery instrument, it may be necessary to remove tissue, bone, or cauterize near the implant or explant which may have led to the damage features noted in this study and the previous literature [3–5]. If this damage occurs during the initial implantation of the devices, it may further exacerbate corrosion in the damaged region and/or alter the mechanical integrity of the constructs (i.e. fatigue performance)

Introduction. In hip arthroplasty, it has been shown that assembly of the femoral head onto the stem remains a non-standardized practice and differs between surgeons [1]. Pennock et al. determined by altering mechanical conditions during seating there was a direct effect on the taper strength [2]. Furthermore, Mali et al. demonstrated that components assembled with a lower assembly load had increased fretting currents and micromotion at the taper junction during cyclic testing [3]. This suggests overall performance may be affected by head assembly method. The purpose of this test was to perform controlled bench top studies to determine the influence of impaction force and compliance of support structure (or damping) on the initial stability of the taper junction. Materials and Methods. Test Specimens. Testing was performed on 36mm +5mm CoCr heads combined with prototype Ti6Al4V locking taper analogs both machined with approximately a 5.67º taper angle. To minimize sample variation, the locking taper analogs were dimensionally matched with CoCr femoral heads to maintain a uniform angle difference. Prior to testing, samples were cleaned with isopropanol and allowed to dry. Effect of Peak Force Magnitude. Testing was performed on a rigid setup where a 10N preload was applied to the femoral head axially. Heads were assembled with loads ranging from 2kN–10kN using an impaction tower and seating loads were recorded at a collection rate of 273kHz. After assembly, tensile loads were applied until the taper junction was fully disassembled and distraction loads were recorded at a collection rate of 500Hz. Effect of Damping. 40 durometer rubber pads were placed underneath the trunnions as well as to the striking surface of the impaction tower to simulate compliance in the supporting structure and the surgical instruments. Aside from the added damping, testing was performed identical to the rigid setup tests. Results. Taper stability (as assessed by disassembly forces) increased linearly with peak assembly force with an R2 value of 0.95 for both rigid and compliant groups (Figure 1). On average a 46% larger input energy was required in the compliant group to achieve a comparable impaction force to the rigid group (Figure 2). However, the correlation between the assembly load and distraction force was not affected. Discussion. As shown in previous studies, impact force has a large effect on initial taper stability. An interesting finding in this study was that system compliance has a large effect on the applied assembly force. The addition of a compliant setup was intended to simulate a surgical scenario where factors such as the patient's leg positioning, patient mass, surgical instruments, and surgical approach may influence the resulting compliance due to the dissipation of impaction energy and reducing the applied impaction force. Based on test results, surgical procedure as well as patient variables may have a significant effect of initial taper stability. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Purpose. When we perform total knee arthroplasty (TKA), the accurate osteotomy and implant setting is important as follows to improve long-term results. As means to perform osteotomy exactly, patient specific surgical instruments (PSI) patient specific surgical instruments planning based on pre-operative MRI (Signature, Materialise) and Image-free navigation system (Navi: Knee unlimited; BrainLAB) exist. However, there is not the report to compare which is exact for the same patient at the same time using two methods. We report to compare the osteotomy plans by two methods. Materials. Nine cases of TKA (Vanguard Complete Knee System, PS, BIOMET) operated on by one operator in our hospital from October 2012 to September 2013. 78.0 years average age (71–81 years old), sex was 6 cases women, 3 men. Methods. Intra-operatively measurements of α, β, γ, δ angle, rotation angle of the femoral component and the size of the components were evaluated between the two groups. Coronal cutting angles were considered as outlier the difference between the 3 ° or more from the preoperative planning on computed tomography (CT) scans made one week after surgery. Results. PSI cases were inclined with respect to Navi cases, coronal plane: average varus 0.4 ° (valgus 1.0° to varus 3.0°), sagittal plane: flexion 1.0° (flexion 5.0° to extension 3.5°), axial plane: internal rotation 0.9° (internal rotation 3.5° to external rotation 0.0°) in the femur. Coronal plane: average valgus 0.5 ° (valgus 1.5° to varus 4.5°), sagittal plane: backward tilt 0.9° (forward tilt 3.0° to backward tilt 4.5°) in the tibia. Three cases of femoral implant were different from PSI plan, 5 cases in tibia. One of PSI cases in the femur and 1 case in tibia is outlier. Discussion. In the femoral side, fitting of the PSI was good, and error is less. However, in the tibia, some cases of fitting were bad and large error. These PSI were not stable on the bone and looks like seesaw motion at the tibial side. It is necessary to final confirmation by using the extramedullary guide in PSI cases. Conclusion. Accuracy of Navi was higher than PSI in our study

Introduction. We are a high-volume arthroplasty unit performing over 800 primary THRs annually at an approximate reimbursement of £6.5 million to the Trust. 70% are hybrid and we have been using the Taperfit - Trinity combination (Corin, Cirencester) since March 2016. We aimed to investigate the potential cost-savings and clinical benefits of instrument rationalisation using this system following GIRFT principles. Methods. Taperfit (ODEP 10A) is a polished, collarless, double tapered stem available in multiple sizes/offsets. Trinity is a hemispherical porous titanium cementless shell. A prospective audit of implant size was performed for the first 50 cases. Based on these findings, instruments were reduced to a single tray per component based on predicted size, named ‘Corin Hip for the Osteoarthritic Patient’ (CHOP). A further re-audit was performed to confirm correct tray constituent sizes. Financial data were calculated using known TSSU costs of approximately £50 per tray. Results. The audit revealed 92% (46/50) of stem sizes 2 or smaller and 86% (43/50) of shell sizes 54 or smaller. Trays per case were then rationalised from 6 to 2. Each acetabular tray had seven reamers (‘CHOP 1’ 42, 46–56 or CHOP 2 46, 54–64) and each femoral tray had broaches sized 0–2 (CHOP 1) or 2–4 (CHOP 2). Re-audit confirmed the CHOP 1 sets covered approximately 85% of cases. A TSSU saving of £192/case was achieved. Additional benefits were: all trays easily kept under laminar flow, time spent counting instruments was reduced and theatre shelving space liberated. Conclusion. Rationalisation of surgical instruments has saved the Trust approximately £100,000/year. Fewer instruments potentially reduce the risk of ‘never events’ and infection. Industry savings on consigned instruments have been passed on with significant reduction in our implant procurement costs allowing the use of hybrid implants for the price of our all cemented combination

Total joint arthroplasty (TJA) is one of the most successful procedures in orthopaedics. Despite the excellent clinical and functional results, periprosthetic joint infection (PJI) following TJA is a feared complication. For instance, the reported PJI rate after primary total knee arthroplasty is about 0.5–1.9%. In general, prevention of periprosthetic joint and surgical site infections is of utmost importance. This can be reduced by strict antisepsis, adequate sterilization of the surgical instruments and meticulous surgical technique. An indisputable role in prevention of SSI in TJA has been the use of peri-operative systemic antibiotic prophylaxis. The most common recommended antibiotics for prophylaxis in TJA are cefazolin or cefuroxime. In contrast, routine use of commercial antibiotic-loaded bone cement (ALBC) in primary total joint arthroplasty is still a concern of open debate. The use of antibiotic-loaded bone cement delivers a high concentration of antibiotics locally and can decrease the infection rate, which is supported by several studies in the literature. In this context, we present the pros of routine use of commercial antibiotic-loaded bone cement

Objectives. Many studies have investigated the kinematics of the lumbar spine and the morphological features of the lumbar discs. However, the segment-dependent immediate changes of the lumbar intervertebral space height during flexion-extension motion are still unclear. This study examined the changes of intervertebral space height during flexion-extension motion of lumbar specimens. Methods. First, we validated the accuracy and repeatability of a custom-made mechanical loading equipment set-up. Eight lumbar specimens underwent CT scanning in flexion, neural, and extension positions by using the equipment set-up. The changes in the disc height and distance between adjacent two pedicle screw entry points (DASEP) of the posterior approach at different lumbar levels (L3/4, L4/5 and L5/S1) were examined on three-dimensional lumbar models, which were reconstructed from the CT images. Results. All the vertebral motion segments (L3/4, L4/5 and L5/S1) had greater changes in disc height and DASEP from neutral to flexion than from neutral to extension. The change in anterior disc height gradually increased from upper to lower levels, from neutral to flexion. The changes in anterior and posterior disc heights were similar at the L4/5 level from neutral to extension, but the changes in anterior disc height were significantly greater than those in posterior disc height at the L3/4 and L5/S1 levels, from neutral to extension. Conclusions. The lumbar motion segment showed level-specific changes in disc height and DASEP. The data may be helpful in understanding the physiologic dynamic characteristics of the lumbar spine and in optimising the parameters of lumbar surgical instruments. Cite this article: M. Fu, Q. Ye, C. Jiang, L. Qian, D. Xu, Y. Wang, P. Sun, J. Ouyang. The segment-dependent changes in lumbar intervertebral space height during flexion-extension motion. Bone Joint Res 2017;6:245–252. DOI: 10.1302/2046-3758.64.BJR-2016-0245.R1

Removal of femoral bone cement is required for preparation of proper implant bed for reimplantation of a new femoral component in revision total hip arthroplasty. Several devices and procedures have been developed for cement removal, including an extracorporal shock-wave lithotripter and YAG laser, as well as a high-powered drill or burr under the control of conventional fluoroscopic images and an intrafemoral endoscopy. Ultrasonic tools are efficient for removal of bone cement with minimal damage to bone. We use a high-powered burr to remove the deep femoral bone cement under the control of conventional fluoroscopic images, although the problem of this procedure is large exposure of X-ray and two dimensional viewing of burr position which can result in perforation in the third plane. Computer-assisted fluoroscopic navigation system allows the surgeons to provide positional information about surgical instrument to target bones during operations. Two-dimensional image data are obtained using the fluoroscope with a reference frame and stored on a computer workstation. A camera interfaced with the computer then tracks the position of the patient and registered surgical instruments during the procedure. Taking advantage of the real-time guidance of computer-assisted fluoroscopic navigation system, we introduce a valuable technique using computer-assisted fluoroscopic navigation system for performing removal of the cement of the femoral canal in revision cemented total hip arthroplasty

The use of surgical navigation in computer assisted or image guided procedures requires the precise measurement of the spatial position of surgical instruments. Investigations of several physical principles have turned out that two technologies are best feasible for application in clinical routines:. optical technology,. electromagnetic technology. Available systems based on either principle deliver measurement information for the 3D-position of a surgical instrument, expressed by the x-y-z coordinates of its tip, and for its 3D-orientation, described by the direction of the instrument axis towards the tip. It is therefore common terminology to describe such measurement systems as 3D/6D digitizing or localizing systems. The presentation will describe basic principles of both technologies, including their main technical features and the design of key components such as rigid bodies for optical systems and sensor coils for electromagnetic systems. The survey includes an overview of known challenges and problems, and how commercial systems cope with these. A comparison of both technologies outlines the advantages and drawbacks in different applications as well as possible future improvements. It leads to the conclusion that both technologies will co-exist for the foreseeable future

The use of surgical navigation in computer assisted or image guided procedures requires the precise measurement of the spatial position of surgical instruments. Investigations of several physical principles have turned out that two technologies are best feasible for application in clinical routines: a) optical technology, b) electromagnetic technology. Available systems based on either principle deliver measurement information for the 3D-position of a surgical instrument, expressed by the x-y-z coordinates of its tip, and for its 3D-orientation, described by the direction of the instrument axis towards the tip. It is therefore common terminology to describe such measurement systems as 3D/6D digitizing or localizing systems. The presentation will describe basic principles of both technologies, including their main technical features and the design of key components such as rigid bodies for optical systems and sensor coils for electromagnetic systems. The survey includes an overview of known challenges and problems, and how commercial systems cope with these. A comparison of both technologies outlines the advantages and drawbacks in different applications as well as possible future improvements. It leads to the conclusion that both technologies will co-exist for the foreseeable future

The December 2023 Wrist & Hand Roundup³⁶⁰ looks at: Volar locking plate for distal radius fractures with patient-reported outcomes in older adults; Total joint replacement or trapeziectomy?; Replantation better than revision amputation in traumatic amputation?; What factors are associated with revision cubital tunnel release within three years?; Use of nerve conduction studies in carpal tunnel syndrome; Surgical site infection following surgery for hand trauma: a systematic review and meta-analysis; Association between radiological and clinical outcomes following distal radial fractures; Reducing the carbon footprint in carpal tunnel surgery inside the operating room with a lean and green model: a comparative study.

Over the past decades, computer-aided navigation system has experienced tremendous development for minimising the risks and improving the precision of the surgery. Nowadays, some commercially-available and self-developed surgical navigation systems have already been tested and proved successfully for clinical applications. However, all of these systems use computer screen to render the navigation information such as the real-time position and orientation of the surgical instrument, virtual path of preoperative surgical planning, so that the surgeons have to switch between the actual operation site and computer screen which is inconvenient and impact the continuity of surgery. In recent years, Augmented Reality (AR)- based surgical navigation is a promising technology for clinical applications. In the AR system, virtual and actual reality are mixed, offering real-time, high-quality visualisation of an extensive variety of information to the users. Therefore, in this study, a pilot study of a surgical navigation system for orthopaedics based on optical see-through augmented reality (AR-SNS) is presented, which encompasses the preoperative surgical planning, calibration, registration, and intra-operative tracking. With the aid of AR-SNS, the surgeon wearing the optical see-through head-mounted display can obtain a fused image that the 3D virtual critical anatomical structures are aligned with the actual structures of patient in intra-operative real-world scenario, so that some disadvantages of the traditional surgical navigation are overcome (For example, surgeon is no longer obliged to switch between the real operation scenario and computer screen), and the safety, accuracy, and reliability of the surgery may be improved

The October 2023 Knee Roundup³⁶⁰ looks at: Cementless total knee arthroplasty is associated with more revisions within a year; Kinematically and mechanically aligned total knee arthroplasties: long-term follow-up; Aspirin thromboprophylaxis following primary total knee arthroplasty is associated with a lower rate of early periprosthetic joint infection compared with other agents; The impact of a revision arthroplasty network on patient outcomes; Re-revision knee arthroplasty in a tertiary centre: how does infection impact on outcomes?; Does the knee joint have its own microbiome?; Revision knee surgery provision in Scotland; Aspirin is a safe and effective thromboembolic prophylaxis after total knee arthroplasty: a systematic review and meta-analysis; Patellar resurfacing and kneeling ability after total knee arthroplasty: a systematic review.

The critical relationship between airborne microbiological contamination in an operating theatre and surgical site infection (SSI) is well known. The aim of this annotation is to explain the scientific basis of using settle plates to audit the quality of air, and to provide information about the practicalities of using them for the purposes of clinical audit. The microbiological quality of the air in most guidance is defined by volumetric sampling, but this method is difficult for surgical departments to use on a routine basis. Settle plate sampling, which mimics the mechanism of deposition of airborne microbes onto open wounds and sterile instruments, is a good alternative method of assessing the quality of the air. Current practice is not to sample the air in an operating theatre during surgery, but to rely on testing the engineering systems which deliver the clean air. This is, however, not good practice and microbiological testing should be carried out routinely during operations as part of clinical audit.

Cite this article: Bone Joint J 2024;106-B(9):887–891.

Aims

Surgical approaches that claim to be minimally invasive, such as the direct anterior approach (DAA), are reported to have a clinical advantage, but are technically challenging and may create more injury to the soft-tissues during joint exposure. Our aim was to quantify the effect of soft-tissue releases on the joint torque and femoral mobility during joint exposure for hip resurfacing performed via the DAA.

Aims

Metal particles detached from metal-on-metal hip prostheses (MoM-THA) have been shown to cause inflammation and destruction of tissues. To further explore this, we investigated the histopathology (aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) score) and metal concentrations of the periprosthetic tissues obtained from patients who underwent revision knee arthroplasty. We also aimed to investigate whether accumulated metal debris was associated with ALVAL-type reactions in the synovium.

The June 2023 Wrist & Hand Roundup³⁶⁰ looks at: Residual flexion deformity after scaphoid nonunion surgery: a seven-year follow-up study; The effectiveness of cognitive behavioural therapy for patients with concurrent hand and psychological disorders; Bite injuries to the hand and forearm: analysis of hospital stay, treatment, and costs; Outcomes of acute perilunate injuries - a systematic review; Abnormal MRI signal intensity of the triangular fibrocartilage complex in asymptomatic wrists; Patient comprehension of operative instructions with a paper handout versus a video: a prospective, randomized controlled trial; Can common hand surgeries be undertaken in the office setting?; The effect of corticosteroid injections on postoperative infections in trigger finger release.

Aims

It is important to analyze objectively the hammering sound in cup press-fit technique in total hip arthroplasty (THA) in order to better understand the change of the sound during impaction. We hypothesized that a specific characteristic would present in a hammering sound with successful fixation. We designed the study to quantitatively investigate the acoustic characteristics during cementless cup impaction in THA.

Aims

It is important to analyze objectively the hammering sound in cup press-fit technique in total hip arthroplasty (THA) in order to better understand the change of the sound during impaction. We hypothesized that a specific characteristic would present in a hammering sound with successful fixation. We designed the study to quantitatively investigate the acoustic characteristics during cementless cup impaction in THA.

The use of artificial intelligence (AI) is rapidly growing across many domains, of which the medical field is no exception. AI is an umbrella term defining the practical application of algorithms to generate useful output, without the need of human cognition. Owing to the expanding volume of patient information collected, known as ‘big data’, AI is showing promise as a useful tool in healthcare research and across all aspects of patient care pathways. Practical applications in orthopaedic surgery include: diagnostics, such as fracture recognition and tumour detection; predictive models of clinical and patient-reported outcome measures, such as calculating mortality rates and length of hospital stay; and real-time rehabilitation monitoring and surgical training. However, clinicians should remain cognizant of AI’s limitations, as the development of robust reporting and validation frameworks is of paramount importance to prevent avoidable errors and biases. The aim of this review article is to provide a comprehensive understanding of AI and its subfields, as well as to delineate its existing clinical applications in trauma and orthopaedic surgery. Furthermore, this narrative review expands upon the limitations of AI and future direction.

Cite this article: Bone Joint Res 2023;12(7):447–454.

Aims

The aims of this study were: 1) to describe extended restricted kinematic alignment (E-rKA), a novel alignment strategy during robotic-assisted total knee arthroplasty (RA-TKA); 2) to compare residual medial compartment tightness following virtual surgical planning during RA-TKA using mechanical alignment (MA) and E-rKA, in the same set of osteoarthritic varus knees; 3) to assess the requirement of soft-tissue releases during RA-TKA using E-rKA; and 4) to compare the accuracy of surgical plan execution between knees managed with adjustments in component positioning alone, and those which require additional soft-tissue releases.

Aims

Ankle fracture fixation is commonly performed by junior trainees. Simulation training using cadavers may shorten the learning curve and result in a technically superior surgical performance.

Aims

Gram-negative periprosthetic joint infection (PJI) has been poorly studied despite its rapidly increasing incidence. Treatment with one-stage revision using intra-articular (IA) infusion of antibiotics may offer a reasonable alternative with a distinct advantage of providing a means of delivering the drug in high concentrations. Carbapenems are regarded as the last line of defense against severe Gram-negative or polymicrobial infection. This study presents the results of one-stage revision using intra-articular carbapenem infusion for treating Gram-negative PJI, and analyzes the characteristics of bacteria distribution and drug sensitivity.

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

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To evaluate if, for orthopaedic trainees, additional cadaveric simulation training or standard training alone yields superior radiological and clinical outcomes in patients undergoing dynamic hip screw (DHS) fixation or hemiarthroplasty for hip fracture.

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The aim of this study was to determine the risk of tibial eminence avulsion intraoperatively for bi-unicondylar knee arthroplasty (Bi-UKA), with consideration of the effect of implant positioning, overstuffing, and sex, compared to the risk for isolated medial unicondylar knee arthroplasty (UKA-M) and bicruciate-retaining total knee arthroplasty (BCR-TKA).

Aims

In the UK, the NHS generates an estimated 25 megatonnes of carbon dioxide equivalents (4% to 5% of the nation’s total carbon emissions) and produces over 500,000 tonnes of waste annually. There is limited evidence demonstrating the principles of sustainability and its benefits within orthopaedic surgery. The primary aim of this study was to analyze the environmental impact of orthopaedic surgery and the environmentally sustainable initiatives undertaken to address this. The secondary aim of this study was to describe the barriers to making sustainable changes within orthopaedic surgery.

Aims

It is common practice for patients to have postoperative blood tests after total joint replacement (TJR). However, there have been significant improvements in perioperative care with arthroplasty surgery, and a drive to reduce the length of stay (LOS) and move towards day-case TJR. We should reconsider whether this intervention is necessary for all patients.

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To determine the major risk factors for unplanned reoperations (UROs) following corrective surgery for adult spinal deformity (ASD) and their interactions, using machine learning-based prediction algorithms and game theory.

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Periprosthetic joint infections (PJIs) with prior multiple failed surgery for reinfection represent a huge challenge for surgeons because of poor vascular supply and biofilm formation. This study aims to determine the results of single-stage revision using intra-articular antibiotic infusion in treating this condition.

In performing posterior cruciate ligament- retaining total knee arthroplasty (CR-TKA), the original surgical instrument was devised to obtain the range of motion and stability of the knee joint adequate for daily life of Japanese people. We have presumed the tentative joint line as intercondylar notch point of the distal femur, and performed surgery using surface replacement to resect metal width of the femoral component for the distal femur by setting the knee to the original position based on understanding of the shape of anterior curvature of the distal femur in Japanese people in case of implanting the femoral component. In order to obtain stability of the knee, we have minimally released the soft tissue and resected the anterior cruciate ligament (ACL), whereas completely preserved the posterior cruciate ligament (PCL) and maintained physiological ligament balance of the knee joint by resecting the medial condyle of the tibia (genu varus). Our surgical procedure enabled deep flexion knee (knee embracing) greater than 145 degrees in 9.7% and also allowed Japanese sitting in three different designs of total knee joints

Computer assisted surgery is becoming more frequently used in the medical world. Navigation of surgical instruments and implants plays an important role in this surgery. OrthoPilot™ Hip Suite (BBraun Aesculap) is one such system used for hip navigation in orthopaedic surgery. However the accuracy of this system remains to be determined independently of the manufacturer. The manufacturer supplies a technical specification for the accuracy of the system (± 2 mm and ± 2°) and previous research has been undertaken to compare its clinical accuracy against conventional hip replacements by x-ray. This clinical validation is important but contains many sources of error or deviation from an ideal outcome in terms of the surgeons' use of the system, inaccurate palpation of landmarks, variation in actual cup position from that given by the navigation system and measurement of the final cup position. It is therefore not possible to validate the claims of the manufacturer from this data. There is no literature evaluating the technical accuracy of the software i.e. the accuracy of the system given known inputs. This study had two main aims 1) validating the accuracy of the OrthoPilot data while navigating the surgical instruments and 2) validating the accuracy of navigation algorithm inside the OrthoPilot system which determines cup implant placement. The OrthoPilot validation was performed and compared against the gold standard of a VICON movement analysis system. The system used was OrthoPilot™ with a Spectra camera from Northern Digital Inc. (Ontario, Canada). Software investigated was the Hip Suite THA cup only navigation software Version 3.1. The validation was performed and compared against the VICON Nexus version 1.4.116 with Bodybuilder software version 3.55. An aluminium pelvis phantom was used for measurement allowing accurate and repeatable inputs. The OrthoPilot system has three types of instruments sets; passive, active and hybrid. This study was carried out with the passive instruments set. Data were captured simultaneously from both the OrthoPilot and VICON systems for the supine position of the phantom. Distances between the anatomical land marks on the phantom were compared to test the data capturing accuracy of the OrthoPilot system. Anatomical land marks of right anterior superior iliac supine (RASIS), left anterior superior iliac supine (LASIS) and Pubic Symphasis (PS) were palpated to define the Anterior Pelvic Plane (APP). Distances between the anatomical landmarks of RASIS to LASIS, RASIS to PS and LASIS to PS were considered for comparison. Width and height of the pelvis was varied to examine different APPs. The width and height used were 170 mm and 53 mm, 230 mm and 88 mm, and 290 mm and 123 mm respectively. One hundred APP data sets were captured at each instance. The accuracy of the hip navigation algorithm was tested by applying similar algorithm to calculate the native anteversion and inclination angles of the acetabulum using the VICON system. Data were captured simultaneously from both OrthoPilot and VICON systems. Radiographic anteversion and inclination angles were obtained with phantom model, which had 14° of anteversion angle and 45° of inclination angle. APP of 230 mm in width and 88 mm in height was used to obtain anterior pelvic plane data. Position vectors for each anatomical land mark from the OrthoPilot system were extracted from relevant transformation matrices, while position vectors from the VICON system were extracted from static trial modelling. The distance data from both systems were compared with calibrated distance data from the phantom model. Mean values of the distances between anatomical landmarks were found to be similar for both OrthoPilot and VICON systems. In addition, these distances were comparable with the pelvic phantom model data, within 1 mm for all measured distances for the VICON and 2 mm for the OrthoPilot. Furthermore, the standard deviations were less than 1% of the measured value. Comparison was also made for the anteversion and inclination angles of the acetabulum of the pelvic model with OrthoPilot and VICON data. Both systems produced similar results for the mean angle values, within 0.5° of the known angles for the VICON and 1° for the OrthoPilot and with standard deviations of the measured values of less than 1%. All the data were captured simultaneously from both OrthoPilot and VICON systems under the same laboratory conditions. According to the above results it is clear that the distance readings obtained from the OrthoPilot are comparable to the results obtained from the gold standard VICON system and the calibrated distance readings of the phantom. In addition, acetabular angle results obtained from OrthoPilot are almost equivalent to results obtained from VICON and the calibrated phantom angles. Finally it is can be concluded that, both the data palpation with OrthoPilot system and acetabular angle calculation algorithm of the OrthoPilot system are accurate enough for the real world clinical tasks they are expected to perform

Introduction. Revision Total Hip Arthroplasties (THA) have a significantly higher failure rate than primary THA's and the most common cause is aseptic loosening of the cup. To reduce this incidence of loosening various porous metal implants with a rough surface and a porous architecture have been developed which are said to increase early osteointegration. However, for successful osteointegration a minimal micromotion between the implant and the host bone (primary stability) is beneficial. It has not been previously determined if the primary stability for the new Gription® titanium cup differs from that of the old Porocoat® titanium cup. Material and Methods. In 10 cadaveric pelvises, divided into 20 hemipelvises, bilateral THA's were performed by an experienced surgeon (RGB) following the implant manufacturer's instructions and with the original surgical instruments provided by the company. In randomized fashion the well established Porocoat® titanium implant was implanted on one side of each each hemipelvis whereas on the corresponding opposite side the modified implant with a Gription® coating was inserted. Radiographs were taken to confirm satisfactory operative results. Subsequently, the hemipelvis and cups were placed in a biomechanical testing machine and subjected to physiological cyclic loading. Three-dimensonal loading corresponded to 30% of the load experienced in normal gait was imposed reflecting the limited weight bearing generally prescribed postoperatively. The dynamic testing took place in a multi-axial testing machine for 1000 cycles. Relative motion and micromotion were quantified using an optical measurement device (Pontos, GOM mbh, Braunschweig, Germany). Statistical evaluation was performed using the Wilcoxon signed-rank test. Results and conclusion. The standard Porocoat® titanium cups showed a mean relative motion with respect to the host bone of 54.74µm (Range 26.04 – 127.06µm), while the porous Gription® titanium cup displayed a relative motion with respect to the host bone of 49.77µm (Range 24.69 – 128.37µm). The Wilcoxon test did not reveal a significant difference between the two surfaces. The in-vitro biomechanical evaluation of both acetabular cups under a physiologic loading scenario showed no significant difference with regard to primary stability. Both the extensively tried and clinically successful Porocoat® titanium cup and the newer Gription® coated cup showed very little micromotion and both implants should therefore allow good osteointegration

Introduction. Dislocation due to suboptimal cup positioning is a devastating complication in the early phase after total hip arthroplasty. Malpositioning can also result in other mechanical complications like subluxation, edge loading, increased debris, surface damage or squeaking in ceramic-on-ceramic hips. Preventing at least some of these complications in younger and more active patients is of paramount interest for the individual patient and for the society since optimized component orientation is an important determinant to reduce such risks and to further increase longevity of the implant. This study reports on two new surgical instruments that help the orthopedic surgeon to manually place both components within the optimized combined safe-zone (cSafe-Zone). Material and Methods. More than 900 minimal-invasive total hip arthroplasties (MIS-THA) have been performed between 2007 and 2015 in our institution using the minimal-invasive direct anterior approach (DAA) on an orthopedic table with foot holder. Cups were implanted applying the “stem-first” surgical technique i.e. the prosthetic stem dictates the orientation of the socket depending on the prosthesis design. A system-specific trial head which indicates the prosthesis-specific relative orientation of cup and stem and a modified cup impactor were used to finally seat the definitive acetabular socket manually during trial stem reduction while fully visually controlling the optimal orientation of the cup during impaction. This surgical technique drives both components into their optimal relative positions according to the combined version and the combined safe-zone concept in total hip arthroplasty. Results. Both new instruments, femoral trial head as well as the modified cup impactor, provide an easy way to manually control the optimal placement of the acetabular socket during impaction intraoperatively. The combined safe-zone is clearly indicated and the inverse interrelationship of stem and cup anteversion is ideally reflected by this simple mechanical system. In patients operated on with the “stem-first” technique the components were placed in the new cSafe-Zone in 94% of the cases and no squeaking or prosthetic impingement did occur in any of these patients. One early dislocation did occur and was treated by closed reduction. Conclusion. Stem-first technique using trial head-controlled impaction with a modified cup impactor is ideally suited for the minimal-invasive direct anterior approach in total hip arthroplasty to control the placement of both prosthetic components. It assists the surgeon in aligning the cup and the stem according to the cSafe-Zone in order to get the intended range of movement (iROM)

INTRODUCTION. Total knee replacement is mostly done with alignment rods in order to achieve a proper Varus / Valgus alignement. Other techniques are computer assisted navigation or MRI based preoperative planning. iASSIST™ is a computer assisted stereotaxic surgical instrument system to assist the surgeon in the positioning of the orthopaedic implant system components intra-operatively. It is imageless and the communication between the PC and the “Pod's” does not require any direct camera view, it is a bluethooth comunication system. This study presents preliminary results utilizing iASSIST™. The aim of this study was to test and compare radiographic alignment, functional outcomes, and perioperative morbidity of the iASSIST™ Knee system versus conventional total knee arthroplasty. METHODS. In a prospective randomized trial we investigated 60 patients with osteoarthritis of the knee joint. Each surgical procedure was conducted by highly experienced surgeons. In both groups the implant Legacy LPS-Flex Fixed Bearing Knee was used (Zimmer®, Warsaw, Indiana). The groups were equally divided and randomized by hazard. For clinical evaluation, the Short Form-36 and Knee Society Score were obtained. For the radiological assessment mediCAD® Classic, a digital measurement system, was used. The aim of the study was the comparison of results after 3 months. Results. 2 patients refused any further participation, and 5 cases required a switch to a conventional alignement technique intraoperatively due to technical problems. Average BMI and average age did not differ in both groups. Surgical time in the iASSIST™ group amounted to 100 minutes, in the conventional group to 76 min. Postoperative functional outcomes were statistically insignificant, showing slight improvements of the Combined Knee Society Score, Knee Society Knee Score, and Knee Society Function Score favouring the iASSIST method, and slight improvements of knee flexion. Short Form-36 physical scales slightly favoured the conventional method but not significantly. The mean deviation from neutral mechanical axis was 1.68°±1.9° within the iASSIST group, and 2.73°±2.1° within the conventional TKA group. Conclusion. IASSIST™ is a valuable computer navigation system. The 5 technical troubles were due to the learning curve. The clinical results after 3 months did not differ significantly, the radiological assessment showed a tendency of improved alignement in the iASSIST™ group

Aims

To determine the value of scoliosis surgery, it is necessary to evaluate outcomes in domains that matter to patients. Since randomized trials on adolescent idiopathic scoliosis (AIS) are scarce, prospective cohort studies with comparable outcome measures are important. To enhance comparison, a core set of patient-related outcome measures is available. The aim of this study was to evaluate the outcomes of AIS fusion surgery at two-year follow-up using the core outcomes set.

Aims

Femoral bone preparation using compaction technique has been shown to preserve bone and improve implant fixation in animal models. No long-term clinical outcomes are available. There are no significant long-term differences between compaction and broaching techniques for primary total hip arthroplasty (THA) in terms of migration, clinical, and radiological outcomes.