Introduction:. The widespread use of TKA promoted studies on kinematics after TKA, particularly of the femorotibial joint. Knee joint kinematics after TKA, including the range of motion (ROM) and the physical performance, are also influenced by the biomechanical properties of the patella. Surgeons sometimes report complications after TKA involvinganterior knee pain, patellofemoral impingement and instability. However, only few studies have focused specially on the patella. Because the patella bone is small and overlapped with the femoral component on scan images. In addition, the patellar component in TKA is made of x-ray–permeable ultra-high molecular weight polyethylene. It is impossible to radiographically determine the external contour of the patellar component precisely. No methods have been established to date to track the dynamic in vivo trajectory of the patella component. In this study, we analyzed the in vivo three-dimensional kinematics of the patellar component in TKA by applying our image matching method with image correlations. Methods:. A computed tomography (CT) and an x-ray flat panel detector system (FPD) were used. FPD-derived post-TKA x-ray images of the residual patellar bone were matched by computer simulation with the virtual simulation images created using pre-TKA CT data. For the anatomic location of the patellar component, the positions of the holes drilled for the patellar component pegs were used. This study included three patients with a mean age of 68 years (three females with right knee replacement) who had undergone TKA with the Quest Knee System and achieved a mean passive ROM of 0 to ≥ 130° after 6 or more month post-TKA. We investigated three-dimensional movements of the patellar component in six degrees of freedom (6 DOF) during squatting and kneeling. Furthermore, we simulated the three-dimensional movement of the patellar component, and we estimated and visualized the contact points between the patellar and femoral components on a three-dimensional model. Results:. Average root mean square errors of this technique with the patellar bone of a fresh-frozen pig complete knee joint have been confirmed as 0.2 mm for the translations and 0.2 degrees for the rotation. The 6 DOF analysis results showed that patellar dynamics were similar for all subjects on squatting and kneeling. For the patellar rotation during squatting, only 1 to 2 additional degrees were noted for all subjects. During kneeling, the patellar rotation noted adduction for all subjects. The patellar contact point on the femoral component gradually showed superior shift, increasing the distance with knee flexion during squatting and kneeling (Fig, 1. 2). Discussions and Conclusions:. In this study, no patellar shifts were detected in rotation or tilt during squatting, suggesting that the patellar component remained in the positions designed for early stages of flexion. And the patellar component shifted towards the lateral side during squatting. This finding suggests the idea that the patellar movement reflected the design of the Quest Knee system. This study demonstrated that the analytical method is useful for evaluating the pathologies and post-surgical conditions of the knee and other joints

Background of Study. Identification of the exact make and model of an orthopaedic implant prior to a revision surgery can be challenging depending upon the surgeon's experience and available knowledge base about the available implants. The current identification procedure is manual and time consuming as the surgeon may have to do a comprehensive search within an online database of radiographs of an implant to make a visual match. There is further time lapse in contacting that particular implant manufacturer to confirm the make and model of the implant and then order the whole inventory for the revision surgery. This leads to delay in treatment thus requiring extra hospital bed occupancy. Materials and Methods. We have analysed image recognition techniques currently in use for image recognition to understand the underlying technologies based on an interface commonly known as Application Programming interface (API). These API's specifies how the software components of the proposed application interact with each other. The objective of this study is to leverage one or a combination of API's to design a fully functional application in the initial phase and that can help recognize the implant accurately from a large database of radiographs and then develop a specialized and advanced API/Technology in the implant identification application. Results. Our study takes into account the existent technologies such as Facebook, Pictoria, Imagga, Google images. We found that there is an API currently available that can be directly applied to build an implant recognition system. However, commonly known Facebook's image tagging algorithms to store unique information with each image is the starting point to help build an intelligent system that in combination with image processing and development of a custom implant recognition API. Conclusion. There is an urgent need to have a robust and accurate system for identification of orthopaedic implants. Revision surgeries may need to be carried out by hospitals without access to index surgery operating notes. Patients may approach the most convenient not necessarily the same surgeon for a revision surgery. The dependency upon surgeon's experience, hospitals facilities and archiving of records can be avoided with the use of a single application that allows multiple manufacturers to contribute to a database of catalogue of their products

Treatment for osteoarthritis (OA) has traditionally focused on joint replacement for end-stage disease. An increasing number of surgical and pharmaceutical strategies for disease prevention have now been proposed. However, these require the ability to identify OA at a stage when it is potentially reversible, and detect small changes in cartilage structure and function to enable treatment efficacy to be evaluated within an acceptable timeframe. This has not been possible using conventional imaging techniques but recent advances in musculoskeletal imaging have been significant. In this review we discuss the role of different imaging modalities in the diagnosis of the earliest changes of OA. The increasing number of MRI sequences that are able to non-invasively detect biochemical changes in cartilage that precede structural damage may offer a great advance in the diagnosis and treatment of this debilitating condition. Cite this article: Bone Joint J 2013;95-B:738–46

CT and MRI scans are complementary preoperative imaging investigations for planning complex musculoskeletal bone tumours resection and reconstruction. Conventionally, tumour surgeons analyse two-dimensional (2-D) imaging information, mentally integrate and formulate a three-dimensional (3-D) surgical plan. Difficulties are anticipated with increase in case complexity and distorted surgical anatomy. Incorporating computer technology to aid in this surgical planning and executing the intended resection may improve precision. Although computer-assisted surgery has been widely used in cranial biopsies and tumour resection, only small case series using CT-based navigation are recently reported in the field of musculoskeletal tumor surgery. We investigated the results of CT/MRI image fusion for Computer Assisted Tumor Surgery (CATS) with the help of a navigation system. We studied 21 patients with 22 musculoskeletal tumours who underwent CATS from March 2006 to July 2009. A commercially available CT-based spine navigation system (Stryker Navigation; CT spine) was used. Of the 22 patients, 10 were males, 11 were females, and the mean age was 32 years at the time of surgery (range, 6–80 years). Five tumours were located in the pelvis, seven sacrum, eight femurs, and two tibia. The primary diagnosis was primary bone tumours in 16 (3 benign, 13 sarcoma) and metastatic carcinoma in four. The minimum follow-up was 17 months (average, 35.5 months; range, 17–52 months). Preoperative CT and MRI scan of each patient were performed. Axial CT slices of 0.0625mm or 1.25mm thickness and various sequences of MR images in Digital Imaging and Communications in Medicine (DICOM) format were obtained. CT and MR images for 22 cases were fused using the navigation software. All the reconstructed 2-D and 3-D images were used for preoperative surgical planning. The plane of tumour resection was defined and marked using multiple virtual screws sited along the margin of the planned resection. We also integrated the computer-aided design (CAD) data of custom-made prostheses in the final navigation resection planning for eight cases. All tumour resections could be carried out as planned under navigation guidance. Navigation software enabled surgeons to examine all fused image datasets (CT/MRI scans) together in two spatial and three spatial dimensions. It allowed easier understanding of the exact anatomical tumor location and relationship with surrounding structures. Intraoperatively, image guidance with the help of fusion images, provided precise visual orientation, easy identification of tumor extent, neural structures and intended resection planes in all cases. The mean time for preoperative navigation planning was 1.85 hours (1 to 3.8). The mean time for intraoperative navigation procedures was 29.6 minutes (13 to 60). The time increased with case complexity but lessened with practice. The mean registration error was 0.47mm (0.31 to 0.8). The virtual preoperative images matched well with the patients' operative anatomy. A postoperative superficial wound infection developed in one patient with sacral chordoma that resolved with antibiotic whereas a wound infection in another with sacral osteosarcoma required surgical debridement and antibiotic. After a mean follow-up of 35.5 months (17–52 months), five patients died of distant metastases. Three out of four patients with local recurrence had tumors at sacral region. Three of them were soft tissue tumour recurrence. The mean functional MSTS score in patients with limb salvage surgery was 28.3 (23 to 30). All patients (except one) with limb sparing surgery and prosthetic reconstruction could walk without aids. Multimodal image fusion yields hybrid images that combine the key characteristics of each image technique. Back conversion of custom prosthesis in CAD to DICOM format allowed fusion with navigation resection planning and prosthesis reconstruction in musculoskeletal tumours. CATS with image fusion offers advanced preoperative 3-D surgical planning and supports surgeons with precise intraoperative visualisation and identification of intended resection for pelvic, sacral tumors. It enables surgeons to reliably perform joint sparing intercalated tumor resection and accurately fit CAD custom-made prostheses for the resulting skeletal defect

Strain is a robust indicator of bone failure initiation. Previous work has demonstrated the measurement of vertebral trabecular bone strain by Digital Volume Correlation (DVC) of µCT scan in both a loaded and an unloaded configuration. This project aims to improve previous strain measurement methods relying on image registration, improving resolution to resolve trabecula level strain and to improve accuracy by applying feature based registration algorithms to µCT images of vertebral trabecular bone to quantify strain. It is hypothesised that extracting reliable corresponding feature points from loaded and unloaded µCT scans can be used to produce higher resolution strain fields compared to DVC techniques. The feature based strain calculation algorithm has two steps: 1) a displacement field is calculated by finding corresponding feature points identified in both the loaded and unloaded µCT scans 2) strain fields are calculated from the displacement fields. Two methods of feature point extraction, Scale Invariant Feature Transform (SIFT) and Skeletonisation, were applied to unloaded (fixed) and loaded (moving) µCT images of a rat tail vertebra. Spatially non-uniform displacement fields were generated by automatically matching corresponding feature points in the unloaded and loaded scans. The Thin Plate Spline method and a Moving Least Squares Meshless Method were both tested for calculating strain from the displacement fields. Verification of the algorithms was performed by testing against known artificial strain/displacement fields. A uniform and a linearly varying 2% compressive strain field were applied separately to an unloaded 2D sagittal µCT slice to simulate the moving image. SIFT was unable to reliably match identified feature points leading to large errors in displacement. Skeletonisation generated a more accurate and precise displacement field. TPS was not tolerant to small displacement field errors, which resulted in inaccurate strain fields. The Meshless Methods proved much more resilient to displacement field errors. The combination of Skeletonisation with the Meshless Method resulted in best performance with an accuracy of −405µstrain and a detection limit of 1210µstrain at a strain resolution of 221.5µm. The DVC algorithm verified using the same validation test yielded a similar detection limit (1190µstrain), but with a lower accuracy for the same test (2370µstrain) for a lower resolution strain field (770µm) (Hardisty, 2009). The Skeletonisation algorithm combined with the Meshless Method calculated strain at a higher resolution, but with a similar detection limit, to that of traditional DVC methods. Future improvements to this method include the implementation of subpixel feature point identification and adapting this method of strain measurement into a 3D domain. Ultimately, a hybrid DVC/feature registration algorithm may further improve the ability to measure trabecular bone strain using µCT based image registration

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

Reverse shoulder arthroplasty has a high complication rate related to glenoid implant instability and screw loosening. Better radiographic post-operative evaluation may help in understanding complications causes. Medical radiographic imaging is the conventional technique for post-operative component placement analysis. Studies suggest that volumetric CT is better than use of CT slices or conventional radiographs. Currently, post-operative CT use is limited by metal-artifacts in images. This study evaluated inter-observer reliability of pre-operative and post-operative CT images registration to conventional approaches using radiographs and CT slices in measuring reverse shoulder arthroplasty glenoid implant and screw percentage in bone. Pre-operative and post-operative CT scans, and post-operative radiographs were obtained from six patients that had reverse shoulder arthroplasty. CT scans images were imported into a medical imaging processing software and each scapula, glenoid implant and inferior screw were reconstructed as 3D models. Post-operative 3D models were imported into the pre-operative reference frame and matched to the pre-operative scapula model using a paired-point and a surface registration. Measurements on registered CT models were done in reference to the pre-operative scapula model coordinate frame defined by a computer-assisted designed triad positioned in respect to the center of the glenoid fossa and trigonum scapulae (medial-lateral, z axis) and superior and inferior glenoid tubercle (superior-inferior, y axis). The orthogonal triad third axis defined the anterior-posterior axis (x axis). A duplicate triad was positioned along the central axis of the glenoid implant model. Using a virtual protractor, the glenoid implant inclination was measured from its central axis and the scapula transverse plane (x - z axes) and version from the coronal plane (y - z axes). Inferior screw percentage in bone was measured from a Boolean intersection operation between the pre-operative scapula model and the inferior screw model. For CT slices and radiographic measurements, a first 90-degree Cobb angle, from medical records software, was positioned from the trigonum scapulae to the centre of the central peg. Using the 90-degree line as reference, a second Cobb angle was drawn from the most superior to the most inferior point of the glenoid implant for inclination and from of the most anterior to the most posterior point for version. Version can only be measured using CT slices. Screw percentage in bone was calculated from screw length measures collected with a distance-measuring tool from the software. For testing the inter-observer reliability of the three methods, measures taken by three qualified observers were analysed using an intra-class correlation coefficient (ICC) method. The 3D registration method showed excellent reliability (ICC > 0.75) in glenoid implant inclination (0.97), version (0.98) and screw volume in bone (0.99). Conventional methods showed poor reliability (ICC < 0.4); CT-slice inclination (0.02), version (0.07), percentage of screw in bone (0.02) and for radiographic inclination (0.05) and percentage screw in bone (0.05). This CT registration of post-operative to pre-operative novel method for quantitatively assessing reverse shoulder arthroplasty glenoid implant positioning and screw percentage in bone, showed excellent inter-observer reliability compared to conventional 2D approaches. It overcomes metal-artifact limitations of post-operative CT evaluation

Retrieval analysis has been valuable in the assessment of in-vivo surface damage of orthopedic devices. Historically, subjective techniques were used to grade damage on the implant's surface. Microscopy improved the ability to localize and quantify damage, but cannot measure volumetric wear due to this damage. Laser scanning provides volumetric wear, but lacks image data. Recent techniques superimpose image data on laser scan data (photorendering) and combine the strengths of both methods. Our goal is to use such methods to improve our damage assessment and potentially correlate this assessment to volumetric wear. This project focused on two areas: image-stitching and photorendering. Image-stitching registers multiple images into large-scale high-resolution composites. Six total disc replacement components were imaged with a digital microscope (Moticam 2, Motic). Three sets were taken of each component: a single template at 10x zoom (1×1), a 4-image composite at 18x zoom (2×2), and a 9-image composite at 18x zoom (3×3). The 2×2 and 3×3 sets were image-stitched to resemble their template counterpart. Measurement error was defined using common pixels identified between the composite and template images for comparison with a semi-automated feature detection algorithm (Figure 1). For photorendering, a pilot study was performed on a single retrieved tibial bearing. The component was imaged with a digital microscope (VHX-2000, Keyence) under a 3D image-stitching setting, providing a high-resolution photo embedded with height values. MATLAB was used to convert the image into a photo-rendered point cloud approximating the surfaces. The component was then laser scanned, creating a 3D point cloud with resolution 0.127 mm. The photo-rendered point cloud data was registered to the laser scan data using an iterative closest point algorithm (Geomagic Studio, Geomagic). An analysis of all composite images showed a mean error of 0.221 mm. Figure 2 compares regions of images for the template, 2×2, and 3×3 composites. Zooming in shows the effect of the increased resolution contained in the composite. The 2×2 and 3×3 composites had mean errors of 0.231 mm and 0.209 mm, respectively; these were not significantly different. Comparisons among image types showed that components with less features exhibited larger errors during image-stitching. Figure 3 shows images resulting from each step of the photorendering process. The final image of the figure shows a qualitative result of our ability to photorender the tibial bearing surface of the component. While combining microscopy and laser scan data works anecdotally, further analyses must be performed to assure the robustness of the technique. The digital microscope's embedded image-stitching software is limited in its maximum field of view; we look to extend this by taking multiple scans and using in-house software to generate a composite of a whole implant. The improved resolution provided by microscopy offer an opportunity to automate damage assessment, yielding damage mapped images which can also be overlaid on laser scan data. This may provide a means to better quantify observed damage and yield meaningful correlations with volumetric loss due to wear

The International Commission on Radiological Protection has established standards for radiation protection. This study aims to determine actual and perceived radiation dose and audit safe practice when using image-intensifiers in theatre. Between September 2012 and March 2013, 50 surgeons were surveyed during 39 procedures. Information collected by radiographers included the number of images the surgeons thought they used, actual number used, dose, screening time, number of people scrubbed, wearing thyroid collars and standing within 1m of the image-intensifier when in use. The primary surgeon was more likely to estimate the number of images used correctly compared to the assistant. Supervising consultants were most accurate, followed by registrars as primary surgeons, consultants as primary surgeons then assisting registrars, and lastly SHOs. Most surgeons underestimated the number of images used. 87.5% of scrubbed staff were standing within 1m of the image-intensifier during screening and 36.5% were wearing thyroid protection. Three surgeons stated they were not wearing collars as they were unavailable. We conclude that surgeons have a reasonable estimation of the x-rays used but are not undertaking simple steps to protect themselves from radiation. We plan to initiate an education program within the department and have ordered new, lightweight thyroid collars

Background. Paediatric pelvic corrective surgery for developmentally dysplastic hips requires that the acetabular roof is angulated to improve stability and reduce morbidity. Accurate bony positioning is vital in a weight-bearing joint as is appropriate placement of metalwork without intrusion into the joint. This can often be difficult to visualise using conventional image intensifier equipment in a 2D plane. Methods. The ARCADIS Orbic 3D image intensifier produces CT-quality multi-axial images which can be manipulated intra-operatively to give immediate feedback of positioning of internal fixation. The reported radiation dose is 1/5 and 1/30 of a standard spiral CT in high and low quality modes, respectively. Results. We present 15 elective cases of paediatric pelvic osteotomy and fixation of SUFE, with use of the ARCADIS Orbic 3D image intensifier. Images were taken intra-operatively in order to confirm satisfactory fracture reduction and appropriate positioning of fixation devices avoiding joint spaces. This was achieved by 3D reconstruction and review of the surgical field in theatre. In all of the cases appropriate bony placement and position of fixation devices was demonstrated in the multi-axial images and 3D reconstruction. Conclusions. The use of 3D image intensification is a novelty in the UK. Our results suggest that the 3D image intensifier is a valuable aid in the field of paediatric surgery. Accurate positioning of internal fixation devices can be confidently confirmed ‘on-table’. The radiation dose is also significantly less than a standard spiral CT

The purpose of this study was to determine the normal angle of rotation of the axis of each finger using digital image analysis, whether the rotation of the digits is symmetrical in the two hands of an individual, and the reliability of this method. Standardised digital photographic images were taken of thirty healthy volunteers. The palm of each hand was placed on a flat bench top with their fingers held in extension and adducted, to give an end-on image of all four fingers. Three independent observers analysed the images using Adobe Photoshop software. The rotational angle of each finger was defined as the angle created by a straight line connecting the radial and ulnar border of the nail plate and the bench top horizon. The three observers showed Inter-Rater Reliability of 92%. The mean angles of rotation were: Index 13°, Middle 10°, Ring 5°, Little 12°. The differences in angle of rotation of the index and middle finger between the left and right hand were statistically significant (p=0.003, and p=0.002 respectively), demonstrating asymmetry between the two sides. The differences in angle of rotation of the ring and little finger of the left and right hand were not significantly significant (p= 0.312 and p=0.716 respectively). In conclusion, symmetry was seen in the little and ring but not in the index and middle fingers. Digital image analysis provides a non-invasive and reproducible method of quantifying the rotation of normal fingers and may be of use as a diagnostic tool in the assessment and management of hand injuries

Introduction. Achieving high flexion after total knee arthroplasty (TKA) is one of the most important clinical results, especially in eastern countries where the high flexion activities, such as kneeling and squatting, are part of the important lifestyle. Numerous studies have examined the kinematics after TKA. However, there are few numbers of studies which examined the kinematics during deep knee flexion activities. Therefore, in the present study, we report analysis of mobile-bearing TKA kinematics from extension to deep flexion kneeling using 2D-3D image matching technique. Materials and Methods. The subjects were 16 knees of 8 consecutive patients (all women, average age 75.9), who underwent primary mobile-bearing PS TKA (P.F.C. sigma RP-F: Depuy Orthopedics Inc., Warsaw, IN, USA) between February 2007 and May 2008. All cases were osteoarthritis with varus deformity. Postoperative radiographs were taken at the position of extension, half-squatting and deep flexion kneeling 3 month after the surgery, and the degrees of internal rotation of the tibial component was measured by 2D-3D image matching technique. Pre- and post-operative ROM was recorded. Then, we compared the absolute value and relative movement of tibial internal rotation between extension, half-squatting and deep flexion kneeling, and evaluated the correlation of the ROM and the internal rotation. Results. The mean preoperative ROM was from -12 to 118 degrees. After the surgery, ROM was from -2 to 123 degrees. Clinical scores of all cases were significantly improved after surgery. Internal rotation of tibial component was -6.8 to 9.7 (mean, 1.7) degrees at half-squatting position, and -7.2 to 13.6 (mean; 1.9) degrees at kneeling position. There was no correlation between maximum flexion angle and tibial rotation during flexion. There was significant negative correlation between tibial internal rotation angle in extension and tibial rotational movement from half-squatting to deep flexion kneeling (R; -0.824, P<0.05). Discussion. The internal rotation of the tibia during high flexion is well known as medial pivot movement in intact knee. And several reports have suggested that the medial pivot movement is related to maximum flexion angle after TKA. In the present study, we showed that there was significant negative correlation between the tibial internal rotation angle in extension and tibial rotational movement from half-squatting to deep flexion kneeling. This result suggested that the internal rotation of the tibial component in extension prevent the medial pivot movement of the knee during deep flexion. Therefore, the rotational alignment of tibial component may have the effect to the flexion angle after TKA

We have been using 3-dimensional CAD software for preoperative planning as a desktop tool daily. In ordinary cases, proper size stems and cups can be decided without much labor but in our population, many arthritic hip cases have dysplastic condition and they often come to see us for hip replacement after severe defects were created over the acetabulum. It is often the case that has Crowe's type III, IV hips with leg length difference. For those cases preoperative planning using 3D CAD is a very powerful tool. Although we only have 2-dimensional display with our computer during preoperative planning, 3 dimensional geometries are not so difficult to be understood, because we can turn the objects with the mouse and can observer from different directions. We can also display their sections and can peep inside of the geometries. It is quite natural desire that a surgeon wishes to see the planed geometries as a 3-dimensional materials. For some complicated cases, we had prepared plastic model and observed at the theater for better understanding. When we ask for a model service, each model costs $2,500. We also have small scale desk top rapid processing tool too, however it takes 2 days to make one side of pelvis. Observation of the geometries using 3-dimensional display can be its substitute without much cost and without taking much time. The problem of using 3D display had been the special goggle to mask either eye alternatively. In the present paper, we have used a 3D display which has micro arrays of powerful prism to deriver different image for each eye without using any goggle. Method. After preoperative planning, 2 images were prepared for right eye and left eye giving 2-3 degree's parallax. These images were encoded into a special AVI file for 3-dimensional display. To keep fingers away from the device, several scenes were selected and 3-dimensional slide show was endlessly shown during the surgery. Result. Cup geometries with screws had been prepared and cup position with screws direction were very useful. The edge of acetabulum and cup edge are well compared then could obtain a better cup alignment. Screws are said to be safe if they were inserted in upper posterior quadrant. However so long as the cluster cup was used, when the cup was given 30 degrees anterior rotation, 25 mm screw was still acceptable using CAT angiography. Conclusion. Three dimensional display without goggle was a useful tool to observe preoperative planning inside the operation theater

Purpose. As human soft tissue is anisotropic, non-linear and inhomogeneous, its properties are difficult to characterize. Different methods have been described that are either based on contact or noncontact protocols. In this study, three-dimensional (3D) digital image correlation (DIC) was adopted to examine the mechanical behaviour of the human Achilles tendon. Despite its wide use in engineering research and its great potential for strain and displacement measurements in biological tissue, the reported biomedical applications are rather limited. To our knowledge, no validation of 3D DIC measurement on human tendon tissue exists. The first goal of this study was to determine the feasibility to evaluate the mechanical properties of the human Achilles tendon under uniaxial loading conditions with 3D Digital Image Correlation. The second goal was to compare the accuracy and reproducibility of the 3D DIC against two linear variable differential transformer (LVDT's). Methods. Six human Achilles tendon specimens were prepared out of fresh frozen lower limbs. Prior to preparation, all limbs underwent CT-scanning. Using Mimics software, the volume of the tendons and the cross sectional area at each level could be calculated. Subsequently, the Achilles tendons were mounted in a custom made rig for uni-axial loading. Tendons were prepared for 3D DIC measurements with a modified technique that enhanced contrast and improved the optimal resolution. Progressive static loading up to 628,3 N en subsequent unloading was performed. Two charge-coupled device camera's recorded images of each loading position for subsequent strain analysis. Two LVDT's were mounted next to the clamped tendon in order to record the displacement of the grips. Results. 3D DIC strain measurement proved to be technical feasible on human tendon tissue if an adapted preparation protocol is used. A spatial resolution of 0,1 mm was reached. Accuracy analysis shows a very low scatter, comparable to that obtained in steel applications (0,03%). When compared to the LVDT measurements, DIC showed excellent correlation (R = 0.99). Apart from the longitudinal strain component, an important transverse strain component was revealed in all specimens (fig 1). Also a significant amount of slip was observed at the clamps. Through the non-contact nature of the measurement, this could be quantified and the analysis became independent of any slip (fig 2). The strain distribution was of a strongly inhomogeneous nature, both within the same specimen (fig 1) and amongst different specimens. Conclusion. 3D DIC is a very promising technique for strain measurement of human collagenous tissue. Accuracy analyses indicate a very low scatter, comparable to that obtained in traditional steel applications. The major advantages of the DIC technique over the LVDTs is the 3D, non-contact, full-field nature of the analysis and the possibility to analyse multidirectional strain, without disturbing slip effects in the grips

Introduction. Peroneal tendon subluxation & dislocation is a rare phenomenon. It is a commonly misdiagnosed cause of lateral ankle pain and instability. Aim(s). Our aim was to establish the morphometric (quantification of components) features of retromalleolar fibular groove in cadavers using 3D technique. Study points. To map the version and inclination based on the 3D techniques. To determine the depth of peroneal groove sufficient to prevent subluxation of tendons. Method/materials. We used 12 of embalmed lower extremities. 6 males and 6 females. All were Caucasians (Age: 61–94). The orientation is calculated using the cartilage boundary of the peroneal groove and using the centroid of the curved surface of the groove. We used rhinoceros software for data collection and mapping of peroneal grooves using 3D imaging Microscribe Digitiser. Results. The retromalleolar groove was concave in 8 ankles. Flat in 3 (female 50%) and Convex in 1 (female) ankle. Differences in length/Width/Depth of the retrotrochlear groove are as follows:. Male: Length 6.2 cm, width 5.4 mm, depth 2.2 mm. Female: Length 5.3 cm, width 4.5 mm, depth 0.1 mm. The deepest part of groove was 2.4 cm from tip of fibula (1.3–3.7 cm). The length of deepest part was 1.9 cm (1.4–2.6). Conclusion. •. Three distinct morphological variations. •. In females; the most frequent is flat variety. •. The deepest part of groove was 2.4 cm from tip of fibula. •. The length of deepest part was 1.9 cm which corresponds with musculo-tendinous junction of peroneus brevis. Clinical relevance. Knowledge of peroneal groove geometry in operative treatment of peroneal tendon subluxation (PTS) is important for a good functional outcome. Orientation of the peroneal groove component may be critical in the operative success

Background. Previously, we demonstrated the effectiveness of phase symmetry (PS) features for segmentation and localisation of bone fractures in 3D ultrasound for the purpose of orthopedic fracture reduction surgery. We recently proposed a novel real-time image-processing method of bone surface extraction from local phase features of clinical 3D B-mode ultrasound data. We are presenting a computational study and outline planned future developments for integration into a computer aided orthopedic surgery framework. Methods. Our image-processing pipeline was implemented on three platforms: (1) using an existing PS extraction C++ algorithm on a dual processor machine with two Xeon x5472 CPUs @ 3GHz with 8GB of RAM, (2) using our proposed method implemented in MATLAB running on the same machine as in (1), and (3) CUDA implementation of our method on a professional GPU (Nvidia Tesla c2050). Results. We ran these three implementations 20 times each on 128×128×128 scans of the iliac crest in live subjects and repeated the processing for 15 combinations of filter parameters. On average, the C++ implementation took 1.93s per volume, the MATLAB implementation 1.28s, and the GPU implementation 0.08s. Overall, our GPU implementation is between 15 and 25 times faster than the state-of-the-art method. Conclusions. Implementing our algorithm on a professional grade GPU produced dramatic computational improvements, enabling full 3D datasets to be processed in an average time of under 100ms, which, if proven in a clinical system, would allow for near-realtime computation. We are currently implementing our algorithm on an open research sonography platform (Ultrasonix Medical Corporation). High-powered graphic cards can easily be integrated into the open architecture of this system, thus enabling GPU computation on diagnostic medical and research ultrasound devices. Clinical Relevance. We intend to use this platform within a surgical environment for accurate and automatic detection of fractures and as an integral part of our developing computer aided surgery pipeline, in which we use PS features to register intra-operative ultrasound to pre-operative computed tomography images

Previously, we demonstrated the effectiveness of phase symmetry (PS) features for segmentation and localisation of bone fractures in 3D ultrasound for the purpose of orthopaedic fracture reduction surgery. We recently proposed a novel real-time image-processing method of bone surface extraction from local phase features of clinical 3D B-mode ultrasound data. We are presenting a computational study and outline of planned future developments for integration into a computer aided orthopaedic surgery framework. Our image-processing pipeline was implemented on three platforms: (1) using an existing PS extraction C++ algorithm on a dual processor machine with two Xeon x5472 CPUs @ 3GHz with 8GB of RAM, (2) using our proposed method implemented in MATLAB running on the same machine as in (1), and (3) CUDA implementation of our method implemented on a professional GPU (Nvidia Tesla c2050). We ran these three implementations 20 times each on 128×128×128 scans of the iliac crest in live subjects and repeated the processing for 15 combinations of filter parameters. On average, the C++ implementation took 1.93s per volume, the MATLAB implementation 1.28s, and the GPU implementation 0.08s. Overall, our GPU implementation is between 15 and 25 times faster than the state-of-the-art method. Implementing our algorithm on a professional grade GPU produced dramatic computational improvements, enabling full 3D datasets to be processed in an average time of under 100ms, which, if proven in a clinical system, would allow for near real time computation. We are currently implementing our algorithm on an open research sonography platform (Ultrasonix Medical Corporation). High-powered graphic cards can easily be integrated into the open architecture of this system, thus enabling GPU computation on diagnostic medical and research ultrasound devices. We intend to use this platform within a surgical environment for accurate and automatic detection of fractures and as an integral part of our developing computer aided surgery pipeline, in which we use PS features to register intra-operative ultrasound to pre-operative computed tomography images

Introduction

Meniscal injuries are very common cause of knee pain and resultant attendance to the orthopaedics or sports medicine clinics. The current protocol stands at clinical examination at first contact and establishing a diagnosis with clinical indicators like joint line tenderness, McMurray's, Apley's and weight-bearing test for meniscal pathology followed by MRI scan to confirm the diagnosis. Either surgical or conservative management follows this. We aim to assess clinical examination alone provide sufficient evidence for further management of meniscal injury and does a role of MRI scan exist to corroborate the findings.

Limited postoperative range-of-motion (ROM) can lead to patient dissatisfaction and dislocation in total hip arthroplasties (THAs). To avoid this, femur first approaches have been developed which optimise particular aspects of ROM by using a virtual analysis of ROM. This study analysis whether it is possible to accurately assess ROM based on an intra-operative acquisition of anatomical structures by using an image-free navigation system. It compares the outcome of a collision detection algorithm when using 3d models from computerised tomography (CT) scans on the one side and intra-operatively acquired 3D models on the other side within a cadaver study. It focuses on peri-acetabular impingements.

During the cadaver session 14 hips (7 cadavers) were treated surgically by using press-fit implants. 3D models of the pelvis and femora were generated based on segmented pre-operative CT data sets. Intra-operative data acquisition was performed by using a CT-free navigation software. Beside standard landmarks, points at the acetabular rim and femoral resection plane were acquired. For assessing ROM, a 3D model of the pelvis was generated. The information about the femoral resection plane was directly entered into the collision detection algorithm. 3D Computer Aided Design (CAD) models provided by the implant manufacturer were used for the implants. Based on this setup, the ROM values for flexion (FLEX), external rotation at 0° flexion (EXT), and internal rotation at 90° flexion (INTROT90) were compared. Differences within intended ROM were considered relevant, since the goal was to enable the prevention of clinically relevant ROM limitations.

The average difference between the CT based and navigation data based ROM analysis was 2.13° ± 3.11° for FLEX, 3.33° ± 5.51° for EXT, and 1.6° ± 3.66° INTROT90. The values reduce to 1.58° ± 2.78° (FLEX) and 0.91° ± 3.77° (INTROT90) when only ROM values within the intended ROM are considered. For EXT all ROM values lied above the threshold for intended ROM. Thus, no relevant differences were found for this motion direction.

In this study, a real-time collision detection based approach was developed and evaluated, which allows to virtually detect prosthetic and bony impingements. It was shown that ROM can be assessed accurately based on an image-free navigation technique. This information can be used intra-operatively to adjust the position of the implants and thus avoid postoperative ROM limitations. In particular, it enables a comprehensive femur first approach which allows us to optimise the post-operative results regarding functional parameters like ROM.

Worldwide, most spine imaging is either “inappropriate” or “probably inappropriate”. The Choosing Wisely recommendation is “Do not perform imaging for lower back pain unless red flags are present.” There is currently no detailed breakdown of lower back pain diagnostic imaging performed in New Brunswick (NB) to inform future directions. A registry of spine imaging performed in NB from 2011-2019 inclusive (n=410,000) was transferred to the secure platform of the NB Institute for Data, Training and Research (NB-IRDT). The pseudonymized data included linkable institute identifiers derived from an obfuscated Medicare number, as well as information on type of imaging, location of imaging, and date of imaging. The transferred data did not include the radiology report or the test requisition. We included all lumbar, thoracic, and complete spine images. We excluded imaging related to the cervical spine, surgical or other procedures, out-of-province patients and imaging of patients under 19 years. We verified categories of X-ray, Computed Tomography (CT), and Magnetic Resonance Imaging (MRI). Red flags were identified by ICD-10 code-related criteria set out by the Canadian Institute for Health Information. We derived annual age- and sex-standardized rates of spine imaging per 100,000 population and examined regional variations in these rates in NB's two Regional Health Authorities (RHA-A and RHA-B). Age- and sex-standardized rates were derived for individuals with/without red flag conditions and by type of imaging. Healthcare utilization trends were reflected in hospital admissions and physician visits 2 years pre- and post-imaging. Rurality and socioeconomic status were derived using patients’ residences and income quintiles, respectively. Overall spine imaging rates in NB decreased between 2012 and 2019 by about 20% to 7,885 images per 100,000 people per year. This value may be higher than the Canadian average. Females had 23% higher average imaging rate than males. RHA-A had a 45% higher imaging rate than RHA-B. Imaging for red flag conditions accounted for about 20% of all imaging. X-rays imaging accounted for 67% and 75% of all imaging for RHA-A and RHA-B respectively. The proportions were 20% and 8% for CT and 13% and 17% for MRI. Two-year hospitalization rates and rates of physician visits were higher post-imaging. Females had higher age-standardized hospitalization and physician-visit rates, but the magnitude of increase was higher for males. Individuals with red flag conditions were associated with increased physician visits, regardless of the actual reason for the visit. Imaging rates were higher for rural than urban patients by about 26%. Individuals in the lowest income quintiles had higher imaging rates than those in the highest income quintiles. Physicians in RHA-A consistently ordered more images than their counterparts at RHA-B. We linked spine imaging data with population demographic data to look for variations in lumbar spine imaging patterns. In NB, as in other jurisdictions, imaging tests of the spine are occurring in large numbers. We determined that patterns of imaging far exceed the numbers expected for ‘red flag’ situations. Our findings will inform a focused approach in groups of interest. Implementing high value care recommendations pre-imaging ought to replace low-value routine imaging