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

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.

In foot and ankle surgery incorrect placement of implants, or inaccuracy in fracture reduction may remain undiscovered with the use of conventional C-arm fluoroscopy. These imperfections are often only recognized on postoperative computer tomography scans. The apparition of three dimensional (3D) mobile Imaging system has allowed to provide an intraoperative control of fracture reduction and implant placement. Three dimensional computer assisted surgery (CAS) has proven to improve accuracy in spine and pelvic surgery. We hypothesized that 3D-based CAS could improve accuracy in foot and ankle surgery. The purpose of our study was to evaluate the feasibility and utility of a multi-dimensional surgical imaging platform with intra-operative three dimensional imaging and/or CAS in a broad array of foot and ankle traumatic and orthopaedic surgery. Cohort study of patients where the 3D mobile imaging system was used for intraoperative 3D imaging or 3D-based CAS in foot and ankle surgery. The imaging system used was the O-arm Surgical Imaging System and the navigation system was the Medtronic's StealthStation. Surgical procedures were performed according to standard protocols. In case of fractures, image acquisition was performed after reduction of the fracture. In cases of 3D-based CAS, image acquisition was performed at the surgical step before implants placement. At the end of the operations, an intraoperative 3D scan was made. We used the O-arm Surgical Imaging system in 11 patients: intraoperative 3D scans were performed in 3 cases of percutaneus fixation of distal tibio-fibular syndesmotic disruptions; in 2 of the cases, revision of reduction and/or implant placement were needed after the intraoperative 3D scan. Three dimensional CAS was used in 10 cases: 2 open reduction and internal fixation (ORIF) of the calcaneum, 1 subtalar fusion, 2 ankle arthrodesis, 1 retrograde drilling of an osteochondral lesion of the talus, 1 Charcot diabetic reconstruction foot and 1 intramedullary screw fixation of a fifth metatarsal fracture. The guidance was used essentially for screw placement, except in the retrograde drilling of an osteochondral lesion where the guidance was used to navigate the drill tool. Intraoperative 3D imaging showed a good accuracy in implant placement with no need to revision of implants. We report a preliminary case series with use of the O-arm Surgical Imaging System in the field of foot and ankle surgery. This system has been used either as intraoperative 3D imaging control or for 3D-based CAS. In our series, the 3D computer assisted navigation has been very useful in the placement of implants and has shown that guidance of implants is feasible in foot and ankle surgery. Intraoperative 3D imaging could confirm the accuracy of the system as no revisions were needed. Using the O-arm as intraoperative 3D imaging was also beneficial because it allowed todemonstrate intraoperative malreduction or malposition of implants (which were repositioned immediately). Intraoperative 3D imaging system showed very promising preliminary results in foot and ankle surgery. There is no doubt that intraoperative use of 3D imaging will become a standard of care. The exact indications need however to be defined with further studies

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

Introduction. Total knee arthroplasty (hereinafter TKA), it is thought that the setting position of each component and the angle have a big influence on surgical results. Preoperative planning with accurate and detailed 3D templates are has been done in many facilities in TKA. However, in the setting position, the 2D evaluation with X-rays is still common after operation, and there are few facilities going in 3D image. A three-dimensional evaluation method of the TKA includes a rating system using CT and the MRI, but influence (artifactual) with the metal occurs, and a detailed evaluation becomes difficult. In this study, we evaluated it after the matching method with the 3D plan using “Physio-Knee” where the materials of the femoral component were alumina ceramics in the preoperation of each component setting position by the CT before and after operation. Patients and methods. We intended for 12 knees which we performed TKA used the Physio-Knee by December, 2011 from October, 2010. The all cases woman, the operation average age were 68.9 years old (62 to 79 years). For these, we performed CT photography of the whole lower limbs after operation like preoperation and each component setting was located after operation using evaluation software made in LEXI company and evaluated it. Results and Discussion. Like 2D evaluation result, as for one, the error with the plan did not recognize errors more than 3 degrees at the setting angle of the each component in the coronal and sagittal plane in preoperation either. A detailed evaluation was possible about the slightly difficult rotation by the 2D evaluation. As for the 3D image matching method that we performed this time, a visual instant evaluation was possible and, in addition, the evaluation of the rotation position was possible and was able to evaluate it in detail and precisely more in comparison with conventional 2D evaluation. A conclusion. In TKA, we think to evaluate correct implant setting, acquisition to alignment that the 3D image matching method that we performed this time is a useful tool

CT-based three-dimensional (3D) pre-operative imaging along with 2D orthogonal sections defined by the plane of the scapula (axial, sagittal and coronal planes) has been demonstrated by many research groups to be a very accurate way to define the bone pathology and alignment/subluxation of the humeral head in relationship to the center line of the scapula or the center of the glenoid fossa. When 3D CT imaging is combined with 3D implant templating the surgeon is best able to define the optimal implant and its location for the desired correction of the bone abnormalities. The use and value of 3D imaging is best when the there is more severe bone pathology and deformity. Transferring the computer-based information of implant location to the surgical site can involve multiple methods. The three methods discussed in the literature to date including use of standard instrumentation in a manner specified by the pre-operative planning, use of single-use patient specific instrumentation and use of reusable patient specific instrumentation. Several cadaver and sawbone studies have demonstrated significant improvement in placement of the glenoid implant with both single use and reusable patient specific instrumentation when compared to use of 2D imaging and standard instrumentation. Randomised clinical trials have also shown that 3D planning and implant templating is very effective in accurate placement of the implant in the desired location using all three types of instrumentation. The optimal use of this technology is dependent upon the severity of the pathology and the experience and preference of the surgeon. With more severe pathology and less surgeon experience 3D pre-operative imaging and templating and use of some level of patient specific instrumentation provides more accurate placement of the glenoid implant

Quantitative assessment of metastatic involvement of the bony spine is important for assessing disease progression and treatment response. Quantification of metastatic involvement is challenging as tumours may appear as osteolytic (bone resorbing), osteoblastic (bone forming) or mixed. This investigation aimed to develop an automated method to accurately segment osteoblastic lesions in a animal model of metastatically involved vertebrae, imaged with micro computed tomography (μCT). Radiomics seeks to apply standardized features extracted from medical images for the purpose of decision-support as well as diagnosis and treatment planning. Here we investigate the application of radiomic-based features for the delineation of osteoblastic vertebral metastases. Osteoblastic lesions affect bone deposition and bone quality, resulting in a change in the texture of bony material physically seen through μCT imaging. We hypothesize that radiomics based features will be sensitive to changes in osteoblastic lesion bone texture and that these changes will be useful for automating segmentation. Osteoblastic metastases were generated via intracardiac injection of human ZR-75-1 breast cancer cells into a preclinical athymic rat model (n=3). Four months post inoculation, ex-vivo μCT images (µCT100, Scanco) were acquired of each rodent spine focused on the metastatically involved third lumbar vertebra (L3) at 7µm/voxel and resampled to 34µm/voxel. The trabecular bone within each vertebra was isolated using an atlas and level-set based segmentation approach previously developed by our group. Pyradiomics, an open source Radiomics library written in python, was used to calculate 3D image features at each voxel location within the vertebral bone. Thresholding of each radiomic feature map was used to isolate the osteoblastic lesions. The utility of radiomic feature-based segmentation of osteoblastic bone tissue was evaluated on randomly selected 2D sagittal and axial slices of the μCT volume. Feature segmentations were compared to ground truth osteoblastic lesion segmentations by calculating the Dice Similarity Coefficient (DSC). Manually defined ground truth osteoblastic tumor segmentations on the μCT slices were informed by histological confirmation of the lesions. The radiomic based features that best segmented osteoblastic tissue while optimizing computational time were derived from the Neighbouring Gray Tone Difference Matrix (NGTDM). Measures of coarseness yielded the best agreement with the manual segmentations (DSC=707%) followed by contrast, strength and complexity (DSC=6513%, 5428%, and 4826%, respectively). This pilot study using a radiomic based approach demonstrates the utility of the NGTDM features for segmentation of vertebral osteoblastic lesions. This investigation looked at the utility of isolated features to segment osteoblastic lesions and found modest performance in isolation. In future work we will explore combining these features using machine learning based classifiers (i.e. decision forests, support vector machines, etc.) to improve segmentation performance

Introduction. Three-dimensional (3D) printing is a precise method of reproducing complex structures. Orthopaedic surgeons may utilize 3D imaging to better plan procedures, design implants, and communicate with other providers and patients. However, one of the limitations of 3D printed models has been the high cost associated with third-party creation of such tools. With the recent increases in the use of 3D printing many publically available software programs have been developed, which allow for inexpensive office-based production of models. We present a simple, inexpensive technique which can be used by surgeons for the rapid fabrication of 3D models in-office. Technique. CT scan and MRI's are stored in DICOM type format which must be transformed into a 3D image. This can be achieved using publically available programs (for example, 3D slicer (. http://www.slicer.org/. )). These images can be manipulated with this software, allowing for separation of individual bones. The files can then be exported from this program in an STL format. These models are then further enhanced and smoothed utilizing another open source software (Blender (. https://www.blender.org. )). The STL file can then be opened in a third open source program (for example, Meshlab . http://meshlab.sourceforge.net/. ) which can analyze the mesh for extra vertices, voids, and discontinuities. At this point the STL file is ready for 3D printing. The file can be loaded onto the slicer software for calculation of a tool path and printing. Case example 1. A 50 year old woman sustained a displaced acetabular fracture during primary total hip arthroplasty. She underwent fracture fixation, but her acetabular component failed to ingrow with bone. Multiple revision procedures were undertaken, but all were unsuccessful. She was finally referred for treatment. Preoperative CT scan showed massive bone loss and distortion of normal pelvic architecture (Figure 1) requiring a custom acetabular implant. A 3D model of the pelvis was produced with the custom implant to assist in preoperative planning (Figure 2a), but this was a costly and time consuming process. Therefore, a smaller scale pelvic model was also rapidly generated using the above technique in order to demonstrate the severity of the patient's pathology (Figure 2b). Case example 2. A 14 year old male presented with a history of knee pain, weakness and buckling over a decade. A CT scan was obtained which demonstrated a dislocated patella, loss of normal trochlea contour, and a concave patella. For demonstration purposes and patient education, the knee joint was 3D printed using the technique discussed above (Figure 3). Conclusion. This technique represents a simple, rapid, and inexpensive method for creation of 3D models. We believe this is a valuable tool in orthopaedic surgery in general and arthroplasty in particular as it can be used for preoperative planning as well as for facilitating communication between surgeons and patients. This technology can greatly increase the surgeon's ability to visualize anatomy, resulting in improved outcomes in difficult cases such as described here

Juvenile Osteochondritis dissecans (JOCD) in humans and subchondral cystic lesions (SCL) in horses (also termed radiolucencies) share similarities: they develop in skeletally immature individuals at the same location in the medial femoral condyle (MFC) and their etiology is only partially understood but trauma is suspected to be involved. JOCD is relatively uncommon in people whereas SCLs arise in 6% of young horses leading to lameness. Ischemic chondronecrosis is speculated to have a role in both osteochondrosis and SCL pathogenesis. We hypothesize that MFC radiolucencies develop very early in life following a focal internal trauma to the osteochondral junction. Our aims were to characterize early MFC radioluciencies in foals from 0 to 2 years old. Distal femurs (n=182) from Thoroughbred horses (n=91, 0–2 years old), presented for post-mortem examination for reasons unrelated to this study, were collected. Radiographs and clinical tomodensitometry were performed to identify lesions defined as a focal delay of ossification. Micro-tomodensitometry (m-CT) and histology was then performed on the MFCs (CT lesions and age-matched subset of controls). Images were constructed in 3D. The thawed condyles, following fixation, were sectioned within the region of interest, determined by CT lesion sites. Hematoxylin eosin phloxin and safran (HEPS) and Martius-Scarlet-Blue (MSB) stains were performed. Histological parameters assessed included presence of chondronecrosis, fibrin, fibroplasia and osteochondral fracture. An additional subset of CT control (lesion-free) MFCs (less 6 months old) were studied to identify early chondronecrosis lesions distant from the osteochondral junction. One MFC in clinical CT triages controls had a small lesion on m-CT and was placed in the lesion group. All m-CT and histologic lesions (n=23) had a focal delay of ossification located in the same site, a weight bearing area on craniomedial condyle. The youngest specimen with lesions was less than 2 months old. On m-CT 3D image analysis, the lesions seemed to progressively move in a craniolateral to caudomedial direction with advancing age and development. Seventy-four percent (n=17/23) of the lesions had bone-cartilage separation (considered to be osteochondral fractures) confirmed by the identification of fibrin/clot on MSB stains, representing an acute focal bleed. Fibroplasia, indicating chronicity, was also identified (74%, n=17/23). In four cases, the chondrocytes in the adjacent cartilage were healthy and no chondronecrosis was identified in any sections in the lesions. Nineteen cases had chondronecrosis and always on the surface adjacent to the bone, at the osteochondral junction. None of the subset of control specimens, less than 6 months old (n=44), had chondronecrosis within the growth cartilage. Early subchondral cystic lesions of the medial femoral condyle may arise secondary to focal internal trauma at the osteochondral junction. The presence of fibrin/clot is compatible with a recent focal bleed in the lesion. Medial femorotibial joint internal forces related to geometry could be the cause of repetitive trauma and lesion progression. In the juvenile horse, and potentially humans, the early diagnosis of MFC lesions and rest during the susceptible period may reduce progression and promote healing by prevention of repetitive trauma, but requires further study

Introduction. Although weight-bearing CT of the foot definitely reflects the morphology and deformity of joint, it is hard to obtain the standing CT due to difficulty of availability. Although 3D imaging reconstruction using radiographs has been reported in other joints, there is no study about foot joint. The purpose of this study is to develop a semi-automatic method based on a deformable surface fitting for achieving the weight-bearing 3D model reconstruction from standing radiographs for foot. Methods. Our method is based on a Laplacian surface deformation framework using a template model of foot. As pre- processing step, we obtained template surface meshes having the average shapes of foot bones (talus, calcaneus) from standing CT images (Planmed Verity) in 10 normal volunteers. In the reconstruction step, the surface meshes are deformed following guided user inputs with geometric constraints to recover the target shapes of 30 patients while preserving average bone shape and smoothness. Finally, we compared reconstructed 3D model to original standing CT images. Analysis was performed using Dice coefficients, average shape distance, maximal shape distance. Results. The obtained reconstruction model is close to the actual standing foot geometry (Dice coefficients 0.89, average shape distance 0.88 mm, maximum shape distance 6.33 mm). We present the accuracy and robustness of our method via comparison between the reconstructed 3D models and the original bone surfaces. Conclusions. Weight-bearing 3D foot model reconstruction from standing radiographs is concise and the effective method for analysis of foot joint alignment and deformity

Biomechanical considerations are relevant to cup positioning in total hip replacement (THR) to optimise the patient-specific post-operative outcome. One goal is to place the hip centre of rotation (COR) such that parameters characterising the biomechanics of the hip joint lie within physiological ranges. Different biomechanical models have been developed and are based on exact knowledge about muscle insertion points whose positions can be estimated on the basis of bony landmarks. Therefore, accurate landmark localisation is necessary to obtain reliable and comparable parameter values. As most biomechanical considerations are limited to the frontal plane, landmark localisation relying on standardised pre-operative radiographs has been established in clinical practice. One potential drawback of this approach is that user-interactive landmark localisation in radiographs might be more error-prone and subjective than localisation in 3D images. Therefore, we investigated the possibility of increasing the reproducibility of interactive landmark localisation by providing 3D localisation techniques. As the so-called BLB score based on Blumentritt's biomechanical hip model has already been introduced into clinical practice as a criterion for cup position planning, we examined the anatomical landmarks involved in BLB score evaluation. We developed a CT-based simulation tool allowing for the generation of 3D bone surface models and standardised digitally reconstructed radiographs (DRRs). Correspondences between points in the 2D DRR and rays in the 3D bone surface model are automatically established and optionally visualised by the tool. Two modes of landmark localisation were examined: In the 2D-mode, only AP DRRs were displayed, and the users had to localise the landmarks by clicking within the DRR image. In the 3D-mode, additionally the arbitrarily rotatable bone surface models together with the aforementioned 2D/3D correspondences were visualised. The user could then choose between landmark localisation by clicking either within the DRR image or within the 3D view. In either case, the 2D landmark positions within the DRR were recorded. The participants were given both an example AP pelvis radiograph with highlighted anatomical landmarks and the following landmark descriptions from the user's manual (v2.06) of the mediCAD software (Hectec GmbH, Landshut, Germany): P4: ca. 3cm distal lesser trochanter minor (in the imagined direction of pull of the rectus femoris muscle towards the medial upper edge of the patella); P5:lateral, most proximal edge of the trochanter major; P6: most cranial edge of the sclerotic area; P7:spina iliaca anterior inferior; P8/P9:most lateral/cranial point of the wing of the ilium. (P1 and P2 are only needed to define the position of the mid-sagittal plane, and P3 is the pre-operative COR. Due to correct radiograph standardisation, we assumed this plane and P3 to be known prior to landmark localisation.). Thirteen surgeons repeated the experiments on four hips (CT datasets of two male patients). The following results were obtained (SD of relevant coordinates obtained with 2D localisation vs. SD of those obtained with 3D localisation) in the first patient (left hip: 1L; right hip: 1R) and the second patient (left hip: 2L; right hip: 2R):P4: 6.3 vs. 9.0 (1L); 6.7 vs. 5.6 (1R); 9.0 vs. 11.1 (2L); 7.1 vs. 8.6 (2R); P5: 4.4 vs. 2.8 (1L); 3.1 vs. 3.1 (1R); 4.3 vs. 2.4 (2L); 4.7 vs. 4.1 (2R); P6: 4.8 vs. 3.8 (1L); 2.9 vs. 2.8 (1R); 3.7 vs. 5.2 (2L); 6.9 vs. 3.5 (2R); P7: 12.2 vs. 6.1 (1L); 12.1 vs. 3.7 (1R); 7.6 vs. 4.6 (2L); 6.2 vs. 4.5 (2R); P8: 1.2 vs. 2.8 (1L); 2.0 vs. 2.6 (1R); 1.5 vs. 2.1 (2L); 2.0 vs. 1.6 (2R);P8: 4.1 vs. 2.1 (1L); 7.3 vs. 3.9 (1R); 1.6 vs. 2.6 (2L); 4.1 vs. 3.2 (2R). The greatest differences in reproducibility were observed in P7, which was barely distinguishable in the radiographs and, hence, showed very low reproducibility only for the 2D-mode. P4 showed low reproducibility in both modes due to its vague description and the relatively small portions of the femurs contained in the CT-scanned volume. In P9 the low reproducibility obtained with the 2D-mode might be partly explained by truncation artefacts present in the DRRs. Although our study needs to be extended to more datasets, we conclude that the availability of 3D data allows for higher landmark localisation reproducibility when compared with the conventional X-ray-based approach, which has additional drawbacks: Standardisation of X-ray imaging, which is necessary to retain comparability of biomechanical parameter values determined in different patients, is hard to achieve; specifications e.g. concerning the central beam may be met only after acquiring several radiographs. Moreover, once a 2D target cup position is defined based on the 2D biomechanical analyses, the transfer of this position into the 3D surgical site is difficult without additional 3D imaging. Hence, the use of 3D imaging and 3D landmark localisation techniques seems more promising for cup positioning based on biomechanical models, which, however, need validation

Cup position planning for total hip replacement (THR) is a complex task which is influenced by several factors. Whereas aspects like appropriate implant fixation and bone stock preservation are rather evaluated according to intra-operative findings, functional analyses using biomechanical hip models can rely on pre-operative imaging. Due to the wide availability and cost-efficiency of X-ray imaging technology along with the common restriction of biomechanical evaluations to the frontal plane, pre-operative imaging for such purposes is usually limited to AP radiographs. One example is biomechanical optimisation based on the so-called BLB score, which has already been introduced into clinical practice. In this approach, the assumed suitability of potential hip centres of rotation (CORs) is presented to the surgeon by applying colour-coding within the pre-operative AP radiograph. However, to realise the plan, the surgeon has to transfer the 2D positions presented in the radiograph into the 3D surgical site. We developed a CT-based simulation tool allowing for the generation of 3D bone surface models as well as standardised digitally reconstructed radiographs (DRRs). Within a 3D view, the cup, which is represented as a hemisphere, can freely be shifted in the coronal plane. The 2D point corresponding to the COR defined by the hemisphere is then automatically computed. In our study, four CT datasets of hips with large bony defects were used. After segmentation 3D bone surface models were generated. These bone surface models were aligned on the basis of the pelvic coordinate system [3], and standardised AP DRRs were computed. BLB score evaluation in intact hips assumes that the central beam passes through the centroid of both hip CORs. As only the contra-lateral hip COR was available due to the defects, a virtual ipsi-lateral COR was obtained by mirroring the contra-lateral hip across the mid-sagittal plane. Twelve surgeons (divided into two groups of six each according to their experience) had the task to shift the cup such that its 3D position would best match a predefined 2D target position, which was close to the virtual ipsi-lateral COR and displayed as a cross within the standardised DRR. However, the current 2D position corresponding to the current 3D position was not revealed during positioning. Once the user was satisfied with the 3D position, the corresponding 2D position was recorded. The following results were obtained (mean ± SD across six surgeons of the respective group) for the four patients:. x-error, more experienced: 2.0 ± 6.1; −3.0 ± 5.9; 4.1 ± 4.8; 2.1 ± 5.2; x-error, less experienced: 4.3 ± 4.2; −3.1 ± 1.8; 1.9 ± 4.0; 5.2 ± 4.1; |x-error|, more experienced: 5.2 ± 3.0; 5.4 ± 3.2; 5.5 ± 2.7; 4.3 ± 3.0;|x-error|, less experienced: 4.3 ± 4.2; 3.1 ± 1.8; 3.3 ± 2.7; 5.7 ± 3.3; y-error, more experienced: 12.0 ± 9.1; 0.3 ± 4.3; 6.2 ± 6.6; 1.9 ± 3.2;. y-error, less experienced: 6.1 ± 3.1; 0.8 ± 4.0; 2.4 ± 5.5; 1.4 ± 4.1;|y-error|, more experienced: 12.0 ± 9.1; 3.2 ± 2.6; 6.2 ± 6.6; 3.0 ± 1.9;|y-error|, less experienced: 6.1 ± 3.1; 3.4 ± 1.6; 4.6 ± 3.3; 3.2 ± 2.6;total error, more experienced: 13.5 ± 8.9; 6.6 ± 3.5; 9.8 ± 4.1; 5.4 ± 3.4;total error, less experienced: 8.5 ± 2.7; 4.9 ± 1.5; 6.5 ± 2.5; 6.7 ± 3.8. Our experimental results show that mental 2D/3D matching for cup positioning in pelvises with bony defects is a difficult task, and that mental 2D/3D matching cannot be expected to yield the correct 3D cup positions corresponding to positions predefined in radiographs. The largest errors were found in the patient with the lowest image quality suggesting that image quality plays an important role. On contrary, experience was not found to be an important factor. We believe that in clinical practice mental 2D/3D matching between pre-operative radiographs and the surgical site without the help of 3D imaging or special tools would be more difficult than the task given in this study because only small portions of the pelvis would be exposed. Furthermore, as additional aspects of cup positioning would need to be taken into consideration simultaneously, the mental load could be expected to be higher. We conclude that in hips with large bony defects cup positioning based on pre-operative radiographs is highly unreliable without additional computer-assistance or intra-operative imaging. If pre-operative radiographs are needed for functional analyses, combination with 3D image data seems attractive: Firstly, 3D images can easily be used for navigation; secondly, they allow for the generation of highly standardised views, which is essential for comparability across multiple patients. Future studies relying on more datasets with a wider range of defects could also investigate whether cranio-caudal or medio-lateral positioning errors prevail. This is an interesting question since the BLB score usually is much more specific in the medio-lateral direction than in the cranio-caudal direction, implying that correct 2D/3D matching for the cranio-caudal direction appears less important. In the current study involving only four hips, however, no clear tendency could be observed. This work has been funded in part by the German Ministry for Education and Research (BMBF) in the framework of the orthoMIT project under grant No. BMBF 01EQ0802/BMBF 01IBE02C

INTRODUCTION. Rotational malalignment of the components in total knee arthroplasty has been linked to patellar maltracking, improper soft tissue balance, abnormal kinematics, premature wear of the polyethylene inlay, and subsequent clinical complications such as anterior knee pain (Barrack et al., 2001; Zihlmann et al., 2005; Lakstein at al., 2010). This study investigates an innovative image-based device that is designed to be used along with an intraoperative Isocentric (ISO-C) 3D imaging C-arm, and the conventional surgical instruments for positioning the femoral component at accurate rotational alignment angles. METHODS. The new device was tested on 5 replica models of the femur (Sawbones). Zimmer NexGen total knee replacement instruments were used to prepare the bones. After making the distal transverse cut on the femurs, the trans-epicondylar-axis (TEA) were defined by a line connecting the medial and lateral epicondyles which were marked by holes on the bone models. The 4-in-1 cutting jig was placed and pinned to the bones with respect to the TEA considering 5 different planned rotational alignments: −10°, −5°, 0°, +5°, and +10° (minus sign indicating external and plus sign internal rotation). At this point, the jig was replaced by the alignment device using the head-less pins as the reference, and subsequently an Iso-c 3D image of the bone was acquired using Siemens ARCADIS Orbic C-arm. The image was automatically analyzed using custom software that determined the angle between the TEA and the reference pins (Fig 1). The difference between the angle read from the device and the planned angle was then used to correct the locations of the reference pins through a custom protractor device. Preparation of the bone was continued by placing the 4-in-1 jigs on the newly placed pins. Three-dimensional images of the bones after completion of the cuts were acquired, and the angle between the final cut surface and the TEA was determined. RESULTS. The results are listed in Fig 2. The rotational angle read from the image-based device showed misalignments in the range of 0.53° to 5.94° (RMS error=3.67°). After alignments were corrected, the final cut accuracy was in the range of 0.3° to 0.74° (RMS error=0.5°). DISCUSSION. The introduced device was very accurate (0.5°) in correcting the rotational alignment of the femoral component. The range of errors for defining the boney landmarks through palpation and visualization is expected to be much larger than was observed in this work (RMS error =3.67°), due to soft tissue obstructions and time pressure during surgery. This would highlight the value of the device even more. The introduced technology is expected to add about 5 to 10 minutes to the surgery at a safe radiation dose comparable to a round transatlantic flight. The surgeon and staff can keep a safe distance during the short imaging time. CONCLUSION. The introduced device provides a fast and safe tool for improving component alignments in total knee arthroplasty

Background. Degeneration of the shoulder joint is a frequent problem. There are two main types of shoulder degeneration: Osteoarthritis and cuff tear arthropathy (CTA) which is characterized by a large rotator cuff tear and progressive articular damage. It is largely unknown why only some patients with large rotator cuff tears develop CTA. In this project, we investigated CT data from ‘healthy’ persons and patients with CTA with the help of 3D imaging technology and statistical shape models (SSM). We tried to define a native scapular anatomy that predesignate patients to develop CTA. Methods. Statistical shape modeling and reconstruction:. A collection of 110 CT images from patients without glenohumeral arthropathy or large cuff tears was segmented and meshed uniformly to construct a SSM. Point-to-point correspondence between the shapes in the dataset was obtained using non-rigid template registration. Principal component analysis was used to obtain the mean shape and shape variation of the scapula model. Bias towards the template shape was minimized by repeating the non-rigid template registration with the resulting mean shape of the first iteration. Eighty-six CT images from patients with different severities of CTA were analyzed by an experienced shoulder surgeon and classified. CT images were segmented and inspected for signs of glenoid erosion. Remaining healthy parts of the eroded scapulae were partitioned and used as input of the iterative reconstruction algorithm. During an iteration of this algorithm, 30 shape components of the shape model are optimized and the reconstructed shape is aligned with the healthy parts. The algorithm stops when convergence is reached. Measurements. Automatic 3D measurements were performed for both the healthy and reconstructed shapes, including glenoid version, inclination, offset and critical shoulder angle. These measurements were manually performed on the mean shape of the shape model by a surgeon, after which the point-to-point correspondence was used to transfer the measurements to each shape. Results. The critical shoulder angle was found to be significantly larger for the CTA scapulae compared to the references (P<0.01). When analyzing the classified scapulae significant differences were found for the version angle in the scapulae of group 4a/4b and the critical shoulder angle of group 3 when compared to the references (P<0.05). Conclusion. Patients with CTA have a larger critical shoulder angle compared with reference patients. Some significant differences are found between the scapulae from patients in different stages of CTA and healthy references, however the differences are smaller than the accuracy of the SSM reconstruction. Therefore, we are unable to conclude that there is a predisposing anatomy in terms of glenoid version, inclination or offset for CTA

Introduction. At present, orthopaedic surgeons utilize either CT, MRI or X-ray for imaging a joint. Unfortunately, CT and MRI are quite expensive, non weight-bearing and the orthopaedic surgeon does not receive revenue for these procedures. Although x-rays are cheaper, similar to CT scans, patients incur radiation. Also, all three of these imaging modalities are static. More recently, a new ultrasound technology has been developed that will allow a surgeon to image their patients in 3D. The objective of this study is to highlight the new opportunity for orthopaedic surgeons to use 3D ultrasound as alternative to CT, MRI and X-rays. Methods. The 3D reconstruction process utilizes statistical shape atlases in conjunction with the ultrasound RF data to build the patient anatomy in real-time. The ultrasound RF signals are acquired using a linear transducer. Raw RF data is then extracted across each scan line. The transducer is tracked using a 3D tracking system. The location and orientation for each scan line is calculated using the tracking data and known position of the tracker relative to the signal. For each scan line, a detection algorithm extracts the location on the signal of the bone boundary, if any exists. Throughout the scan process, a 3D point cloud is created for each detected bone signal. Using a statistical bone atlas for each anatomy, the patient specific surface is reconstruction by optimizing the geometry to match the point cloud. Missing regions are interpolated from the bone atlas. To validate reconstructed models output models are then compared to models generated from 3D imaging, including CT and MRI. Results. 3D ultrasound, which now has FDA approval in the United States, is presently available for an orthopaedic surgeon to use. Error analyses have been conducted in comparison to MRI and CT scans and revealed that 3D ultrasound has a similar accuracy of less than 1.0 mm in the creation of a 3D bone and soft-tissues. Unlike CT and MRI scans that take in excess of 2–3 weeks to create human bones, 3D ultrasound creates bones in 4–6 minutes. Once the bones are created, the surgeon can assess bone quality, ligament and cartilage conditions, assess osteophytes, fractures and guide needles into the 3D joint space. The creation of 3D bones has been accurately assessed for the spine, shoulder, knee, hip and ankle joints. A 3D joint pre-operative planning module has also been developed for a surgeon to size and position components before surgery. Discussion. 3D ultrasound is an exciting new imaging technology available for orthopaedic surgeons to use in their practice. Existing CPT codes are readily available for 3D ultrasound procedures. A surgeon can now evaluate and diagnose bone and soft- tissue conditions, in 3D, using ultrasound, which is safer and is an easier procedure compared to CT, MRI and X-rays. This new ultrasound technology is a highly accurate imaging technique that will allow a surgeon to diagnose bone and soft-tissue concerns in 3D, under weight-bearing, dynamic conditions and guide needle injections to correct location, in 3D

INTRODUCTION. The cup component of modern resurfacing systems are often coated creating a cementless press-fit fixation in the acetabulum based on surgical under-reaming, also enabling osseoconduction/integration. Due to the higher density of cortical bone along the antero-superior and postero-inferior regions of the acetabulum, the greatest forces occur between the anterior and posterior columns of the pelvis. This produces pinching of the implant that can result in deformation of the cup. Metal shell/modularpress-fit acetabular cups are susceptible to substantial deformation immediately after implantation. This deformation may affect the lubrication, producing point loading and high friction torques between the head and the cup that increase wear and may lead to head clamping and subsequent cup loosening. We sought to test a novel ceramic on ceramic (CoC) hip resurfacing system that should allay any concerns with the Adverse Reaction to Metal Debris associated with metal on metal (MoM) resurfacing devices. AIM. We sought to quantify the deformation of a novel CoC hip-resurfacing cup after implantation, using a standard surgical technique in a cadaveric model, and compare to the MoM standard. We also assessed if the design clearances proposed for this CoC hip resurfacing implant are compatible with the measured deformations, allowing for an adequate motion of the joint. METHODS. The pelvis from four fresh frozen cadavers were placed into the lateral position. One surgeon with extensive experience in hip resurfacing surgery (JH) prepared all the pelvises for implantation using a posterior approach to the joint and sequential reaming of the acetabulum to 1mm below the implant outer diameter. The acetabulum components were then impacted into the prepared pelvis. We used four ceramic and four metal implants of equal and varying size. (2 × (40/46mm, 44/50mm, 50/56mm, 52/58mm)). The acetabulum cup bearing surface diameter and deformation was measured using a GOM-ATOS optical high precision 3D scanner. 3-Dimensional measurements were taken pre-implantation, immediately after and at 30 minutes following implantation. Two techniques were used to analyse the 3D images: by maximum inscribed diameter and by radial segments. These were compared to the known articulating surface clearance values. RESULTS. The diameter of the cups in both metal and ceramic systems was reduced after implantation when analysing by maximum inscribed diameter and by radial segments. This deformation was maintained at 30 minutes. We can infer there is no significant bone stress relaxation effect following implantation. On ceramic cups, the deformation was larger in larger sizes. However, the 44/50 (the second smallest cup) deformed the least. Despite this, the difference in deformation between these two sizes is minimal. The deformation of sizes 50/56 and 52/58 was equivalent. For the metal cups, there was not a clear correlation between the cup size and the deformation. The largest cup size had the same deformation as the smallest size. CONCLUSIONS. The deformation following implantation of the cup component in a ceramic acetabulum resurfacing behave similarly to a metal implant. Cup deformation measured after implantation is minimal when compared to the minimum design clearance in both systems

Introduction. The degree of glenoid bone loss associated with primary glenohumeral osteoarthritis can influence the type of glenoid implant selected and its placement in total shoulder arthroplasty (TSA). The literature has demonstrated inaccurate glenoid component placement when using standard instruments and two-dimensional (2D) imaging without templating, particularly as the degree of glenoid deformity or bone loss worsens. Published results have demonstrated improved accuracy of implant placement when using three-dimensional (3D) computed tomography (CT) imaging with implant templating and patient specific instrumentation (PSI). Accurate placement of the glenoid component in TSA is expected to decrease component malposition and better correct pathologic deformity in order to decrease the risk of component loosening and failure over time. Different types of PSI have been described. Some PSI use 3D printed single use disposable instrumentation, while others use adjustable and reusable-patient specific instrumentation (R-PSI). However, no studies have directly compared the accuracy of different types of PSI in shoulder arthroplasty. We combined our clinical experience and compare the accuracy of glenoid implant placement with five different types of instrumentation when using 3D CT imaging, preoperative planning and implant templating in a series of 173 patients undergoing primary TSA. Our hypothesis was that all PSI technologies would demonstrate equivalent accuracy of implant placement and that PSI would show the most benefit with more severe glenoid deformity. Discussion and Conclusions. We demonstrated no consistent differences in accuracy of 3D CT preoperative planning and templating with any type of PSI used. In Groups 1 and 2, standard instrumentation was used in a patient specific manner defined by the software and in Groups 3, 4, and 5 a patient specific instrument was used. In all groups, the two surgeons were very experienced with use of the 3D CT preoperative planning and templating software and all of the instrumentation prior to starting this study, as well as very experienced with shoulder arthroplasty. This is a strength of the study when defining the efficacy of the technology, but limits the generalizability of the findings when considering the effectiveness of the technology with surgeons that may not have as much experience with shoulder arthroplasty and/or the PSI technology. Conversely, it could be postulated that greater improvements in accuracy may be seen with the studied PSI technology, when compared to no 3D planning or PSI, with less experienced surgeons. There could also be differences between the PSI technologies when used by less experienced surgeons, either across all cases or based upon the severity of pathology. When the surgeon is part of the method, the effectiveness of the technology is equally dependent upon the surgeon using the technology. A broader study using different surgeons is required to test the effectiveness of this technology. Comparing the results of this study with published results in the literature, 3D CT imaging and implant templating with use of PSI results in more accurate placement of the glenoid implant when compared to 2D CT imaging without templating and use of standard instrumentation. In previous studies, this was most evident in patients with more severe bone deformity. We believe that 3D CT planning and templating provides the most value in defining the glenoid pathology, as well as in the selection of the optimal implant and its placement. However, it should be the judgment of the surgeon, based upon their experience, to select the instrumentation to best achieve the desired result

INTRODUCTION. In living normal knee the lateral femoral condyle rolls posteriorly more than the medial side to the extent that in deep flexion the lateral femoral condyle sublux from the tibial surface (Nakagawa et al). The purpose of this presentation is to study the tibiofemoral movement in patients who had full flexion after total knee replacements and to compare it with that of normal knee. MATERIALS AND METHODS. 23 knees were scanned using SIEMENS SIREMOBILE Iso-C with 3D Extension C-arm. The system is able reconstruct 3D images that can be viewed from deferent angle and precise measurements of distances between the deferent components of the implant can be made. The knee was scanned while the patient is sitting in kneeling position with the calf touching the thigh (flexion of over 150 degree). RESULTS. All the cases studied showed a variable roll back between the medial and lateral femoral condyle. In all cases the lateral roll back was much more than the medial. In 14 cases we confirmed lateral condyle subluxation similar to what is seen in normal knee. The position of the foot (internal or external rotation) during scanning did not affect the lateral femoral condyle role back. DISCUSSION. Although previous studies have shown paradoxical types of tibiofemoral movement in patients who have total knee replacements throughout the range of movement, the knees in patients who had full flexion after TKA tend to have the same tibiofemoral movement as the normal knee in deep flexion. The lateral femoral condyles spin off or subluxation could adversely affect the implant components especially if the design does not accommodate this movement. CONCLUSION. The lateral femoral condyle may sublux from the tibia during kneeling in patients who had full flexion after TKA. These findings should call for changes in the implant design to accommodate the lateral condyle roll back

[Background]. Factors determining improvement of the long-term outcome of total knee arthroplasty include accurate reproduction of lower limb alignment. To acquire appropriate lower limb alignment, tibial component rotation is an important element for outcomes. We usually determine the tibial component rotation using the anatomical rotaional landmark of the proximal tibia and range of motion technique. In addition we followed by confirmation of overall lower limb alignment referring to the distal tibial index. When the tibia have a rotational mismatch between its proximal and distal AP axis, a larger error of the distal tibial index than those of other rotational landmark is of concern. The purpose of this study is to evaluate the reliability of the distal tibial AP axis as a reference axis of tibial compornent rotation in the intraoperative setting. [Subjects and Methods]. The 86 patients (104 knees) with osteoarthritis of the knee who underwent primary TKA were evaluated with use of computerized tomography scans. A 3D images of the proximal tibial and ankle joint surfaces and foot were prepared, and the reference axis was set. In measurement, the images and reference axes were projected on the same plane. We measured the angle caluculated by the proximal and distal tibial AP axes (torsion angle) in preoperative 3D CT images. As a proximal tibial AP reference axis, AP-1 is a line connecting the medial margin of the tibial tubercle and Middle of the PCL attachment site and AP-2 is a line connecting the 1/3 medial site of the tibial tubercle and center of the PCL attachment site. As a distal tibial AP reference axis, D3 is a line connecting the anteroposterior middle point of the talus, D4 is a perpendicular line of transmalleoler axes, and D5 is the second metatarsal bone axis. [Results]. AP-2 was 9.9±1.1°externally rotated relative to AP-1. And D4 was externally rotated relative to D3 in all cases, and the mean external rotation was 11.6°. The mean torsion angle of the distal tibial AP axis relative to AP-1 were all positive and D3:3.7°, D4:15.3°, D5:0.1° respectively. D5 was internally rotated relative to D3 in 67 cases, externally rotated in 31, consistent in only 6, and the mean torsion angle was 3.5°internal rotation. The mean torsion angle of AP-2 axis were D3, 6.3°internal rotation; D4, 5.3°external rotation; and D5, 9.8°internal rotation respectively. [Discussion]. In our department, after determining the rotation using the proximal tibial AP axis and ROM method, the alignment is confirmed referring to the distal tibial AP axis. However, a torsion angle of 25° or greater was noted in some cases, while it was within 3° in about 35–40% of cases, showing that the distal tibial AP axis was inappropriate as a reference axis for some cases. To perform TKA, it is important to identify the difference (torsion angle) between the proximal and distal tibial AP axes to prevent errors in the intraoperative setting of rotation

Scaphoid non-union results the typical humpback deformity, pronation of the distal fragment, and a bone defect in the non-union site with shortening. Bone grafting, whether open or arthroscopic, relies on fluoroscopic and direct visual assessment of reduction. However, because of the bone defect and irregular geometry, it is difficult to determine the precise width of the bone gap and restore the original bone length, and to correct interfragmentary rotation. Correction of alignment can be performed by computer-assisted planning and intraoperative guidance. The use of computer navigation in guiding reduction in scaphoid non-unions and displaced fractures has not been reported. Objective. We propose a method of anatomical reconstruction in scaphoid non-union by computer-assisted preoperative planning combined with intraoperative computer navigation. This could be done in conjunction with a minimally invasive, arthroscopic bone grafting technique. Methods. A model consisting of a scaphoid bone with a simulated fracture, a forearm model, and an attached patient tracker was used. 2 titanium K-wires were inserted into the distal scaphoid fragment. 3D images were acquired and matched to those from a computed tomography (CT) scan. In an image processing software, the non-union was reduced and pin tracts were planned into the proximal fragment. The K-wires were driven into the proximal fragment under computer navigation. Reduction was assessed by direct measurement. These steps were repeated in a cadaveric upper limb. A scaphoid fracture was created and a patient tracker was inserted into the radial shaft. A post-fixation CT was obtained to assess reduction. Results and Discussion. In both models, satisfactory alignment was obtained. There were minimal displacement and articular stepping, and scaphoid length was restored with less than 1mm discrepancy. This study demonstrated that an accurate reduction of the scaphoid in non-unions and displaced fractures can be accurately performed using computed navigation and computer-assisted planning. It is the first report on the use of computer navigation in correction of alignment in the wrist