Among the advanced technology developed and tested for orthopaedic surgery, the Rizzoli (IOR) has a long experience on custom-made design and implant of devices for joint and bone replacements. This follows the recent advancements in additive manufacturing, which now allows to obtain products also in metal alloy by deposition of material layer-by-layer according to a digital model. The process starts from medical image, goes through anatomical modelling, prosthesis design, prototyping, and final production in 3D printers and in case post-production. These devices have demonstrated already to be accurate enough to address properly the specific needs and conditions of the patient and of his/her physician. These guarantee also minimum removal of the tissues, partial replacements, no size related issues, minimal invasiveness, limited instrumentation. The thorough preparation of the treatment results also in a considerable shortening of the surgical and of recovery time. The necessary additional efforts and costs of custom-made implants seem to be well balanced by these advantages and savings, which shall include the lower failures and revision surgery rates. This also allows thoughtful optimization of the component-to-bone interfaces, by advanced lattice structures, with topologies mimicking the trabecular bone, possibly to promote osteointegration and to prevent infection. IOR's experience comprises all sub-disciplines and anatomical areas, here mentioned in historical order. Originally, several systems of Patient-Specific instrumentation have been exploited in total knee and total ankle replacements. A few massive osteoarticular reconstructions in the shank and foot for severe bone fractures were performed, starting from mirroring the contralateral area. Something very similar was performed also for pelvic surgery in the Oncology department, where massive skeletal reconstructions for bone tumours are necessary. To this aim, in addition to the standard anatomical modelling, prosthesis design, technical/technological refinements, and manufacturing, surgical guides for the correct execution of the osteotomies are also designed and 3D printed. Another original experience is about en-block replacement of vertebral bodies for severe bone loss, in particular for tumours. In this project, technological and biological aspects have also been addressed, to enhance osteointegration and to diminish the risk of infection. In our series there is also a case of successful custom reconstruction of the anterior chest wall. Initial experiences are in progress also for shoulder and elbow surgery, in particular for pre-op planning and surgical guide design in complex re-alignment osteotomies for severe bone deformities. Also in complex flat-foot deformities, in preparation of surgical corrections, 3D digital reconstruction and 3D printing in cheap ABS filaments have been valuable, for indication, planning of surgery and patient communication; with special materials mimicking bone strength, these 3D physical models are precious also for training and preparation of the surgery. In Paediatric surgery severe multi planar & multifocal deformities in children are addressed with personalized pre-op planning and custom cutting-guides for the necessary osteotomies, most of which require custom allografts. A number of complex hip revision surgeries have been performed, where 3D reconstruction for possible final solutions with exact implants on the remaining bone were developed. Elective surgery has been addressed as well, in particular the customization of an original total ankle replacement designed at IOR. Also a novel system with a high-tibial-osteotomy, including a custom cutting jig and the fixation plate was tested. An initial experience for the design and test of custom ankle & foot orthotics is also in progress, starting with 3D surface scanning of the shank and foot including the plantar aspect. Clearly, for achieving these results, multi-disciplinary teams have been formed, including physicians, radiologists, bioengineers and technologists, working together for the same goal

3D accurate measurements of the skeletal structures of the foot, in physiological and impaired subjects, are now possible using Cone-Beam CT (CBCT) under real-world loading conditions. In detail, this feature allows a more realistic representation of the relative bone-bone interactions of the foot as they occur under patient-specific body weight conditions. In this context, varus/valgus of the hindfoot under altered conditions or the thinning of plantar tissues that occurs with advancing age are among the most complex and interesting to represent, and numerous measurement proposals have been proposed. This study aims to analyze and compare these measurements from CBCT in weight-bearing scans in a clinical population. Sixteen feet of diabetic patients and ten feet with severe adult flatfoot acquired before/after corrective surgery underwent CBCT scans (Carestream, USA) while standing on the leg of interest. Corresponding 3D shapes of each bone of the shank and hindfoot were reconstructed (Materialise, Belgium). Six different techniques found in the literature were used to calculate the varus/valgus deformity, i.e., the inclination of the hindfoot in the frontal plane of the shank, and the distance between the ground and the metatarsal heads was calculated along with different solutions for the identification of possible calcifications. Starting with an accurate 3D reconstruction of the skeletal structures of the foot, a wide range of measurements representing the same angle of hindfoot alignment were found, some of them very different from each other. Interesting correlations were found between metatarsal height and subject age, significant in diabetic feet for the fourth and fifth metatarsal bones. Finally, CBCT allows 3D assessment of foot deformities under loaded conditions. The observed traditional measurement differences and new measurement solutions suggest that clinicians should consider carefully the anatomical and functional concepts underlying measurement techniques when drawing clinical and surgical conclusions

Biomedical imaging is essential in the diagnosis of musculoskeletal pathologies and postoperative evaluations. In this context, Cone-Beam technology-based Computed Tomography (CBCT) can make important contributions in orthopaedics. CBCT relies on divergent cone X-rays on the whole field of view and a rotating source-detector element to generate three-dimensional (3D) volumes. For the lower limb, they can allow acquisitions under real loading conditions, taking the name Weight-Bearing CBCT (WB-CBCT). Assessments at the foot, ankle, knee, and at the upper limb, can benefit from it in situations where loading is critical to understanding the interactions between anatomical structures. The present study reports 4 recent applications using WB-CBCT in an orthopaedic centre. Patient scans by WB-CBCT were collected for examinations of the lower limb in monopodal standing position. An initial volumetric reconstruction is obtained, and the DICOM file is segmented to obtain 3D bone models. A reference frame is then established on each bone model by virtual landmark palpation or principal component analysis. Based on the variance of the model point cloud, this analysis automatically calculates longitudinal, vertical and mid-lateral axes. Using the defined references, absolute or relative orientations of the bones can be calculated in 3D. In 19 diabetic patients, 3D reconstructed bone models of the foot under load were combined with plantar pressure measurement. Significant correlations were found between bone orientations, heights above the ground, and pressure values, revealing anatomic areas potentially prone to ulceration. In 4 patients enrolled for total ankle arthroplasty, preoperative 3D reconstructions were used for prosthetic design customization, allowing prosthesis-bone mismatch to be minimized. 20 knees with femoral ligament reconstruction were acquired with WB-CBCT and standard CT (in unloading). Bone reconstructions were used to assess congruency angle and patellar tilt and TT-TG. The values obtained show differences between loading and unloading, questioning what has been observed so far. Twenty flat feet were scanned before and after Grice surgery. WB-CBCT allowed characterization of the deformity and bone realignment after surgery, demonstrating the complexity and multi-planarity of the pathology. These applications show how a more complete and realistic 3D geometric characterization of the of lower limb bones is now possible in loading using WB-CBCT. This allows for more accurate diagnoses, surgical planning, and postoperative evaluations, even by automatisms. Other applications are in progress

Background. Radiological and clinical results of total shoulder arthroplasty are dependent upon ability to accurately measure and correct glenoid version. There are a variety of imaging modalities and computer-assisted reconstruction programmes that are employed with varying degrees of success. We have compared three freely available modalities: unformatted 2D CT; formatted 2D CT; and 3D CT reconstructions. Methods. A retrospective analysis of 20 shoulder CT scans was performed. Glenoid version was measured at the estimated mid-point of the glenoid from unformatted 2D CT scans (Scapula body method) and again following formatting of 2D CT scans in the plane of the scapula (Friedman method). 3D scapula reconstructions were also performed by downloading CT DICOM images to OSIRIX 6 and plotting ROI points on Friedman's axis to most accurately define glenoid version. Both measurements taken from 2D CT were compared to those from 3D CT. Eleven CT scans were of male patients, 9 female. Mean age was 55.2 years (Range: 23–77 years). Fourteen scans were performed for trauma, 6 for arthroplasty. Twelve scans were of the left shoulder. Results. Mean glenoid version as measured on: unformatted 2D CT was −4.51 degrees (−29.67 – 7.22 degrees); formatted 2D CT was −2.04 degrees (−36.96 – 9.72 degrees); and on 3D reconstructions was −3.01 degrees (−32.57 – 14.33 degrees). Sixty percent of measurements taken on formatted 2D CT were within 3 degrees of those taken on 3D reconstructions, with 85% within 5 degrees. This proportion fell to 30% and 50% respectively on unformatted 2D CT. Discussion. In this small study measurements of glenoid version taken on formatted 2D CT demonstrated greater accuracy than unformatted 2D CT when comparing to 3D reconstruction measurements as the gold standard. Although we demonstrated no significant statistical difference between measurements in this pilot study we believe significance will be obtained as we increase our sample size

Introduction and Objective. Heterotopic ossification is the formation of extraskeletal mineralized tissue commonly associated with either trauma or surgery. While several mouse models have been developed to better characterize the pathologic progression of HO, no model currently exists to study HO of the hip, the most common location of acquired HO in patients. Owing to the unique biological mechanisms underpinning the formation of HO in different tissues, we sought to develop a model to study the post-surgical HO of the hip. Materials and Methods. Wild-type mice C57BL/6J mice were used to study the procedure outcomes, while Pdgfra-CreERT2;mT/mG and Scx-GFP reporter animals were used for the lineage tracing experiments (total n=16 animals, male, 12 weeks old). An anterolateral approach to the hip was performed. Briefly, a 2 cm incision was made centered on the great trochanter and directed proximal to the iliac crest and distally over the lateral shaft of the femur. The joint was then reached following the intermuscular plane between the rectus femoris and gluteus medius muscles. After the joint was exposed, the articular cartilage was removed using a micropower drill with a 1.2 mm reamer. The medius gluteus and superficial fascia were then re-approximated with Vicryl 5-0 suture (Ethicon Inc, Somerville, NJ) and skin was then closed with Ethilon 5-0 suture (Ethicon Inc). Live high resolution XR imaging was performed every 2 wks to assess the skeletal tissues (Faxitron Bioptics, Tucson, AZ). The images were then scored using the Brooker classification. Ex-vivo microCT was conducted using a Skyscan 1275 scanner (Bruker-MicroCT, Kontich, Belgium). 3D reconstruction and analysis was performed using Dragonfly (ORS Inc., Montreal, Canada). For the histological analysis of specimens, Hematoxylin and Eosin (H&E), modified Goldner's Trichrome (GMT) stainings were performed. Reporter activity was assessed using fluorescent imaging. Results. Substantial periarticular heterotopic bone was seen in all cases. A periosteal reaction and an initial formation of calcified tissue within the soft tissue was apparent starting from 4 wks after surgery. By XR, progressive bone formation was observed within the periosteum and intermuscular planes during the subsequent 8 weeks. Stage 1 HO was observed in 12.5% of cases, stage 2 in 62.5% of cases, and stage 3 HO in 25% of cases. 3D microCT reconstructions of the treated hip joints demonstrated significant de novo heterotopic bone in several location which phenocopy human disease. Heterotopic bone was observed in an intracapsular location, periosteal location involving the iliac bone and proximal femur, and intermuscular locations. Histological analyses further confirmed these findings. To assess the cells which gave rise to HO in this model, an inducible PDGFRα and constitutive Scx-GFP reporter mice were used. A dramatic increase in mGFP reporter activity was noted PDGFRα within the HO injury site, including in areas of new cartilage and bone formation. Scx-associated reporter activity increased in the soft tissue and periosteal periacetabular areas of injured hips. Conclusions. HO has a diverse set of pathologies, of which joint associated HO after elective surgery is the most common. Here, we present the first mouse model of hip dislocation and acetabular reaming that mimics elements of human periarticular HO. The diverse locations of HO after acetabular reaming (intracapsular, intermuscular and periosteal) suggests the activation of different and specific HO program after surgery. Such a field effect would be consistent with local trauma and inflammation, which is a well-studied contributor to HO genesis. Not surprisingly, joint-associated HO significantly derives from PDGFRα-expressing cells, which has been shown to similarly give rise to intramuscular and intratendinous HO

Summary. The EOS stereography system has been developed for the evaluation of prosthetic alignment. This new low-dose device provides reliable 2D/3D measurements of knee prosthesis alignment. Introduction. Achieving optimal prosthetic alignment during Total Knee Arthroplasty (TKA) is an essential part of the surgical procedure since malpositioning can lead to early loosening of the prosthesis and eventually revision surgery. Conventional weight-bearing radiographs are part of the usual clinical follow-up after both primary TKA and revision TKA (rTKA), to assess alignment in the coronal and sagittal planes. However, proportions and angles may not be correct on radiographs since divergence exists in the vertical and horizontal planes. Furthermore estimating the exact planes by looking at the position of the patella depends on rotation in the hip joint and this may be misinterpreted by the investigator. A computed tomography (CT) scanogram can also be used. However, due to high levels of radiation and costs it is not routinely used. To this end, a new device, the EOS stereography system, has been developed. With this biplanar low-dose X-ray technique, orthogonally made 2D images and 3D reconstructions can be obtained. Advantages of EOS are that images of the leg are obtained on a 1:1 scale with an amount of radiation 800–1000 times lower than CT-scans and 10 times lower than conventional radiographs. Another advantage is that the 3D reconstructions lead to determination of the real coronal and sagittal planes. However, the software for creating 3D reconstructions is developed for the lower limbs without knee prosthesis material. Consequently a reliability study concerning the generation of 2D images and 3D reconstructions of a leg containing a knee prosthesis has not been performed yet. Therefore objective of this study was to investigate interobserver and intraobserver reliability of knee prosthetic alignment measurements after rTKA using EOS. Patients and Methods. Forty anteroposterior and lateral images of 37 rTKA patients were included. Two observers independently performed measurements on these images twice. Measured angles were varus/valgus angle in 2D (VV2D) and 3D (VV3D). Intraclass correlation coefficients (ICCs) were used to determine relative reliability and the Bland and Altman method was used to determine absolute reliability. T-tests were used to test potential differences between the two observers, first and second measurement sessions and 2D and 3D measurements. Results. Relative interobserver reliability was excellent for both VV2D and VV3D with ICCs > 0.95, and no significant differences between the two observers. For the absolute reliability of VV2D, a bias of −0.16° (95%CI: −0.31–0.01) existed between both observers. Absolute reliability of VV3D was good. Relative intraobserver reliability was excellent for both VV2D and VV3D with ICCs > 0.97. No significant difference and no bias between the first and second measurements were found. A significant difference existed between the angles measured in 2D and 3D (p=0.01). Discussion / Conclusion. The EOS low-dose stereography system provides reliable varus/valgus measurements in 2D and 3D for the alignment of the knee joint with a knee prosthesis. However, significant differences exist between the varus/valgus measurements in 2D and in 3D. Therefore, a validation study is suggested to investigate the difference between the 2D measurements and 3D reconstructions and to find a possible explanation for this difference

Introduction and Objective. Medial Knee Osteoarthritis (MKO) is associated with abnormal knee varism, this resulting in altered locomotion and abnormal loading at tibio-femoral condylar contacts. To prevent end-stage MKO, medial compartment decompression is selectively considered and, when required, executed via High Tibial Osteotomy (HTO). This is expected to restore normal knee alignment, load distribution and locomotion. In biomechanics, HTO efficacy may be investigated by a thorough analysis of the ground reaction forces (GRF), whose orientation with respect to patient-specific knee morphology should reflect knee misalignment. Although multi-instrumental assessments are feasible, a customized combination of medical imaging and gait analysis (GA), including GRF data, rarely is considered. The aim of this study was to report an original methodology merging Computed-Tomography (CT) with GA and GFR data in order to depict a realistic patient-specific representation of the knee loading status during motion before and after HTO. Materials and Methods. 25 MKO-affected patients were selected for HTO. All patients received pre-operative clinical scoring, and radiological/instrumental assessments; so far, these were also executed post-operatively at 6-month follow-up on 7 of these patients. State-of-the-art GA was performed during walking and more demanding motor tasks, like squatting, stair-climbing/descending, and chair-rising/sitting. An 8-camera motion capture system, combined with wireless electromyography, and force platforms for GRF tracking, was used together with an own established protocol. This marker-set was enlarged with 4 additional skin-based non-collinear markers, attached around the tibial-plateau rim. While still wearing these markers, all analyzed patients received full lower-limb X-ray in standing posture a CT scan of the knee in weight-bearing Subsequently, relevant DICOMs were segmented to reconstruct the morphological models of the proximal tibia and the additional reference markers, for a robust anatomical reference frame to be defined on the tibia. These marker trajectories during motion were then registered to the corresponding from CT-based 3D reconstruction. Relevant registration matrices then were used to report GRF data on the reconstructed tibial model. Intersection paths of GRF vectors with respect to the tibial-plateau plane were calculated, together with their centroids. Results. Pre-operative clinical and radiological scoring confirmed MKO and associated abnormal varism. The morphological characterization of GRF was successfully achieved pre- and post- HTO on patient-specific tibial plateau. Pre-operative GFR patterns and peaks, including those related to knee joint moments, were observed medially on the knee, as expected. In post-HTO, these resulted lateralized and much closer to the tibial plateau spine, as desired. In detail, when post- is compared to pre-op, the difference of the centroids were, on average, 54.6±18.1 mm (min÷max: 36.7÷72.8 mm) more lateral during walking and 52.5±28.5 mm (24.7÷87.6 mm) during stair climbing. When reported in % of the tibial plateau width, these values became 69.2±20.1 (46.1÷81.4) and 78.1±30.1 (43.4÷98.0), respectively. Post-op also clinical scores and GA revealed a considerable overall improvement, especially in functional performances. Conclusions. The reported novel approach allows a combination of motion data, including GFR, and tibial-plateau morphology. Relevant pre- and post-operative routine application offer a quantification of the effect of the original deformity and executed joint realignment, and an assistance for surgical planning in case of HTO as well as ideally in other orthopedic treatments

Introduction. The human wrist is a highly complex joint, offering extensive motion across various planes. This study investigates scapholunate ligament (SLL) injuries’ impact on wrist stability and arthritis risks using cadaveric experiments and the finite element (FE) method. It aims to validate experimental findings with FE analysis results. Method. The study utilized eight wrist specimens on a custom rig to investigate Scapho-Lunate dissociation. Contact pressure and flexion were measured using sensors. A CT-based 3D geometry reconstruction approach was used to create the geometries needed for the FE analysis. The study used the Friedman test with pairwise comparisons to assess if differences between testing conditions were statistically significant. Result. The study found significant variations in scaphoid and lunate bone movement based on ligament condition. Full tears increased scapholunate distance in the distal-proximal direction and decreased in the medial-lateral direction. Lunate angles shifted from flexion to extension with fully torn ligaments. Conversely, the scaphoid shifted significantly from extension to flexion with full tears. A proximal movement was observed in the distal-proximal direction in all groups, with significant differences in the partial tear group. Lateral deviation of the scaphoid and lunate occurred with ligament damage, being more pronounced in the partial tear group. All groups exhibited statistically significant movement in the volar direction, with the full tear group showing the least movement. Also, radiocarpal joint and finger contact pressure and contact area were studied. Whereas the differences in contact area were not significant, scapholunate ligament tears resulted in significantly decreased finger contact pressures. FEA confirmed these findings, showing notable peak radiocarpal contact pressure differences between intact and fully torn ligaments. Conclusion. Our study found that SLL damage alters wrist stability, potentially leading to early arthritis. The FEA model confirmed these findings, indicating the potential for the clinical use of computer models from CT scans for treatment planning

Summary Statement. We successfully delineated the 3D micro morphology of chondrocytes in patella-patellar tendon using IL-XPCT for the first time. Compared with conventional histology, IL-XPCT can not only provide a higher resolution imgaing but also keep the 3D integrity of the specimen. Introduction. The morphology of the bone-tendon junction was complex and quite different from other organs, which result the injured bone-tendon junction repair process too slowly. To study the micro morphology of the bone-tendon junction in 3D may have a great significant value to revealing the repair mechanisms of this pathological process and accelerating injured bone-tendon junction repair. However, it was hindered by the convention methods such as histologic section. In our study, a novel imaging tool, synchrotron radiation based in-line x-ray phase contrast imaging (IL-XPCT) was used to research the 3D micro morphology of the bone-tendon junction. Methods. 1) Sample Preparation: 3 patella-patellar tendons was harvested from the knee joint of New Zealand adult rabbits and was immediately fixed, rinsed in water for 2 hours. Dehydration was done using a series of graded ethanol. The sample was cut out for the CCD pixel resolution in sagittal section. 2) Image Acquisition: The IL-XPCT was performed at the BL13W1 of the Shanghai Synchrotron Radiation Facility (SSRF) in China. The CCD pixel resolution was 0.74 μm. Image Acquisition include three steps, such as the the acquisition of tomo projections, CT slices and and 3D reconstruction of patella-patellar tendon on full scale by using VG Studio Max version 2.1. 3) Histological characterization observation: After scanning, the specimen was cut to histologic sectioning and used for morphology staining by safranin O staining and H&E staining. The histological morphology then compared with the IL-XPCT imaging dateset. Results. (1) The tissue gradations of patella-patellar tendon are clearly detected by IL-XPCT. (2) The 3D reconstruction image of patella-patellar tendon sample were largely match with the histological morphology stained by safranin O and H&E in sagittal view. (3) After the image segmentation, the 3D micro morphology of the bone-tendon junction could be vividly visualised in multi-angles. Through manipulate threshold of the 3D image, we can successfully obtained the 3D morphology of the chondrocyte, and the smallest diameter is approximately 5μm. Discussion & Conclusion. In the present study, we successfully delineated the 3D micro morphological features of chondrocytes in normal patella-patellar tendon using SR-based IL-XPCT for the first time. Compared with conventional histology, IL-XPCT can not only provide a higher resolution ratio without distortion but also keep the three-dimensional integrity of the specimen. Above all, IL-XPCT opens access to a new dimension in the morphological investigation of bone-tendon junction tissues, giving important complementary information to the conventional morphological analyses in view of the three-dimensional composition of bone-tendon junction tissues, On the other hand, it could be helpful to understanding the repair processes of bone-tendon junction injury and promoting the injured bone-tendon junction repair fast and high quality

High ankle sprains (HAS) cause subtle lesions in the syndesmotic ligaments of the distal tibiofibular joint (DTFJ). Current intrinsic anatomical parameters of the DTFJ are determined based on 2D imaging and uncertainty remains whether they differ in a HAS patients. The aim of this study is therefore two-fold: radiographic parameters will be determined in 3D and compared in a healthy vs sprained group. Ten patients with a mean age of 42,56 (SD = 15,38) that sustained a HAS and twenty-five control subjects with a mean age of 47,44 (SD = 6,55) were retrospectively included. The slices obtained from CT analysis were segmented to have a 3D reconstruction. The following DTFJ anatomical parameters were computed using CAD software: incisura width, incisura depth, incisura length, incisura angle, and incisura-tibia ratio. The mean incisura depth in the sprained group was 3,93mm (SD = 0,80) compared to 4,76 mm (SD = 1,09) in the control group, which showed a significant difference (P < 0.05). The mean incisura length in the group of patients with HAS was 30,81 mm (SD = 3,17) compared to 36,10mm (SD = 5,27) in the control group which showed a significant difference (P < 0.05). The other DTFJ anatomical parameters showed no significant difference. This study shows a significant difference in both incisura depth and incisura length between HAS patients and control subjects. These parameters could be used to identify potential anatomical intrinsic risk factors in sustaining a HAS

Reconstruction of severe acetabular defects during revision hip arthroplasty presents a significant surgical challenge. Such defects are associated with significant loss of host bone stock, which must be addressed in order to achieve stable implant fixation. A number of imaging techniques including CT scanning with 3D image reconstruction are available to assist the surgeon in the pre-operative planning of such procedures. We describe the use of a novel technique to assist the pre-operative planning of severe acetabular defects during revision hip arthroplasty. Patient and Methods – We present the use of this technique in the case of a 78 year old patient who presented 20 years from index procedure with severe hip pain and inability to weight bear due aseptic loosening of a previously revised total hip arthroplasty. A Paprosky 3B defect was noted with intra-pelvic migration of the acetabular component. Pre-operative investigations included: inflammatory markers, pelvic CT scan with 3D reconstruction, pelvic angiography and hip aspiration. Using DICOM images obtained from the CT scan, we used free open source software to carry out a 3D surface render of the bony pelvis. This was processed and converted to a suitable format for 3D printing. Using selective laser sintering, a physical 3D model of the pelvis, acetabular component and proximal femur were produced. Using this model the surgeon was able to gain an accurate representation of both the position of the intra-pelvic cup and more accurately assess the loss of bone stock. This novel technique is particularly useful in the pre-operative planning of such complex acetabular defects in order to determine if/which reconstruction technique is most likely to be successful. 3D printing is a relatively recent technology, which has numerous potential clinical applications. This is the first reported case of this technology being used to assess acetabular defects during revision hip arthroplasty. The use of this technology gives the surgeon a 3D model of the pelvis, quickly (7 days from CT) and at a tenth of the cost (£280) of producing such a model through the traditional commercial routes. The model allowed the surgeon to size potential implant, quantify the amount of bone graft required (if applicable) and to more accurately classify the loss of acetabular bone stock

Aims

This study intended to investigate the effect of vericiguat (VIT) on titanium rod osseointegration in aged rats with iron overload, and also explore the role of VIT in osteoblast and osteoclast differentiation.

Background. Achieving optimal prosthesis alignment during total knee arthroplasty (TKA) is essential. Imageless computer-assisted surgery (CAS) is developed to improve knee prosthesis alignment and with CAS it is possible to perform intraoperative alignment measurements. Lower limb alignment measurements are also performed for preoperative planning and postoperative evaluation. A new stereoradiography system, called EOS, can be used to perform these measurements in 3D and thus measurement errors due to malpositioning can be eliminated. Since both CAS and EOS are based on 3D modeling, measurements should theoretically correlate well. Therefore, objective was to compare intraoperative CAS-TKA measurements with pre- and postoperative EOS 3D measurements. Methods. In a prospective study 56 CAS-TKAs were performed and alignment measurements were recorded two times: before bone cuts were made and after implantation of the prosthesis. Pre- and postoperative coronal alignment measurements were performed using EOS 3D. CAS measurements were compared with EOS 3D reconstructions. Measured angles were: varus/valgus (VV), mechanical lateral distal-femoral (mLDFA) and medial proximal tibial angle (mMPTA). Results. Significantly different VV angles were measured pre- and postoperatively with CAS compared to EOS. For preoperative measurements, mLDFA did not differ significantly, but a significantly larger mMPTA in valgus was measured with CAS. Conclusions. EOS 3D measurements overestimate VV angle in lower limbs with substantial mechanical axis deviation. For lower limbs with minor mechanical axis deviation as well as for mMPTA measurements, CAS measures more valgus compared to EOS. Results of this study indicate that differences in alignment measurements between CAS measurements and pre- and postoperative EOS 3D are mainly due to the difference between weight bearing and non-weight bearing position and potential errors in validity and reliability of the CAS system. Surgeons should be aware of these measurement differences and the pitfalls of both measurement techniques. Level of evidence. IIb. Disclosures. The department of Orthopaedics, University of Groningen, University Medical Center Groningen receives research institutional support from InSpine (Schiedam, NL) and Stryker (Kalamazoo, Mich. USA). One of the authors (ALB) will be and has been paid as a consultant by Zimmer (Warsaw, IN, USA) for purposes of education and training in knee arthroplasty

3D printing can be used for the regeneration of complex tissues with intricate 3D microarchitecture. Trabecular bone is a complex and porous structure with a high degree of anisotropy. Changes in bone microarchitecture are associated with pathologies such as osteoporosis [1]. The objective of this study is to determine the viability of using 3D printing to replicate trabecular bone structures with a good control over the microarchitecture and mechanical properties. Cylindrical samples of bovine trabecular bone were used in this study. Micro-computed tomography (microCT) was carried out and an isotropic voxel size of 22 µm was obtained (Xradia Versa 520, Zeiss, USA). After 3D reconstruction the main microstructure characteristics were analysed using ImageJ (NIH, US). The 3D printed bone replicas were created by segmenting the microCT imaged bone tissue and then converted into a STL file using Avizo (FEI, US). The 3D printer used for this study was the ProJet 5500X (3D Systems, US), which allows a number of different materials to be printed in the same built with a resolution of 25 µm. Preliminary results were obtained using one single material (VisiJet CR-WT, Tensile Modulus: 1–1.6 GPa, Tensile Strength: 37–47 MPa). The 3D printed bone replicas followed a critical cleaning step to remove any remaining support material in the pores. MicroCT was then carried out for the bone replicas obtaining the same isotropic voxel size as for their biological counterparts. ImageJ was used to obtain the main microstructure characteristics. The values of bone volume fraction (BV/TV), mean trabecular thickness (Tb.Th), mean trabecular spacing (Tb.Sp), and degree of anisotropy (DA) were measured for bone samples and their 3D printed replicas [2]. Preliminary results on the first bone sample with its 3D printed replica showed similar apparent trabecular structures. Their respective BV/TV was found to be 0.24 (bone) and 0.43 (replica). The Tb.Th and Tb.Sp were 0.222 mm and 0.750 mm respectively for the bone and 0.376 mm and 0.575 mm for the replica. Finally, their respective DA was found to be 0.68 (bone) and 0.66 (replica). The main microstructure characteristics analyzed showed some differences between the bone sample and the 3D printed replica. In particular, the 3D microstructures resulted over-dimensioned mainly due to factors such as microCT voxel size, resolution of the 3D printer and supporting material removal. However this is a preliminary investigation. Further analysis will focus on optimizing the microCT imaging as well as the 3D printing process to achieve more accurate bone replicas. In addition, multi-material printing will be employed to optimize some of the mechanical properties obtained through in situ microCT testing and FE subject-specific modelling

DVC is a novel full-field and contactless measurement technique for calculating displacements and strains inside bones (Grassi and Isaksson 2015) through the comparison of 3D reconstructions (CT, micro-CT, MRI, etc.) from unloaded and loaded samples. Recent in zero-strain tests to estimate the measurement precision by applying a known state of strain (Palanca, Tozzi et al. 2015) suggested that DVC is suitable to identify regions where bone tissue is yielded (i.e. subjected to high strains). Conversely to reliably measure strain in the physiological range a severe compromise with spatial resolution is necessary (Dall'Ara, Barber et al. 2014, Palanca, Tozzi et al. 2015). In order to use DVC to explore the relationship between the local physiological strain and bone microarchitecture, an error lower than 200 microstrain (an order of magnitude lower than the mean strain) and a spatial resolution of the strain measurement lower than 100 μm is required. The aim of this work is to define if, and to what extend, high-quality images obtained by synchrotron radiation micro computed tomography (SR-μCT) improve the precision of a global DVC approach. Cylindrical specimens of cortical and trabecular bone were extracted from a fresh bovine femur and embedded in acrylic resin. Both samples were scanned twice without any repositioning (‘repeated scantest’) at beamline l13–2 of Diamond Light Source (Oxford, UK). 4000 projections of 53 ms exposure were collected via fly-scanning with a CdWO. 4. scintillator-coupled pco.edge 5.5 detector with 4× magnification and an effective pixel size of 1.6μm. Strains were evaluated using a global DVC approach (ShIRT-FE) in two cubic volumes of interest (VOI) of 1,000 voxels in side length, for each specimen, exploring a DVC spatial resolution from 16 to 498 μm. The precision of measurements was evaluated extracting a similar indicator to (Liu and Morgan 2007). Precision improved with decreasing spatial resolution, confirming a trend similar to that obtained with ‘laboratory source’ μCT on similar specimens (Palanca, Tozzi et al. 2015). To obtain a precision of better than 200 microstrains the cortical and trabecular samples required spatial resolutions of 41 and 80 μm respectively. Comparing these results to those of previous studies, where similar specimens were scanned with ‘laboratory source’ μCT (effective voxel size of the order of ten μm) the errors were vastly reduced (approximately one order of magnitude). In fact, in order to obtain a precision of better than 200 microstrain, spatial resolutions of 550 (cortical) and 480 (trabecular) μm were needed (Dall'Ara, Barber et al. 2014). This work showed that using high-quality tomograms obtained by synchrotron radiation μCT decreases the measurement uncertainties of a global DVC approach with respect to those obtained with laboratory source μCT. DVC could therefore be used with μCT data to evaluate displacement and strain in the physiological range with remarkable spatial resolution

Background:. The Lateral Intercondylar Ridge (LIR) gained notoriety with arthroscopic trans-tibial Anterior Cruciate Ligament (ACL) reconstruction where it was mistakenly used to position the ‘over the top’ guide resulting in graft malposition. With anatomic ACL reconstruction some surgeons use the same ridge to define the anterior margin of the ACL femoral insertion in order to guide graft placement. However there is debate about whether this ridge is a consistent and reliable anatomical structure. The aim of our study was to identify whether the LIR is a consistent anatomical structure and to define its relationship with the femoral ACL insertion. Methods:. In the first part, we studied 23 dry bone specimens. Using a digital microscribe, we created a 3D model of the medial surface of the lateral femoral condyle to evaluate whether there was an identifiable bony ridge. In the second part, we studied 7 cadaveric specimens with soft tissues intact. The soft tissues were dissected to identify the femoral ACL insertion. A 3D reconstruction of the femoral insertion and the surface allowed us to define the relationship between the LIR and the ACL insertion. Results:. All specimens (23 dry bones; 7 intact soft tissues) had a defined ridge on the medial surface of the lateral femoral condyle. The ridge extends from the apex point of the lateral intercondylar notch, where the posterior condyle meets the femoral shaft, and extends obliquely to the articular margin. The mean distance from the midpoint of the posterior condylar articular margin was 10.1 mm. The ridge was consistently located just anterior to the femoral ACL insertion. Conclusion:. This study shows that the LIR is a consistent anatomical structure that defines the anterior margin of the femoral ACL insertion. This supports its use as a landmark for femoral tunnel placement in ACL reconstruction surgery. Abstract 28

Introduction. The equine SDFT tendon is a complex hierarchal structure that transmits force from muscle to bone and stores energy through its stretching and recoiling action. It is a common site of pathology in athletic horses. Our aim was to describe the ultrastructural anatomy of the SDFT as part of a larger programme to understand the structure-functional relationship of this tendon. Materials and Methods. Fifteen SDFT from different aged horses, sectioned transversely (2–3 mm thickness) and then photographed using Canon EOS 5D Mark III (100 mm focal length). Images processed through ImageJ and IMOD software for 3D reconstruction. Samples were also taken from the proximal, middle and distal part of the SDFT from a foetal, one and nine years old horse, processed for H&E staining and sectioned longitudinally in series into 20 sections (5µm), additionally the mid metacarpal region of one year old was fully sectioned into 250 sections. The entire cut surface on the slide was imaged and transformed to one collated image using Inkscape. Using IMOD collated photos transformed to mrc file (Z-stack) and in order to reconstruct 3D forms. Results. A tertiary fascicle was defined as a bundle of collagen fibres surrounded by a well-defined interfascicular matrix IFM (width 34.56 µm +/− 16.43 (St.Dev)). Secondary fascicles were defined as subdivisions of the tertiary fascicles (IFM width 11.1 µm +/− 4.01 (St.Dev)) (n=2). Using this classification we found that the numbers of the secondary and tertiary fascicles were not continuous through the tendon in a proximal to distal regions of the tendon. The histological 3D anatomy manifests similar fascicular structure in all ages, but their fascicular contours were less irregular in aged and in the mid-metacarpal region. The 3D anatomy of the mid-metacarpal tendon demonstrated heterogeneous fascicles, which had helical arrangement in their longitudinal axis. Discussion. Secondary and tertiary fascicles are heterogeneous in numbers, shapes and interconnections with each other in different regions. Fascicles appear to branch from proximal to distal through the tendon and are not always continuous through the tendon length. Some fascicles intercommunicating with each other and have helical configuration. Understanding the 3D anatomy will facilitate understanding of tendon structure-function relationships and injury predisposition

Talar neck fractures are associated with high complication rates with significant associated morbidity. Adequate exposure and stable internal fixation remains challenging. We investigated the anterior extensile approach for exposure of these fractures and their fixation by screws introduced through the talo-navicular articulation. We also compared the quality and quantity of exposure of the talar neck obtained by this approach, with the classically described medial/lateral approaches. An anterior approach to the talus between the tibialis anterior and the extensor hallucis tendons protecting both the superficial and deep peroneal nerves was performed on 5 fresh frozen cadaveric ankles . The surface area of talar neck accessible was measured using an Immersion Digital Microscribe and analysed with Rhinoceros 3D graphics package. Standard antero-medial and antero –lateral approaches were also carried out on the same ankles, and similar measurements taken. Seven talar neck fractures underwent operative fixation using the anterior approach with parallel cannulated screws inserted through the talo-navicular joint. 3D mapping demonstrated that the talar surface area visible by the anterior approach (mean 1200sqmm) is consistently superior to that visible by either the medial or lateral approaches in isolation or in combination. Medial malleolar osteotomy does not offer any additional visualisation of the talar neck. 3D reconstruction of the area visualised by the three approaches confirms that the anterior approach provides superior access to the entirety of the talar neck. 5 male and 2 female patients were reviewed. All had anatomical articular restoration, and no wound problems. None developed non union or AVN. The anterior extensile approach offers superior visualisation of the talar neck in comparison to other approaches for anatomical articular restoration. We argue that this approach is safe, adequate and causes less vascular disruption

The arterial supply of the talus has been extensively studied in the past but there is a paucity of information on the arterial supply to the navicular and a very limited understanding of the intra-osseous supply to the surface of either of these bones. This is despite the likely importance of this supply in relation to conditions such as osteochondral lesions of the dome of the talus, and avascular necrosis and stress fracture of the navicular. Using cadaveric limbs, dissection of the source vessels was performed followed by arterial injection of latex. The talus and navicular were then removed en bloc, preserving the integrity of the injected arterial vasculature. The specimens were then processed using a new, accelerated diaphanisation technique. This rendered the tissue transparent, allowing the injected vessels to be visualised and then mapped onto a 3D virtual reconstruction of the bone. The vasculature to the subchondral surfaces of the talus and navicular, and the source vessel entry points that provide arterial supply into the navicular were identified. This study gives quantifiable evidence of the areas of consistently poor blood supply which may help explain the clinical pattern of talar and navicular pathology. It also provides as yet unpublished information on the arterial supply of the human navicular bone

3D printing and rapid prototyping in surgery is an expanding technology. It is often used for preoperative planning, procedure rehearsal and patient education. There have been recent advances in orthopaedic surgery for the development of patient specific guides and jigs. The logical next step as the technology advances is the production of custom orthopaedic implants. I aimed to use freely available open source software and online cloud 3D printing services to produce a patient specific orthopaedic implant without requiring the input of a university department, specialised equipment or implant companies. Using standard CT scan DICOM data, a 3D surface reconstruction was made of a patient's uninjured radial head using open source DICOM viewer OsiriX. This was then manipulated in other open source software packages called Meshlabs and Netfabb to create a mirror image 3D model of the radial head with a stem to produce a prosthesis suitable to replace the contralateral fractured radial head. This was then uploaded and printed in stainless steel via cloud printing service . Shapeways.com. . The model produced was an exact replication of the patient's original anatomy, except a mirror image suitable for replacement of the contralateral side. The process did not involve any specialist equipment or input from an academic department or implant company. It took a total of 10 days to produce and cost less than £40. From this study I was able to show that production of patient specific orthopaedic implants is possible. It also highlights that the technology is accessible to all, and does not require any special equipment or large investment. It can be achieved quickly and for a very small financial outlay. As a proof of concept it has been very successful