Summary Statement. It is now possible to diagnose osteoporosis using incidental abdominal CT scans; applying this approach to fractures of the cervical spine demonstrates levels of osteoporosis in patients over 65. Introduction. Recently published data now makes it possible to screen for osteoporosis in patients who, in the course of their hospital stay, have had Computed Tomography (CT) scans of their abdomen for reasons other than direct imaging. This is as a result of CT derived bone mineral density (BMD) in the first lumbar vertebra (L1) being correlated BMD derived from Dual-energy X-ray absorptiometry (DEXA) scans. The advantage of this is the reduction in both cost and radiation exposure. Although age has a detrimental effect on BMD, relatively few patients have formal DEXA studies. The aims of this study were to evaluate the utility of this new technique in a cohort of patients with acute fractures of the cervical spine and to compare relative values for BMD in patients aged over 65 with those aged under 65, and thus define the role of osteoporosis in these injuries. Methods & Patients. Following Institutional review board approval, we performed a retrospective study of patients who presented to a level I trauma center with acute fractures of the cervical spine between 2010 and 2013; patients also had to have had a CT scan of their L1 vertebra either during the admission or within 6 months of their admission (for any other clinical reason). Using a picture archiving and communication (PACS) system, we generated regions of interest (ROI) of similar size in the body of L1 (excluding the cortex), in line with the publication by Pickhardt et al., and computed the mean values for Hounsfield units (HU). These values were compared against established threshold values which differentiate between osteoporosis and osteopenia; for a balanced sensitivity and specificity, <135 HU is the threshold and for 90% sensitivity a HU threshold of <160 HU is set. Comparisons were also performed between age stratified groups. Results. A total of 187 patients were reviewed for eligibility, 91 patients met the criteria with 53 patients aged 64 years or younger (range 23–64) and 38 patients aged above 65 years (range 65–98). In the younger cohort, 6/53 (11% were osteoporotic, using the lower threshold, while the higher threshold indicated 5/53 (17%) of patients under 65 years were osteoporotic; mean HU for the group was 195.8 (SD 43.3). In the older cohort, 24/38 (63%) were osteoporotic using the lower threshold, whereas 34/38 (89%) were osteoporotic using the higher threshold. Mean HU for the cohort aged over 65 years was 118.7 (SD 38.4). Age based comparison of the mean values, regardless of threshold, was statistically significant (p<0.001) in both cases. Discussion and Conclusions. This study demonstrates, for the first time in the cervical spine (including C2), the role of age related osteoporosis in acute fractures of the cervical spine. This new technique harnessing the presence of opportunistic CT scans of the abdomen saves on the extra cost and radiation exposure that may be associated with DEXA scanning. In younger patients, the higher threshold indicated 17% were osteoporotic – in the setting of an opportunistic scan, this may afford them the opportunity to commence prophylactic treatment to prevent future fractures. We believe these result have the potential to significantly impact future clinical practice

Summary Statement. Using abdominal CT scans to evaluate bone mineral density following acute fractures of the thoracic and lumbar spine demonstrates significant levels of osteoporosis in older patients; this approach may help save on time and resources, and reduce unnecessary radiation exposure. Introduction. While a reduction in bone mineral density (BMD) is associated with aging, relatively few patients have formal dual-energy X-ray absorptiometry (DXA) to quantify the magnitude of bone loss, as they age. This loss of bone may predispose to fractures. Recent data, which correlates mean Hounsfield units (HU) in an area of the L1 vertebra with BMD, now makes it possible to screen for osteoporosis using incidental abdominal Computed Tomography (CT) scans to measure bone density. This innovation has the potential to reduce both cost and radiation exposure, and also make it easier to identify patients who may be at risk. The aims of this study were to evaluate the utility of this approach in patients with acute thoracic and lumbar spine fractures and to evaluate the impact of aging on BMD, using CT screening. Patients & Methods. Following institutional review board approval, we performed a retrospective study of patients who presented to a level I trauma center with acute fractures of the thoracic and lumbar spine between 2010 and 2013; patients also had to have had an abdominal (or L1) CT scan either during the admission or in the 6 months before or after their injury. Using a picture archiving and communication (PACS) system, we generated regions of interest (ROI) of similar size in the body of L1 (excluding the cortex) and computed mean values for HU. Values derived were compared against threshold values which differentiate between osteoporosis and osteopenia - for specificity of 90%, a threshold of 110 was set; for balanced sensitivity and specificity, a threshold of <135 HU was set and for 90% sensitivity a threshold of <160 HU was set. A student's t test was used to compare the age stratified mean HU (younger than 65yrs; 65yrs and older), while Fisher's exact test was used to perform aged stratified comparisons between the proportions of patients above and below the thresholds outlined (in each of the three threshold groups). Results. A total of 124 patients were evaluated, with 74 having thoracic and 50 having lumbar fractures. Among those with thoracic fractures, there were 33patients in the younger cohort, who also had a mean BMD of 196.51HU and 41 in the older cohort, who had mean BMD of 105.90HU (p<0.001). In patients with lumbar fractures, 27 patients were in the younger cohort, with mean BMD of 192.26HU and 23 patients in the older cohort with mean BMD of 114.31HU (p<0.001). At the threshold of 110 HU, set for specificity, the magnitude of difference between the age stratified cohorts was greater in the thoracic spine (p<0.001 vs. p=0.003). At the other thresholds: 135HU (balanced for sensitivity and specificity) and 160 HU (90% sensitivity), age of 65 years or older was significantly associated with reduction in CT derived measure of BMD (p<0.001 in all cases). Discussion. This study demonstrates the relative frequency of osteoporosis in acute fractures of the thoracic and lumbar spine, and how this changes with age; it is also the first study to do this using opportunistic CT scans. There seems to be a strong association between a reduction in bone mineral density and advanced age, in patients presenting with acute fractures of the spine. This approach may save on the extra cost and additional radiation exposure that may be associated with DXA scanning; in addition, it may help provide clinicians and patients with an approach to monitor developing problems with BMD before it becomes clinically apparent, especially in younger patients

Summary Statement. It is now possible to diagnose osteoporosis using incidental CT scans; this approach has been used to objectively demonstrate the role of osteoporosis in fracture in ankylosing spondylitis patients. Background. In advanced disease, Ankylosing Spondylitis (AS) is frequently associated with a reduction in bone mineral density (BMD), this contributes to pain and predisposes to fractures. Quantifying this reduction in BMD is complicated by the simultaneous processes occurring, in which there is both an overgrowth of bone (syndesmophytes) and a concurrent loss of trabecular bone. Traditional methods such as dual-energy X-ray absorptiometry (DXA) struggle to generate accurate estimates for BMD in these patients. It has recently become possible to diagnose osteoporosis, with a high sensitivity and specificity, using incidental CT scans of the L1 vertebra. The purpose of this study was to evaluate the use of opportunistic CT screening in the diagnosis of osteoporosis in patients with AS who had sustained vertebral fractures. Patients & Methods. Following Institutional review board approval, patients with AS who presented, with acute fractures of the spine, to our facility between 2004 and 2013 were reviewed to assess whether or not they had a Computed Tomography (CT) scan of the abdomen on admission or in the 6 months before or after injury. In addition, patients were also required to have signs of advanced AS such as the presence of syndesmophytes and syndesmophyte bridging; patients with fractures through L1 were excluded. Of those fitting the criteria, a region of Interest (ROI) was generated over the body of L1, Hounsfield unit (HU) were then measured. Results. Of the 42 patients reviewed, a total of 17 AS patients fit the above criteria. 15 were male and 2 were female, mean age of the whole cohort was 69.9years (range 22–85; SD 15.9). Using a threshold balanced for sensitivity and specificity (<135 HU) which differentiates between osteopenia and osteporosis, 14 (82%) patients were found to have a BMD less than 135HU; a higher threshold (<160 HU) with 90 % sensitivity for differentiating osteoporosis from osteopenia was applied to the group, and 15 patients (88%) were found to be osteoporotic. Of note all the females in the study were osteoporotic. Discussion and Conclusion. This study demonstrates, for the first time, using opportunistic CT screening, that a high proportion of AS patients who sustain fractures have osteoporosis; this overcomes the difficulties that have been encountered with the use of DXA in this unique group of patients. This simple and accessible method saves on excess cost and exposure to radiation. With a high sensitivity, patients identified using this method can then be managed more proactively. We believe these data have the potential to significantly impact the day to day management of patients with spondyloarthropathies

Introduction

Histology remains the gold standard in morphometric and pathological analyses of osteochondral tissues in human and experimental bone and joint disease. However, histological tissue processing is laborious, destructive and only provides a two-dimensional image in a single anatomical plane. Micro computed tomography (μCT) enables non-destructive three-dimensional visualization and morphometry of mineralized tissues and, with the aid of contrast agents, soft tissues. In this study, we evaluated phosphotungstic acid-enhanced (PTA) μCT to visualize joint pathology in spine osteoarthritis.

Objectives

The clinical utility of routine cross sectional imaging of the abdomen and pelvis in the screening and surveillance of patients with primary soft-tissue sarcoma of the extremities for metastatic disease is controversial, based on its questionable yield paired with concerns regarding the risks of radiation exposure, cost, and morbidity resulting from false positive findings.

Objectives

This study aims to assess the correlation of CT-based structural rigidity analysis with mechanically determined axial rigidity in normal and metabolically diseased rat bone.

The aim of this study was to investigate the effect of different loading scenarios and foot positions on the configuration of the distal tibiofibular joint (DTFJ). Fourteen paired human cadaveric lower legs were mounted in a loading frame. Computed tomography scans were obtained in unloaded state (75 N) and single-leg loaded stand (700 N) of each specimen in five foot positions: neutral, 15° external rotation, 15° internal rotation, 20° dorsiflexion, and 20° plantarflexion. An automated three-dimensional measurement protocol was used to assess clear space (diastasis), translational angle (rotation), and vertical offset (fibular shortening) in each foot position and loading condition. Foot positions had a significant effect on the configuration of DTFJ. Largest effects were related to clear space increase by 0.46 mm (SD 0.21 mm) in loaded dorsal flexion and translation angle of 2.36° (SD 1.03°) in loaded external rotation, both versus loaded neutral position. Loading had no effect on clear space and vertical offset in any position. Translation angle was significantly influenced under loading by −0.81° (SD 0.69°) in internal rotation only. Foot positioning noticeably influences the measurement when evaluating the configuration of DTFJ. The influence of the weightbearing seems to have no relevant effect on native ankles in neutral position

Acetabular morphology and orientation differs from ethnic group to another. Thus, investigating the natural history of the parameters that are used to assess both was a matter of essence. Nevertheless, clarification the picture of normal value in our society was the main aim of this study. However, Acetabular head index (AHI) and center edge angle (CEA) were the most sensitive indicative parameters for acetabular dysplasia. Hence, they were the main variables used in evaluation of acetabular development. A cross-sectional retrospective study that had been done in a tertiary center. Computed tomography abdomen scouts’ radiographs of non-orthopedics patients were included. They had no history of pelvic or hips’ related symptoms or fractures in femur or pelvis. Images’ reports were reviewed to exclude those with tumors in the femur or pelvic bones. A total of 81 patients was included with 51% of them were males. The mean of age was 10.38± 3.96. CEA was measured using Wiberg technique, means of CEA were 33.71±6.53 and 36.50±7.39 for males and females, respectively. Nonetheless, AHI means were 83.81±6.10 and 84.66±4.17 for males and females, respectively. On the other hand, CEA was increasing by a factor 0.26 for each year (3-18, range). In addition, positive significant correlation was detected between CEA and age as found by linear regression r 2 0.460 (f(df1,79) =21.232, P ≤0.0001). Also, Body mass index (BMI) was positively correlated with CEA r 0.410, P 0.004). This study shows that obesity and aging are linked to increased CEA. Each ethnic group has its own normal values that must be studied to avoid premature diagnosis

Acetabular morphology and orientation differs from ethnic group to another. Thus, investigating the normal range of the parameters that are used to assess both was a matter of essence. Nevertheless, the main aim of this study was clarification the relationship between acetabular inclination (AI) and acetabular and femoral head arcs’ radii (AAR and FHAR). A cross-sectional retrospective study that had been done in a tertiary center where Computed tomography abdomen scouts’ radiographs of non-orthopedics patients were included. They had no history of pelvic or hips’ related symptoms or fractures in femur or pelvis. A total of 84 patients was included with 52% of them were females. The mean of age was 30.38± 5.48. Also, Means of AI were 38.02±3.89 and 40.15±4.40 (P 0.02, significant gender difference) for males and females, respectively. Nonetheless, Head neck shaft angle (HNSA) means were 129.90±5.55 and 130.72±6.62 for males and females, respectively. However, AAR and FHAR means for males and females were 21.3±3.1mm, 19.9±3.1mm, P 0.04 and 19.7±3.1mm, 18.1±2.7mm, P 0.019, respectively. In addition, negative significant correlations were detected between AI against AAR, FHAR, HNSA and body mass index (BMI) (r 0.529, P ≤0.0001, r 0.445, P ≤0.0001, r 0.238, P 0.029, r 0.329, P ≤0.007, respectively). On the other hand, high BMI was associated with AAR and FHAR (r 0.577, P 0.0001 and r 0.266, p 0.031, respectively). This study shows that high AI is correlated with lower AAR, FHAR. Each ethnic group has its own normal values that must be studied to tailor the path for future implications in clinical setting

Aneurysmal bone cyst (ABC) of the spine is a locally aggressive benign lesion which can be treated by en bloc resection with wide margin to reduce the risk of local recurrence. To avoid morbidity associated with surgery, selective arterial embolization (SAE) can be considered the first-line treatment for ABCs of the spine. We previously introduced the use of autologous bone marrow concentrate (BMC) injection therapy to stimulate bone healing and regeneration in ABC of the spine. In this prospective study we described the clinical and radiological outcomes of percutaneous injection of autologous BMC in a series of patients affected by ABCs of the spine. Fourteen patients (6 male, 8 female) were treated between June 2014 and December 2019 with BMC injection for ABC of the spine. The mean age was 17.85 years. The mean follow up was 37.4 months (range 12–60 months). The dimension of the cyst and the degree of ossification were measured by Computed Tomography (CT) scans before the treatment and during follow-up visits. Six patients received a single dose of BMC, five patients received two doses and in three patients three doses of BMC were administered. The mean ossification of the cyst (expressed in Hounsfield units) increased statistically from 43.48±2.36 HU to 161.71±23.48 HU during follow-up time and the ossification was associated to an improvement of the clinical outcomes. The mean ossification over time was significantly higher in patients treated with a single injection compared to patients treated with multiple injections. No significant difference in ossification was found between cervical and non-cervical localization of the cyst. Moreover, the initial size of the cyst was not statistically associated with the degree of ossification during follow-up. The results of this study reinforce our previous evidence on the use of BMC as a valid alternative for spinal ABC management when SAE is contraindicated or ineffective. The initial size of the cyst and its localization does not influence the efficacy of the treatment. However, data suggest that BMC injection could be indicated as treatment of choice for spinal ABC in young adolescent women

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

Abstract. Objectives. The fidelity of a 3D model created using image segmentation must be precisely quantified and evaluated for the model to be trusted for use in subsequent biomechanical studies such as finite element analysis. The bones within the ankle joint vary significantly in size and shape. The purpose of this study was to test the hypothesis that the accuracy and reliability of a segmented bone geometry is independent of the particular bone being measured. Methods. Computed tomography (CT) scan data (slice thickness 1 mm, pixel size 808±7 µm) from three anonymous patients was used for the development of the ankle geometries (consisting of the tibia, fibula, talus, calcaneus, and navicular bones) using Simpleware Scan IP software (Synopsys, Exeter, UK). Each CT scan was segmented 4 times by an inexperienced undergraduate, resulting in a total of 12 geometry assemblies. An experienced researcher segmented each scan once, and this was used as the ‘gold standard’ to quantify the accuracy. The solid bone geometries were imported into CAD software (Inventor 2023, Autodesk, CA, USA) for measurement of the surface area and volume of each bone, and the distances between bones (tibia to talus, talus to navicular, talus to calcaneus, and tibia to fibula) were carried out. The intra-class coefficient (ICC) was used to assess intra-observer reliability. Bland Altman plots were employed as a statistical measure for criteria validity (accuracy) [1]. Results. The average ICC score was 0.93, which is regarded as a high reliability score for an inexperienced user. The talus to navicular and talus to tibia separations, which had the smallest distances, showed a slight decrease in reliability and this was observed for all separations shorter than 2 mm. According to the Bland-Altman plots, more than 95% of the data points were inside the borders of agreement, which is an excellent indication of accuracy. The bias percentage (average error percentage) varied between 1% and 4% and was constant across all parameters, with the proportion rising for short distance separations. Conclusions. The current study demonstrates that an inexperienced undergraduate, with access to software manuals, can segment an ankle CT scan with excellent reliability. The present study also concluded that all five bones were segmented with high levels of accuracy, and this was not influenced by bone volume or type. The only factor found to influence the reliability was the magnitude of distance between bones, where if this was smaller than 2 mm it reduced the reliability, indicating the influence of CT scan resolution on the segmentation reliability. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction and Objective. Virtual Surgical Planning (VSP) is becoming an increasingly important means of improving skills acquisition, optimizing clinical outcomes, and promoting patient safety in orthopedics and traumatology. Pediatric Orthopedics (PO) often deals with the surgical treatment of congenital or acquired limbs and spine deformities during infancy. The objective is to restore function, improve aesthetics, and ensure proper residual growth of limbs and spine, using osteotomies, bone grafts, age-specific or custom-made hardware and implants. Materials and Methods. Three-dimensional (3D) digital models were generated from Computed Tomography (CT) scans, using free open-source software, and the surgery was planned and simulated starting from the 3D digital model. 3D printed sterilizable models were fabricated using a low-cost 3D printer, and animations of the operation were generated with the aim to accurately explain the operation to parents. All procedures were successfully planned using our VSP method and the 3D printed models were used during the operation, improving the understanding of the severely abnormal bony anatomy. Results. The surgery was precisely reproduced according to VSP and the deformities were successfully corrected in eight cases (3 genu varum in Blount disease, 2 coxa vara in pseudo achondroplasia, 1 SCFE, 1 missed Monteggia lesion and 1 post-traumatic forearm malunion deformity). In one case, a focal fibrocartilaginous dysplasia, the intraoperative intentional undersizing of the bone osteotomy produced an incomplete correction of a congenital forearm deformity. Conclusions. Our study describes the application of a safe, effective, user-friendly, VSP process in PO surgery. We are convinced that our study will stimulate the widespread adoption of this technological innovation in routine clinical practice for the treatment of rare congenital and post-traumatic limb deformities during childhood

Introduction and Objective. Aneurysmal bone cyst (ABC) of the spine is a locally aggressive benign lesion which can be treated by en bloc resection with wide margin to reduce the risk of local recurrence. To avoid morbidity associated with surgery, selective arterial embolization (SAE) can be considered the first-line treatment for ABCs of the spine. Other emerging treatments for ABCs include bisphosphonates, percutaneous doxycycline, sclerotherapy and Denosumab. In addition, we previously introduced the use of autologous bone marrow concentrate (BMC) injection therapy to stimulate bone healing and regeneration in ABC of the spine. One of the potential advantages of such a method is that surgical treatments are not necessary, thus allowing for both a minimally invasive approach and the treatment of poorly accessible lesions. In this prospective study we described the clinical and radiological outcomes of percutaneous injection of autologous BMC in a series of patients affected by ABCs of the spine and followed for at least one year. Materials and Methods. Fourteen patients (6 male, 8 female) were treated between June 2014 to December 2019 with BMC injection for ABC of the spine. The mean age was 17.85 years. The mean follow up was 37.4 months (range 12– 60 months). The dimension of the cyst and the degree of ossification were measured by Computed Tomography (CT) scans before the treatment and during follow-up visits. Results. Six patients received a single dose of BMC, five patients received two doses and in three patients three doses of BMC were administered. The mean ossification of the cyst (expressed in Hounsfield units) increased statistically from 43.48±2.36 HU to 161.71±23.48 HU during follow-up time and the ossification was associated to an improvement of the clinical outcomes. The mean ossification over time was significantly higher in patients treated with a single injection compared to patients treated with multiple injections. No significant difference in ossification was found between cervical and non-cervical localization of the cyst. Moreover, the initial size of the cyst was not statistically associated with the degree of ossification during follow-up. We also observed that five out of six female patients (83.3%) were less than sixteen years old and four of these (66.7%) were managed with a single dose of BMC injection, while a higher percentage of male patients (6/8, 75%) were more than sixteen years old and more than one injection was administered to them. Conclusions. The results of this study reinforce our previous evidence on the use of BMC as a valid alternative for spinal ABC management when SAE is contraindicated or ineffective. The initial size of the cyst and its localization does not influence the efficacy of the treatment. However, BMC injection could be indicated as treatment of choice for spinal ABC in young adolescent women

Introduction and Objective. Curative resection of proximal humerus tumours is now possible in this era of limb salvage with endoprosthetic replacement considered as the preferred reconstructive option. However, it has also been linked with mechanical and non-mechanical failures such as stem fracture and aseptic loosening. One of the challenges is to ensure that implants will endure the mechanical strain under physiological loading conditions, especially crucial in long surviving patients. The objective is to investigate the effect of varying prosthesis length on the bone and implant stresses in a reconstructed humerus-prosthesis assembly after tumour resection using finite element (FE) modelling. Methods. Computed tomography (CT) scans of 10 humeri were processed in Mimics 17 to create three-dimensional (3D) cortical and cancellous solid bone models. Endoprostheses of different lengths manufactured by Stryker were modelled using Solidworks 2020. The FE models were divided into four groups namely group A consisting of the intact humerus and groups B, C and D composed of humerus-prosthesis assemblies with a body length of 40, 100 and 120 mm respectively and were meshed using linear 4-noded tetrahedral elements in 3matic 13. The models were then imported into Abaqus CAE 6.14. Isotropic linear elastic behaviour with an elastic modulus of 13400, 2000 and 208 000 MPa were assigned to the cortical bone, cancellous bone and prosthesis respectively and a Poisson's ratio of 0.3 was assumed for each material. To represent the lifting of heavy objects and twisting motion, a tensile load of 200 N for axial loading and a 5 Nm torsional load for torsional loading was applied separately to the elbow joint surface with the glenohumeral joint fixed and with all contact interfaces defined as fully bonded. A comparative analysis against literature was performed to validate the intact model. Statistical analysis of the peak von Mises stress values collected from predicted stress contour plots was performed using a one-way repeated measure of analysis of variance (with a Bonferroni post hoc test) using SPSS Statistics 26. The average change in stress of the resected models from the intact state were then determined. Results. The validation of the intact humerus displayed a good agreement with literature values. The peak bone stress occurred distally above the coronoid and olecranon fossa closer to the load application region in the intact and resected bone models with a significant amount of loading borne by the cortical bone, while the peak implant stress occurred at the bone-prosthesis contact interface under both loading conditions. Based on the results obtained, a statistically significant difference (p =.013) in implant stress was only seen to occur between groups B and C under tension. Results illustrate initiation of stress shielding with the bone bearing lesser stress with increasing resection length which may eventually lead to implant failure by causing bone resorption according to Wolff's law. The peak implant stress under torsion was 3–5 times the stress under tension. The best biomechanical behaviour was exhibited in Group D, having the least average change in stress from the intact model, 5% and 3.8% under tension and torsion respectively. It can be deduced that the shorter the prosthesis length, the more pronounced the effect on cortical bone remodelling. With the maximum bone and implant stresses obtained being less than their yield strength, it can be concluded that the bone-implant construct is safe from failure. Conclusions. The developed FE models verified the influence of varying the prosthesis length on the bone and implant stresses and predicted signs of stress shielding in longer endoprostheses. By allowing for 2 cm shortening in the upper extremity and post-surgical scarring, it is beneficial to err towards a shorter endoprosthesis

Summary. Quantification of Three-Dimensional Computed Tomography (Q3DCT) is a reliable and reproducible technique to quantify and characterise ankle fractures with a posterior malleolar fragment (. www.traumaplatform.org. ). This technique could be useful to characterise posterior malleolar fragments associated with specific ankle fracture patterns. Introduction. Fixation of posterior malleolar fractures of the ankle is subject of ongoing debate1. Fracture fixation is recommended for fragments involving 25–30% of articular surface1. However, these measurements -and this recommendation- are based on plain lateral radiographs only. A reliable and reproducible method for measurements of fragment size and articular involvement of posterior malleolar fractures has not been described. The aim of this study is to assess the inter-observer reliability of Quantification using Three-Dimensional Computed Tomography (Q3DCT) –modelling. 2,3,4,5. for fragment size and articular involvement of posterior malleolar fractures. We hypothesize that Q3DCT-modelling for posterior malleolar fractures has good to excellent reliability. Patients & Methods. To evaluate inter-observer reliability of Q3DCT-modelling, we included a consecutive series of 43 patients with an ankle fracture involving the posterior malleolus and a complete radiographic documentation (radiographs and computed tomography) Fractures of the tibial plafond (pilon type fractures) were excluded. These 43 patients were divided in 3 different types (Type I, II or III) as described by Haraguchi6. Five patients of each type were randomly selected for an equal distribution of articular fragment sizes. 3D models were reconstructed by 1) creating a mask for every respective slice; 2) select the appropriate dots that separate fracture from tibialshaft; 3) connect masks of each respective slice; and 4) reconstruct a 3D-mesh. After reconstruction of 3D-models, 1) fragment volume; 2) articular surface of the posterior malleolar fragment; 3) articular surface of intact tibia and 4) articular surface of the medial malleolus were calculated by all three observers. A summary of this technique is shown on . www.traumaplatform.org. The inter-observer reliability of these measurements was calculated using the ICC, which can be interpreted as the kappa coefficient. Results. Measurements of the volume of posterior malleolar fracture fragments ranged from 357 to 2904 mm3 with an ICC of 1.00 (Confidence interval (CI) 0.999 – 1.000) Measurements of the articular surface of the posterior malleolar fracture fragment ranged from 25 to 252 mm2 with an ICC of 0.998 (CI 0.996 – 0.999); the articular surface of the intact tibia plafond ranged from 375 to 1124 mm2 (ICC 0.998, CI 0.996 – 0.999); and the articular surface of the medial malleolus ranged from 79 to 149 mm2 (ICC 0.978, CI 0.978 – 0.911). The categorical ratings for all ICC's were defined as almost perfect according to the system of Landis7. Discussion/Conclusion. This study showed that our Q3DCT-modelling technique. 2,3,4,5. is reliable and reproducible to reconstruct ankle fractures, in order to assess fracture characteristics of posterior malleolar fracture fragments. Future research will focus on the association between overall ankle fracture patterns according to Lauge-Hansen, and characterization of posterior malleolar fragment morphology. We hypothesise that supination-exorotation type fractures are associated with smaller (in volume and involved articularsurface) “pull-off” fragments, while pronation-exorotation type ankle fractures are associated with larger (in volume and involved articular surface) “push-off” fragments. The clinical relevance might be that smaller “pull-off” type fractures benefit from positioning screws, while larger “push-off” type fractures require direct open reduction and internal fixation of the posterior malleolar fragment

Background. Despite the known multifactorial nature of scaphoid wrist fracture non-union, a possible genetic predisposition for the development of this complication remains unknown. This pilot study aimed to address this issue by performing Single Nucleotide Polymorphisms (SNPs) analysis of specific genes known to regulate fracture healing. Materials and Methods. We reviewed 120 patients in a retrospective case-control study from the Hand Surgery Department of Asepeyo Hospital. The case group comprised 60 patients with confirmed scaphoid wrist non-union, diagnosed by Magnetic Resonance Imaging (MRI) and Computed Tomography (CT). The control group comprised 60 patients with scaphoid fracture and complete bone consolidation. Sampling was carried out with a puncture of a finger pad using a sterile, single-use lancet. SNPs were determined by real-time polymerase chain reaction (PCR) using specific, unique probes with the analysis of the melting temperature of hybrids. The X2 test compared genotypes between groups. Multivariate logistic regression analysed the significance of many covariates and the incidence of scaphoid wrist non-union. Results. We found significant differences in subjects who had a smoking habit (p=0.001), high blood pressure (p<0.001), and surgical treatment (p=0.002) in patients with scaphoid non-union. There were more Caucasians (p=0.04) and males (p=0.001) in the case group. Falls were the main mechanism of fracture. The CC genotype in GDF5 (rs143383) was more frequent in patients with scaphoid non-union compared to the controls (p=0.02). CT was prevalent in the controls (p=0.02). T allele in GDF5 was more frequent in patients without non-union (p=0.001). Conclusions. Individuals who were carriers of the CC genotype in GDF5 showed higher susceptibility to suffering scaphoid wrist non-union. Furthermore, being a carrier of CT and T allele suggests that this could be behave as a protection factor against non-union. This is the first clinical study to investigate the potential existence of genetic susceptibility to scaphoid wrist fracture non-union. Level of evidence. Level III, Cross Sectional Study, Epidemiology Study

Background. Bone Morphogenetic Protein (BMP) has been used in clinical practice to stimulate fracture healing and spinal arthrodesis. Difficulty in localising and maintaining BMP at the target site has resulted in the use of large doses of BMP, and has been associated with significant adverse effects. We have previously shown clay hydrogels can bind growth factors for localised efficacy. We hypothesised that localisation of BMP within clay gels would reduce the dose required to mediate bone formation. Methods. 2×10-4mg and 1×10-5 mg BMP were mixed in Laponite and applied to collagen sponge. 3 sponges containing high dose, and 3 containing low dose BMP were implanted subcutaneously in a mouse. This process was repeated in 8 mice, for controls, alginate hydrogel was used in a further 8 mice, and 1 mouse received 6 blank collagen scaffolds. Micro Computed Tomography was used to assess bone formation fortnightly; at 8 weeks the mice were culled and underwent histological analysis. Results. Mean Bone Volume formed within collagen per μg BMP was significantly greater with Laponite and low dose BMP compared to Alginate and Laponite with high dose BMP (p<0.0001). No bone formation was observed with Alginate and low dose BMP. Conclusions. We have demonstrated that Laponite is able to reduce, by several orders, the effective dose of BMP required to mediate ectopic bone formation compared to current gold standard methods of BMP delivery. Clinical translation of this finding offers, potentially, great significance to orthopaedic surgery. Level of Evidence. In vivo study. Approval. Our study received ethical approval complied with Home Office licensing. Acknowledgments. Funded by grants from EU(FP7) Biodesign, Rosetrees Trust, BBSRC and EPSRC

Summary Statement. In a retrospective study, FE-based bone strength from CT data showed a greater ability than aBMD to discriminate proximal femur fractures versus controls. Introduction. Personalised Finite Element (FE) models from Computed Tomography (CT) data are superior to bone mineral density (BMD) in predicting proximal femoral strength in vitro [Cody, 1999]. However, results similar to BMD were obtained in vivo, in retrospective classification of generic prevalent fractures [Amin, 2011] and in prospective classification of femoral fractures [Orwoll, 2009]. The aim of this work is to test, in a case-control retrospective study, the ability of a different, validated FE modelling procedure [Schileo, 2008] to: (i) discriminate between groups of proximal femoral fractures and controls; (ii) individually classify fractures and controls. Patients & Methods. 55 women (22 incident low-trauma proximal femur fractures and 33 controls) were enrolled in 3 clinical centres in Emilia Romagna region, Italy. All received a full femoral CT and DXA exams (in acute conditions for fractured cases) with a standardised protocol. Femoral neck aBMD was measured from DXA. FE models were built from CT (right femur for controls, intact for fractured) [Schileo, 2008]. Differently from existing works, FE strength was calculated for a range of 12 physiological directions of hip joint reactions [Bergmann, 2001] and 10 fall directions [Grassi, 2012]. Bone strength (in stance and fall) was the minimum load inducing on the femoral neck surface an elastic principal strain value greater than the yield limit [Bayraktar, 2004]. Fracture classification was analysed through logistic regressions and AUC of ROC curves. Results. Mean FE strength and aBMD were significantly lower in the fractured than in the control group (33%, p<0.0001 for strength; 12% p=0.01 for aBMD). Logistic regression on single variables. All classifiers were significant (p<0.001, AUC=0.88 for both stance and fall FE strength, p=0.02, AUC=0.72 for aBMD). The statistical power of the logistic regressions [Vaeth, 2004] was >0.9 for FE strength, 0.86 for aBMD. Logistic regressions on multiple variables. Only FE strength was retained significant (p<0.001, AUC=0.88) when including aBMD in the regression. Adding age to the logistic regression, FE strength and age (but not aBMD) remained significant, with AUC=0.95. Discussion. FE strength could discriminate the fractured group better than aBMD and than [Keyak, 2011]. FE strength was a better fracture classifier than aBMD, and obtained AUC values slightly higher than [Amin, 2011; Orwoll, 2009]. The high statistical power mildens the small sample numerosity. Cases and controls were not age matched, but FE strength and age were found to be independent classifiers. In conclusion the proposed FE method was superior to aBMD in the classification of proximal femoral fractures

Summary Statement. A population based finite element study that accounts for subject-specific morphology, density and load variations, suggests that osteoporosis does not markedly lower the mechanical compliance of the proximal femur to routine loads. Introduction. Osteoporosis (OP) is a bone disease defined by low bone density and micro-architectural deterioration. This deterioration is neither uniform nor symmetric at the proximal femur. Evidence from analyses performed at the tissue level suggests that the cortical shell at the femoral neck is thinner in OP patients, especially in the superior regions, but not in the infero-anterior ones [Poole, Rubinacci]. Analogously, OP femurs show a higher anisotropy of the trabecular bone than controls [Ciarelli], suggesting a preservation of load bearing capacity in the principal loading direction vs. the transverse one. There is general consensus that the regions subjected to higher loads during walking, which is the predominant motor activity in the elderly, are mostly preserved. All these findings suggest that the OP femur should exhibit an almost normal mechanical competence during daily activities. This would be in accordance with the very low incidence of spontaneous fractures [Parker] and with the moderate fracture predictivity of BMD. Although reasonable, this hypothesis has never been tested at the organ level. Aim of the present study was to verify it with a population-based finite element (FE) study. Patients & Methods. Whole femur Computed Tomography (CT) scans of 200 patients (115 women) with normal femoral anatomy were retrieved from a repository of the Istituto Ortopedico Rizzoli. The database is representative of an adult Italian population (mean 57yrs, range 23–84), and spans a wide range of morphological and densitometric characteristics (CT-simulated T-score of femoral neck BMD ranging from 1 to −4.6). Personalised FE models of all femurs were built from CT data using a validated procedure [Schileo]. A personalised estimate of the variability of loads acting on the proximal femur during normal walking (NW) and stair climbing (SC) was obtained by querying an indexed and searchable database of joint and muscle loads obtained from musculoskeletal models of 90 subjects. 78 possible loading combinations for NW and 50 for SC were defined for each subject, taking into account individual characteristics (height, weight, femoral antetorsion, CCD angle and neck length). Risk of fracture (RF) was defined for each subject as the maximum principal strain / limit strain (1.04% compressive, 0.73% tensile) ratio over the whole loading spectrum. Results and Discussion. No fracture was predicted by the FE models throughout the entire population, yielding an average safety coefficient of between 4 and 5, which is consistent with experimentally determined failure loads in the single leg stance configuration (around 11 BW [Cristofolini]). While a general inverse association was observed with R2∼0.2, no clear correlation was present between the fracture risk and the T-score. The hypothesis that OP does not macroscopically influence the mechanical competence of the femur for daily activities was therefore corroborated, suggesting that the highest risk of fracture in OP patients might be related to a lower OP induced compliance to accidental loads