Background and purpose — Being able to predict the hip–knee–ankle angle (HKAA) from standard knee radiographs allows studies on malalignment in cohorts lacking full-limb radiography. We aimed to develop an automated image analysis pipeline to measure the femoro-tibial angle (FTA) from standard knee radiographs and test various FTA definitions to predict the HKAA. Patients and methods — We included 110 pairs of standard knee and full-limb radiographs. Automatic search algorithms found anatomic landmarks on standard knee radiographs. Based on these landmarks, the FTA was automatically calculated according to 9 different definitions (6 described in the literature and 3 newly developed). Pearson and intra-class correlation coefficient [ICC]) were determined between the FTA and HKAA as measured on full-limb radiographs. Subsequently, the top 4 FTA definitions were used to predict the HKAA in a 5-fold cross-validation setting. Results — Across all pairs of images, the Pearson correlations between FTA and HKAA ranged between 0.83 and 0.90. The ICC values from 0.83 to 0.90. In the cross-validation experiments to predict the HKAA, these values decreased only minimally. The mean absolute error for the best method to predict the HKAA from standard knee radiographs was 1.8° (SD 1.3). Interpretation — We showed that the HKAA can be automatically predicted from standard knee radiographs with fair accuracy and high correlation compared with the true HKAA. Therefore, this method enables research of the relationship between malalignment and knee pathology in large (epidemiological) studies lacking full-limb radiography.

This paper investigates the variations of mode I stress intensity factor (KI) for inner penny-shaped and circumferential cracks in functionally graded solid and hollow thick walled cylinders, respectively with the changes of crack geometry, material gradation and loading conditions. The functionally graded material of cylinders consists of epoxy and glass. It is assumed that the mechanical properties vary with a power law in the radial direction of cylinders. Micromechanical models for conventional composites are used to estimate the material properties of functionally graded cylinders. The equations of motion obtained from the extended finite element discretization are solved by the Newmark method in the time domain. The interaction integral method is employed to calculate the mode I stress intensity factor (KI). The MATLAB programming environment was implemented to solve the problem.Citation: Shariati, M., Mahdizadeh Rokhi, M., Rayegan, H., Investigation of stress intensity factor for internal cracks in FG cylinders under static and dynamic loading, Frattura ed Integrità Strutturale, 39 (2017) 166-180.

Purpose: Studies in OA commonly focus on a single joint. However, clinical outcomes such as quality of life questionnaires, physical performance-based tests, and systemic biochemical marker levels will be influenced by OA affecting multiple joints. Low dose computed tomography (CT) provides valuable information on the bony aspects of the joints, including osteophyte formation, sclerosis and joint space width with a relative high signal-to-noise ratio as a result of the high density of bone. Whole-body low dose CTs (WBLDCT) with an effective radiation dose <3 mSv (comparable to one year of background radiation) can be used to capture osteoarthritis of joints throughout the body.In the present study we developed an atlas describing a new scoring system for degenerative joint disease and tested its reliability. Methods: WBLDCTs from 198 patients in a cohort of clinical scans in our hospital (indications include cancer, vascular and infectious disease) were used to develop the atlas. The acromioclavicular, glenohumeral, hip, patellofemoral, tibiofemoral, facet and ankle joints and intervertebral discs were incorporated in the scoring system. The elbow is frequently positioned outside the field of view of the WBLDCT and was excluded. We modified existing radiographic and CT-based scoring instruments to fourgrade scores per joint. Example images of scored items were collected in an atlas. The goal was to enable to reliably score all joints of a single patient in approximately 15 minutes. We produced a Whole-body OA grade by summing the grades of 24 separate joints (0-3) to obtain a score ranging from 0 to 72. We additionally calculated an Extremity-OA grade, by summing the grades of all joints except the intervertebral discs and facet joints. To test intra-observer reliability a medical doctor/researcher (WPG) scored 25 randomly selected WBLDCTs twice, with at least one week in between. To test inter-observer reliability the atlas was used as reference for the grading system by one radiologist in training with a subspecialization in musculoskeletal radiology (WF) and a fellowshiptrained musculoskeletal radiologist with five years of experience (FJN). WF and FJN scored the same random sample of 25 scans independently. Scores for the IVD and facet joints were not yet available for FJN at the time of this interim analysis. Reliability was tested using Cohen's kappa for binominal grade, squared weighted kappa for ordinal grade and Intraclass Correlation Coefficient (ICC) for continuous grades. In addition to kappa statistics, absolute agreement percentages for binominal and ordinal grades were assessed. All analyses were carried out in R v3.4.4 using IRR package v0.84. Results: The 25 patients (14 female) had a mean age (SD) of 54 (±17) years. Prevalence of OA scores per joint are shown in Table 1. Intraobserver reliability and agreement of the separate grades were good with kappa's ranging from 0.79 to 0.95 and absolute agreement ranging from 67% to 92% (Table 2). Intra-observer reliability of the Whole-body OA grade and ...

Objective Herewith, we report the development of Orthopedic Digital Image Analysis (ODIA) software that is developed to obtain quantitative measurements of knee osteoarthritis (OA) radiographs automatically. Manual segmentation and measurement of OA parameters currently hamper large-cohort analyses, and therefore, automated and reproducible methods are a valuable addition in OA research. This study aims to test the automated ODIA measurements and compare them with available manual Knee Imaging Digital Analysis (KIDA) measurements as comparison. Design This study included data from the CHECK (Cohort Hip and Cohort Knee) initiative, a prospective multicentre cohort study in the Netherlands with 1,002 participants. Knee radiographs obtained at baseline of the CHECK cohort were included and mean medial/lateral joint space width (JSW), minimal JSW, joint line convergence angle (JLCA), eminence heights, and subchondral bone intensities were compared between ODIA and KIDA. Results Of the potential 2,004 radiographs, 1,743 were included for analyses. Poor intraclass correlation coefficients (ICCs) were reported for the JLCA (0.422) and minimal JSW (0.299). The mean medial and lateral JSW, eminence height, and subchondral bone intensities reported a moderate to good ICC (0.7 or higher). Discrepancies in JLCA and minimal JSW between the 2 methods were mostly a problem in the lateral tibia plateau. Conclusions The current ODIA tool provides important measurements of OA parameters in an automated manner from standard radiographs of the knee. Given the automated and computerized methodology that has very high reproducibility, ODIA is suitable for large epidemiological cohorts with various follow-up time points to investigate structural progression, such as CHECK or the Osteoarthritis Initiative (OAI).