IntroductionFor optimal treatment of femoral fractures, it is essential to understand the anatomical antecurvation of the human femur. Recent clinical studies have highlighted the problem of distal anterior encroachment or even perforation of the nail tip. The aim of this study was to accurately describe the femoral antecurvation in a large cohort. Another objective was to identify the most important influences on femoral antecurvation, such as age, femur length, gender and ethnicity.MethodsA three dimensional modelling and analytical technology was applied for the analysis of 1,232 femurs. Individual femoral antecurvation was precisely computed to determine whether gender, femur length, age, ethnicity or body mass index influence the radius of curvature (ROC).ResultsThe calculated mean ROC for all femurs was 943 mm. The lowest ROC of 826 mm was found in female Asian femurs. A regression analysis demonstrated that age and femur length could predict the variability of the curvature, with femoral length as most powerful predictor. A matched pair subgroup analysis between Asians and Caucasians could not show any significant differences of ROC values.ConclusionsThe mean radius of the femoral antecurvation may be smaller than previously reported revealing a significant mismatch between the actual individual anatomy and existing implants. In opposite to existing literature, this study suggests, that antecurvation differences between various ethnicities may exclusively be attributed to differences in femoral length and age. The findings of this study may be found helpful in the development of novel designs for intra- and extramedullary implants.

information compared to the traditional greyscale CT-slides. We hypothesized that there would be a constant lower bone density in the posterior pelvic ring screw corridors in individuals with decreased bone stock in the 5th lumbar vertebra. Methods Study population. Five hundred and thirty-seven (n = 537) raw CT datasets were analyzed. These had all originally been obtained for medical reasons: 20% patients after trauma, 70% for CT angiography and 10% for non-defined indications (median pixel spacing: 0.78 mm, median slice spacing: 1.00 mm). The data was collected retrospectively by Stryker Trauma GmbH between 2008 and 2017 with the prior written consent of the patient. Personal data such as name, date of birth or date of CT associated with the datasets were removed and not provided to the company. CT scans that included the skull were also excluded. The available demographic data generally included age, BMI and gender. In some cases, BMI, age or gender were not provided due to individual hospital data protection policies. Fractured or severely malformed pelvises (tumorous, post-osteomyelitis, post-traumatic) and pelvises with implants were excluded in advance. With these preconditions, the inclusion criteria were a fully scanned pelvis, without radiological artifacts, and the patient informed consent. The following inclusion criteria were applied to the initial study cohort: the fifth lumbar vertebra had to be included in the CT scan and the vertebral body had to be clearly defined and exhibit no degenerative changes in L5, or a sacralization or lumbalization of vertebral bodies; the S1 and S2 screw corridors (as defined below) did not interfere with the cortical boundary. This resulted in a final study cohort of 324 datasets. The mean age and standard deviation of the study population was 60.4 ± 17.6 years (17 to 93 years); 49 datasets were for patients of unknown age. There were 107 female (33%) and 217 male (67%) patients.

This study evaluated the implementation and effectiveness of an iterative process aimed to quantify and enhance the anatomical fit of an osteosynthesis plate design for the fifth metacarpal bone regarding a defined shape-based acceptance criterion (SAC) while complying with basic clinical requirements and engineering limitations. The process was based on employing virtual tools (a database of individual three-dimensional bone models, statistical analysis of the bone geometry, and proprietary software tools) to evaluate conformity between plate designs and bone shape. The conformity was quantified by the mean distance between plate and bone (MBP). The enhancement was completed when the median MBP of the population was below the SAC threshold. This was fulfilled by the third plate design (two enhancement iterations). The intentionally abstract enhancement process may serve as a guideline for development of plate designs for other indications.