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Finite element (FE) models of long bones are widely used to analyze implant designs. Experimental validation has been used to examine the accuracy of FE models of cadaveric femurs; however, although convergence tests have been carried out, no FE models of an intact and implanted human cadaveric tibia have been validated using a range of experimental loading conditions. The aim of the current study was to create FE models of a human cadaveric tibia, both intact and implanted with a unicompartmental knee replacement, and to validate the models against results obtained from a comprehensive set of experiments. Seventeen strain rosettes were attached to a human cadaveric tibia. Surface strains and displacements were measured under 17 loading conditions, which consisted of axial, torsional, and bending loads. The tibia was tested both before and after implantation of the knee replacement. FE models were created based on computed tomography (CT) scans of the cadaveric tibia. The models consisted often-node tetrahedral elements and used 600 material properties derived from the CT scans. The experiments were simulated on the models and the results compared to experimental results. Experimental strain measurements were highly repeatable and the measured stiffnesses compared well to published results. For the intact tibia under axial loading, the regression line through a plot of strains predicted by the FE model versus experimentally measured strains had a slope of 1.15, an intercept of 5.5 microstrain, and an [R.sup.2] value of 0.98. For the implanted tibia, the comparable regression line had a slope of 1.25, an intercept of 12.3 microstrain, and an [R.sup.2] value of 0.97. The root mean square errors were 6.0% and 8.8% for the intact and implanted models under axial loads, respectively. The model produced by the current study provides a tool for simulating mechanical test conditions on a human tibia. This has considerable value in reducing the costs of physical testing by pre-selecting the most appropriate test conditions or most favorable prosthetic designs for final mechanical testing. It can also be used to gain insight into the results of physical testing, by allowing the prediction of those variables difficult or impossible to measure directly. Keywords: human tibia bone, experimental validation, validated FE model of implanted tibia, finite element analysis, tibial metaphysis, Oxford knee

This study involved the development and testing of a system for the simultaneous in vitro measurement of tibiofemoral kinematics and patellofemoral kinematics and forces. Knee motion was tracked using a Vicon 370, and patellofemoral force was measured using a six degree-of-freedom transducer based on the design of Singerman et al. Using this system, twelve knee specimens were tested in supine leg extension under a simulated quadriceps force. The comprehensive set of results corresponds well to the individual results of previous studies. The measurement system will be of value in assessing the effects of total knee arthroplasty on patellar function.

Marker-based clinical gait analysis and multi-segment foot models (MSFM) have been successfully used for the diagnosis and clinical management of various lower limb disorders. The accuracy and validity of the kinematics measured depend on the design of the model, as well as on the adherence to its inherent rigid body assumption. This study applies a Monte-Carlo based global sensitivity analysis to evaluate the efficacy of using 'rigid body error ( σ RBE )' in quantifying the rigidity of a MSFM marker-cluster. A regression model is proposed. It is concluded that σ RBE is effective in quantifying rigidity. [ABSTRACT FROM AUTHOR]

Rowing ergometers can be found in most gyms and fitness centers, but many people who use them regularly have little or no instruction in rowing technique. It is not known whether nonrowers who regularly practice ergometer rowing are at risk of musculoskeletal problems. This study was done to quantify the differences in kinematics, kinetics, and musculoskeletal loading of competitive rowers and nonrowers during ergometer rowing. An experiment was performed to collect kinematic, external force, and EMG data during ergometer rowing by 5 university-level competitive rowers and 5 nonrowers. Kinematic and external force data were input to a 3-D whole-body musculo-skeletal model which was used to calculate net joint forces and moments, muscle forces, and joint contact forces. The results showed that competitive rowers and nonrowers are capable of rowing an ergometer with generally similar patterns of kinematics and kinetics; however, there are some potentially important differences in how they use their legs and trunk. The competitive rowers generated higher model quadriceps (vastus) muscle forces and pushed harder against the foot cradle, extending their knees more and their trunks less than the nonrowers during the drive phase. They also had higher contact forces at the knee and higher peak lumbar and knee flexion moments. The ratio of average peak vastus force to average peak erector spinae force in the experienced rowers was 1.52, whereas it was only 1.18 in the nonexperienced rowers. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSThe Oxford Foot Model (OFM) is a widely-used multi-segment foot model for the evaluation of foot motion. To date, custom code based on the original scientific publications have failed to reproduce results available through the Vicon plug-in (ViconOFM). This highlights a lack of transparency, affecting the accessibility and understanding of the model. Therefore, the aims of this study are to (1) replicate ViconOFM using Python for open-source distribution (openOFM v1.0) and (2) reproduce the original scientific description of the OFM in a second version (openOFM v1.1), highlighting differences between both versions. A dataset comprising one healthy adult and a set of five patients with heterogeneous foot pathologies was used for analyses. Evaluation was conducted using the normalised root mean square error (NRMSE) between the inter-segment angles and arch heights of both implementations. The openOFM v1.1 was developed based on the original OFM publications. The average NRMSE between ViconOFM and openOFM v1.0, using both healthy and pathological gait, was of 0.0012. Based on our openOFM v1.1 implementation, differences between ViconOFM and the original OFM description from the literature are due to an integrated smoothing and gap filling function and changes in segment definitions. The negligible differences between ViconOFM and openOFM v1.0 in healthy and pathological gait supports the concurrent validity of openOFM. Providing users with both openOFM versions enables informed use of either model and allows further investigation into the implications of these differences. The open-source nature of the project promotes further development.Modelling foot movement is a complex task requiring methodological transparencyThe Oxford Foot Model (OFM) is only accessible within commercial software (Vicon)Open-source code for the OFM (openOFM) was developed and validatedDifferences were found between Vicon OFM and the OFM descriptions in literatureopenOFM addresses these differences and provides a platform for future developmentModelling foot movement is a complex task requiring methodological transparencyThe Oxford Foot Model (OFM) is only accessible within commercial software (Vicon)Open-source code for the OFM (openOFM) was developed and validatedDifferences were found between Vicon OFM and the OFM descriptions in literatureopenOFM addresses these differences and provides a platform for future development [ABSTRACT FROM AUTHOR]