In vivo contact stresses at the radiocarpal joint using a finite element method of the complete wrist joint

A small number of cadaveric studies have been carried out looking at the force transmission through the radiocarpal joint. In this study subject specific finite element models were created of the whole wrist joint using measured biomechanical data to capture the forces acting on the wrist with the hand generating a maximum gripping force

Hip joint forces Hip joint forces of 40 to 60 year old normal and total hip replacement subjects during walking and stair, ramp and camber negotiation

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Computational modelling of the wrist

Little has been published about the modelling of multibone joints such as the ankle and wrist compared to modelling studies of other joints such as the hip and knee. There are many challenges associated with the modelling of a multibone joint such as the wrist which can be credited for the lack of published papers. With increased computing power and improved software packages, the modelling of such multi bone joints has become more obtainable. The finite element method is a powerful tool to investigate the loading on such joints and can predict possible outcomes of surgical interventions. This paper describes the finite element modelling of the wrist joint and how the model can be used to predict in vivo loading

Load transfer through the radiocarpal joint and the effects of partial wrist arthrodesis on carpal bone behaviour : a finite element study

A finite element model of the wrist was developed to simulate mechanical changes that occur after surgery of the wrist. After partial arthrodesis, the wrist will experience altered force transmission during loading. Three different types of partial arthrodesis were investigated: radiolunate, radioscaphoid and radioscapholunate fusions and compared to the healthy untreated wrist. The results showed that the compressive forces on the radiocarpal joint decreased compared to the untreated wrist with both radiolunate and radioscaphoid fusions. The load transmission through the mid carpal joints varied depending on arthrodesis type. The forces in the extrinsic ligaments decreased with the fusion, most noticeably in the dorsal radiotriquetral ligament, but increased in the dorsal scaphotriquetral ligament. From the results of the study it can be concluded that the radioscapholunate fusion shows the most biomechanically similar behaviour out of the three fusion types compared to the healthy wrist. The modelling described in this paper may be a useful approach to pre-operative planning in wrist surgery

Step accumulation per minute epoch is not the same as cadence for free-living adults

Purpose: The term cadence has been used interchangeably to describe both the rate of stepping and the number of steps in a minute epoch. This is only strictly true if walking is continuous within that epoch. This study directly compared these two outcomes in minute epochs of data from free-living adults to assess the scale of any difference between them.Methods: A convenience sample of healthy adults wore an activPAL activity monitor for seven days. The event record output of the activPAL, providing the start time and duration of each stride to the nearest 0.1s, was used to calculate step accumulation (number of steps), duration of walking and cadence (number of steps/ duration of walking) for each minute of measurement.Results: Data from 117 individuals (78 female, mean age 46±16 years, mean BMI 24.9±3.7 kg·m) were analysed. Twenty-one percent of minutes (n=310/day) contained walking. The distribution (most minutes less than 40 steps/min) and mean (34±9 steps/min) of step accumulation, was very different from that of cadence (most minutes between 60-100 steps/min, mean 76±6 steps/min). Only 12% of minutes with stepping were walked continuously, while 69% of minutes with stepping contained less than 30s of walking. This is key to the difference between step accumulation and cadence, and means that cadence cannot be reconstructed from step accumulation without also knowing the duration that was walked.Conclusion: Step accumulation, the number of steps in a fixed period of time, and cadence, the rate of stepping whilst walking, are not interchangeable outcome measures. It is vitally important that unambiguous terminology is used to describe the rate of stepping so that the outcomes of studies can be correctly interpreted