1,721,177 research outputs found
A passive prosthetic limb and process for realising the passive prosthetic limb
No full textA passive artificial limb (1), comprising: a socket
(3) arranged at a first end (4) of the prosthetic limb (1)
and exhibiting a shape designed to abut a stump (5) of
a subject's limb, a terminal part (7), optionally shaped as
a hand or a foot, arranged at a second end (8) of the
passive prosthetic limb (1) opposite the first end (4), a
connecting part (6) interposed between the socket (3)
and the terminal part (7); the connecting part (6) com-
prising at least an adjusting device (10) configured such
as to vary at least an moment of inertia of the passive
prosthetic limb (1) with respect to at least a reference
axis
Application of the desing of experiments for the evaluation of the robustness of video-densitometric measurements
No full textRoentgenographic features of digitised clinical orthopaedic radiographs of follow-up after total hip arthroplasty
No full textEstimating safety factor for femoral plates subjected to in vivo loads
No full textFatigue behaviour is a crucial aspect of mandatory mechanical tests for regulatory purposes, aimed at determining the load at which the bone plate withstands under a specific number of cycles, known as the runout condition. However, current test standards, such as ASTM F382, provide setup configurations without explicit guidelines on required fatigue strength. The determination of the minimum level of in vivo performance that the plate must fulfil remains an open issue, which is frequently addressed by the direct comparison with predicate devices. To address this gap, this study proposes an in silico framework to estimate maximum stress on implanted femoral plates for comparison with four-point bending tests described in the ASTM standard, deriving appropriate safety factors. As case studies, three femoral plates were assessed, and results showed safety factors above 1.1, indicating the reliability of the implanted plates
Osservazioni sulla precisione di identificazione di parametri modali di strutture meccaniche
No full text
An analytical and in silico strategy for estimating maximum stress and fatigue life of bone plates under in vivo loads: a rationale for regulatory testing
Full text linkDespite the innovations introduced by locking compression plates (LCP), implant failures still occur due to fatigue fractures caused by cyclic loads. The endurance of LCP, especially in lower limb plates subjected to ambulatory cyclic loads, is a critical factor that needs to be understood. Unfortunately, there is limited information available on the fatigue failure of LCP. The fatigue behavior is a crucial aspect of mandatory mechanical tests for regulatory purposes, which aim to determine the load at which the plate withstands under a specific number of cycles, known as the runout condition. The current test standards, such as ASTM F382, only provide the setup configuration without furnishing explicit guidelines
regarding the required fatigue strength of the bone plate in the runout condition. The determination of the minimum level of in vivo performance that the plate must fulfill remains an open issue, which is frequently addressed by the direct comparison with predicate devices. To address this issue, this study proposes a rationale that combines analytical and in silico approaches to estimate the maximum stress and fatigue life of a bone plate under in vivo loads. Four-point bending tests were conducted on a diaphyseal femoral plate to determine the experimental runout load. Analytical and finite element (FE) models were first implemented to replicate the four-point bending setup and to calculate the maximum stress on the plate. The Goodman and Gerber criteria were exploited to determine the mean stress effect due to the four-point bending setup and to verify the predicted number of cycles. In addition, the forcedisplacement curves of the FE model were validated by means of experimental results. Analytical and FE models were then applied to calculate the maximum stress and assess the performance of the implanted plate under in vivo loading
conditions. In the implanted plate condition, a mean number of cycles higher than 1.5 million was estimated. Analytical models showed good performance compared with in silico strategies, exhibiting errors below 6%. The comparison between the obtained results provides valuable insights for constructing a robust rationale to support the regulatory process in order to obtain CE marking
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