Physical validation of a patient-specific contact finite element model of the ankle

Abstract

A validation study was conducted to determine the extent to which computational ankle contact finite element (FE) results agreed with experimentally measured tibio-talar contact stress. Two cadaver ankles were loaded in separate test sessions, during which ankle contact stresses were measured with a high-resolution (Tekscan) pressure sensor. Corresponding contact FE analyses were subsequently performed for comparison. The agreement was good between FE-computed and experimentally measured mean (3.2% discrepancy for one ankle, 19.3% for the other) and maximum (1.5% and 6.2%) contact stress, as well as for contact area (1.7% and 14.9%). There was also excellent agreement between histograms of fractional areas of cartilage experiencing specific ranges of contact stress. Finally, point-by-point comparisons between the computed and measured contact stress distributions over the articular surface showed substantial agreement, with correlation coefficients of 90% for one ankle and 86% for the other. In the past, general qualitative, but little direct quantitative agreement has been demonstrated with articular joint contact FE models. The methods used for this validation enable formal comparison of computational and experimental results, and open the way for objective statistical measures of regional correlation between FE-computed contact stress distributions from comparison articular joint surfaces (e.g., those from an intact versus those with residual intra-articular fracture incongruity).

Effect of microseparation on contact mechanics in metal‐on‐metal hip replacements—A finite element analysis

“…Currently, direct measurement of contact stress requires use of pressure sensors 41. However, with the challenges associated with a highly conforming joint and limited resolution of sensors, this method is generally not suitable for a contact with highly concentrated stress resulting from rim contact.…”

Assessment of stress distribution in ankle joint: simultaneous application of experimental and finite element methods

“…Determination of contact area between these ankle joint components as a function of loading, ankle position, and stability, is crucial for understanding the pathogenesis of ankle disorders, such as degenerative arthrosis amongst other ankle abnormalities (Hideji et al, 1998). In order to measure contact pressures, most studies used pressure-sensitive film, or pressure transducers mounted at or below the joint surface (Beaudoin et al, 1991;Anderson et al, 2007;Michael et al, 2008). In some studies, finite element method was used and validated by comparing the computed pressure distribution with those derived by various experimental methods (Anderson et al, 2007).…”

“…In order to measure contact pressures, most studies used pressure-sensitive film, or pressure transducers mounted at or below the joint surface (Beaudoin et al, 1991;Anderson et al, 2007;Michael et al, 2008). In some studies, finite element method was used and validated by comparing the computed pressure distribution with those derived by various experimental methods (Anderson et al, 2007). Magnetic resonance imaging (MRI) and CT data, which are used for generating finite element modes (FEMs), can facilitate pre-operative planning in many surgeries (Arbabi et al, 2007;Gilles et al, 2006;Ringleb et al, 2005).…”

“…Even though forces and ranges of motion at the ankle joint can be determined using various biomechanical methods, a comprehensive solution for determining the stress distribution within this joint has not been proposed yet. In most studies, which consist of pressure sensitive films or pressure transducers mounted at or below the joint (Anderson et al, 2007;McKinley et al, 2006), inherent limitations exist in these techniques, for example, crinkling artefacts caused by using the pressure sensitive film between curved joint surfaces (Hideji et al, 1998). Periarticular soft tissue dissection is also required for putting the film and transducers, which may alter the stability of the joint and soft tissue envelope (Anderson et al, 2007;Macirowski et al, 1994;Tochigi et al, 2006).…”

“…In most studies, which consist of pressure sensitive films or pressure transducers mounted at or below the joint (Anderson et al, 2007;McKinley et al, 2006), inherent limitations exist in these techniques, for example, crinkling artefacts caused by using the pressure sensitive film between curved joint surfaces (Hideji et al, 1998). Periarticular soft tissue dissection is also required for putting the film and transducers, which may alter the stability of the joint and soft tissue envelope (Anderson et al, 2007;Macirowski et al, 1994;Tochigi et al, 2006). Synovial fluid leakage in the joint region during the loading cycle may also occur, and it is known that pressure transducers only provide information for a limited region of the joint (Hideji et al, 1998;Anderson et al, 2007;McKinley et al, 2006).…”