Quantitative CT with finite element analysis: towards a predictive tool for bone remodelling around an uncemented tapered stem

Abstract

Purpose We used quantitative CT in conjunction with finite element analysis to provide a new tool for assessment of bone quality after total hip arthroplasty in vivo. The hypothesis of this prospective five-year study is that the combination of the two modalities allows 3D patientspecific imaging of cortical and cancellous bone changes and stress shielding. Method We tested quantitative CT in conjunction with finite elements on a cohort of 29 patients (31 hips) who have been scanned postoperatively and at one year, two years and five years follow-up. The method uses cubic Hermite finite element interpolation for efficient mesh generation directly from qCT datasets. The element Gauss points that are used for the geometric interpolation functions are also used for interpolation of osteodensitometry data. Results The study showed changes of bone density suggestive of proximal femur diaphysis load transfer with osteointegration and moderate metaphyseal stress shielding. Our model revealed that cortical bone initially became porous in the greater trochanter, but this phenomenon progressed to the cortex of the lesser trochanter and the posterior aspect of the metaphysis. The diaphyseal area did not experience major change in bone density for either cortical or cancellous bone. Conclusion The combination of quantitative CT with finite element analysis allows visualization of changes to bone density and architecture. It also provides correlation of bone density/architectural changes with stress patterns enabling the study of the effects of stress shielding on bone remodelling in vivo. This technology can be useful in predicting bone remodeling and the quality of implant fixation using prostheses with different design and/or biomaterials.

Use of high resolution dual‐energy x‐ray absorptiometry‐region free analysis (DXA‐RFA) to detect local periprosthetic bone remodeling events

“…2 DXA-RFA provides a lowradiation dose alternative to computed tomography for such imaging. This approach may provide a novel opportunity to study non-invasively in clinical trials the effect of investigational drugs or implant surface modifications suggested in animal studies to modulate prosthesis osseointegration.…”

“…1 This value is calculated as the mean BMD value derived from large numbers of pixels contained within the defined ROI. However, bone remodeling events occurring after prosthesis insertion are spatially complex and may not be uniform across a given ROI, 2 For example, within a large ROI the BMD change occurring over a given time at the bone-prosthesis interface may differ substantially to that occurring at the bone periosteal surface. 2 Such differences cannot be resolved using ROI-based DXA analysis technology, whilst the alternate computed tomography-based approach is accompanied with a higher radiation exposure dose.…”

“…However, bone remodeling events occurring after prosthesis insertion are spatially complex and may not be uniform across a given ROI, 2 For example, within a large ROI the BMD change occurring over a given time at the bone-prosthesis interface may differ substantially to that occurring at the bone periosteal surface. 2 Such differences cannot be resolved using ROI-based DXA analysis technology, whilst the alternate computed tomography-based approach is accompanied with a higher radiation exposure dose. 3,4 Further, different ROI models may also be required to measure BMD change around prostheses with differing geometries, [5][6][7] making quantitative comparisons of bone remodeling between prostheses challenging.…”

Subject-specific finite element analysis to characterize the influence of geometry and material properties in Achilles tendon rupture

“…We used high order cubic Hermite elements, which preserve both the continuity of nodal values and their first derivatives. This type of element can describe smooth surfaces often found in biological structures such as the heart (Stevens et al, 2003), muscle (Oberhofer et al, 2010) and bone (Munro et al, 2013;Shim et al, 2012) with a lot fewer elements as each node has total 24 degrees of freedom. Therefore, our model has 32 elements and 72 nodes, which corresponds to 1728 degrees of freedom.…”

Four decades of finite element analysis of orthopaedic devices: Where are we now and what are the opportunities?

“…Bone adaptation and remodelling: Bone remodelling simulations have been performed extensively, primarily to assess stress shielding around the femoral component of hip arthroplasty (Perez et al, 2010;Taylor et al, 2004;Weinans et al, 1994;Gupta et al, 2006;Huiskes et al, 1992;Weinans et al, 1992Weinans et al, , 1993Stulpner et al, 1997;Folgado et al, 2009;Pal and Gupta 2011;Shim et al, 2012). Since the publication of the first bone remodelling simulations around implants by Huiskes and co-workers (Huiskes, 1988), there have only been incremental developments, for example accounting for overload induced bone loss (Behrens et al, 2009;Scannell and Prendergast, 2009).…”