Nonlinear Computational Biomechanics of the Hip

Sponsor: NIH Bioengineering Research Partnership

Thomas D. Brown, Ph.D.
Richard C. Johnston Chair of Orthopaedic Biomechanics
The University of Iowa

Iowa City, IA 52242
e-mail: Thomas-Brown@uiowa.edu

Name	Organization	Role on Project
Douglas R. Pedersen, Ph.D.	University of Iowa	Co-Investigator
Anneliese D. Heiner, Ph.D.	University of Iowa	Co-Investigator
Richard A. Brand, M.D.	University of Iowa	Clinical Co-Investigator
John J. Callaghan, M.D.	University of Iowa	Clinical Co-Investigator
J. Lawrence Marsh, M.D.	University of Iowa	Clinical Co-Investigator
Stuart L. Weinstein, M.D.	University of Iowa	Clinical Co-Investigator
Michael G. Conzemius, D.V.M.	Iowa State University	Investigator
Robert A. Poggie, Ph.D.	Implex Corporation	Investigator

Disorders of the hip comprise a substantial fraction of current musculoskeletal disease burden. Complex nonlinear mechanical phenomena pervade many aspects of treatment of hip disease and injury, including total hip arthroplasty, intra-articular fractures, osteonecrosis, and developmental dysplasia. While bioengineering capabilities exist – in principle – to quantify key mechanical factors influencing treatment outcomes in these areas, contemporary clinical decision making still rests almost entirely on subjective empirical experience. This Bioengineering Research Partnership (BRP) brings together the capabilities of an experienced computational biomechanics research group, four senior orthopaedic hip surgeons, a veterinary research orthopaedist, and an industry-based materials scientist, in order to advance the state of the art in biomechanically-grounded management of disorders and injuries of the human hip. The central focus of the research Partnership lies in applying nonlinear finite element formulations to address as-yet-unquantified mechanical phenomena that are clinically recognized as being crucial to patient outcome. Building on previous and ongoing finite element work, new computational formulations will be developed to tackle nonlinearities currently limiting the accuracy of numerical simulations in five clinically important areas of hip surgery. The first two areas involve leading complications of total hip arthroplasty.

First, as regards abrasive wear of polyethylene, we propose to incorporate local directionality of femoral head counterface motion in computing wear rates with a sliding-distance-coupled contact finite element formulation.

Second, as regards dislocation, we propose to introduce soft tissue tethering into a large-displacement sliding contact model of resistance to dislocation.

The third area involves intra-articular fractures of the acetabulum: estimating residual cartilage contact stress elevations accompanying attempts at surgical restoration of articular surface congruity.

The fourth area involves osteonecrosis: computationally characterizing a new animal model (the emu) which unlike previous animal models progresses to human-like femoral head collapse, and using that model for in-vivo testing of computationally optimized placement of a novel head-preserving implant device.

The fifth application area involves surgical management of developmental hip dysplasia: using novel mesh pre-processing techniques to quantify improvements of intra-articular contact stress achieved by pelvic osteotomies.

This Partnership will bring together a critical mass of engineers and surgeons, to achieve clinically-grounded advances in nonlinear numerical simulations of surgery of the hip.

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