A multibody model for the optimization of hip arthroplasty in relation to range of movement

Elisabetta Maria Zanetti, Cristina Bignardi, Mara Terzini, Giovanni Putame, Alberto Luigi Audenino


The dislocation of the prosthesized hip is a relevant post-operative complication; this adverse outcome is dependent on the specific patient anatomy and on the artificial joint design. The geometry of the reconstructed hip is one of the key factors and it is usually designed at the time of pre-operative planning when the stem model and size, the head diameter and its offset, and the acetabular cup orientation are selected.

In this work, the authors have developed a numerical model to support to pre-operative planning, allowing assessing the allowed range of motion, once the geometry of the implant has been defined.

A multi-body model of a prosthesized hip has been developed, and a dislocating movement has been applied; the software is able to assess the entity of displacements and of applied forces which can produce hip dislocation.

As a proof of concept, multiple combinations of geometric factors have been examined that are the head diameter, the acetabular cup anteversion and its inclination, reaching a total number of 675 configurations. This software is able to analyse and compare all configurations in few minutes.

The developed numerical model can be a support to quickly compare a great number of solutions from the point of view of hip stability, reaching a comprehensive view of all possibilities, and giving a contribute to the final aim that is surgery optimization, in relation to each specific patient.
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