Abstract
We present a framework for statistical finite element analysis allowing performing statistical statements of biomechanical performance of peri-articular implants across a given population. In this paper, we focus on the design of orthopaedic implants that fit a maximum percentage of the target population, both in terms of geometry and biomechanical stability. CT scans of the bone under consideration are registered non-rigidly to obtain correspondences in position between them. A statistical model of shape is computed by means of principal component analysis. A method to automatically propagate standardize fractures on the statistically-based bone population has been developed as well as tools to optimize implant position to best-fit the bone surface. Afterwards, finite element analysis is performed to analyse the biomechanical performance of the bone/implant construct. The mechanical behaviour of different PCA bone instances is compared for tibia representing the Asian and Caucasian populations.
Keywords
Source Code and Data
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Reviews
Adam Wittek
Monday 30 June 2008
(This review can be also viewed by opening the attached PDF file)
The paper addresses an important problem of the design of orthopaedic implants to to
ensure that they fit the maximum of the target population. The Authors build statistical
shape model of a tibia and use to optimise the implant position. They also conduct
modelling analysis (FE method is used) biomechanical performance of bone-implant
construct. The methodology appears to be original and technically sound. However, some
aspects (bone-to-bone and bone-to-implant interactions) of the modelling conduct require
further clarification. Therefore, my opinion is that before the paper can be regarded as
ready for publication/presentation in the Workshop, the Authors should answer the
questions given below and modify the paper following them.
Major comments
1) Biomechanical FE Simulations: How were the interactions between two split (as a
result of fracture) bone parts and between the bones and implant modelled?
The Authors write that “3D beam elements were used to fix implant to the bone”
and that “Attachment of the beam to the bone was preformed using an embedded
element technique”. However, in order for such modelling of attachment to be
meaningful, the implant should be allowed to move/slide in relation to the bone. This
would require application of contact interface (or similar type of constrain) between
the implant and bone, and between two split bone parts. The paper does not mention
existence of any type of such interface between the bone and implant and between
two split bone parts.
2) What finite element solver was used and what type of finite element analysis (i.e.
geometrically linear or non-linear) was applied?
3) Legend of Table 1 (p. 8): Was the bone-implant distance determined using imagebased
methods described in Sections 2-4?
Minor comments
1) P. 2 reference [Rueckert] is missing in the Reference list
2) P. 2, figure 1 caption. Is: “axis”, should be: “axes” (plural)
3) P. 3, second column, second paragraph. Is: “the fracture should be a continuous”,
should be: “the fracture should be continuous”
4) P. 4, last sentence. Is “in Eq. 3”, should be: “in Eq. 4”.