Hi,
I am currently struggling to virtually ream an acetabulum from a segmented hemipelvis. This is required for an implantation of an uncemented cup. As my analysis involves FEA (ABAQUS), I am currently performing the virtual reaming using a sphere. I am currently applying a boolean subtraction operation in ABAQUS to remove the cortical bone (and expose the subchondral bone) by positioning the sphere on the Centre of Rotation of the Hip.
Nevertheless, I seem to get rid of more than desired trabecular bone. Thus, my uncemented cup doesn't seem to have contact with the reamed acetabulum unless the cup is deepened, which leads me to the next question of How to virtually implant an uncemented cup in an already reamed acetabulum?
I have reviewed some literature and some researchers seemed to have used a step in ABAQUS where they perform a displacement control until the uncemented cup is overhanged(certain level of contact is achieved). I haven't used this FEA technique before, so any comments about this is widely appreicated.
I hope I was able to explain myself and this questions aren't too technical to be answered.
Thanks!
Dear Jose, why don't you perform the boolean with the modeled acetabular cup ? And it's very easy if you can use such boolean operations in another CAD software which is much flexible to use....
Hi Rajdeep Ghosh , it's not possible to do the boolean operation with the modeled acetabular cup because the size of the cup must be bigger than the geometry where I am introducing it by pressure. The only problem of using other CAD softwares is that my geometry has 2 materials which aren't being distinguished if I perform a boolean operation in them (e.g. Solidworks).
Hi Jose I personally use Rhinoceros for such implantation and boolean operations and thereafter export it into FE softwares....And contact elements might be introduced at the interface between bone and the implant...
Hi Rajdeep. I have seen published work of people using Rhinoceros. However, I have never used it before. Can you please specify what do you mean by contact elements being introduced in the interface?
For modelling the interface I was thinking about extracting the cup outside of hip and then introducing it by displacement control with a penalty friction coefficient between bone and implant.
Yeah Jose this is how you are supposed to create a contact between the bone and the implant by introducing penalty friction coefficient to define the fuzzy nature of the interface. You may study the portion of contact elements in Abaqus before providing any coulomb friction model or any such model to define contacts.
Regarding Rhino, it is somewhat different from traditional CAD modelers like SW, Catia etc. Rhino works on the curve modeling technique in its NURBS environment and is relatively easy for all such implantation purposes. I had tried with CATIA during my initial days but I found Rhino to be more easy to use as far as such procedures are concerned.
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