Biomedical Engineering Reference
In-Depth Information
FIGURE 15.9
Computational procedure to simulate intraoperative retraction: (a) the retractor blade is
described by a patch description inserted into the model, (b) the patch description guides
the splitting of the finite element mesh, (c) the retraction occurs with the application of
boundary conditions separating the tissue.
the blade, whereas in the simulation it separates. Clearly, boundary conditions
on both sides of the blade-tissue interface require further study. Figure 15.11b
contains additional data acquired by placing a small pressure sensor on the
face of the retractor blade which could be helpful in this regard and easily
deployed in the human OR as well. The recordings show a pressure spike
immediate to the initialization of a retraction event followed by a period of
transient decay until the next retraction occurs. This information could be use-
ful for defining appropriate boundary conditions for retraction on a case-by-
case basis. If both displacement and normal stresses at the retractor surface can
be measured, the opportunity also exists to estimate local mechanical proper-
ties
in vivo
.
Interestingly, the pressure measurements at the retractor surface in Figure
15.11b are similar in character to interstitial pressure measurements which
