ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

Table 2. Variability of measured surgical resections.
For the tibia the absolute difference in the ML and AP dimensions averaged over all
bones between the surgical resection and the resection created with the mean parameters
is shown in Figure 2a. On average the difference is less than 1.5 mm and the AP
dimensions show more variability than the ML dimension. The differences are slightly
less when the dimensions from the mean resection parameters are compared with the
perturbed resections. The varus / valgus degree of freedom shows consistent deviation
in the ML and AP dimensions while the posterior slope affects the AP dimension more
than the ML dimension.
Figure 3. Tibia Average absolute difference between
A) surgical and mean parameter resections B) mean and perturbed resections
For the femur, the absolute difference in ML and AP dimensions for the contours
generated with the surgical parameters and the mean resection parameters (Figure 3A)
are slightly larger than the tibia. Similar to the tibia, the femur AP dimension changes
more than the ML. The comparison between the mean resection and perturbed
resections showed a similar trend that the AP dimension is affected more than ML. The
femur AP dimension is not affected by changes in the varus / valgus angle since the
rotation is in the same plane as the measurement.
Figure 3. Femur Average absolute difference between
A) surgical and mean parameter resections B) mean and perturbed resections