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

5. DISCUSSION
This study proposes a methodology for characterizing variability in resections during
TKA, quantified as surgical resection envelopes for femur and tibia. Additionally, a
robustness analysis on dimensional measurements of the resected tibia and femur was
performed based on the reported variability.
The results suggest that resections generated using a set of mean surgical parameters
might not accurately capture all specific TKA cases (Table 1). In particular, the
resection parameters listed in Table 1 demonstrated specimen-to-specimen variations
which can be more than 8° in V/V alignment and 2 mm in depth for the tibia, and up to
12° in angular orientations for the femur. Relative to mean values, however, standard
deviations of angular parameters for both the tibia and femur were on the order of
several degrees and several millimeters (Table 2), with greater variations seen for
posterior slope (tibia) and flexion angle (femur). These variations could be due to
fundamental differences in surgical philosophy (e.g. selection of relevant anatomical
landmarks and axes used for alignment), the use of potted cadaver knees instead of
actual patients, or the expected anatomical variation, and warrant further investigation
The ML and AP measurements of the resected tibia and femur showed that the linear
dimensions of the tibia, when compiled across the sample set considered here, are
relatively insensitive to variations (1-2 mm) within the surgical envelope of coronal and
sagittal alignment. Expansion of the variability characterization activity using bigger
sample size over more diversified surgeons may further improve the data. Such
methodology can also be applied on other joints to assist the understanding of joint
replacements.
8. REFERENCES
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