Validation of Subject-Specific Knee Models from In Vivo Measurements
Journal:
arXiv
Published Date:
Dec 27, 2024
Abstract
Calibration to experimental data is vital when developing subject-specific
models towards developing digital twins. Yet, to date, subject-specific models
are largely based on cadaveric testing, as in vivo data to calibrate against
has been difficult to obtain until recently. To support our overall goal of
building subject-specific models of the living knee, we aimed to show that
subject-specific computational models built and calibrated using in vivo
measurements would have accuracy comparable to models built using in vitro
measurements. Two knee specimens were imaged using a combination of computed
tomography (CT), and surface scans. Knee laxity measurements were made with a
custom apparatus used for the living knee and from a robotic knee simulator.
Models of the knees were built using the CT geometry and surface scans, and
then calibrated with either laxity data from the robotic knee simulator or from
the knee laxity apparatus. Model performance was compared by simulation of
passive flexion, knee laxity and a clinically relevant pivot shift. Performance
was similar with differences during simulated anterior-posterior laxity tests
of less than 2.5 mm. Additionally, model predictions of a pivot shift were
similar with differences less than 3 deg or 3 mm for rotations and
translations, respectively. Still, differences in the predicted ligament loads
and calibrated material properties emerged, highlighting a need for methods to
include ligament load as part of the underlying calibration process. Overall,
the results showed that currently available methods of measuring knee laxity in
vivo are sufficient to calibrate models comparable with existing in vitro
techniques, and the workflows described here may provide a basis for modeling
the living knee. The models, data, and code are publicly available.
