| Summary: | The biomechanical goals of total knee replacement surgery are to restore
neutral alignment to the lower limb and balance the soft tissues of the knee.
Currently, this soft tissue balancing is considered an art; there are few ways to
quantify the appropriateness of the soft tissue balancing that a surgeon does.
Furthermore, the few existing techniques for quantifying balance are applied
after the bone cut is complete, so the state of the soft tissue cannot enter into
the surgical planning process. Since problems with soft tissue balancing
represent one of the major unsolved problems in knee surgery, there is
considerable interest in developing tools to assist with this process
In this thesis, I report on the development and preliminary testing of two
specific algorithms. The first is an intraoperative method to precisely identify
ligament anatomy for use in a kinematic knee model using a computer assisted
surgical system. The second is a method to determine the component
placement that minimizes ligament strain and laxity throughout the entire
range of motion of the knee. Both methods are requirements for a
comprehensive surgical advisory system.
The ligament identification method proved sufficiently repeatable on porcine
specimens to warrant further testing on cadaver specimens. The component
placement algorithm was able to determine optimal placement locations
accounting for imbalances introduced on a simulated knee model, and was
robust to errors introduced when using the ligament measurement routine to
obtain model inputs. Further testing on physical knee models is required for
validation of the method's ability to determine optimal component placement
and predict passive kinematics. I conclude that the two methods presented
have the potential to provide the surgeon with accurate quantitative
intraoperative information for use in soft-tissue balancing and surgical
planning procedures and warrant further investigation.
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