Design of an affordable, modular implant device for soft tissue tension
assessment and range of motion tracking during total hip arthroplasty
Abstract
Inexperienced surgeons undertaking hip arthroplasties are twice as
likely to experience errors than their experienced colleagues, leading
to dislocations, pain and discomfort for the patients. To address this
issue, a new 3DOF force measurement system was developed and integrated
in multiple new prototypes able to measure forces and movements
intraoperatively in 3D. The prototypes were evaluated in three cadaver
trials, with the goal of providing surgeons objective data to help
determine the optimal implant fit and configuration. The devices
comprise deformable polymer material that provide strain-based
displacements measured with electromagnetic-based sensors and inertial
measurement unit (IMU) for motion data. Device results show an accuracy
of approx. 2 N and a sensitivity of approx. 1 N. Cadaver results
indicated that soft tissue forces on the hip joint peak in the order of
~100 N and trend with positions of the leg during range
of motion (ROM) tests, although force patterns differ between each
cadaver. We propose that by monitoring forces and force patterns, in
combination with standardised ROM tests, anomalies could be detected and
corrected during surgery.