Three-DOF Reference Jig for Knee Implant Alignment
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Solution Overview
Problem
Existing inertial sensors used in computer-assisted surgery are limited to two degrees of freedom (DOF) orientation tracking, necessitating additional steps to provide necessary navigation parameters for accurate implant positioning in knee arthroplasty.
Innovation Solution
A reference jig with a base, adjustment mechanism, and landmark alignment unit is used to secure to the distal end of the femur, allowing for three DOF tracking and alignment with bone landmarks, combined with inertial sensors to create a femoral coordinate system for precise cut guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If inertial sensors with two DOF orientation tracking are used, then device complexity is reduced, but measurement precision and navigation parameter completeness deteriorate
Solution Approach 1:
The system segments the tracking function by using two separate inertial sensors: one sensor tracks orientation (two DOF) and another sensor tracks position. This segmentation allows each sensor to be optimized for its specific function while collectively providing complete six-DOF tracking capability, resolving the contradiction between device complexity and measurement precision
Solution Approach 2:
The patent makes the inertial sensor system multi-functional by configuring it to perform both orientation tracking and position tracking through the use of multiple sensors. This universal approach allows the system to provide complete navigation parameters (both orientation and position) without requiring a single complex sensor, thus resolving the contradiction
2Measurement precision
If additional steps are taken to provide navigation parameters, then measurement precision improves, but productivity and ease of operation deteriorate
Solution Approach 1:
The system performs preliminary action by pre-configuring the inertial sensors to automatically provide both orientation and position tracking data. This preliminary setup eliminates the need for additional manual steps during surgery to obtain navigation parameters, as the system continuously provides complete navigation data, thus resolving the contradiction between measurement precision and productivity
Solution Approach 2:
The inertial sensor system serves itself by automatically generating and providing both orientation and position navigation parameters without requiring external intervention or additional surgical steps. The sensors self-manage the complete tracking function, improving both measurement precision and surgical efficiency simultaneously
Data Source
AI summary
A reference jig comprises a base adapted to be secured to a distal end of a bone. An adjustment mechanism has a bracket, one or more rotational joints operatively mounting the bracket to the base, whereby the bracket is rotatable in two or more rotational degrees of freedom relative to the base, and one or more translational joints. A landmark alignment unit is operatively connectable to the bracket by the at least one translational joint, the landmark alignment unit having a bone alignment component configured to be aligned with at least one bone landmark.