Instrumented Trial Guide for Revision Knee Arthroplasty
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Solution Overview
Problem
During revision knee arthroplasty, there is a need for precise planning and execution of bone resections and implant placement, especially due to variations in human anatomy and the requirement for offset and angulation of stem components to accommodate bowing of the intramedullary canal.
Innovation Solution
A trial guide system is provided, which includes a body with articulating and posterior surfaces, a trial stem, stem adapter, offset couplers, patient tracker array, and a tracking system with sensors to detect the position and orientation of the trial components. This system allows for adjustment of the trial stem's alignment and angulation to match the patient's specific anatomy, and generates a surgical plan for the revision implant based on the geometry determined.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If trial-first hardware is temporarily placed in the distal end of the femur to determine changes to existing distal femoral geometry, then the surgeon can assess implant balance, but the procedure relies on guess-and-check or eyeballing by the surgeon
Solution Approach 1:
The patent replaces the manual mechanical assessment method (surgeon's eyeballing and guess-and-check) with an optical tracking system using cameras and fiducial markers. The system captures images of the trial hardware and bone, detects fiducial marker positions, and computationally determines the geometry and alignment of the trial stem relative to the bone, providing precise measurement without relying on surgeon estimation.
2Adaptability or versatility
If multiple offset couplers are provided to adjust lateral alignment and angular offset of the trial stem, then the system can accommodate variations in human anatomy and bowing of the intramedullary canal, but the device complexity increases
Solution Approach 1:
The trial guide system is divided into multiple independent modular components: a body portion, a trial stem, an offset coupler, and a stem adapter. Each component can be independently adjusted or replaced. The offset coupler specifically provides separate adjustments for lateral alignment and angular offset, allowing the system to adapt to various anatomical configurations without requiring a completely different device for each case.
Solution Approach 2:
The system incorporates dynamic adjustability through the offset coupler, which can be rotated about the trial stem's longitudinal axis to adjust lateral alignment, and through the stem adapter, which can translate with respect to the body to adjust anterior-posterior alignment. These dynamic adjustments allow the trial stem to be precisely positioned to match the patient's specific anatomy and compensate for intramedullary canal bowing.
3Measurement precision
If a tracking system with sensors is used to detect position and orientation of trial components, then precise geometry determination is achieved, but the procedure time and system complexity increase
Solution Approach 1:
Fiducial markers are pre-attached to the trial hardware components (body, stem, offset coupler) during manufacturing. These markers are ready for immediate detection by the tracking system without requiring additional setup time in the operating room. The tracking system can immediately capture images and compute positions once the components are in place, minimizing procedure time while maintaining high measurement precision.
Data Source
AI summary
A trial guide for temporary placement on the distal end of the femur during a knee revision includes instrumented components that allow a surgeon to determine distal and posterior extension gaps for balancing the revised implant, and an adjustable stem component that allows the surgeon to translate a trial stem and rotate a selected offset coupling for the trial stem to ensure proper trial placement before the revision procedure. Fiducial markers can be affixed to the body or components of the trial guide to allow a surgical system to map the trial guide onto a reference frame for the surgery, such as the femur reference frame, thereby allowing the surgical system to update the surgical plan and assist the surgeon in implementing the plan for a revision the arthroplasty.