Extramedullary Tibia Guidance Jig for Accurate Ankle Alignment
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Solution Overview
Problem
Current systems for total ankle replacement lack a simple, lightweight, and surgeon-manipulatable extra-medullary jig that can accurately and efficiently implant an intra-medullary total ankle prosthesis, often requiring complex and rigid foot holders that constrain the patient's foot and leg, leading to potential misalignment and discomfort.
Innovation Solution
A C-bracket system with fixation features in the calcaneus, distal tibia, and proximal tibia, combined with a joint space filling device, heel cups, and forefoot blocks, allowing for a streamlined extra-medullary jig that maintains proper alignment and positioning during intramedullary reaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large rigid foot holder is used to constrain the foot and leg, then the positioning stability is improved, but the device complexity and ease of operation deteriorate
Solution Approach 1:
The foot holder is divided into modular components: a base plate for stability, adjustable alignment rods for positioning, and detachable fixation elements. This segmentation allows the system to achieve rigid positioning when needed while enabling easy reconfiguration and storage when not in use, thereby reducing overall device complexity.
Solution Approach 2:
The alignment rods and fixation elements are designed to be adjustable and reconfigurable during the surgical procedure. The alignment rods can be positioned at different angles and heights, and the fixation elements can be attached or removed as needed, providing dynamic adaptability that reduces device complexity while maintaining positioning stability.
2Stability of the object's composition
If a large rigid foot holder is used to constrain the foot and leg, then the positioning stability is improved, but the ease of operation deteriorates
Solution Approach 1:
By dividing the foot holder into modular components, each with a specific function, the surgeon can quickly assemble and disassemble the system without manipulating a single large complex device. The base plate provides stable foundation while alignment rods and fixation elements can be independently adjusted and positioned.
Solution Approach 2:
The adjustable alignment rods and detachable fixation elements allow the surgeon to reconfigure the positioning system during the procedure without removing the entire apparatus. This dynamic reconfigurability significantly improves ease of operation while maintaining the rigid positioning stability required for accurate ankle replacement.
3Ease of operation
If the foot is moved to position on the jig, then the ease of operation is improved, but the measurement precision deteriorates
Solution Approach 1:
Instead of moving the foot to match the jig's fixed geometry, the jig's alignment rods and positioning elements are adjusted to match the patient's specific anatomical geometry. This inversion of the traditional approach maintains measurement precision by adapting the device to the patient rather than forcing the patient to conform to the device.
Solution Approach 2:
The alignment rods can be adjusted in position, angle, and height to accommodate variations in patient anatomy. This dynamic adjustability ensures that each patient's foot and leg can be precisely positioned according to their unique measurements while maintaining ease of operation through simple rod adjustments rather than complex foot manipulations.
4Reliability
If fixation features in calcaneus, distal tibia, and proximal tibia are used, then the reliability of fixation is improved, but the device complexity increases
Solution Approach 1:
The fixation system is divided into separate fixation features at different anatomical locations (calcaneus, distal tibia, proximal tibia), each served by dedicated fixation elements. This segmentation allows each fixation point to be independently optimized and secured, enhancing overall reliability while keeping individual components simple and manageable.
Data Source
AI summary
A system and method fare provided for preparing the distal tibia in an ankle replacement via an extra-medullary jig. An extra-medullary jig or C-bracket is positioned on the tibia with a registration reference and positioned with respect to a resection in the distal tibia via an anterior mounting block which is independent of the surface of the tibia. The mounting block allows the adjustment of the stem cartridge with respect to the registration reference such that the stem cartridge is properly aligned within the resection. The C-bracket is further attached to the tibia via an adjustable proximal alignment arm which attaches to a pin embedded in the proximal tibia. The C-bracket aligns the tibia, foot and ankle and the trajectory of the reamer, and is universal with respect to the left and right ankle.