Articulated Reaming Guide Alignment for Intramedullary Canal Angles
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Solution Overview
Problem
Existing reaming instruments for long bones, such as in total knee arthroplasty, are limited in their ability to maintain a desired angle relative to the bone due to the convergence of the intramedullary canal, restricting the usable range of reaming.
Innovation Solution
An alignment instrument with an adjustable shaft and articulation component that allows for three degrees of freedom and locking, enabling precise alignment and stabilization of a reamer within the intramedullary canal, allowing for adjustable and fixed angles during reaming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rigid linear rod is inserted straight into the intramedullary canal, then the rod provides initial alignment, but the decreasing radius of the canal forces the rod alignment to converge with the axis of the canal, limiting the ability to use the guide at a desired angle
Solution Approach 1:
The guide rod is designed with an articulation mechanism that allows it to transition from a rigid linear configuration to an articulated configuration with adjustable angles. The articulation component enables the guide rod to maintain desired angles relative to the bone axis throughout the reaming process, preventing convergence with the canal axis and providing multiple reaming angle options.
Solution Approach 2:
The guide rod is divided into multiple segments or components including a proximal portion, distal portion, and articulation component. This segmentation allows each portion to be independently positioned and articulated, enabling the guide rod to maintain specific angles relative to the bone axis while still providing stable guidance for the reamer.
2Stability of the object's composition
If the guide rod structure is made rigid to ensure stability, then the rod provides stable guidance, but the rigid structure limits the angle at which the reamer can be advanced through the canal
Solution Approach 1:
The guide rod incorporates an articulation mechanism that allows it to transition between stable rigid guidance and flexible angled positioning. During insertion, the guide rod maintains rigidity for stability, then the articulation component is activated to establish and lock at desired angles, providing both stability and angular flexibility as needed.
Solution Approach 2:
The guide rod's geometric parameters, specifically the angle between the proximal and distal portions, can be changed through the articulation mechanism. This allows the guide rod to adapt its configuration to match the required reaming angles while maintaining structural integrity and stability during the reaming procedure.
3Device complexity
If a fixed angle guide rod is used to simplify the structure, then the rod structure is simpler, but the desirable portion of the bone that can be reamed is limited
Solution Approach 1:
The guide rod transitions from a simple fixed structure to a dynamic articulated structure that can be adjusted to multiple angles. This allows the guide rod to access different portions of the bone canal by articulating to various angles, thereby expanding the reaming coverage without requiring multiple separate guide rods.
Solution Approach 2:
The articulation mechanism enables a single guide rod to perform multiple functions by adjusting its angle to match different implant orientations and reaming requirements. This multi-functional capability eliminates the need for multiple specialized guide rods, reducing overall device complexity while increasing versatility.
Data Source
AI summary
A system includes a hollow reamer and an alignment instrument. The alignment instrument includes a shaft contoured to receive the hollow reamer such that the hollow reamer is translatable therealong. The alignment instrument further includes an articulation component coupled to the distal end of the shaft and a stem coupled to the articulation component. The shaft is configured to articulate relative to the articulation component. Further, the shaft includes a movable component configured to transition the alignment instrument between an unlocked state and a locked state via contact between the movable component and the articulation component. In the unlocked state, the articulation component is configured to articulate with respect to the shaft. In the locked state, the articulation component is configured to be fixed relative to the shaft.