Joint Resection Guide With Six-Degree-of-Freedom Linkage
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Solution Overview
Problem
Current arthroplasty procedures face challenges in achieving accurate implant alignment due to the limitations of existing instrumentation, which can result in translational or rotational misalignments, leading to imbalanced ligaments, post-surgery pain, and reduced range of motion.
Innovation Solution
A modular linkage system comprising an anchor, cutting block, and pivotably interconnectable links with frictional connections is used to position a cutting guide, allowing for flexible linkage with six degrees of freedom, enabling precise resection of bones by aligning the cutting block with the intended resection plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard alignment instrumentation is used for locating the position and orientation for resection, then the procedure can be performed with conventional tools, but the accuracy of implant alignment is insufficient, resulting in translational or rotational misalignment
Solution Approach 1:
The alignment device is divided into multiple modular components including a base plate, a positioning arm, and a cutting guide. Each component can be independently adjusted and positioned to achieve precise alignment. The base plate attaches to the bone, the positioning arm extends to the cutting location, and the cutting guide provides the cutting path, allowing segmented adjustment for high precision without requiring a monolithic complex device.
Solution Approach 2:
The positioning arm incorporates adjustable joints and movable connections that allow dynamic positioning in multiple degrees of freedom. The cutting guide can be adjusted relative to the positioning arm, and the entire assembly can be reconfigured during the procedure to accommodate different anatomical variations and achieve optimal alignment accuracy for each specific case.
2Manufacturing precision
If more accurate cutting guides are used to improve resection accuracy, then implant alignment precision improves, but the device complexity and difficulty of operation increase
Solution Approach 1:
The base plate serves as an intermediary element that attaches to the bone and provides a stable foundation for the positioning arm. This intermediary structure simplifies the connection between the cutting guide and the bone, distributing the positioning function across multiple components rather than requiring a single complex mechanism, thereby maintaining ease of operation while achieving high precision.
Solution Approach 2:
By segmenting the alignment device into a base plate, positioning arm, and cutting guide, each component can be independently adjusted and positioned. This segmentation allows the surgeon to focus on positioning each element separately, reducing the cognitive load and operational difficulty compared to adjusting a single monolithic structure, while still achieving high overall precision.
3Adaptability or versatility
If a rigid fixed-position cutting guide is used, then the structure is simple, but it cannot accommodate variations in bone anatomy and intended resection planes
Solution Approach 1:
The linkage between the base plate and cutting guide is designed to be dynamic rather than rigid, allowing adjustment of the cutting guide's position and orientation relative to the base plate. This dynamic linkage enables adaptation to various bone anatomies and resection plane requirements while maintaining structural integrity during the cutting procedure.
Solution Approach 2:
The device is segmented into modular components with reversible connections, allowing the cutting guide to be repositioned and reconfigured to match different bone geometries. This modular segmentation provides versatility for accommodating anatomical variations without requiring a completely different device for each case, balancing adaptability with manageable complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The modular linkage system enhances the accuracy of bone resection by allowing for precise alignment of the cutting guide, reducing the risk of misalignment and improving the success of arthroplasty procedures by ensuring proper implant placement and functionality.
Implementation Method 1
The connections may have enough friction to prevent, or at least slow, flexure of a linkage of typical length in the absence of active manipulation by the surgeon
Data Source
AI summary
A resection guide includes an anchor having bone anchoring features, a cutting block having a cutting guide defined therein, and a linkage flexibly connecting the cutting block to the anchor. The flexibility of the linkage provides the cutting block with six degrees of freedom of motion relative to the anchor.