Total Knee Alignment Guide System for Ligament Tension Balancing
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Solution Overview
Problem
Current total knee replacement surgeries face challenges in accurately aligning and balancing the artificial knee components to replicate the natural ligament tensions across the knee joint, leading to potential post-operative instability and discomfort.
Innovation Solution
A predictive total knee alignment and balancing system that includes a set of guide units and a tension tool to ensure precise alignment and tensioning of artificial tibial and femoral components, using a sequence of guides to match the geometries of the artificial components with the patient's bone cuts and replicate ligament tensions across the knee's range of motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional total knee replacement alignment methods are used, then the surgical procedure is simpler, but the accuracy of ligament tension balancing deteriorates
Solution Approach 1:
The alignment system is divided into multiple guide units (first guide unit for tibial alignment, second guide unit for femoral alignment, third guide unit for rotational alignment) that perform specific alignment functions sequentially. Each guide unit addresses a specific alignment requirement, allowing the complex task of total knee replacement alignment to be broken down into manageable segments that collectively achieve high precision ligament tension balancing.
Solution Approach 2:
The guide units are designed to establish alignment references and bone cuts before the actual implantation of artificial components. The system performs preliminary alignment actions by creating precisely oriented bone surfaces that will subsequently receive the artificial knee components, ensuring that ligament tensions are balanced before final implantation occurs.
2Manufacturing precision
If multiple guide units are used to improve alignment accuracy, then the manufacturing precision improves, but the device complexity increases
Solution Approach 1:
Multiple guide units are merged into a coordinated alignment system where the first guide unit (for tibial alignment), second guide unit (for femoral alignment), and third guide unit (for rotational alignment) work together as an integrated system. The guide units reference previously created bone surfaces and align subsequent cuts, merging their functions to achieve cumulative precision that would be difficult to obtain with any single guide unit alone.
3Measurement precision
If the guide units reference previously created bone surfaces, then the alignment accuracy improves, but the number of surgical steps increases
Solution Approach 1:
The guide units are designed to maintain continuous alignment references throughout the surgical procedure. Each guide unit references previously created bone surfaces and establishes new references for subsequent steps, creating an unbroken chain of alignment accuracy from initial bone cuts through final component implantation. This continuous referencing eliminates the need to re-establish alignment baselines between surgical steps.
Data Source
AI summary
Once variation of a system for total knee replacement includes: a first alignment guide defining first set of guides that locate a first set of pins on a first bone of a joint in extension and defining a reference surface relative to the first set pin guides; a second alignment guide constrained relative to the first alignment guide by the reference surface and defining a second set of guides, relative to the first set of guides, that locate a second set of pins on a second bone of the joint; a first cut guide located by the first set of pins and defining a first cut plane for resecting the first bone; and a second cut guide located by the second set of pins and defining a second cut plane, linearly offset from the first cut plane, for resecting the second bone.