Dual Stylus Knee Instruments for Precise Resection Angle Adjustment

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Solution Overview

Problem

Existing knee resection and ligament balancing instruments lack the ability to measure the angle of the current joint surface on both the femur and tibia, restore the joint surface to its pre-arthritic level, allow specific bone resection from medial and lateral aspects, and provide infinite angle adjustment within an acceptable range, which limits their effectiveness in achieving precise knee implant alignment.

Innovation Solution

The development of knee resection and ligament balancing instruments featuring a stable portion, a resection guide portion, and a resection guide body that can pivot and lock at various orientations, allowing for precise measurement and adjustment of resection angles on both the femur and tibia, enabling the restoration of the joint surface to its pre-arthritic state and facilitating selective bone resection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If existing knee resection instruments are used, then basic bone resection can be performed, but the ability to measure and adjust resection angles precisely is limited

Engineering Contradiction:

Improveresection angle measurementVSAvoidinstrument structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The instrument is divided into distinct functional modules: a stable portion for reference, a resection guide portion for defining the cut, and a resection guide body for angle adjustment. This segmentation allows each component to be optimized independently while maintaining overall precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resection guide body is made pivotally connected to the stable portion, allowing dynamic adjustment of the resection angle. The guide body can rotate relative to the stable portion to accommodate different resection angles while maintaining precise measurement capability through associated gauges.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If fixed angle resection guides are used, then manufacturing is simplified, but the ability to float the angle infinitely within an acceptable range is lost

Engineering Contradiction:

Improveangle adjustment rangeVSAvoidguide body construction

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The guide body incorporates a pivotal connection that enables continuous angle adjustment rather than fixed discrete positions. This dynamic mechanism allows the resection angle to float infinitely within the acceptable range while maintaining manufacturability through standard rotational joints and locking mechanisms.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The instrument allows the resection angle parameter to be continuously varied within an acceptable range rather than being fixed at specific values. This is achieved through the pivotal connection that permits smooth rotation and positioning at any angle within the functional range.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If simple resection instruments are used, then the procedure is faster, but the ability to restore the joint surface to its pre-arthritic level is compromised

Engineering Contradiction:

Improvejoint surface restorationVSAvoidinstrument features

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The instrument incorporates measurement capabilities that allow the surgeon to assess the current joint surface state before resection and plan the necessary bone removal in advance. This preliminary measurement and planning ensures accurate restoration to the pre-arthritic level.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The instrument provides real-time feedback through gauges and measurement features that indicate the resection angle and depth, allowing the surgeon to monitor progress and make adjustments to achieve precise restoration of the joint surface to its original configuration.

Inventive Principle:

Principle #23Feedback

4Loss of information

If angle measurement is not provided, then the instrument is simpler, but the ability to visualize and control the resection angle is lost

Engineering Contradiction:

Improveresection angle visualizationVSAvoidmeasurement features

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

Gauges and measurement features act as intermediaries between the physical resection process and the surgeon's decision-making. These intermediaries provide visual feedback on the resection angle and position, enabling precise control without adding excessive complexity to the basic resection function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20240173038A1Dual Stylus Variable Angle Total Knee Instruments and Methods

Publication Date: 2024.05.30 STEENSEN ORTHOPEDIC SYST LLC

AI summary

Methods for determining an amount of distal femoral resection, methods for determining the amount of proximal tibial resection and methods for setting a position of a resection of a distal femur or a proximal tibia in a total knee arthroplasty using instruments to obtain intraoperative patient-specific measurements and positioning or resecting the target bone based on intraoperative patient-specific measurements.