Variable Collet Knee Cutting Guide for Varus Valgus Adjustment

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Solution Overview

Problem

Current cutting guides for femur preparation in knee replacement surgery lack adjustability, leading to potential errors and increased operating room time due to fixed angular offsets and variability in cutting block orientations, which can result in improper prosthesis installation and performance.

Innovation Solution

A device comprising a distal cutting guide, valgus guide, and variable collet that allows angular adjustment of the cutting guide relative to the intramedullary rod, enabling precise alignment and depth adjustment of the distal cutting block, thereby accommodating various varus/valgus angles and reducing the need for multiple cutting blocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If fixed angular offset cutting guides are used, then the cutting guide can be easily manufactured and sterilized, but the surgeon cannot adjust the varus/valgus angle and may require multiple cutting blocks

Engineering Contradiction:

Improveadjustability of varus/valgus angleVSAvoidcomplexity of adjustable mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cutting guide employs a dynamic adjustment mechanism where the distal cutting guide can be rotated relative to the intramedullary rod through a variable collet system. This allows the varus/valgus angle to be changed during surgery by rotating the distal cutting guide to different angular positions, transforming a static fixed-angle device into a dynamic adjustable one.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The cutting guide is divided into separable components including the intramedullary rod, the variable collet, and the distal cutting guide. This segmentation allows the distal cutting guide to be independently adjusted and repositioned relative to the rod, enabling angle changes without requiring complete replacement of the entire cutting guide assembly.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If multiple cutting blocks with different fixed orientations are prepared, then all possible varus/valgus angles can be accommodated, but the number of sterilized blocks increases and operating room time increases

Engineering Contradiction:

Improvecoverage of all varus/valgus anglesVSAvoidoperating room time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The distal cutting guide serves multiple functions by being adjustable to various angular positions. A single cutting guide assembly can accommodate different varus/valgus angles through rotation, replacing the need for multiple specialized cutting blocks. The guide can be positioned at different angles and locked in place, making one device perform the function of several fixed-angle devices.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of using multiple separate cutting blocks that would need to be sterilized and brought into the operating room, the system uses a single reusable cutting guide that can be adjusted and repositioned. This reduces the number of components that need sterilization and preparation, thereby reducing operating room time and potential for error.

Inventive Principle:

Principle #34Discarding and recovering

3Ease of manufacture

If fixed cutting guide orientations are built into the cutting block, then the cutting block structure can be simplified, but variability in cutting guides relative to pinned portions affects resection accuracy

Engineering Contradiction:

Improvesimplicity of cutting block structureVSAvoidprecision of distal resection

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention replaces the traditional mechanical fixed-offset system with a rotational adjustment system. Instead of building different fixed angles into different cutting blocks, the system uses a variable collet mechanism that allows rotational adjustment of the distal cutting guide to achieve different angles, substituting mechanical variety with mechanical adjustability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2079406B1Device and method for distal resections of a knee prosthetic

Publication Date: 2016.03.30 SMITH & NEPHEW INC

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AI summary

A device and method for resecting a distal portion of a femur comprises a distal cutting guide [98], a valgus guide [102], and a variable collet [10]. The distal cutting guide [98] is configured to overlie an anterior portion of the femur and comprises a slot for guiding a cutting tool across a distal portion of the femur. The valgus guide [102] is configured to connect to the distal cutting guide [98]. The valgus guide [102] is configured to align the slot of the distal cutting guide[98] at the proper varus/ valgus angle. The variable collet [10] is configured to attach to an intramedullary rod and the valgus guide [102]. The variable collet [10] comprises a port [30] for receiving the intramedullary rod. The port [30] is angularly adjustable with respect to the valgus guide [102] such that adjusting the port [30] adjusts the varus/ valgus angle of the distal cutting guide [98].