Anterior Posterior Sizer With Statistical Reference Surfaces

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Solution Overview

Problem

Current anterior/posterior (A/P) sizers for knee arthroplasty procedures are too large for minimally invasive surgeries, requiring extensive incisions and complicating patient recovery due to their universal, broad design that fails to accurately account for individual patient anatomy.

Innovation Solution

Development of A/P sizers with reduced profiles and reference surfaces based on statistical analysis of femur bone data, allowing precise placement and alignment within minimally invasive incisions, and enabling accurate determination of posterior condylar prominences and rotational positioning of femoral prostheses tailored to individual patients.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional universal A/P sizers with large broad feet are used to ensure contact with posterior condylar prominences, then measurement reliability is improved, but the incision size must be large and arthrotomy is extensive, complicating patient recovery

Engineering Contradiction:

Improvecontact reliability with posterior condylar prominencesVSAvoidfoot size and incision requirement

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent applies parameter changes by transitioning from universal fixed-size feet to statistically optimized foot dimensions. The foot reference surface area and position are calculated based on statistical analysis of posterior condylar prominence locations across a population, allowing the sizer to be tailored to specific patient demographics (gender, height, age) while maintaining reliable contact with the condylar prominences.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements local quality by making the foot reference surface characteristics specific to the patient's anatomy rather than universally applicable. The foot's area, shape, and position are optimized for the specific population the patient belongs to, ensuring accurate reference to posterior condylar prominences while minimizing the required incision size.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If traditional universal A/P sizers are used to accommodate all patients, then adaptability is improved, but manufacturing precision and individual patient alignment accuracy deteriorate

Engineering Contradiction:

Improveuniversal applicability across populationVSAvoidindividual patient alignment accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the sizer adaptable to different patient populations through statistical parameters. The foot reference surface characteristics (area, position, shape) are dynamically adjusted based on the patient's demographic data (gender, height, age) rather than being fixed for all patients, enabling both universal applicability and individual precision.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent uses parameter changes to transition from a universal fixed design to a statistically optimized variable design. The foot's geometric parameters are calculated based on statistical analysis of condylar prominence locations for specific patient populations, allowing the same sizer design to achieve high precision across different individuals while maintaining manufacturability.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If traditional A/P sizers with fixed 3-degree external rotation are used, then ease of operation is improved, but measurement precision for individual patient rotational positioning deteriorates

Engineering Contradiction:

Improvestandardized rotational positioningVSAvoidindividual patient rotational alignment accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies parameter changes by replacing the fixed 3-degree external rotation parameter with statistically optimized rotational values. The rotational positioning is calculated based on statistical analysis of individual patient anatomy and population data, allowing the sizer to provide both ease of operation through automated calculation and high precision through patient-specific customization.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10405994B2Femoral sizer

Publication Date: 2019.09.10 HOWMEDICA OSTEONICS CORP

AI summary

A surgical referencing guide includes a body having a contact surface and a first foot extending away from the body. The first foot includes a first reference surface having a first area defined by a standard deviation of a first dataset extracted from a database and being comprised of a plurality of first data points each corresponding to an individual bone within a population of bones and each corresponding to a location of a preselected point on the bone within a predetermined coordinate system.