Patient-Specific Prosthesis Stem Design for Bone Fragment Loading

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Solution Overview

Problem

Existing shoulder prostheses do not ensure appropriate mechanical loading of bone fragments due to variations in shape and size among patients, leading to a risk of osteonecrosis.

Innovation Solution

A patient-specific prosthesis is designed with a stem part tailored to fit the medullary cavity of a fractured long bone, applying mechanical stress to specific contact zones based on patient data, ensuring appropriate mechanical loading and reducing the risk of osteonecrosis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a standard prosthesis is used, then the device complexity is reduced and ease of manufacture is improved, but the prosthesis cannot ensure appropriate mechanical loading of bone fragments due to variations in patient anatomy

Engineering Contradiction:

Improvemechanical loading of bone fragmentsVSAvoidprosthesis design

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The prosthesis stem is designed with varying cross-sectional shapes and sizes along its length, with each section tailored to contact specific zones of the patient's medullary cavity. This local customization ensures that mechanical stress is appropriately distributed to specific bone fragments while maintaining overall structural integrity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Patient-specific CT scans and 3D modeling are performed before prosthesis manufacturing to precisely map the medullary cavity geometry and identify optimal contact zones. This preliminary analysis allows the prosthesis design to be customized in advance, ensuring proper mechanical loading from the moment of implantation.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a patient-specific prosthesis is designed, then the mechanical loading of bone fragments is improved, but the manufacturing complexity and time are increased

Engineering Contradiction:

Improvereduction of osteonecrosis riskVSAvoidprosthesis manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The prosthesis manufacturing process utilizes additive manufacturing technology, which allows for the production of complex patient-specific geometries by varying material deposition parameters layer by layer. This manufacturing method transforms the complexity of custom design into a controllable process parameter, making patient-specific prostheses manufacturable without proportionally increasing difficulty.

Inventive Principle:

Principle #35Parameter changes

3Stress or pressure

If the stem part is customized to fit the medullary cavity, then the mechanical stress distribution is improved, but the adaptability to different patients is reduced

Engineering Contradiction:

Improvemechanical stress on bone fragmentsVSAvoidprosthesis applicability

Core Design Contradiction:

Stress or pressureVSAdaptability or versatility

Solution Approach 1:

The prosthesis stem is divided into multiple sections along its length, with each segment designed to contact a specific zone of the medullary cavity. This segmentation allows the stem to be customized for each patient's unique anatomy while maintaining a modular structure that can be systematically designed and manufactured.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12409038B2Method for manufacturing a patient-specific prosthesis for a fractured long bone

Publication Date: 2025.09.09 HOWMEDICA OSTEONICS CORP

AI summary

Provided is a method of manufacturing a prosthesis for a fractured long bone of a patient, the method including the steps of: A) providing data representative of the fractured long bone in a patient; B) based on said data, designing the prosthesis specifically to the patient, the prosthesis including a stem part that is configured to secure fragment(s) of the fractured long bone at chosen securing position(s) that will apply chosen mechanical stress onto the bone fragments and reduce the risk of osteonecrosis of the bone fragments.