Polymer Interlock Orthopedic Implant Thinner Profile

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Solution Overview

Problem

Cementless orthopedic implants with multiple layers have a thicker profile than their cemented counterparts, requiring more bone removal and being more invasive, necessitating a thinner profile without compromising strength or stability.

Innovation Solution

A porous structure for orthopedic implants featuring a metallic insert with a solid layer, an interlock layer, and a tapered surface, where the interlock layer is interlocked with a polymeric bearing structure, allowing for a uniform thickness and additional support where needed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a cementless implant with multiple layers is used, then bone ingrowth and articulation functions are improved, but the implant thickness increases requiring more bone removal

Engineering Contradiction:

Improveimplant stabilityVSAvoidimplant thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The implant is divided into distinct functional layers: a porous bone ingrowth layer, a solid intermediate layer, and a porous bearing support layer. Each layer performs its specific function while the overall structure maintains a thinner profile through optimized layer thicknesses and the intermediate layer preventing interdigitation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the implant have different material properties and thicknesses. The bearing support layer has higher porosity for bone ingrowth, the intermediate layer is solid for structural support, and the thickness varies locally to accommodate the tapered surface while maintaining uniform overall profile.

Inventive Principle:

Principle #3Local quality

2Length of stationary object

If the implant profile is made thinner, then bone removal is reduced and tissue irritation is minimized, but structural strength and stability may be compromised

Engineering Contradiction:

Improveimplant thicknessVSAvoidimplant strength

Core Design Contradiction:

Length of stationary objectVSStrength

Solution Approach 1:

The implant uses composite construction combining porous metal layers for bone ingrowth and articulation with a solid intermediate layer for structural support. This composite approach allows thinner overall profile while maintaining strength through the strategic placement of solid and porous materials.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The implant incorporates a tapered surface that creates a thickness gradient from one dimension, allowing the overall profile to be thinner while the intermediate layer provides localized reinforcement. The tapered geometry enables reduced bone removal while maintaining structural integrity through dimensional optimization.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS12263271B2Polymer interlock support structure and method of manufacture thereof

Publication Date: 2025.04.01 HOWMEDICA OSTEONICS CORP

AI summary

An orthopedic implant includes a porous insert having a first insert portion having a first insert thickness and a second insert portion having a second insert thickness. The implant includes a non-metallic structure having a first non-metallic portion having a first non-metallic thickness and a second non-metallic portion having a second non-metallic thickness. The first non-metallic portion is attached to the first insert portion and the second non-metallic portion is attached to the second insert portion. Either or both of the second insert thickness being different from the first insert thickness and the second non-metallic thickness being different from the first non-metallic thickness. The porous insert includes a porous projection extending into the non-metallic structure.