Hollow Metal Core Hip Spacer for Strength and Antibiotic Loading

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Solution Overview

Problem

Existing hip joint placeholders are not strong enough and prone to breakage, and the built-in metal reinforcing structures affect the antibiotic content, posing challenges in weight-bearing and infection control.

Innovation Solution

A metal inner core for a hip joint bone cement placeholder is designed with a frame body and supporting portion, featuring a hollow structure and connecting rods, integrated with an antibiotic bone cement shell, prepared through 3D printing and mold filling processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a metal reinforcing framework is built into the placeholder to enhance strength, then the placeholder can bear higher loads, but the antibiotic content is affected and the weight increases

Engineering Contradiction:

Improveplaceholder strengthVSAvoidantibiotic content

Core Design Contradiction:

StrengthVSQuantity of substance

Solution Approach 1:

The patent uses composite materials by combining bone cement with a metal mesh framework. The metal mesh provides structural reinforcement while the bone cement matrix maintains antibiotic content. This composite structure resolves the contradiction by distributing functions: the metal framework bears mechanical loads while the bone cement preserves antibiotic efficacy without being displaced or diluted.

Inventive Principle:

Principle #40Composite materials

2Strength

If a solid supporting metal structure is used to enhance strength, then the placeholder can bear higher loads, but the weight increases and the placeholder becomes more complex

Engineering Contradiction:

Improveplaceholder strengthVSAvoidplaceholder weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent segments the reinforcing structure into a mesh framework rather than using a solid metal block. This segmentation provides sufficient structural support through the distributed network of metal strands while minimizing material usage, thereby reducing weight compared to solid metal structures while maintaining adequate strength for load-bearing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs a thin metal mesh framework that acts as a flexible yet strong reinforcement structure. The mesh configuration provides structural integrity with minimal material thickness, achieving strength enhancement without significant weight increase or structural complexity.

Inventive Principle:

Principle #30Flexible shells and thin films

3Ease of operation

If hand-kneaded antibiotic bone cement is used to allow mobility and restore limb length, then the placeholder can be removed during revision surgery, but the shape control is difficult and the surface is not smooth

Engineering Contradiction:

Improvemobility and removabilityVSAvoidshape control and surface smoothness

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-forming the bone cement placeholder with an integrated metal mesh framework before implantation. The placeholder is manufactured with precise shape and smooth surface through molding processes, eliminating the need for intraoperative hand-kneading while maintaining the ability to control shape and surface quality. The placeholder remains removable during revision surgery due to its modular design.

Inventive Principle:

Principle #10Preliminary action

4Ease of manufacture

If mold-pressed placeholders with limited specifications are used to achieve smooth surface and low cost, then production is simple, but individual patient needs cannot be met

Engineering Contradiction:

Improveproduction simplicity and costVSAvoidpatient-specific fit

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent enables parameter changes by allowing customization of the placeholder dimensions, shape, and metal mesh configuration to match individual patient anatomy. The manufacturing process can be adjusted to produce patient-specific placeholders while maintaining the cost-effectiveness and production simplicity of mold-pressed techniques. This resolves the contradiction by making the manufacturing process adaptable to individual requirements.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12478485B2Preparation method of a hip joint bone cement placeholder

Publication Date: 2025.11.25 THE THIRD AFFILIATED HOSPITAL OF GUANGZHOU MEDICAL UNIVERSITY (GUANGZHOU SEVERE MATERNAL TREATMENT CENTER GUANGZHOU ROUJI HOSPITAL)

AI summary

Disclosed are a metal inner core, a placeholder and a preparation method for a hip joint bone cement placeholder. By designing the metal inner core including a frame body and a supporting portion inside the hip joint bone cement placeholder, the strength of the placeholder is enhanced; due to the fact that the metal inner core is hollow, the antibiotic bone cement can fill the inner portion of the metal inner core, the content of antibiotics in the placeholder cannot be affected, and infection is effectively controlled; the hollowed-out structure endows the placeholder with lighter weight and stronger structural strength, and meanwhile, the material cost is effectively reduced; and according to the preparation method of the hip joint bone cement placeholder, the size design of the placeholder and the metal inner core is carried out, so that the joint matching degree between the placeholder and the patient is high.