Hip Prosthesis Stem Taper Angles for Anatomical Fit

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Solution Overview

Problem

Current orthopaedic hip prostheses with femoral stem components face challenges in achieving optimal fixation stability and anatomical fit, particularly in varying femur sizes, which can complicate the surgical process and affect long-term bone remodeling.

Innovation Solution

The design incorporates femoral stem components with varying anterior/posterior taper angles, while maintaining consistent medial/lateral taper angles and cross-sectional shapes, allowing for a range of lengths and diameters to accommodate different patient anatomies, and utilizing a taper lock mechanism for secure implantation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If femoral stem components are designed with varying anterior/posterior taper angles to accommodate different patient anatomies, then adaptability is improved, but device complexity increases

Engineering Contradiction:

Improveadaptability to varying femur sizesVSAvoidcomplexity of femoral preparation

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention segments the femoral stem components into multiple variants, each with a specific anterior/posterior taper angle (e.g., 5°, 7.5°, 10°, 12.5°, 15°). This segmentation allows selection of the appropriate stem variant based on patient anatomy without requiring complex customization during surgery, thereby improving adaptability while keeping the surgical process straightforward.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a universal system where a limited set of standardized stem components with different taper angles can accommodate a wide range of patient anatomies. The consistent medial/lateral taper angle and cross-sectional shape across all variants provide universality in the implantation approach, while the varying anterior/posterior angles provide the necessary adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If multiple stem component variants with different taper angles are used to improve anatomical fit, then fixation stability is enhanced, but the complexity of inventory and selection increases

Engineering Contradiction:

Improvefixation stabilityVSAvoidcomplexity of component selection

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention applies local quality by varying only the anterior/posterior taper angle specific to each stem variant while keeping other geometric parameters (medial/lateral taper angle, cross-sectional shape) consistent. This allows optimization of local fit characteristics for different anatomies without introducing overall complexity into the component design system.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention systematically changes the anterior/posterior taper angle parameter across different stem variants (e.g., 5°, 7.5°, 10°, 12.5°, 15°) to match different femoral anatomies. This controlled parameter variation improves fixation stability by optimizing the stem-femur interface geometry while maintaining a manageable component selection process through standardized increments.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If femoral stem components are customized for each patient anatomy, then anatomical fit is improved, but surgical time and procedure complexity increase

Engineering Contradiction:

Improveanatomical fitVSAvoidsurgical time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The invention performs preliminary action by pre-defining multiple stem component variants with specific anterior/posterior taper angles before surgery. During the surgical procedure, the appropriate variant is selected based on pre-operative planning and intraoperative assessment, eliminating the need for complex intraoperative customization or machining, thereby reducing surgical time while maintaining excellent anatomical fit.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances fixation stability, simplifies the surgical process by reducing the complexity of femoral preparation, and ensures a desirable fit and fill for both short and long femurs, promoting improved bone integration and long-term stability.

Implementation Method 1

a tapered trunnion configured to be separately received into the tapered bore of the femoral head component

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

taper lock mechanism for secure implantation

Methodology Applied

Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentEP2712582B1Orthopaedic hip prosthesis

Publication Date: 2017.03.08 DEPUY SYNTHES PROD INC

AI summary

A femoral prosthesis for use during performance of a hip replacement procedure includes a femoral head component having a tapered bore formed therein. A plurality of femoral stem components have a tapered trunnion configured to be separately received into the tapered bore of the femoral head component. Each of the plurality of femoral stem components has (i) a trunnion taper angle and diameter that is the same as each of the other of the plurality of femoral stem components, and (ii) an anterior/posterior stem taper angle that is different from at least some of the other of the plurality of femoral stem components.