One-Piece Variable Angle Locking Washer for Orthopedic Bone Plates

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Solution Overview

Problem

Existing variable angle locking washer assemblies require three separate components, making them difficult to manufacture and use, especially in orthopedic applications where precise assembly is necessary for stabilizing bone fragments at non-collinear angles.

Innovation Solution

A one-piece variable angle locking washer with a hollow cylindrical body featuring a central bore with both threaded and unthreaded portions and radial slots that function as a spring, allowing the washer to be securely locked to a bone plate at various angles without the need for multiple components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a three-piece variable angle locking washer assembly is used, then the spring functionality is provided, but the assembly complexity and difficulty of use increase

Engineering Contradiction:
Improvespring functionalityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the spring member, first washer, and second washer into a single integrated washer component. The radial slots formed in the washer body provide the spring functionality that previously required a separate spring member, while the washer simultaneously performs the functions of both washers in the traditional assembly. This merging eliminates assembly complexity while maintaining all necessary functions.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If a three-piece variable angle locking washer assembly is used, then the spring functionality is provided, but the manufacturing complexity increases

Engineering Contradiction:
Improvespring functionalityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The integration of multiple components into a single washer reduces the number of manufacturing steps. Instead of producing separate spring members, washers, and assembling them with precise orientation, the single washer can be manufactured in one process with the radial slots providing both structural and spring functions.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a one-piece washer is used, then the assembly process is simplified, but the spring functionality must be integrated into the single piece

Engineering Contradiction:
Improveease of useVSAvoidintegrated structure
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The washer features radial slots localized in specific regions to provide spring functionality only where needed. The slots are positioned to allow radial expansion and contraction while maintaining the overall structural integrity of the washer. This localized feature addition keeps the integrated structure simple while providing the necessary spring behavior.

Inventive Principle:
Principle #3Local quality

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

Simplifies the assembly process by integrating the spring-like functionality into a single washer piece, providing secure angular locking capabilities while reducing manufacturing complexity and improving ease of use in orthopedic applications.

Implementation Method 1

a plurality of radial slots peripherally positioned along the body, each slot defining a channel that extends between the outer surface of the body and the central bore

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2840988B1One-piece variable angle locking washer
Publication Date: 2016.10.12 BIOMET MFG LLC
  • EP2840988B1 patent drawingFigure 1~2
  • EP2840988B1 patent drawingFigure 3
  • EP2840988B1 patent drawingFigure 4~5

AI summary

A variable angle locking washer comprising a body having an outer surface circumferentially disposed between a top surface and a bottom surface, a central bore extending between the top and bottom surfaces, the central bore having a threaded portion and an unthreaded portion, and a plurality of radial slots peripherally positioned along the body, each slot defining a channel that extends between the outer surface of the body and the central bore.