Bone Plate Locking Hole Collection Cavity for Cross-Thread Shavings

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Solution Overview

Problem

The existing bone screw fixation systems face issues with cross-threading between the threaded locking heads and internal locking surfaces, leading to the production of shavings and a reduced interference fit, which can result in loosening or backing out of the screws.

Innovation Solution

The bone plate is designed with a collection cavity to capture shavings produced during the mating of locking screws, featuring a recessed surface that interrupts the threads and collects material, preventing it from entering surrounding soft tissue and maintaining the stability of the bone fixation system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If locking screws are driven into the bone plate to secure the bone, then the bone fixation stability is improved, but cross-threading between the screw head threads and internal locking surface threads produces shavings that reduce the interference fit and may cause screw loosening

Engineering Contradiction:

Improvebone fixation stabilityVSAvoidscrew locking reliability

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent converts the harmful effect of cross-threading (which produces shavings) into a beneficial outcome by designing a collection cavity that captures these shavings. The cavity transforms the potential harm of shavings reducing interference fit and causing loosening into a controlled environment where shavings are contained and even help to maintain the interference fit by being compressed within the cavity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The collection cavity acts as an intermediary structure between the threading interface and the external environment. It mediates the interaction by providing a designated space for shavings, preventing them from escaping into surrounding soft tissue and maintaining the structural integrity of the bone fixation system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the threaded head of the locking screw cross-threads with the internal locking surface, then the interference fit is reduced and shavings are produced, but this may lead to screw loosening or backing out

Engineering Contradiction:

Improvescrew insertion easeVSAvoidthreaded connection strength

Core Design Contradiction:

Ease of operationVSStrength

Solution Approach 1:

The collection cavity converts the harmful byproduct of cross-threading (shavings) into a beneficial feature. By providing a designated space for shavings, the cavity prevents them from compromising the threaded connection strength, and the compression of shavings within the cavity actually helps maintain the interference fit between the screw and bone plate.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention extracts the harmful element (shavings) from the critical threading interface by providing a separate collection cavity. This separation allows the threading operation to proceed with ease while the shavings are isolated in a dedicated space, preventing them from interfering with the threaded connection strength.

Inventive Principle:

Principle #2Taking out (Extraction)

3Manufacturing precision

If shavings are produced during screw mating, then the interference fit is compromised, but shavings may escape into surrounding soft tissue causing additional harm

Engineering Contradiction:

Improvethread mating precisionVSAvoidshavings escaping into soft tissue

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The collection cavity serves as an intermediary barrier between the thread mating process and the surrounding soft tissue. It captures shavings produced during threading, preventing them from escaping into the soft tissue, and provides a controlled environment for shavings that maintains manufacturing precision of the thread connection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful escape of shavings into soft tissue into a beneficial containment system. The collection cavity not only prevents shavings from escaping but also utilizes the compressed shavings within the cavity to help maintain the interference fit of the threaded connection.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS10925651B2Implant having locking holes with collection cavity for shavings

Publication Date: 2021.02.23 DEPUY SYNTHES PROD INC

AI summary

A bone plate includes locking holes that reconfigured to threadedly mate with locking screws to fix the bone plate to an underlying bone. Some of the locking holes are standard-type locking holes. Alternatively or additionally, some of the locking holes are variable-angle locking holes. The bone plate defines a collection cavity in the locking holes that are configured to collect shavings that can be produced if the bone screw is cross threaded in the locking hole.