Bone Plate Aperture Columns for Variable-Angle Screw Locking

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Solution Overview

Problem

Variable-angle locking screws tend to cause cross-threading within the apertures of bone plates, reducing the interference fit and stability between the screw head and the bone plate, which can lead to poor alignment and clinical outcomes.

Innovation Solution

The bone plate apertures are designed with a plurality of columns and recesses that deform radially to lock the screw head in place, providing a form-fit and compression fit that inhibits cross-threading, using internal threading that terminates between the upper and lower ends of the columns, and accommodating standard-type and variable-angle locking screws at nominal and angulated orientations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable-angle locking screws are used to accommodate angulated orientations, then versatility is improved, but cross-threading occurs which reduces interference fit and stability

Engineering Contradiction:

Improveaccommodation of angulated orientationsVSAvoidinterference fit and stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The aperture locking structure is segmented into multiple columns (at least five) arranged circumferentially, with recesses between them. This segmentation allows the columns to independently deform and adapt to screw insertion at various angles while maintaining overall structural integrity and preventing cross-threading.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The columns are designed to undergo dynamic deformation in the radial direction upon engagement with the screw head. This dynamic response allows the locking structure to adapt to both nominal and angulated screw orientations, providing reliable interference fit regardless of insertion angle.

Inventive Principle:

Principle #15Dynamics

2Reliability

If standard locking structures are used to ensure stable locking, then reliability is improved, but they cannot accommodate variable angles which reduces versatility

Engineering Contradiction:

Improvelocking stabilityVSAvoidaccommodation of nominal and angulated orientations

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The locking structure with multiple columns and recesses serves multiple functions: it provides stable locking for nominal orientation screws while simultaneously accommodating angulated orientation screws. The same structural elements adapt their deformation pattern based on the screw insertion angle.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The locking structure changes its deformation parameters (radial displacement of columns) in response to different screw orientations. The columns deform radially to accommodate the screw head at various angles, allowing the same structure to reliably lock both standard and variable-angle screws.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If more columns are added to improve locking engagement, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvelocking engagementVSAvoidnumber of columns and recesses

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent specifies at least five columns, which provides sufficient locking engagement reliability without excessive complexity. This number represents an optimal balance where additional columns would yield diminishing returns relative to the increased manufacturing complexity.

Inventive Principle:

Principle #16Partial or excessive 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 design enhances the locking engagement between the screws and the bone plate, reducing cross-threading and improving stability, allowing for secure fixation of bone segments without loosening or misalignment, thereby promoting effective fracture healing.

Implementation Method 1

Each of the columns is configured to undergo deformation at least in a radial direction perpendicular to the central aperture axis responsive to engagement with a head of a locking bone screw

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The plurality of columns sequentially located about a circumference of the interior surface... configured to undergo deformation... so as to lock the head to the bone plate

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS10772665B2Locking structures for affixing bone anchors to a bone plate, and related systems and methods

Publication Date: 2020.09.15 DEPUY SYNTHES PROD INC

AI summary

A bone plate includes an upper surface, an opposed lower surface configured to face a bone, and at least one aperture extending through the bone plate from the upper to the lower surface along a central aperture axis. The aperture is defined by an interior surface of the bone plate. The interior surface defines a plurality of columns sequentially located about a circumference of the interior surface and a plurality of recesses located circumferentially between the columns. Each of the columns is configured to undergo deformation at least in a radial direction perpendicular to the central aperture axis responsive to engagement with a head of a locking bone screw that is receivable within the at least one aperture so as to lock the head to the bone plate. The plurality of columns comprises at least five columns.