Bone Plate Variable-Angle Hole Stress Distribution

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Solution Overview

Problem

Bone plates with variable-angle through holes experience stress peaks when subjected to bending loads due to the design of rib-like structures and recesses, particularly near the side edges, which can lead to increased risk of breakage.

Innovation Solution

A bone plate design featuring a depression on the non-bone-facing surface that overlaps with the through hole, reducing stress peaks by distributing stress more evenly and minimizing sharp edges, combined with a rib-like structure within the through hole that allows for variable-angle locking of screws.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If variable-angle through holes with rib-like structures and recesses are provided in the bone plate, then adaptability for different screw angles is improved, but stress peaks occur when bending loads are applied

Engineering Contradiction:

Improvevariable-angle locking capabilityVSAvoidresistance to bending loads

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent applies local quality by providing recesses at specific locations within the variable-angle portion of the through hole, particularly near the side edges where stress peaks occur during bending loads. These localized recesses modify the stress distribution in critical areas without affecting the overall variable-angle locking functionality of the through hole.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The rib-like structure in the through hole is segmented by introducing recesses that divide the continuous rib structure into separate segments. This segmentation allows the structure to better accommodate bending stresses by creating stress relief zones, while maintaining the ability to lock screws at variable angles.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If recesses extend in the direction of side walls to enable variable-angle locking, then ease of operation is improved, but stress peaks occur on the plate's upper surface

Engineering Contradiction:

Improvevariable-angle screw lockingVSAvoidstress peaks on upper surface

Core Design Contradiction:

Ease of operationVSStress or pressure

Solution Approach 1:

The patent converts the potentially harmful stress peaks into beneficial stress distribution patterns by strategically positioning recesses in the variable-angle portion. These recesses, which could be seen as reducing material, actually serve to redirect and distribute stresses more evenly across the bone plate structure, particularly on the upper surface that faces away from the bone.

Inventive Principle:

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

Data Source

PatentUS10004545B2Bone plate

Publication Date: 2018.06.26 DEPUY SYNTHES PROD INC

AI summary

A bone plate having a first, bone-facing surface and an opposing second surface has an elongate shaft portion and a head portion that is shorter and wider in comparison thereto, with at least one through hole extending through the bone plate from the first surface to the second surface in the shaft portion. The through hole comprises a variable-angle portion with a hole axis configured to receive a threaded head of a locking screw therein at a desired angle within a permitted range of angulation relative to the hole axis. The second surface has at least one depression which extends therein along a portion of the second surface between the side wall and the through hole, the depression extending about a periphery of the through hole.