Bone Plate Anchor Retaining Mechanism for Backout Prevention

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Solution Overview

Problem

Existing bone plate retaining devices face challenges such as interference with anchor positioning, difficulty in handling, and inefficiency in preventing anchor backout, especially when anchors move relative to the plate or are not at the same position.

Innovation Solution

A system featuring a bone plate with a hole and a partially annular retaining member that moves radially to engage the anchor head, blocking backout while allowing for easy installation and removal through an access bore, and can toggle to accommodate anchor movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a retaining device is placed over the bone plate and anchors, then the anchors are blocked from backing out, but the head of the anchor interferes with positioning and alignment of the retaining device

Engineering Contradiction:

Improveanchor retentionVSAvoidpositioning and alignment

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The retaining member is received within a receptacle in the bone plate, nesting the retaining mechanism inside the plate structure rather than placing it over the anchors. This allows the retaining member to engage the anchor head from within the plate, eliminating interference with anchor positioning while maintaining retention function.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The receptacle acts as an intermediary structure that receives the retaining member and positions it relative to the anchor hole. This intermediary mechanism allows the retaining member to engage the anchor head without requiring direct manual positioning over the anchor, solving the alignment interference problem.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If prior retaining devices are used, then anchors are retained, but the devices are difficult to handle, install and/or manipulate

Engineering Contradiction:

Improveanchor retentionVSAvoidhandling, installation and manipulation

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The retaining mechanism is segmented into distinct components: a retaining member and a receptacle. The retaining member can be inserted through the access bore and manipulated independently within the receptacle, making it easier to handle and install compared to monolithic prior designs. The segmentation allows for simplified manipulation during surgical procedures.

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If the retaining member is made radially movable, then it can engage and disengage anchors easily, but the device complexity increases

Engineering Contradiction:

Improveengagement and disengagementVSAvoidretaining member mechanism

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The retaining member is designed with radial movability, allowing it to dynamically change its position between engaged and disengaged states. This dynamic capability is achieved through simple radial movement within the receptacle rather than complex mechanisms, providing ease of operation while minimizing added complexity.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8353939B2Anchor retaining mechanisms for bone plates

Publication Date: 2013.01.15 WARSAW ORTHOPEDIC INC

AI summary

A system involving anchor retaining mechanisms for a bone plate includes a plate with at least a first hole therethrough between an upper surface and a lower surface of the plate to receive an anchor for engaging a bony segment. The system also includes a partially annular retaining member engageable to the plate and positionable in the hole of the plate to prevent anchor backout while allowing insertion of the anchor through the plate hole and removal of the anchor from the plate hole.