Resilient Retainer Bone Plate Back-Out Prevention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing bone plate systems face issues with bone anchors loosening or backing out, which can compromise bone fusion and alignment, leading to potential damage or loss of bone and graft material.

Innovation Solution

A bone plate system with a resilient retainer disposed in throughbores to resist back-out of bone anchors, featuring elongate arm portions and interference portions that deflect and return to an interference position to securely engage the bone anchor head, allowing for oblique insertion without compromising the plate's thickness or interfering with adjacent tissues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking ring is used to resist bone anchor back-out, then back-out resistance is improved, but the flange contacts and irritates adjacent tissues

Engineering Contradiction:

Improveback-out resistanceVSAvoidtissue irritation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The harmful flange portion is removed from the locking ring design. The retainer is configured without a flange that extends above the bone plate surface, extracting the tissue-irritating element while preserving the back-out resistance function through the interference portions that engage the bone anchor head.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The retainer is designed with differentiated local properties: the interference portions provide engagement with the bone anchor head for back-out resistance, while the body of the retainer remains recessed within the throughbore to avoid tissue contact. This local differentiation allows simultaneous achievement of reliability and tissue compatibility.

Inventive Principle:

Principle #3Local quality

2Reliability

If the bone plate is made relatively thick to accommodate radially enlarged sections of the bone anchor head, then back-out resistance is improved, but the plate thickness increases excessively

Engineering Contradiction:

Improveback-out resistanceVSAvoidbone plate thickness

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

Instead of increasing plate thickness in the vertical dimension to accommodate the bone anchor head, the solution moves the retention mechanism into the horizontal dimension by using interference portions that extend radially into the throughbore. This dimensional shift allows effective retention without increasing overall plate thickness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The interference portions are nested within the throughbore, with the retainer body recessed into the bone plate and only the interference portions extending forward to engage the bone anchor head. This nesting configuration provides retention functionality while maintaining a compact plate profile.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Reliability

If the resilient retainer interference portions extend far into the throughbore to resist back-out, then back-out resistance is improved, but the raised portion of the bone anchor head interferes with the retainer

Engineering Contradiction:

Improveback-out resistanceVSAvoidretainer-bone anchor interference

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The throughbore is segmented into distinct functional zones: an interference zone where the retainer's interference portions engage the bone anchor head for back-out resistance, and a raised portion zone where the bone anchor head extends above the retainer body. This spatial segmentation eliminates interference while maintaining retention effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution creates vertical separation between the retainer body and the raised portion of the bone anchor head. The interference portions extend radially in the horizontal dimension to provide engagement, while the raised portion extends vertically above the retainer, eliminating interference in the vertical dimension.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

The solution effectively prevents bone anchor back-out while minimizing the bone plate's thickness and avoiding tissue irritation, ensuring secure bone alignment and fusion without excessive plate thickness or tissue interference.

Implementation Method 1

a resilient retainer disposed in a bone plate throughbore to resist back-out of a bone anchor from the throughbore

Methodology Applied

Scientific EffectResilience: Elasticity

Data Source

PatentUS10166051B2Bone plate system

Publication Date: 2019.01.01 XTANT MEDICAL HOLDINGS INC

AI summary

A bone plate system having a retainer for resisting back-out of a bone anchor from a throughbore of a bone plate is provided. In one aspect, a bone plate system having a resilient retainer disposed in a bone plate throughbore with a pair of elongate arm portions of the resilient retainer extending along opposite sides of the throughbore. In another aspect, a bone plate system having a resilient retainer with a pair of elongate interference portions completely exposed in the throughbore and spaced from each other across the throughbore to retain a head of a bone anchor received in the throughbore. In addition, a bone plate system having a resilient retainer with a pair of opposite end portions disposed within a groove of a throughbore wall such that a bone anchor may be inserted into the throughbore without contacting either of the opposite end portions of the retainer.