Bone Screw Closure Device Preventing Cement Leakage

Solution Overview

Problem

Bone cement often escapes unintentionally through the central through-bore of bone screws during minimally invasive procedures, posing a clinical challenge and complicating intra-operative handling, especially in bicortical screw connections.

Innovation Solution

A closure device comprising a sleeve with radially arranged tongues that mechanically lock the central passage opening, allowing guide wire insertion and automatic resealing, which can be designed as a one-way mechanical lock or with elastic deformation for automatic closure, to prevent cement leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a central through-opening is provided in bone screws for minimally invasive procedures, then guide wire insertion is enabled, but bone cement can escape unintentionally through the central passage

Engineering Contradiction:

Improveguide wire insertion capabilityVSAvoidcement leakage

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The closure device is pre-positioned on the guide wire before bone cement injection. The tongues are initially in an open state allowing guide wire passage, then automatically close during cement injection to prevent leakage through the central through-opening

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The closure device features dynamic tongues that can change state from open to closed. The tongues are designed to be deformable under axial load, automatically transitioning from an open configuration (allowing guide wire insertion) to a closed configuration (preventing cement leakage) based on applied forces

Inventive Principle:

Principle #15Dynamics

2Object-generated harmful factors

If a closure device with complex locking mechanism is used to prevent cement leakage, then cement leakage is prevented, but manufacturing costs increase and handling becomes more difficult

Engineering Contradiction:

Improvecement leakage preventionVSAvoidclosure device structure

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The closure device is self-actuating through mechanical forces present during the procedure. Axial compression during cement injection automatically closes the tongues to seal the central passage, eliminating the need for manual operation or complex control mechanisms

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The closure device utilizes changes in axial load parameters to control tongue position. During guide wire insertion, low axial load allows tongues to remain open; during cement injection, high axial load automatically closes the tongues, providing passive sealing through parameter变化

Inventive Principle:

Principle #35Parameter changes

3Object-generated harmful factors

If the closure device remains closed during guide wire insertion, then cement leakage is prevented, but guide wire insertion becomes impossible

Engineering Contradiction:

Improvecement leakage preventionVSAvoidguide wire insertion

Core Design Contradiction:

Object-generated harmful factorsVSEase of operation

Solution Approach 1:

The closure device features dynamic tongues that can change state from open to closed. The tongues are designed to be deformable under axial load, automatically transitioning from an open configuration (allowing guide wire insertion) to a closed configuration (preventing cement leakage) based on applied forces

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The closure device is pre-positioned on the guide wire before bone cement injection. The tongues are initially in an open state allowing guide wire passage, then automatically close during cement injection to prevent leakage through the central through-opening

Inventive Principle:

Principle #10Preliminary 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

The solution simplifies and safes the application of bone cement, reducing manufacturing costs and enhancing handling ease while effectively preventing cement leakage, thus improving anchoring stability and procedural efficiency.

Implementation Method 1

The pedicle screw shaft has at least one elastically deformable tongue (113) which closes the central passage opening (13)

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The closure device (3) has an anchoring area (32) which serves as a fixing device between the pedicle screw shaft (1) and the closure device (3)

Methodology Applied

Scientific EffectMechanical interlocking: Mechanical Fastener

Data Source

PatentEP2893891B1Closure device for cannulated bone screws

Publication Date: 2017.01.11 SILONY MEDICAL INT

AI summary

The invention describes a bone screw with a centrally arranged opening and a plurality of openings radial thereto. Bone cement can be injected into the bone through these openings. In order to avoid a cement distribution outside of the bone, a closure apparatus for cementable bone screws is proposed. The closure apparatus according to the invention is fixedly connected to an application instrument via a predetermined breaking point such that handling and production is simplified. Alternatively, the closure apparatus can be embodied such that the closure allows a passage in one direction but is impermeable in the other direction to the greatest possible extent. Hence the screw can be pushed via a guide wire from the distal direction, but a cement injection from the proximal direction is effectively prevented from emerging.