Orthopedic Screw with Tapered Locking for Bone Fixation Stability

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Solution Overview

Problem

Conventional orthopedic screws implanted in bones tend to loosen and partially screw out over time under stress, hindering bone growth and healing, and potentially causing secondary damage, thus affecting patient quality of life.

Innovation Solution

An orthopedic implanted screw design featuring a fixed seat with a deformation limiting portion and taper portion, where the screw body is detachably mounted and drills into the bone, forming a stable connection to prevent loosening, with a pad and micropore structures for enhanced bone integration and growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional bone screw is directly screwed into bone blocks or bone plates, then the fixation is initially achieved, but the screw easily gets loose and screws out from the bone after working under complicated stress for a long time

Engineering Contradiction:
Improvescrew fixation stabilityVSAvoidlong-term fixation duration
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The invention divides the screw structure into multiple functional segments: a screwing portion with threaded structure for initial bone engagement, a middle portion with grooves for bone ingrowth, and a head portion with limiting cavity. This segmentation allows each part to perform its specific function optimally, preventing the screw from loosening as a whole system rather than relying on a single continuous structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the screw are given different local properties: the screwing portion has a threaded structure for secure initial fixation, the middle portion has grooves to promote bone ingrowth and integration, and the head portion has a limiting cavity to prevent over-screwing. This local differentiation ensures that each region contributes to overall reliability under long-term stress.

Inventive Principle:
Principle #3Local quality

2Reliability

If a screw is designed to be securely anchored in bone, then bone integration and self-locking are achieved, but the structure becomes more complex with multiple components

Engineering Contradiction:
Improvebone integration and self-lockingVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges multiple functions into a single integrated screw structure. The screw combines the screwing portion for fixation, the middle portion for bone integration, and the head portion for self-locking, all in one continuous component. This merging achieves reliable bone integration and self-locking without requiring separate auxiliary devices or complex assembly mechanisms.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The screw design incorporates self-service features: the grooves in the middle portion automatically promote bone ingrowth and integration over time, and the limiting cavity in the head portion automatically prevents over-screwing and loosening. These self-service mechanisms reduce the need for additional complex components or post-operative interventions.

Inventive Principle:
Principle #25Self-service

3Ease of manufacture

If a screw structure is simplified for ease of manufacture, then production cost is reduced, but the screw may not provide sufficient bone integration and self-locking functions

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidbone integration and self-locking
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The invention achieves reliable bone integration and self-locking by optimizing geometric parameters rather than adding complex components. The threaded structure pitch, groove depth and spacing, and limiting cavity dimensions are carefully designed to provide the necessary mechanical interlocking and biological integration. These parameter optimizations can be achieved through standard manufacturing processes without significantly increasing complexity.

Inventive Principle:
Principle #35Parameter changes

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 design ensures stability of the screw within the bone, facilitating quick and stable bone growth, preventing secondary damage, and improving patient quality of life by securely anchoring the screw.

Implementation Method 1

an interior of the pad is provided with a plurality of micropore structures

Methodology Applied
Scientific EffectPorous material structure: Porosity

Implementation Method 2

the screw body positioned in the limiting cavity abuts against the inner wall surface of the seat body so that the taper portion drills into the bone, to accordingly prevent the screw body from dropping out of the bone

Methodology Applied
Scientific EffectMechanical interlock through tapered geometry: Wedge

Implementation Method 3

the deformation limiting portion is configured on an inner wall surface of the seat body, protrudes toward an inner part of the limiting cavity and is positioned at the top avoidance opening

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3698744B1Orthopedic implant screw
Publication Date: 2022.03.02 BEIJING AKEC MEDICAL
  • EP3698744B1 patent drawingFigure 1
  • EP3698744B1 patent drawingFigure 2
  • EP3698744B1 patent drawingFigure 3~4

AI summary

Provided is an orthopedic implanted screw. The orthopedic implanted screw may include a fixed seat and a screw body. The fixed seat may include a seat body, a deformation limiting portion and a taper portion. Herein, the seat body is provided with a limiting cavity, a top avoiding opening and a bottom avoiding opening, the deformation limiting portion is provided on an inner wall surface of the seat body, and the taper portion is provided on an outer wall surface of the seat body. The screw body is detachably mounted on the fixed seat, the screw body being configured to drill into a bone in a rotating mode, a part of the screw body is limited in the limiting cavity, another part of the screw body drills into the bone after passing through the bottom avoiding opening, and the screw body positioned in the limiting cavity abuts against the inner wall surface of the seat body so that the taper portion may drills into the bone, to accordingly prevent the screw body from dropping out of the bone. The disclosure solves the problem that a bone screw in the conventional art may easily get loose or screw out from the bone after working in presence of a complicated stress for a long time, accordingly it is not only unfavorable to quick and stable growth and healing of the bone but may cause secondary damage of an affected area, and consequently living quality of a patient may be influenced seriously.