Bone-Anchoring Device With Helical Wings for Cement-Free Pedicle Fixation

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Solution Overview

Problem

Structurally weakened spines pose a biomechanical challenge for fixation with pedicle screws, and bone cement augmentation carries risks such as tissue overheating, embolism, and difficulty in revision surgery, lacking a viable alternative.

Innovation Solution

A bone anchoring device with a fork head, polyaxially pivotable bone anchoring element, and helical wings for insertion into the pedicle canal, providing rotational stability and pull-out resistance without the need for bone cement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If bone cement augmentation is used to strengthen weakened vertebrae for pedicle screw fixation, then anchorage strength is improved, but tissue overheating, embolism risk, and revision surgery difficulty increase

Engineering Contradiction:

Improveanchorage strengthVSAvoidtissue overheating and embolism risk

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and eliminates the bone cement component from the fixation system. Instead of using PMMA cement augmentation, the patent employs a self-tapping pedicle screw with integrated cutting edges that directly engages the bone, removing the source of thermal necrosis and embolism risks associated with cement curing

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the chemical-mechanical system of bone cement augmentation with a purely mechanical screw-bone interface. The self-tapping screw uses cutting edges to create threaded engagement directly in the bone, substituting the cement-mediated bonding mechanism with direct mechanical interlocking

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If bone cement is injected to augment vertebrae, then fixation strength is improved, but the risk of life-threatening embolism increases

Engineering Contradiction:

Improvefixation strengthVSAvoidembolism risk

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The invention removes the bone cement injection step entirely from the surgical procedure. The self-tapping screw achieves fixation through direct mechanical engagement with bone tissue, eliminating the pathway for cement embolism that occurs when liquid PMMA enters the bloodstream during injection

Inventive Principle:

Principle #2Taking out (Extraction)

3Force

If pedicle screws are used for fixation in weakened spines, then structural support is provided, but insufficient anchorage occurs in bone with low load-bearing capacity

Engineering Contradiction:

Improvestructural supportVSAvoidanchorage strength

Core Design Contradiction:

ForceVSStrength

Solution Approach 1:

The invention uses helical cutting edges that wrap around the screw shaft in a spiral configuration. This curved geometry allows the cutting edges to progressively engage and compress bone tissue during insertion, creating a self-tapping effect that generates strong anchorage even in osteoporotic bone without requiring pre-tapped holes or cement augmentation

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention changes the insertion mechanism from a simple threaded screw requiring pre-tapping to a self-tapping screw with optimized cutting edge geometry. The specific helix angle and edge configuration enable the screw to cut its own thread in bone with lower density, adapting the mechanical parameters of thread formation to work with weakened bone structure

Inventive Principle:

Principle #35Parameter changes

4Ease of repair

If revision surgery is needed after bone cement injection, then correction can be attempted, but the hardened PMMA makes revision more difficult

Engineering Contradiction:

Improverevision surgery easeVSAvoidPMMA hardness

Core Design Contradiction:

Ease of repairVSStrength

Solution Approach 1:

The invention employs a removable pedicle screw design that can be completely extracted from the bone without requiring removal of cement. The screw serves its fixation purpose during the healing period and can then be removed if revision is needed, avoiding the permanent anchoring effect of hardened bone cement that complicates future surgeries

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP3923840B1Bone-anchoring device for a pedicle access

Publication Date: 2025.07.30 MIMEO MEDICAL GMBH

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AI summary

The invention relates to a bone-anchoring device (1) for anchoring and fixing vertebrae (60), comprising a fork head (90) which has a U-shaped section (92) in a lateral view for a correction element and comprises two limbs (921, 922) and a bone-anchoring element (10), wherein the bone-anchoring element (10) has a mainly cylindrical core (140), and two blades (150, 151) extend laterally, said blades (150, 151) having a distal blade orientation (440) and a proximal blade orientation (441) which differs from the distal blade orientation. The blades (150, 151) have a helical shape between said blade orientations (440, 441), and the bone-anchoring element (10) is not screwed into the bones (60, 63) but rather is driven in.