Cranial Bone Flap Fixation via Self-Centering Burr Hole Fitting

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Solution Overview

Problem

Current methods for fixating cranial bone flaps during craniotomy procedures, such as those using cranial flap clamps, face challenges in securely attaching the bone flap to the cranial bone mass, especially at burr holes, due to limited adaptability with varying drill sizes and potential interference with the scalp surface.

Innovation Solution

The development of a closure plate and support plate system with a burr hole fitting that allows for flexible insertion and self-centering within the burr hole, utilizing resilient materials and designs that maintain a spaced relationship with the substrate, ensuring secure fixation without slipping on the scalp.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If cranial flap clamps with inner and outer plates are used to secure the bone flap, then fixation strength is improved, but adaptability to varying burr hole sizes deteriorates

Engineering Contradiction:

Improvefixation strengthVSAvoidadaptability to burr hole sizes

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The closure plate incorporates a burr hole fitting with peripheral portions that can change their configuration parameter (from constrained to free movement) to adapt to different burr hole sizes. The fitting's peripheral portions are initially constrained during insertion but gain freedom of movement afterward, allowing the same device to accommodate varying drill sizes while maintaining secure fixation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The burr hole fitting transitions from a static constrained structure during insertion to a dynamic structure with mobile peripheral portions after insertion. This dynamic characteristic allows the fitting to adapt its shape and position within the burr hole, providing both ease of insertion and adaptability to different hole sizes while maintaining fixation strength.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the closure plate is pressed firmly against the outer surface of the bone flap, then fixation reliability is improved, but interference with the scalp surface worsens

Engineering Contradiction:

Improvefixation reliabilityVSAvoidinterference with scalp surface

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The closure plate is segmented into distinct functional components: a substrate providing structural support, a burr hole fitting for anchoring, and surface features for scalp interface. This segmentation allows the substrate to be pressed firmly against the bone flap for reliable fixation while the designed surface features minimize harmful interference with the scalp by distributing pressure and reducing direct contact area.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the burr hole fitting is inserted entirely into the burr hole, then adaptability to drill sizes is improved, but device complexity worsens

Engineering Contradiction:

Improveadaptability to drill sizesVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The burr hole fitting is designed as a nested structure that fits entirely within the burr hole, with peripheral portions that can move freely once inserted. This nesting approach allows the fitting to adapt to different drill sizes without requiring multiple device variants, as the same fitting structure can accommodate varying hole dimensions through its mobile peripheral portions, thereby improving adaptability without proportionally increasing overall device complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

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

This solution provides a secure and adaptable fixation method for cranial bone flaps at burr holes, regardless of drill size, minimizing interference with the scalp and ensuring stable placement, thus enhancing the reliability of bone flap fixation during craniotomy procedures.

Implementation Method 1

utilizing resilient materials and designs that maintain a spaced relationship with the substrate, ensuring secure fixation without slipping on the scalp

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS9265530B2Apparatus and methods for fixating a cranial bone flap with a cranial bone mass

Publication Date: 2016.02.23 NEOS SURGERY SL

AI summary

A fixation device for use in securing a cranial bone flap with a cranial bone mass at the location of a burr hole. In one implementation the fixation device includes a closure plate having a substrate with an outer surface and an inner surface and with at least a portion of the inner surface adapted to be applied against the outer face of the outer edges of the cranial bone mass and the cranial bone flap at the location of the burr hole. The closure plate is also adapted with a burr hole fitting coupled to and spaced a distance below the inner surface of the substrate and adapted for being inserted entirely into the burr hole. The fitting may include one or more peripheral portions adapted for being pressed against the inner wall of the burr hole when the fitting is inserted therein. The peripheral portions are endowed with a freedom of movement that enables the fitting to be inserted into the burr hole.