Pivot Fastener Rotational Joint for Dynamic Bone Flap Decompression
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Solution Overview
Problem
Existing dynamic systems for bone flaps in surgical procedures, such as craniotomies and craniectomies, are voluminous and exhibit unnecessary resistance to movement, leading to insufficient decompression and an unesthetic appearance.
Innovation Solution
A pivot fastener system comprising a body, head, and shoulder with a rotational joint, allowing for a cranioplasty prosthesis to move dynamically while minimizing resistance and maintaining a sleek appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dynamic systems with telescopic or spring-based expansion are used to allow bone flap movement, then bone flap mobility is improved, but device volume increases and resistance to movement increases
Solution Approach 1:
The patent employs a dynamic hinge mechanism that allows the bone flap to rotate and move relative to the skull while maintaining a compact profile. The hinge enables controlled movement through a defined range of motion without requiring large expansion space, thus achieving bone flap mobility while minimizing device volume.
Solution Approach 2:
The fastening system is divided into separate components: a skull-mounted anchor, a hinge mechanism, and a bone flap attachment. This segmentation allows each component to be optimized independently, with the hinge providing mobility in a compact form factor rather than requiring a single large voluminous device.
2Ease of operation
If dynamic systems with telescopic or spring-based expansion are used to allow bone flap movement, then bone flap mobility is improved, but resistance to movement increases leading to insufficient decompression
Solution Approach 1:
The hinge mechanism provides dynamic movement capability with low friction bearings that minimize resistance to bone flap movement. This allows the bone flap to move freely through the desired range of motion for effective decompression without the high resistance characteristic of spring-based systems.
3Ease of operation
If dynamic systems with telescopic or spring-based expansion are used, then bone flap movement is enabled, but aesthetic appearance deteriorates due to lumps on the head
Solution Approach 1:
The hinge mechanism is designed to nest within the contours of the skull and bone flap, with components fitting together in a compact arrangement. The low-profile design allows the fastening system to be concealed beneath the skin surface, maintaining aesthetic appearance while providing the necessary movement capability.
4Ease of operation
If a rotational joint is formed with a shoulder in the connection hole, then controlled movement is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The rotational joint design incorporates tolerances and clearances that balance controlled movement with manufacturability. The shoulder diameter is specifically dimensioned to provide sufficient clearance for rotation while maintaining positional control, optimizing the trade-off between movement capability and manufacturing precision requirements.
Data Source
AI summary
An assembly comprising a cranioplasty prosthesis component having a connection hole(s). A pivot fastener may have a body being threaded and adapted to be screwed to cranium bone. A shoulder is between the body and a head of the pivot fastener, the shoulder having a circular section. A diametrical dimension of the circular section is less than a diametrical dimension of the connection hole, such that the shoulder forms a rotational joint with the cranioplasty component when the shoulder is in the connection hole.