Cortical Bone Pin with Barbs for Toe Alignment
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Solution Overview
Problem
Existing methods for aligning and securing bones, such as K-wires and metal pins, face issues like exposure leading to infection, non-resorbable and removable pins causing instability, and pin migration, especially in treating deformities like hammer toe.
Innovation Solution
A cortical bone pin with barbs and a shoulder design that resists migration and promotes fusion, made from cortical bone and treated to reduce brittleness, allowing for secure bone alignment and integration without the need for precise length matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a K-wire is used to align bones, then bone alignment is achieved, but the wire is exposed allowing it to slide out and creating an open wound that risks infection
Solution Approach 1:
The patent introduces a cortical bone pin as an intermediary device that replaces the exposed K-wire. The pin is inserted through a tunnel drilled in the bone, with its distal end positioned within the bone tissue and proximal end exiting through skin. This intermediary structure provides stable bone alignment while eliminating the harmful exposure and displacement issues of K-wires, as the pin is anchored within the bone tunnel.
Solution Approach 2:
The cortical bone pin is made from biocompatible and biodegradable cortical bone material, making it a temporary, resorbable fixation device. The pin serves its purpose during bone healing and then naturally degrades, eliminating the need for removal surgery and avoiding long-term complications associated with permanent metal implants.
2Reliability
If a metal pin is inserted through the exposed interphalangeal joint, then bone alignment is achieved, but the pin is not resorbable and may migrate causing instability
Solution Approach 1:
The patent changes the material parameter of the pin from non-resorbable metal to biodegradable cortical bone. This parameter change allows the pin to maintain structural integrity during the healing period while gradually degrading afterward, eliminating migration issues and providing a stable, temporary fixation solution that naturally integrates with the surrounding bone tissue.
Solution Approach 2:
The cortical bone pin represents a composite approach, combining the structural strength needed for temporary fixation with the biodegradability of natural bone material. The pin is made from processed cortical bone that maintains mechanical properties suitable for bone alignment while being inherently biocompatible and resorbable, unlike pure metal or simple polymer alternatives.
3Reliability
If a cortical bone pin with barbs is used, then pin migration is resisted and fusion is promoted, but the pin structure becomes more complex
Solution Approach 1:
The pin structure is segmented into distinct functional zones: a smooth cylindrical shaft for insertion and positioning, barbed sections for anchoring and preventing migration, and a shoulder for additional stabilization. This segmentation allows each portion to perform its specific function optimally while maintaining overall structural coherence and relatively simple manufacturing.
Solution Approach 2:
Different portions of the pin have different surface qualities - the shaft is smooth for easy insertion and proper positioning, while specific sections have barbs for anchoring. This local differentiation of surface properties allows the pin to achieve both easy insertion and secure fixation without requiring complex overall structure, as each local region is optimized for its specific function.
Data Source
AI summary
A pin made of cortical bone may be inserted into adjoining bones of a toe to align and secure the bones. The pin may have barbs to prevent migration of the pin. The pin may include a shoulder to further prevent migration of the pin from the bones, to increase the strength of the pin, and to increase the surface area between the bone pin and the host bone. The pin may further include flattened portions on its circumference to aide in rotating the pin during insertion. The pin may be treated to reduce brittleness.