Bone Compression Mechanism With Nested Bodies for Small-Bone Fusion
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Solution Overview
Problem
Existing bone fusion devices for foot and ankle surgeries are complex, costly, and unsuitable for small bones due to their lengthy structure and reliance on shape memory alloys, failing to provide sustained compression under varying loads.
Innovation Solution
A bone compression device with a primary and secondary body, allowing adjustable compression through a guide pin and slot mechanism, eliminating the need for shape memory alloys, and enabling adjustment of compression force post-insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If shape memory alloy (nitinol) material is used to maintain tension between bone parts, then sustained compression can be provided during extended time period, but device complexity increases and manufacturing costs increase
Solution Approach 1:
The patent removes the shape memory alloy component from the device entirely, replacing it with a simple compression spring and threaded adjustment mechanism. This extraction of the complex material eliminates the associated complexity while maintaining the sustained compression function through mechanical means.
Solution Approach 2:
The patent employs inexpensive, readily available components such as standard compression springs and threaded fasteners instead of expensive shape memory alloys. These conventional components achieve the same functional outcome at significantly lower cost and complexity.
2Duration of action of moving object
If shape memory alloy (nitinol) material is used to maintain tension between bone parts, then sustained compression can be provided during extended time period, but manufacturing costs increase
Solution Approach 1:
The patent substitutes expensive shape memory alloys with inexpensive conventional components including standard compression springs, threaded rods, and locking mechanisms. These components are mass-producible and significantly reduce manufacturing costs while achieving the same sustained compression effect.
Solution Approach 2:
By removing the expensive shape memory alloy material from the design, the patent eliminates the associated high manufacturing costs. The function is achieved through simpler, cheaper mechanical components that are easier and less costly to manufacture.
3Duration of action of moving object
If a lengthy device structure is used to provide sustained compression, then compression can be maintained, but the device becomes unsuitable for small bones in foot and ankle
Solution Approach 1:
The patent employs a nested structure where the secondary body with the spring mechanism is positioned within the inner bore of the primary body. This nesting arrangement compactly houses the compression mechanism, significantly reducing the overall device length to make it suitable for small bones in the foot and ankle while maintaining sustained compression capability.
Solution Approach 2:
The patent transitions from a linear, lengthy device structure to a compact, multi-dimensional arrangement. By utilizing the radial space within the bone marrow cavity and arranging components in three dimensions (primary body outer structure, inner bore, nested secondary body), the device achieves sustained compression function in a compact form factor suitable for small bones.
4Device complexity
If fixed compression structure is used, then simple structure is achieved, but adjustment of compression force after insertion is not possible
Solution Approach 1:
The patent incorporates a dynamic adjustment mechanism allowing the compression force to be modified after device insertion. The threaded rod with external threads engages with the compression spring assembly, enabling surgeons to adjust the compression force by rotating the threaded rod, thus providing adaptability while maintaining relatively simple structure.
Solution Approach 2:
The device is designed with pre-configured adjustment capabilities built into the structure. The threaded rod and spring assembly are preliminarily arranged to allow easy adjustment of compression force without requiring complex additional components or procedures after insertion.
Data Source
AI summary
Bone compression device with a primary body (2) having a primary bone fixation pin assembly (4, 5) extending at an angle to the longitudinal axis (A), and a secondary body (3) having a secondary bone fixation pin assembly (6, 7) extending at an angle to the longitudinal axis (A). The secondary body (3) is positioned in the inner bore (2a) and moveable with respect to the primary body (2) over an adjustment range. The primary body (2) comprises a guide pin (8) and the secondary body (3) comprises a guide slot (9) having an inner guide slot (9a), the guide pin (8) extending through the guide slot (9) and in contact with the inner guide slot (9a) during operation. An adjustment assembly (10) is provided which is connected to the primary body (2) and secondary body (3) for mutual adjustment thereof along the longitudinal axis (A).