Intramedullary Nail Locking for Screw Alignment and Rotation Control
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Solution Overview
Problem
Traditional intramedullary devices for bone fractures suffer from implant failure, difficulty in alignment of fixation screws, and issues such as cutout, cephalad cutout, proximal fragment rotation, and nonunion, which are not adequately addressed by existing systems.
Innovation Solution
Intramedullary nails with proximal and distal locking features, including interlocking fixation devices and headless fasteners, along with guide wire placement mechanisms to prevent rotation and backout, and a ratchet system for secure guide sheath retention, are provided.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional intramedullary devices are used for bone fracture fixation, then the basic fixation function is provided, but implant failure, cutout, and rotation occur due to insufficient stability and alignment control
Solution Approach 1:
The fixation system is divided into multiple functional components: intramedullary nail with proximal and distal locking mechanisms, guide wire placement system with ratchet mechanism, and separate alignment features. This segmentation allows each component to perform its specific function optimally while maintaining overall system reliability without excessive complexity.
Solution Approach 2:
The guide wire is placed through the ratchet mechanism before nail insertion, establishing the correct trajectory and preventing rotation during subsequent steps. The ratchet mechanism pre-sets the alignment, ensuring proper screw placement without requiring complex real-time adjustment during surgery.
2Manufacturing precision
If fixation screws are inserted without precise alignment guidance, then the insertion process is simple, but difficulty in alignment and improper screw placement occur
Solution Approach 1:
A guide wire serves as an intermediary tool that establishes the precise trajectory for screw insertion. The ratchet mechanism acts as a mediator that both guides the wire placement and locks it in position, providing alignment precision while maintaining ease of operation through a straightforward sequential process.
Solution Approach 2:
The ratchet mechanism automatically maintains the guide wire in the correct position through its self-locking feature, eliminating the need for continuous manual adjustment or complex alignment tools. The system self-regulates the alignment, making the procedure both precise and easy to perform.
3Reliability
If guide sheath retention mechanisms are not sufficiently secure, then the device structure is simpler, but guide sheath backout and rotation occur during implantation
Solution Approach 1:
The ratchet mechanism converts the potential harm of guide sheath backout and rotation into a beneficial self-locking feature. The ratchet teeth engage with the guide sheath, allowing insertion motion while preventing reverse motion, thus transforming a potential failure mode into a reliable retention mechanism.
Solution Approach 2:
The complex mechanical retention system is replaced with a simple ratchet mechanism that uses directional friction and tooth engagement to prevent backout. This substitution maintains reliability while minimizing structural complexity, using a well-established mechanical principle rather than a complex multi-component system.
Data Source
AI summary
Intramedullary nails, systems, and methods. The intramedullary nail may include a generally elongate body extending from a first, distal end to a second, proximal end. The distal end may include one or more openings configured to receive one or more bone anchors that extend transversely through the distal end intramedullary nail, and thereby configured to secure the distal end of the nail. The proximal end may also include one or more openings configured to receive one or more bone anchors that extend transversely through the proximal end of the intramedullary nail, and thereby configured to secure the proximal end of the nail.