Intramedullary Nail System with Guide Sheath Alignment
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Solution Overview
Problem
Traditional intramedullary nail implantation systems face issues such as susceptibility to implant failure, difficulty in alignment of fixation screws, and inadequate prevention of bone fragment rotation and backout during the implantation process, which can lead to complications like axial cutout, cephalad cutout, proximal fragment rotation, and nonunion in bone fractures.
Innovation Solution
The development of an intramedullary nail system with proximal and distal locking mechanisms, including interlocking fixation devices and a ratchet-like mechanism in the insertion tool to prevent backout, which allows for secure alignment and stabilization of the nail within the bone, using guide wires to prevent rotation and enhance bony fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional intramedullary nails are used for fixation, then the implantation procedure is simple, but the susceptibility to implant failure and difficulty in alignment of fixation screws increases
Solution Approach 1:
The guide sheath is inserted through the insertion tool, and the intramedullary nail is inserted through the guide sheath. This nested arrangement ensures precise alignment and prevents deviation during implantation, thereby improving reliability without significantly increasing operational complexity
Solution Approach 2:
The guide sheath acts as an intermediary component between the insertion tool and the intramedullary nail. It provides a controlled pathway that maintains alignment and prevents harmful deviations, resolving the contradiction between reliability and complexity by introducing a specialized guiding component
2Manufacturing precision
If fixation screws are inserted without a guiding mechanism, then the implantation process is faster, but the alignment precision of fixation screws deteriorates
Solution Approach 1:
The guide sheath is pre-positioned and aligned before the fixation screws are inserted. This preliminary alignment action ensures that subsequent screw insertions follow the correct trajectory, achieving high precision without requiring complex real-time adjustment mechanisms that would slow down the procedure
3Reliability
If no anti-rotation mechanism is provided, then the insertion tool is simpler, but bone fragment rotation and backout occur during implantation
Solution Approach 1:
The insertion tool is divided into functional segments including a handle portion, a shaft portion, and a guide sheath. The guide sheath specifically provides anti-rotation functionality through its structured design with retention members, isolating the complexity to a specific component while maintaining overall tool functionality and reliability
4Reliability
If the guide sheath can move freely in the insertion tool, then the insertion tool is simpler, but the guide sheath may backout and cause implant failure
Solution Approach 1:
The retention mechanism allows dynamic adjustment during insertion while preventing backward movement. The ratchet-like mechanism with movable and fixed retention members enables forward motion control while blocking reverse motion, providing intelligent directional constraint that enhances reliability without excessive complexity
Solution Approach 2:
The retention mechanism provides more constraint than minimally required by allowing controlled movement in one direction while completely preventing movement in the opposite direction. This excessive action in the critical direction (preventing backout) ensures reliability without adding unnecessary complexity in non-critical directions
Data Source
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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. In some embodiments, the proximal end may further include a cross-locking feature, which includes a second bone anchor that interlocks with a first bone anchor, for example, for enhanced bone purchase and bony fixation.