Intramedullary Nail Insert Segmentation for Locking Screw Fixation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing intramedullary nails face challenges in securely attaching locking screws and incorporating an attachment mechanism for surgical instruments due to limitations in biocompatible materials and processing techniques, particularly with Ultra High Molecular Weight Poly-Ethylene (UHMWPE), which is difficult to process accurately and requires a small outer diameter for the insert to fit through the central opening.
Innovation Solution
An intramedullary nail design featuring a cavity with a first locking hole and inserts with transverse bores that allow for increased diameter inserts made from UHMWPE, including an anti-rotation mechanism and a second insert that locks in place via laser-welds or threads, enabling secure screw fixation and attachment of surgical instruments without needing an internal thread at the proximal end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the insert is made with a small outer diameter to fit through the central opening of the attachment mechanism, then the insert can be assembled through the attachment mechanism, but the locking screws cannot be firmly secured in the locking holes
Solution Approach 1:
The invention divides the fixation system into two separate inserts: a first insert with transverse bores for securing locking screws, and a second insert that locks the first insert in place within the cavity. This segmentation allows the first insert to have a larger diameter for secure screw fixation while still being deliverable through the attachment mechanism's central opening as part of the two-stage delivery system
Solution Approach 2:
The first insert is nested within the second insert during the delivery process. The first insert with the larger diameter (for secure locking screw fixation) is contained within the second insert, allowing both to be delivered through the attachment mechanism's central opening. The second insert acts as a delivery sheath that protects and transports the first insert to the implantation site
2Reliability
If the insert is made from UHMWPE material for biocompatibility, then the material is biocompatible and approved for implantation, but the material is difficult to process with required accuracy using conventional techniques
Solution Approach 1:
The fixation system is segmented into two separate inserts that can be manufactured independently. This allows each insert to be optimized for its specific function and manufactured using appropriate techniques. The first insert (with transverse bores) and second insert (locking mechanism) can be produced separately, potentially using different manufacturing approaches suited to their respective requirements
Solution Approach 2:
The invention changes the geometric parameters of the inserts, particularly the outer diameter of the first insert, to enable secure locking screw fixation. By optimizing the diameter and other dimensional parameters, the design achieves both secure fixation and compatibility with conventional manufacturing techniques, reducing the processing difficulty associated with UHMWPE
3Reliability
If the insert has a large outer diameter for secure locking screw fixation, then the locking screws can be firmly secured, but the insert cannot be introduced through the central opening of the attachment mechanism
Solution Approach 1:
The first insert with the larger outer diameter (necessary for secure locking screw fixation) is nested within the second insert during delivery. This nested configuration allows the combination to pass through the attachment mechanism's central opening, while the first insert maintains its larger diameter for proper locking screw engagement at the implantation site
Solution Approach 2:
The system is divided into two inserts with different functional requirements. The first insert has the larger diameter needed for secure fixation, while the second insert serves as a delivery vehicle. This segmentation allows each component to be optimized for its specific function without compromise
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for secure locking screw fixation and attachment of surgical instruments, enabling improved rigidity and ease of manufacturing with conventional processing techniques, while preventing unintentional screw loosening and rotation of the insert.
Implementation Method 1
a second insert sized and shaped to be lockingly received within the cavity proximal of the insert to lock the insert at the desired position in the cavity
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An intramedullary device includes an intramedullary nail (9) extending along a longitudinal axis from a proximal end to a distal end, a proximal portion of the intramedullary nail including a cavity (14) extending from an opening at the proximal end along the longitudinal axis and a locking hole (15) extending transversely therethrough along with a first insert (2) sized and shaped for insertion into the cavity along the longitudinal axis thereof and including a transverse bore (20) aligning with the locking hole and a second insert (3) for engaging an inner surface of the cavity proximally of the first insert to retain the first insert within the cavity and including a central bore (30) extending longitudinally therethrough for coupling to an insertion instrument.