Endosseous Screw Assembly with Deformable Interference Locking
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Solution Overview
Problem
Current internal fixation systems in orthopaedic surgery require complex and time-consuming procedures for screw insertion and locking, which can be challenging for less experienced surgeons and increase surgical duration and patient risk, especially in elderly patients.
Innovation Solution
An endosseous screw assembly with a longitudinally extending stem, a connection sleeve, and a ring nut with deformable interference means, allowing for simplified screw insertion and locking by preventing rotation and ensuring axial sliding, reducing the number of surgical operations and tools required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex connection systems are used to ensure stable screw-to-plate/nail connection, then the connection stability and stress transmission are improved, but the surgical operation time and complexity increase
Solution Approach 1:
The connection system is divided into separate functional components: a connection sleeve with internal threading for the screw stem, and a ring nut with external threading for the connection sleeve. This segmentation allows each component to be optimized independently and simplifies the assembly process during surgery.
Solution Approach 2:
The connection sleeve and ring nut are designed to work together as an integrated locking mechanism. The ring nut rotates relative to the connection sleeve during tightening, and the deformable interference means engage with the conical portion to prevent rotation, creating a unified locking action that secures the screw assembly in a single surgical motion.
2Reliability
If multiple surgical operations are performed for screw insertion and locking, then the fixation reliability is improved, but the surgical duration and patient risk increase
Solution Approach 1:
The connection sleeve is pre-formed with internal threading and a conical portion, while the ring nut is pre-formed with external threading and deformable interference means. These preliminary preparations allow the surgeon to simply insert and rotate the ring nut during surgery, eliminating the need for multiple separate operations to create threading or prepare components.
Solution Approach 2:
The deformable interference means automatically engage with the conical portion of the connection sleeve during the tightening process. As the ring nut rotates and the connection sleeve is compressed, the interference means deform and lock into place, providing self-locking functionality that eliminates the need for additional locking operations.
3Manufacturing precision
If specialized tools and multiple operations are used for screw insertion, then the insertion precision is improved, but the ease of operation for less experienced surgeons decreases
Solution Approach 1:
The connection sleeve and ring nut design allows the same components to serve multiple functions: the connection sleeve provides both the interface for the screw stem and the conical surface for locking, while the ring nut provides both the threading for attachment and the deformable interference means for securing. This multi-functionality reduces the need for specialized tools and simplifies the procedure for less experienced surgeons.
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
The solution simplifies the surgical procedure, reducing operation duration and allowing less experienced surgeons to perform the implantation safely and effectively, while ensuring stable fixation of the fracture site.
Implementation Method 1
said plurality of deformable interference means being oriented so that relative sliding of the ring nut and the connection sleeve during the screwing action of the ring nut results in deformation of the deformable interference means thus obtaining a contact force between the endomedullary nail and the ring nut inside the connection hole locking the endosseous screw in the connection hole of the endomedullary nail
Implementation Method 2
a ring nut rotatably mounted on one end of the connection sleeve by means of a threaded connection
Data Source
AI summary
An endosseous screw assembly for an internal fixation system, comprising: a stem extending longitudinally and having at least one threaded distal portion for allowing anchoring to a bone site of a patient; a connection sleeve suitable for introduction inside a connection hole of a fixation member; and a ring nut rotatably mounted on the connection sleeve. The ring nut may be threadably mounted on the connection sleeve and may comprise a rim with teeth designed to cooperate with a step formed on the fixation member, in the vicinity of the connection hole, so as to prevent rotation of the ring nut with respect to the fixation member when the connection sleeve is introduced into the connection hole of the fixation member. The ring nut may further comprise multiple deformable interference fit components which lie along a conical portion of the connection sleeve.