Cervical Spine Screw Locking via Floating Spherical Ring
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Solution Overview
Problem
Current orthopaedic devices for cervical spine implantation require additional equipment and increased operating time due to complex screw locking mechanisms, and often necessitate the use of extra screws and equipment, which are costly and difficult to remove without damaging the material.
Innovation Solution
A simplified orthopaedic device with a support plate and screw design featuring a spherical contact surface and a radially deformable locking ring, allowing for efficient locking and easy removal of screws without additional equipment, using an annular groove and protuberance to secure the screw in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking ring is pre-mounted on each screw to prevent back movement, then screw security is improved, but device complexity and cost increase
Solution Approach 1:
The locking function is merged with the plate structure itself through the annular groove and spring ring mechanism, eliminating the need for separate locking rings on each screw. The spring ring is integrated into the plate's orifice structure, combining the locking and anchoring functions in a single integrated system.
Solution Approach 2:
The spring ring automatically engages with the screw head's annular protuberance through radial elastic deformation when the screw is tightened, providing self-locking without requiring additional locking operations or complex mechanisms. The system uses the screw tightening process itself to activate the locking function.
2Reliability
If a slide mechanism is used to cover screw heads after tightening, then screw back movement is prevented, but operating time and equipment requirements increase
Solution Approach 1:
The spring ring is pre-positioned in the annular groove of the plate before screw insertion. When the screw is tightened, the locking action occurs automatically through the pre-positioned spring ring engaging with the screw's protuberance, eliminating the need for subsequent locking operations or additional equipment.
Solution Approach 2:
The complex slide mechanism is replaced with a simple elastic spring ring that uses radial deformation to achieve locking. This mechanical substitution simplifies the system from a multi-component sliding structure to a single elastic element that automatically engages and disengages.
3Adaptability or versatility
If spherical contact surfaces are used for angular adjustment, then adaptability is improved, but manufacturing precision requirements increase
Solution Approach 1:
Spherical contact surfaces are used on both the screw head (annular protuberance) and the plate (orifice) to enable angular adjustment during screw tightening. The spherical geometry allows for self-alignment and angular adaptation while maintaining relatively simple manufacturing requirements compared to other adjustable mechanisms.
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 provides a reliable, efficient, and cost-effective locking mechanism that allows for easy screw removal and reusability, optimizing the rest surface area for preventing screw back movement and reducing operational complexity and costs.
Implementation Method 1
said locking means consisting of an annular groove formed in a portion of the height of the internal surface of the plate orifice... within which groove is added a slotted metal ring having a radial elastic deformation ability
Implementation Method 2
The orifice (3) is shaped so as to enable passage of said screw, the contact between said screw head and said plate being made through complementary spherical surfaces
Implementation Method 3
its spring ring is radially compressed by the above-mentioned beveled top surface, then it automatically expanses within this groove to form the required stop for preventing back-moving or unscrewing
Data Source
AI summary
The invention relates to an implantable orthopaedic device, in particular for the cervical spine, of the type formed by a support plate (2) provided with at least one orifice (3) for passage of a fixing screw (4), which orifice (3) is provided with locking means comprising a slotted metal ring (8) accommodated in a receiving groove (5) on the circumference of said orifice (3) of the plate and intended to cooperate with an annular channel (10) formed in the screw head (4a). According to the invention, the annular chamber (10) of the screw head (4a) is framed by an end of male spherical contour (11′) and by a truncated annular protuberance (12). This end of male spherical contour (11′) is designed to cooperate with the complementary female spherical contour (7a′) formed on the upper flange (7a) of the plate groove (5). Moreover, the locking ring (8) is mounted “floating” in its receiving groove (5), and the channel (10) of the screw head (4a) is connected to said annular protuberance (12) via a truncated part (10c) allowing the screw to be undone.