Polyaxial Bone Plate Rotatable Lock Mechanism
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Solution Overview
Problem
Conventional bone plate implants for spinal stabilization face challenges such as excessive tissue damage from screw tightening, risk of screw backout, and complex installation processes, which hinder secure and efficient immobilization of vertebral bodies.
Innovation Solution
The development of polyaxial bone plates with rotatable locks and locking mechanisms that prevent screw backout, featuring a locking cavity with a post and a noncircular head element, allowing for secure attachment with minimal tissue damage and rapid installation, reducing the risk of parts being lost or broken during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional bone plates with friction-based screw fixation are used, then simple attachment is achieved, but excessive tissue damage occurs and screw backout risk increases
Solution Approach 1:
The patent replaces the conventional friction-based mechanical screw fixation system with a positive locking mechanism featuring a locking element with engagement features that physically interlock with the bone plate, eliminating reliance on friction and preventing screw backout without excessive tightening force
Solution Approach 2:
The bone plate is divided into functional segments including screw holes for bone attachment, a dedicated locking cavity for the locking element, and engagement features distributed across the structure, allowing each component to perform its specific function independently and efficiently
2Manufacturing precision
If internal stabilization with bone plates is implemented, then precision in aligning broken bones is improved, but surgical time and access requirements increase
Solution Approach 1:
The locking element is pre-formed with specific engagement features that match corresponding features on the bone plate, allowing for rapid assembly without complex alignment procedures or specialized tools during surgery
Solution Approach 2:
The locking mechanism is extracted as a separate, standalone component (locking element) that can be independently manufactured and then simply installed into the locking cavity, separating the alignment function from the locking function and simplifying the surgical procedure
3Reliability
If conventional anti-backout mechanisms are used, then screw backout is prevented, but parts are small and delicate leading to breakage or loss during installation
Solution Approach 1:
The locking element combines multiple functions into a single robust component: it provides positive locking through engagement features, prevents screw backout through the locking cavity configuration, and serves as the attachment interface for the bone screw, eliminating the need for separate delicate locking parts
Solution Approach 2:
The locking element features self-aligning engagement surfaces and a configuration that automatically ensures proper positioning within the locking cavity, eliminating the need for specialized alignment tools or complex installation procedures while maintaining reliable backout prevention
Data Source
AI summary
A bone plate assembly includes a bone plate and a rotatable lock. The bone plate includes a superior surface, an inferior surface, and at least one screw through-hole that is configured to receive a bone screw. The bone plate includes a locking cavity that defined in the superior surface. The locking cavity includes a bottom surface that is recessed relative to the superior surface, and also includes a post that extends upwards from the bottom surface. The rotatable lock is supported on the post such that the rotatable lock is at least partially within the locking cavity.