Polyaxial Bone Plate Locking Assembly for Spinal Stabilization
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Solution Overview
Problem
Conventional bone plate implants for spinal stabilization face challenges such as excessive stress from screw tightening, misalignment during healing, and the risk of screw backout due to the complexity of external immobilization and the delicacy of anti-backout mechanisms, which can be lost or difficult to secure during surgery.
Innovation Solution
The development of polyaxial bone plates with a locking assembly that includes a lock with distinct positions for secure and rapid installation, minimizing the risk of screw backout and requiring minimal moving parts, allowing for ease of use without specialized tools and reducing the risk of parts being lost or broken during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anti-backout mechanisms are used, then screw backout is prevented, but the mechanisms are small and delicate, can be broken during installation or lost by the surgeon within the surgical wound
Solution Approach 1:
The locking mechanism is integrated directly into the bone plate structure, merging the plate and lock into a single unit. This eliminates separate anti-backout components that could be lost or broken, while maintaining reliable screw fixation. The lock is formed as part of the bone plate body, creating a unified structure that prevents screw backout without adding delicate separate parts.
Solution Approach 2:
The invention removes traditional separate anti-backout mechanisms (such as nuts, washers, or locking screws) from the system. By extracting these independent components and integrating the locking function directly into the bone plate, the design eliminates the risk of losing or breaking separate small parts while maintaining the essential backout prevention function.
2Reliability
If bone screws are tightened to achieve friction-based holding, then the screws are secured to the bone plate, but the force generated may cause excessive damage to the bone
Solution Approach 1:
The invention replaces the friction-based mechanical holding system with a positive locking mechanism. Instead of relying on friction between screw threads and bone/plate, the lock provides geometric interlocking that secures the screw without requiring excessive tightening force, thereby reducing bone damage while maintaining reliable fixation.
Solution Approach 2:
The locking mechanism is designed to prevent screw backout and loosening before it can occur during the healing process. By providing preliminary mechanical constraint through the lock, the system eliminates the need for high tightening forces that would otherwise be required to prevent screw migration, thus protecting the bone from excessive stress.
3Manufacturing precision
If bone plates are attached with multiple screws in several directions for optimal alignment, then precise alignment is achieved, but the surgery requires more time and access to the bone
Solution Approach 1:
The polyaxial locking mechanism allows the screw and lock assembly to be inserted at various angles and then locked into position. This dynamic capability enables precise alignment to be achieved through a single approach direction, reducing surgical time and access requirements while maintaining the ability to achieve optimal bone alignment through the polyaxial design.
Data Source
AI summary
A cervical plate and one or more locking assemblies that help prevent screw backout without impinging on therapeutically valuable settling of the screws. In some cases, the locking assembly is configured to be permanently attached to the plate, to be securely but efficiently locked, to be readily unlocked for revision surgery, and/or to reduce the possibility of operator error in installation by providing simplified visible and tactile indicia of the locked and unlocked positions.