Rotating Screw Lock for Interbody Spacer Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current intervertebral spacers face issues with bone screw stability, as they may vibrate, toggle, loosen, or become dislodged due to anatomical forces and degeneration of vertebral bone quality, leading to instability and increased pain.
Innovation Solution
An interbody spacer with a screw lock mechanism that rotates between unlocked and locked positions, preventing bone screws from backing out by covering their heads, ensuring secure anchoring between vertebrae.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bone screws are used to secure the interbody spacer to the spine, then the implant can be anchored to adjacent vertebrae, but the screws may vibrate, toggle, loosen, or become dislodged due to anatomical forces and bone degeneration
Solution Approach 1:
The lock assembly is designed to rotate from an unlocked position during implantation to a locked position that prevents screw backout. This dynamic transformation allows the system to adapt from a state requiring screw insertion to a state providing screw retention, resolving the contradiction between initial ease of installation and long-term stability.
Solution Approach 2:
The lock assembly is positioned and configured to prevent the harmful action of screw backout and loosening before it can occur. By pre-positioning the locking mechanism to engage with the screw heads, the system proactively counteracts the anatomical forces and bone degeneration that would otherwise cause screw failure.
2Reliability
If the screw lock mechanism is added to prevent bone screw backout, then screw stability is improved, but the device complexity increases
Solution Approach 1:
The lock assembly is integrated directly into the cage structure, merging the locking function with the existing implant body. This integration eliminates the need for separate locking components and reduces the overall number of parts, thereby minimizing the increase in device complexity while still providing reliable screw retention.
Solution Approach 2:
The lock assembly serves multiple functions: it prevents screw backout, maintains cage position, and provides structural support. By designing a single component that performs multiple functions, the patent avoids adding unnecessary complexity while achieving reliable screw retention through the rotational locking mechanism.
Data Source
AI summary
An interbody spacer for the spine is provided. The interbody spacer includes a cage and at least one bone screw configured to anchor the cage between two vertebrae of the spine. The cage includes a lock rotationally movable with respect to the cage between a locked configuration and an unlocked configuration. When in an unlocked configuration, bone screws may be inserted and removed from the cage. When in a locked configuration, the insertion and removal pathway of the bone screw is blocked by the lock, thereby, providing backout protection for the bone screws. The lock is coupled to the cage by a retaining ring. The lock assembly also includes a timing lock to provide for incremental rotation of the lock. The lock includes a space-saving shape providing for maximum bone screw angulation on a laterally smaller anterior platform.