Multi-Axis Intervertebral Cage Expansion With Rotation-Locked Insertion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for instruments that can securely insert and expand multi-axis expandable intervertebral cages without rotation, accommodate bone graft delivery, and provide a stable implantation process, particularly in challenging spinal procedures like transforaminal lumbar interbody fusion.
Innovation Solution
The development of implant insertion instruments with a draw bar and actuator system that allows for translation along a central longitudinal axis without rotation, featuring a rotation lock mechanism to prevent axial rotation during expansion, and includes a graft funnel for convenient bone graft delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the implant insertion instrument is actuated to expand the implant, then the implant expands horizontally and/or vertically, but the draw bar may rotate about the instrument axis causing misalignment
Solution Approach 1:
The rotation lock mechanism applies a preliminary counteracting force to prevent the draw bar from rotating about the instrument axis during implant expansion. This preliminary anti-action ensures that the draw bar remains stable and aligned while the implant expands horizontally and/or vertically, resolving the contradiction between expansion precision and rotational stability
Solution Approach 2:
The rotation lock acts as an intermediary mechanism between the draw bar and the instrument axis. It mediates the interaction by selectively allowing or preventing rotation, thereby maintaining draw bar stability during expansion while still permitting the necessary implant size adjustments
2Stability of the object's composition
If the instrument handle assembly is fixed, then the instrument structure is stable, but the instrument weight increases causing force moment on the implant
Solution Approach 1:
The handle assembly transitions from a fixed state to a removable state, allowing the instrument to adapt its weight characteristics based on procedural needs. When attached, the handle provides structural stability; when removed, the instrument weight is reduced, minimizing force moments on the implant during critical expansion phases
3Ease of operation
If the draw bar is free to rotate for connection and disconnection, then the instrument is easier to operate, but the draw bar rotates during expansion causing misalignment
Solution Approach 1:
The rotation lock mechanism dynamically changes the draw bar's rotational characteristics based on the procedural phase. During connection and disconnection, the draw bar is free to rotate for ease of operation. During expansion, the rotation lock engages to prevent rotation, ensuring expansion alignment precision
Solution Approach 2:
The rotation lock applies preliminary anti-action by preventing draw bar rotation during the expansion phase. This counteracts the potential harmful rotation that would occur if the draw bar were completely free, thereby maintaining alignment precision while still allowing ease of operation during connection phases
Data Source
AI summary
An instrument may be coupled to a multi-axis expandable intervertebral cage so that the cage may be inserted into an intervertebral space, expanded along multiple different directions, filled with bone graft, and locked with a fastener. The instrument may be part of an instrument set that includes auxiliary instruments to determine implant size, insert bone graft into the cage, and deliver the fastener.