Expandable Corpectomy Cage with Tuning-Fork Instrument
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Solution Overview
Problem
Current spinal corpectomy procedures using a posterior approach with small access portals face challenges in cage placement due to limited access, often requiring nerve root retraction and parallel expansion devices, which necessitate open surgery.
Innovation Solution
An expandable corpectomy cage and insertion instrument designed for minimally invasive procedures, featuring a tuning-fork shaped holder and lever with spherical end, allowing rotation and expansion without disconnection from delivery instruments, eliminating the need for nerve root retraction and parallel expansion devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a posterior approach with small access portal is used, then the incision size is reduced, but the access to the spine becomes limited and nerve root retraction is required
Solution Approach 1:
The delivery system is segmented into multiple functional components: an outer sheath for initial access, an inner expandable cage, and a rotation mechanism. This segmentation allows the system to navigate through a small incision while providing the capability to expand and rotate the cage once positioned within the spinal defect.
Solution Approach 2:
The cage is inserted in a collapsed state through the small portal, then expanded in the radial dimension to achieve full size within the vertebral body space. The rotation mechanism allows transition from axial insertion orientation to the final radial orientation, utilizing dimensional transformation to overcome access limitations.
2Length of moving object
If existing corpectomy cages are manipulated into position using sutures and small instruments, then the access window remains small, but the cage placement becomes more time-consuming and complex
Solution Approach 1:
The cage is pre-assembled with the delivery system in a collapsed, navigable configuration before insertion. The expansion and rotation mechanisms are pre-positioned and activated after insertion, eliminating the need for time-consuming manual manipulation with sutures and small instruments during the procedure.
Solution Approach 2:
The cage performs self-positioning through its built-in expansion and rotation mechanisms that are activated by the delivery system. Once inserted, the cage automatically transitions to its final position and orientation without requiring extensive manual manipulation by the surgeon.
3Volume of moving object
If parallel expansion devices are used, then the cage can be expanded, but open surgery is required which increases surgical invasiveness
Solution Approach 1:
The expandable cage is nested within the delivery system in a collapsed state, allowing it to pass through a small incision. Once positioned within the vertebral body, the cage is expanded radially to its full size, achieving the volume needed for structural support without requiring open surgery or parallel expansion devices.
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
Facilitates safer and faster cage placement through small incisions, maintaining sufficient graft volume and avoiding open surgery, while enabling precise alignment and expansion of the cage between vertebral bodies.
Implementation Method 1
The tapered surface may be movable relative to the locking element to transversely shift the locking element into engagement with the scalloped surface
Implementation Method 2
an inner member having an outer surface and an end plate... wherein the outer surface of the inner member is received within the inner wall of the outer member and is axially adjustable relative thereto
Data Source
AI summary
An assembly comprising an expandable corpectomy cage and an insertion instrument, wherein the expandable cage comprises an instrument attachment features, including mating holes on the sides of the outer sleeve, and a ball-shaped pocket on the endplate of the inner sleeve, and the insertion instrument features a tuning-fork shaped holder, which attaches to the mating holes on the implant's outer sleeve using small bosses which mate with the holes under the spring tension of the fork, and a lever with a spherical end that mates with the ball-shaped pocket in the inner sleeve endplate.