Expandable Vertebral Body Replacement Device with Longitudinal Housing
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Solution Overview
Problem
Current expandable Vertebral Body Replacement (VBR) devices in spinal surgery face limitations such as inadequate packing of graft material, unsatisfactory matching with adjacent bone surfaces, and complex or time-consuming expansion mechanisms following vertebral corpectomy.
Innovation Solution
An expandable VBR device comprising an inner and outer housing that moves longitudinally for height adjustment, along with a VBR expansion tool using an actuation member and leveling members to facilitate easy expansion, and a method for placing and fixing the device with bone growth promoting materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expandable VBR devices are used to fill the gap after corpectomy, then spinal stabilization is achieved, but the ability to adequately pack graft material in the channel is limited
Solution Approach 1:
The VBR device employs an expandable structure that transitions from a compressed insertion state to an expanded stabilization state. The inner and outer housings move relative to each other along the longitudinal axis, dynamically changing the internal channel volume to first accommodate graft material during insertion, then provide structural support when expanded, thereby resolving the contradiction between graft packing capability and stabilization reliability
Solution Approach 2:
The device is divided into distinct functional segments: an inner housing containing the graft material channel, an outer housing providing structural support, and bone contact members for anchoring. This segmentation allows the inner housing to be optimized for graft accommodation while the outer housing is optimized for stabilization, with both working together to resolve the technical contradiction
2Length of stationary object
If expandable VBR devices are used to restore spacing between adjacent bones, then proper spinal alignment is achieved, but the match between implant surfaces and adjacent bone surfaces is unsatisfactory
Solution Approach 1:
The bone contact members feature locally optimized surfaces with varying degrees of porosity and roughness. The outer housing provides a smooth expandable surface for uniform spacing restoration, while the bone contact members incorporate porous coatings and irregular surface geometries that promote bone ingrowth and improve local surface matching with the adjacent vertebral bodies, resolving the contradiction between spacing restoration and surface compatibility
3Reliability
If current expandable VBR devices are used for spinal stabilization, then the device can be expanded to provide support, but the expansion mechanisms are complex or take an inordinate amount of time to actuate
Solution Approach 1:
The expansion mechanism replaces complex multi-component mechanical systems with a simplified actuation system. A single actuator applies force through a lever arm to simultaneously expand both bone contact members, eliminating the need for separate expansion mechanisms for each side. This substitution reduces device complexity while maintaining reliable spinal support through controlled expansion
Solution Approach 2:
The expansion mechanism merges the expansion functions of both bone contact members into a single actuated system. The lever arm connects both expansion actuators, allowing simultaneous expansion of the inner and outer housings through one actuation motion, thereby reducing overall mechanism complexity and actuation time while ensuring coordinated expansion for proper spinal support
Data Source
AI summary
An expandable vertebral body replacement is presented. The device has an inner and outer housing longitudinally moveable on one-another which locks in place using a retention member. This can be locked or fortified by several described options. Also presented is a method for expanding said device embodiments and a system for an expandable vertebral body replacement.