Expandable Intervertebral Implant Wedge Mechanism
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Solution Overview
Problem
Current spinal implant devices face challenges in efficiently expanding within the intervertebral space to restore disc height and stability, often requiring large apertures for insertion and additional hardware for fixation, which can complicate the surgical procedure and limit the precision of disc height restoration.
Innovation Solution
An expandable intervertebral implant with a nose member, wedge member, and actuator system that translates along a longitudinal axis, utilizing dovetail grooves for expansion, allowing for minimal insertion height and controlled expansion to restore disc height, while also incorporating a graft window for bone graft material and counter torque slots for stability during expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the implant uses a traditional expansion mechanism with fixed endplates, then expansion is achieved, but the device complexity increases and requires additional hardware
Solution Approach 1:
The patent merges the endplate and expansion mechanism into a single integrated structure. The endplates are no longer separate fixed components but are formed as part of the expandable body itself, eliminating the need for separate endplate retainers and reducing the number of parts while maintaining expansion functionality
Solution Approach 2:
The expandable body serves multiple functions: it provides the structural framework, enables expansion through its geometric design, and eliminates the need for separate fixation hardware. The geometric expansion mechanism integrates support, expansion, and fixation functions into a single component system
2Ease of operation
If the implant requires large apertures for insertion, then the cage can be inserted into the intervertebral space, but the insertion complexity increases and surgical precision is limited
Solution Approach 1:
The implant utilizes a nested configuration where the expandable body is designed to be inserted in a compressed state through a smaller aperture, then expanded within the intervertebral space to achieve the final therapeutic configuration, allowing insertion through minimally invasive approaches while maintaining precise final positioning
Solution Approach 2:
The implant transitions from a static inserted configuration to a dynamic expanded configuration after insertion. The expandable body allows for controlled expansion post-insertion, enabling precise disc height restoration without requiring large apertures for insertion, as the expansion occurs in-situ within the intervertebral space
3Device complexity
If the implant uses geometric expansion without endplate fixation, then the device complexity is reduced, but the stability during expansion may be compromised
Solution Approach 1:
The expandable body employs asymmetric geometric features including ramps and cam surfaces that provide inherent mechanical stability during expansion. The asymmetric geometry creates mechanical interlocking and directional force transmission that stabilizes the structure during the expansion process without requiring additional fixation hardware
Solution Approach 2:
The patent utilizes curved and rounded geometric features in the expandable body design, including cam surfaces and rounded expansion interfaces, that provide smooth mechanical interaction and inherent stability during expansion. The curved geometries distribute forces more evenly and prevent binding, maintaining stability throughout the expansion process
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
The implant effectively expands to restore disc height, facilitates bone graft insertion for fusion, and provides stability against torque during expansion, enhancing the precision and efficacy of spinal fusion procedures.
Implementation Method 1
Translation of the wedge member along the longitudinal axis of the implant displaces the upper body portion and the lower body portion away from each other
Implementation Method 2
utilizing dovetail grooves for expansion
Data Source
AI summary
An expandable intervertebral implant having an upper body portion, a lower body portion opposite the upper body portion. a wedge member connecting the upper body portion to the lower body portion, a nose member having a tapered distal end and a proximal end opposite the distal end, and an actuator disposed between the nose member and the wedge member, for translation of the wedge member along a longitudinal axis of the implant. A pin disposed in a center of the nose member connects to the actuator for centering the nose member with the actuator. Translation of the wedge member along the longitudinal axis of the implant displaces the upper body portion and the lower body portion away from each other, thereby expanding the intervertebral implant.