Expandable Intervertebral Implant Height Adjustment
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Solution Overview
Problem
Existing spinal implants lack the ability to adjust height post-implantation, which can lead to inadequate support and stability for adjacent vertebrae, particularly in cases of degenerative diseases or fractures, where additional support is required to maintain optimal spinal alignment and height.
Innovation Solution
An adjustable intervertebral implant with endplates having ramped surfaces and a sliding frame mechanism, allowing for expansion and retraction via an actuator screw, enabling the implant to be inserted in a collapsed state and expanded to restore disc space height, while also allowing for repositioning as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-height intervertebral implant is used, then the implant structure is simple and easy to manufacture, but the implant cannot be adjusted post-implantation to restore optimal disc space height
Solution Approach 1:
The implant transitions from a static fixed-height structure to a dynamic adjustable structure through the actuator screw mechanism that enables post-implantation height adjustment while maintaining overall structural simplicity
Solution Approach 2:
The actuator screw and carriage mechanism are nested within the implant body, allowing the adjustment mechanism to be contained within the overall implant structure without significantly increasing external complexity
2Reliability
If a fixed-height implant is inserted, then the insertion procedure is quick and simple, but the implant may cause inadequate support or tissue impaction if the height does not match the optimal disc space
Solution Approach 1:
The implant is pre-configured with an actuator mechanism that enables subsequent height adjustment, allowing the surgeon to insert a compact implant and then expand it to the optimal height, ensuring reliable support without requiring complex pre-planning
Solution Approach 2:
The implant height parameter can be changed post-implantation through the actuator screw mechanism, allowing optimization of vertebral support and prevention of tissue impaction by adjusting to the precise disc space height required
3Adaptability or versatility
If an adjustable mechanism is added to the implant, then the implant can be expanded to restore disc space height, but the implant structure becomes more complex with additional components
Solution Approach 1:
The actuator screw serves multiple functions: it acts as both a fastening element and an expansion mechanism, while the ramped surfaces provide both structural support and the mechanical advantage needed for expansion, reducing the need for separate dedicated components
Solution Approach 2:
The ramped surfaces between the endplate and carriage create a self-contained expansion mechanism where the existing structural elements work together to provide both support and adjustability without requiring additional complex mechanisms
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 provides continuous expansion and retraction capabilities, allowing for customized fit and optimal height restoration, reducing tissue impaction during insertion and maintaining spinal stability through adjustable height adjustment, thus addressing the limitations of fixed-height implants.
Implementation Method 1
an actuator screw rotatably connected to the frame; and a carriage (a) forming an open area aligned with the openings in the first and second endplates... (b) threadably connected to the actuator screw, whereby rotation of the actuator screw moves the carriage with respect to the frame and the first and second endplates
Implementation Method 2
including a plurality of ramps each mateable with at least one of the at least one ramped surfaces of the first and second endplates, wherein when the carriage is moved by rotation of the actuator screw, at least one of the at least one ramped surface of the first endplate and at least one of the at least one ramped surface of the second endplate each slide along at least one of the plurality of ramps of the carriage to cause the endplates to move relative to each other
Data Source
Figure 1~3
Figure 4~6B
Figure 7A~8
AI summary
An implant for therapeutically separating bones of a joint has two endplates each having an opening through the endplate, and at least one ramped surface on a side opposite a bone engaging side. A frame is slideably connected to the endplates to enable the endplates to move relative to each other at an angle with respect to the longitudinal axis of the implant, in sliding connection with the frame. An actuator screw is rotatably connected to the frame. A carriage forms an open area aligned with the openings in the endplates. The openings in the endplates pass through the carriage to form an unimpeded passage from bone to bone of the joint. The carriage has ramps which mate with the ramped surfaces of the endplates, wherein when the carriage is moved by rotation of the actuator screw, the endplates move closer or farther apart.