Spinal Implant Rack and Pinion Expansion Mechanism
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Solution Overview
Problem
Current surgical treatments for spinal disorders, such as degenerative disc disease and osteoporosis, often require high force to expand implants, which can be challenging and may not adequately address the mechanical support needs of vertebrae, especially in minimally invasive procedures.
Innovation Solution
An expandable interbody spinal implant system utilizing a rack and pinion mechanism or a threaded bar to rotate a cam and expand the device, allowing for reduced zero-height force expansion and adjustable height based on spur gear size, enabling effective mechanical support and accommodation of various spinal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high force is applied to expand implants in current surgical treatments, then the implant can be expanded to provide mechanical support, but the procedure becomes more challenging and requires more complex surgical intervention
Solution Approach 1:
The implant transitions from a compressed low-profile state for minimally invasive insertion to an expanded state for mechanical support. The expandable cage changes its volume and structural characteristics dynamically during implantation, allowing easy insertion followed by post-insertion expansion to provide the necessary mechanical strength without requiring high expansion forces during the surgical procedure
Solution Approach 2:
The implant is designed with a nested structure where the expandable cage components are contained within each other in a compressed state for minimally invasive insertion. After insertion, the nested components are deployed outward to expand the cage to its functional size, providing mechanical support while avoiding the need for high expansion forces during the critical insertion phase
2Force
If a rack and pinion mechanism is used to expand the implant, then the initial force required for expansion is reduced, but the device complexity increases
Solution Approach 1:
The traditional direct mechanical expansion system is replaced with a rack and pinion mechanism that converts rotational motion into linear expansion motion. This substitution reduces the initial expansion force required by using the mechanical advantage of the gear system, where a smaller rotational force on the pinion generates the necessary linear force to expand the rack and thereby expand the implant structure
Solution Approach 2:
The rack and pinion mechanism acts as an intermediary between the actuator and the implant expansion. The pinion gear converts the rotational input from the actuator into linear motion of the rack, which then drives the expansion of the implant. This intermediary mechanism allows for controlled expansion with reduced initial force requirements compared to direct actuation
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 system provides efficient and minimally invasive expansion of spinal implants with reduced initial force requirements, accommodating different spinal conditions and allowing for greater starting forces and expansion heights, enhancing mechanical support and stability in spinal treatments.
Implementation Method 1
A rack is coupled to the first member. A gear is coupled to the second end of the second member such that the gear engages the rack.
Implementation Method 2
utilizing a rack and pinion mechanism or a threaded bar to rotate a cam and expand the device
Implementation Method 3
utilizing a rack and pinion mechanism or a threaded bar to rotate a cam and expand the device
Data Source
AI summary
A spinal implant includes a first member extending along a first axis between opposite first and second ends. The first end includes a first part. A rack is coupled to the first member. A second member extends along a second axis between opposite first and second ends. A gear is coupled to the second member such that the gear engages the rack. An actuator includes a second part that engages the first part such that rotation of the actuator relative to the members translates the rack relative to the first member along the first axis to move the implant between a first orientation in which the second longitudinal axis extends parallel to the first longitudinal axis and a second orientation in which the second longitudinal axis extends at an acute angle relative to the first longitudinal axis. Systems and methods are disclosed.