Expandable Spinal Implant Rack and Pinion Mechanism
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Solution Overview
Problem
Current spinal implant technologies are limited in their ability to provide continuous and incremental expansion to accommodate varying spinal conditions, often failing to adequately restore mechanical support and stability in procedures such as corpectomy and discectomy.
Innovation Solution
A continuously expandable spinal implant system featuring a rack and pinion driven threaded mechanism, with a monolithic rack and a locking spring mechanism, allowing for incremental expansion of up to 1.0 mm, and a sliding lock mechanism to prevent collapse, enabling adjustable expansion and secure fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional spinal implants are used, then the implant structure is simple, but the ability to provide continuous and incremental expansion is limited
Solution Approach 1:
The spinal implant utilizes a nested structure where an inner body is positioned within an outer body, both defining concentric cylindrical surfaces. This nesting arrangement allows the inner body to expand axially relative to the outer body while maintaining a compact overall structure, enabling continuous expansion capability without proportionally increasing the device's external dimensions.
Solution Approach 2:
The implant incorporates a dynamic expansion mechanism where the inner body can axially translate relative to the outer body through a gear rack and pinion system. This dynamic structure allows the implant to adjust its axial length continuously from an inserted configuration to an expanded configuration, providing adaptability to varying spinal conditions while maintaining structural integrity.
2Adaptability or versatility
If expandable mechanisms are added to spinal implants, then continuous expansion capability is improved, but the device complexity increases
Solution Approach 1:
The implant replaces complex multi-component mechanical expansion systems with a streamlined gear rack and pinion mechanism. The gear rack is integrally formed with the inner body, and the pinion gear is rotatably mounted on the outer body, creating a compact mechanical system that achieves continuous expansion through rotational motion converted to axial translation, reducing overall mechanism complexity.
Solution Approach 2:
The gear rack is integrally formed as a single piece with the inner body, merging the expansion mechanism directly into the structural component. This integration eliminates separate attachment mechanisms and reduces the number of parts, achieving adjustable expansion capability while minimizing the increase in device complexity.
3Manufacturing precision
If incremental expansion up to 1.0 mm is enabled, then precision of vertebral spacing restoration is improved, but the manufacturing complexity increases
Solution Approach 1:
The pinion gear engages with the gear rack teeth to provide periodic, incremental axial translation of the inner body relative to the outer body. Each rotation of the pinion gear advances the inner body by a precise amount determined by the gear tooth pitch, enabling controlled incremental expansion in 1.0 mm increments while maintaining a relatively simple locking mechanism structure.
Solution Approach 2:
The gear rack and pinion mechanism provides self-locking capability through the engagement of gear teeth, where the mechanical engagement itself prevents reverse motion and maintains the expanded position. This self-service locking function eliminates the need for additional complex locking components while achieving precise incremental positioning.
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 stable and adjustable expansion to restore vertebral spacing and mechanical support, accommodating the growth of vertebrae and adapting to different spinal conditions, enhancing the effectiveness of spinal fusion and fixation treatments.
Implementation Method 1
A continuously expandable spinal implant system featuring a rack and pinion driven threaded mechanism
Implementation Method 2
a locking spring mechanism, allowing for incremental expansion of up to 1.0 mm, and a sliding lock mechanism to prevent collapse
Data Source
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AI summary
A spinal implant comprises a first member defining a longitudinal axis and including a wall that defines an axial cavity and at least one lateral opening configured for disposal of an instrument. A second member is configured for disposal with the axial cavity and includes a wall having an axial surface disposed along a thickness thereof. The axial surface defines at least a portion of an axial opening and includes a plurality of gear teeth disposed therealong. The instrument is engageable with the teeth to axially translate the second member relative to the first member. Systems and methods of use are disclosed.