Expandable Vertebral Prosthesis with Exposed Gear Mechanism
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Solution Overview
Problem
Current vertebral body replacement prosthetics face challenges in achieving a precise fit and optimal expansion within the spinal cavity, particularly during insertion and load-bearing capabilities, due to limited design considerations for small clearances and varied surgical approaches.
Innovation Solution
An expandable prosthetic device comprising an inner and outer member with a gear mechanism, allowing for axial movement and in situ adjustment, featuring a PEEK plastic material construction, exposed gear teeth for tool accessibility, and adjustable end plates for optimal vertebral engagement, facilitating bone growth and fusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an expandable prosthetic device is used for vertebral body replacement, then the device can be adjusted to fit the cavity size and provide immediate load bearing, but the device complexity increases due to the need for expansion mechanisms and instrumentation tools
Solution Approach 1:
The prosthetic device employs a nested structure where the inner member is inserted into the outer member, and the gear member is positioned within the hollow interior portion of the outer member. This nesting arrangement allows multiple functional components to be integrated in a compact configuration, reducing overall device complexity while maintaining expandability and adaptability to different cavity sizes.
2Manufacturing precision
If the prosthetic device is designed for precise insertion with small clearances, then the fit is optimized, but the ease of operation decreases due to limited space for instrumentation and alignment
Solution Approach 1:
The gear teeth are exposed to the exterior of the prosthetic device and configured to be accessible by a tool member at a plurality of angular positions around the perimeter. This preliminary exposure of the gear mechanism allows surgeons to engage and adjust the device using standard instrumentation tools before final insertion and expansion, facilitating easier operation within the constrained surgical space while maintaining precise fit.
3Device complexity
If the gear member is made freely rotatable with respect to the outer member, then the expansion mechanism is simplified, but the reliability decreases due to potential misalignment or loosening
Solution Approach 1:
The gear member is designed to be freely rotatable with respect to the outer member during the expansion process, allowing dynamic adjustment and engagement. This rotational freedom enables the expansion mechanism to self-align and accommodate variations in insertion angles and cavity geometries, maintaining reliability while simplifying the overall expansion mechanism through natural self-adjustment rather than complex constraint systems.
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 device provides a secure, adjustable, and expandable solution for vertebral body replacement, enabling precise fit, immediate load-bearing capacity, and accommodating various surgical approaches, while promoting bone growth and fusion through its design and material properties.
Implementation Method 1
The gear member is axially fixed to the outer member and freely rotatable with respect to the outer member and the gear member threadedly engages the threaded portion of the inner member
Data Source
AI summary
The present invention relates to an expandable prosthetic implant device for engagement between vertebrae generally comprising an inner member, outer member, and gear member positioned coaxial with respect to each other such that the inner and outer members are moveable relative to each other along an axis. The gear member is axially fixed to the outer member and freely rotatable with respect to the outer member and the gear member threadedly engages a threaded portion of the inner member to translate inner member along the axis. The implant is configured to engage the vertebrae in a predetermined alignment and the gear member includes gear teeth exposed to the exterior and configured to be accessible by a tool member at a plurality of angular positions around the perimeter of the implant device.