Miniaturized Bone Elongation Device Using Nested Actuator
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Solution Overview
Problem
Existing bone elongation devices are too large for pediatric use and lack miniaturization, making them unsuitable for treating pediatric cases effectively.
Innovation Solution
A compact bone elongation device with an outer and inner rod configured in threaded telescopic engagement, featuring a rotational actuator and lead screw assembly positioned in parallel to minimize overall length while maintaining maximum stroke length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If traditional distraction devices are used, then bone elongation function is achieved, but device size is too large for pediatric use
Solution Approach 1:
The patent applies nesting by placing the lead screw inside the actuator housing, and the actuator inside the outer rod, creating a compact nested structure. The inner rod telescopes within the outer rod, with the lead screw nested within the actuator assembly, achieving maximum miniaturization for pediatric application.
Solution Approach 2:
The patent transitions from a series configuration (actuator connected end-to-end with lead screw) to a parallel configuration where the lead screw is positioned coaxially within the actuator housing. This dimensional reorganization dramatically reduces the overall device length while maintaining the required stroke length.
2Length of moving object
If series configuration of actuator and lead screw is used, then mechanical function is achieved, but overall device length is excessive
Solution Approach 1:
The patent repositions the lead screw from a series arrangement to a parallel/coaxial arrangement within the actuator housing. The lead screw rotates within the actuator's internal cavity, converting rotational motion to linear motion of the inner rod relative to the outer rod, thereby minimizing overall length.
Solution Approach 2:
The patent merges the actuator housing and lead screw support structure into a single integrated assembly. The lead screw is housed within the actuator housing, and both components work together as a unified mechanism for converting rotational to linear motion, reducing the number of separate mechanical elements.
3Volume of moving object
If compact design is implemented, then device length is reduced, but internal volume for housing systems decreases
Solution Approach 1:
The patent creates nested cavities within the inner rod and actuator housing to accommodate electronics, power supplies, and control systems. The inner rod contains an internal cavity, and the actuator housing contains additional internal volume, providing sufficient space for electro-mechanical systems despite the compact overall dimensions.
Solution Approach 2:
The patent divides the device into modular segments (outer rod, inner rod, actuator housing, lead screw) with distinct functional zones. Each segment contains specific components, and the segmented structure allows for optimized space utilization while maintaining compact overall dimensions.
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 achieves a significant reduction in overall length, allowing for effective treatment of pediatric cases with longer stroke lengths and increased internal volume for housing electro-mechanical systems.
Implementation Method 1
a lead screw disposed at the end of the inner rod and in threaded engagement with the threaded inner surface of the outer rod. Rotation of the lead screw converts rotation motion into linear motion resulting in telescopic movement of the outer rod relative to the inner rod.
Data Source
AI summary
An implant includes: an inner rod having an outer surface; an outer rod in telescopic engagement with the inner rod, the outer rod having a threaded inner surface in axial slidable engagement with the outer surface of the inner rod; the inner rod and the outer rod each having an end configured for attachment to bone; a rotational actuator housed within the inner rod; and a lead screw in axial alignment with the rotational actuator and rotationally coupled thereto, the lead screw in threaded engagement with the threaded inner surface of the outer rod, whereby rotational motion of the actuator is converted into linear motion, resulting in telescopic changes in the overall axial length of the device.