Extendible Spinal Rod Gear Mechanism
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Solution Overview
Problem
Current growing rods for treating spinal deformities, such as scoliosis in children, require frequent surgical interventions to extend as the patient grows, which is cumbersome and complex, necessitating a more efficient and less invasive solution.
Innovation Solution
A growing rod system with a base rod and an extendible rod connected via a distraction unit, featuring a rotatable drive interface and gear mechanism that allows manual extension and retraction without a power source, enabling periodic adjustments to accommodate spinal growth without frequent surgeries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional growing rods are used to treat spinal deformities, then the rods can be secured to the spine and allow for continued growth, but the rods require frequent surgical interventions to extend as the patient grows
Solution Approach 1:
The rod is divided into a base rod and an extendible rod that can be independently positioned. The extendible rod includes a distal portion that is slidably coupled to the base rod, allowing the rod to be extended in segments rather than requiring complete replacement or complex adjustment mechanisms
Solution Approach 2:
A distraction unit with a gear rack and drive gear mechanism is introduced as an intermediary component between the base rod and extendible rod. This mechanism translates rotational movement into linear extension, providing a controlled and simplified method for rod length adjustment without requiring frequent surgical interventions
2Adaptability or versatility
If traditional growing rods are used, then spinal growth can be accommodated, but frequent surgeries are required to extend the rods
Solution Approach 1:
The extendible rod is pre-configured with a gear rack and slidable coupling mechanism that enables future extension without requiring surgical intervention. The distraction unit is implanted along with the rod, preparing the system for non-invasive or minimally invasive extension procedures as the patient grows
Solution Approach 2:
The rod system transitions from a static structure to a dynamic one with the extendible rod that can be adjusted as the patient grows. The slidable coupling and gear mechanism allow the rod to adapt its length over time, reducing the frequency of surgical interventions
3Adaptability or versatility
If complex growing rod systems are used, then extension capability is provided, but the system has more elements and greater complexity
Solution Approach 1:
The distraction unit with the gear rack is integrated directly into the extendible rod structure, merging the extension mechanism with the rod itself rather than using separate complex adjustment systems. This reduces the overall number of elements while maintaining extension capability
Solution Approach 2:
The complex mechanical adjustment systems traditionally used in growing rods are replaced with a simplified gear rack and drive gear mechanism. This substitution provides extension capability with fewer elements and reduced complexity while maintaining adaptability to spinal growth
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 allows for less complex and fewer elements to extend and retract the growing rod, reducing the need for frequent surgeries and minimizing complications, providing a more efficient and patient-friendly solution for managing spinal growth.
Implementation Method 1
a drive gear mechanism housed within the housing and coupled to the rotatable drive interface and the gear rack such that rotation of the rotatable drive interface causes linear movement of the extendible rod through the gear rack
Data Source
AI summary
An implantable growing rod assembly adapted to be secured along a length of a spine for treating deformities of the spine. The assembly includes a housing, a fixed rod extending along a longitudinal axis away from the housing, and an expansion rod extendible from the housing along the longitudinal axis. A driver assembly is fixed to the housing and adapted to translate the expansion rod along the longitudinal axis.