Growing Rod with Gear Rack Distraction Unit for Spinal Deformities
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Solution Overview
Problem
Current growing rods for treating spinal deformities, such as scoliosis, require frequent surgical interventions to extend and keep pace with a patient's growth, which is complex and invasive.
Innovation Solution
A manually extendible growing rod system with a distraction unit that includes a base rod, an extendible rod with a gear rack, and a distraction unit featuring a rotatable drive interface and latching mechanism, allowing for linear movement and extension without the need for a power source, and alternative embodiments using fluid pressure or a toggling switch for extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional growing rods are used to treat spinal deformities, then the spine can be supported and secured, but frequent surgical interventions are required to extend the rods to keep pace with patient growth
Solution Approach 1:
The growing rod system transitions from static fixed-length rods to dynamic adjustable-length rods. The distraction unit with gear rack and rotatable drive interface enables the rod length to be dynamically adjusted non-invasively after implantation, allowing the rod to adapt to patient growth without requiring repeated surgical interventions for rod replacement or extension.
Solution Approach 2:
The system enables self-adjustment capability through the distraction unit that can be operated externally without requiring full surgical intervention. The gear mechanism allows the rod to be extended by rotating the drive interface, which can be accessed through a small incision, thereby serving the patient's growth needs with minimal external intervention.
2Length of moving object
If growing rods are extended through frequent surgical interventions, then the rod length can be maintained, but the complexity and invasiveness of procedures increases
Solution Approach 1:
The growing rod system is segmented into a fixed base rod and an extendible rod portion that can be independently adjusted. The distraction unit is integrated at a specific location along the rod, separating the adjustment mechanism from the structural support function, allowing for simplified extension procedures without complicating the overall surgical implantation.
Solution Approach 2:
The system replaces complex surgical intervention mechanisms with a simpler mechanical gear-based distraction unit. Instead of requiring surgical exposure and manual rod manipulation, the gear rack and pinion system converts rotational motion at the drive interface into linear extension of the rod, simplifying the extension procedure to a rotational operation accessible through minimal incision.
3Loss of time
If manual extension mechanism is added to the growing rod, then surgical intervention frequency is reduced, but the device complexity increases
Solution Approach 1:
The distraction unit with its gear mechanism is nested within or integrated into the existing rod structure. The extendible rod portion is housed within or alongside the base rod, with the gear rack engaged to the housing. This nested arrangement allows the extension mechanism to be compact and integrated without requiring separate external components, thereby limiting the increase in overall device complexity.
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 reduces the complexity and frequency of surgical interventions by enabling manual extension of the growing rod, allowing for longer growth periods before replacement and minimizing the number of surgical visits, thus improving patient care and reducing surgical burdens.
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
A growing rod adapted to be secured along a length of a spine for treating deformities of the spine. The growing rod comprises a base rod, an extendible rod having a proximal portion that is slidably coupled to the base rod and arranged with a gear rack, and a distraction unit. The distraction unit includes a housing attached to the base rod, a rotatable drive interface accessible by an external driver from outside of the housing, and 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.