Extendable Spinal Rod Assembly for Surgery-Free Length Adjustment
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Solution Overview
Problem
Surgical procedures for extending spinal rods to correct spinal irregularities, such as scoliosis, are invasive, time-consuming, and costly, posing risks to patients, especially children with early onset scoliosis who require repeated interventions to accommodate growth.
Innovation Solution
An extendable rod assembly comprising an elongate sleeve, actuating and fixed rods, and a valve assembly that allows for minimally-invasive or non-invasive length adjustment through fluid control, enabling automatic extension in response to spinal growth without surgical intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surgical procedures are used to extend spinal rods, then the spinal alignment can be corrected and maintained, but the procedure becomes invasive, time-consuming, and costly with repeated interventions required
Solution Approach 1:
The spinal rod is designed with dynamic extension capability through a telescoping mechanism consisting of an inner rod and an outer tube. The inner rod can slide relative to the outer tube, allowing the rod to extend automatically in response to spinal growth without requiring surgical intervention. This dynamic structure transforms a static implant into an adaptive device that grows with the patient.
Solution Approach 2:
The extendable rod assembly incorporates a self-extending mechanism that responds to physiological conditions. A pressure-sensitive element detects increased spacing between vertebrae caused by spinal growth and automatically triggers extension of the inner rod relative to the outer tube, eliminating the need for repeated surgical procedures and allowing the device to serve itself.
2Ease of manufacture
If traditional fixed-length rods are used, then surgical procedure is straightforward, but repeated surgeries are required to accommodate spinal growth in children
Solution Approach 1:
The spinal rod is designed with dynamic extension capability through a telescoping mechanism consisting of an inner rod and an outer tube. The inner rod can slide relative to the outer tube, allowing the rod to extend automatically in response to spinal growth without requiring surgical intervention. This dynamic structure transforms a static implant into an adaptive device that grows with the patient.
Solution Approach 2:
The rod is pre-configured with the capacity for future extension during the initial surgical procedure. The telescoping mechanism is assembled and implanted in a single operation, with the inner rod positioned within the outer tube and locking mechanisms pre-installed. This preliminary preparation eliminates the need for subsequent surgical interventions to accommodate growth.
3Reliability
If repeated surgical interventions are performed to extend spinal rods, then spinal alignment can be maintained, but patient risk and treatment cost increase
Solution Approach 1:
The extendable rod assembly incorporates a self-extending mechanism that responds to physiological conditions. A pressure-sensitive element detects increased spacing between vertebrae caused by spinal growth and automatically triggers extension of the inner rod relative to the outer tube, eliminating the need for repeated surgical procedures and allowing the device to serve itself.
Solution Approach 2:
The device incorporates a feedback mechanism through the pressure-sensitive element that continuously monitors the spacing between vertebrae. When growth creates increased spacing, the pressure change is detected and triggers automatic extension of the rod through the interaction between the pressure-sensitive element and the extension mechanism, maintaining alignment without external intervention.
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 extendable rod assembly minimizes the need for repeated surgeries by allowing automatic lengthening in vivo, reducing complications and costs, and facilitating growth accommodation in children with spinal irregularities.
Implementation Method 1
introducing the fluid into the cannula; wherein the fluid causes the actuating rod to translate at least partially out of the cannula
Data Source
AI summary
Embodiments herein are generally directed to extendable rods for use in orthopedic assemblies. In some embodiments, these implants may be used in conjunction with procedures to treat spinal deformities, including, but not limited to, early onset scoliosis.