Magnetically Actuated Expandable Spinal Rod for Scoliosis
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Solution Overview
Problem
Conventional scoliosis treatments, particularly in juvenile patients, often require invasive surgeries that fuse the spine, which can be detrimental before skeletal maturity, and do not effectively address the need for gradual correction and growth of the spine without repeated surgeries.
Innovation Solution
A non-fusion scoliosis construct featuring a magnetically actuated growing rod that can be extended and corrected without significant invasive surgery, using a gear reduction mechanism and magnetic activation from outside the body to adjust the rod's length, allowing for gradual spinal correction and growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional fusion surgery is performed to correct scoliosis, then spinal stability is improved, but the patient loses spinal growth potential and requires multiple surgeries
Solution Approach 1:
The spinal rod is designed as an expandable dynamic structure that can grow with the patient's spine. The rod includes an inner rod and outer rod that can slide relative to each other, allowing the construct to adapt to spinal growth while maintaining stability. This dynamic design eliminates the need for fusion surgery and multiple revision surgeries.
Solution Approach 2:
The expandable rod employs a nested structure where an inner rod is positioned within an outer rod. This nested doll configuration allows the inner rod to slide within the outer rod, enabling length adjustment to accommodate spinal growth while maintaining structural integrity and stability.
2Shape
If multiple surgeries are performed to correct progressive scoliosis, then curvature correction is improved, but surgical trauma and recovery time increase
Solution Approach 1:
The expandable rod is implanted during a single initial surgery and is designed to progressively correct spinal curvature over time as it expands. The preliminary implantation of the expandable construct eliminates the need for multiple corrective surgeries, reducing total recovery time while achieving the desired shape correction.
Solution Approach 2:
The rod expansion occurs in periodic stages through non-invasive magnetic actuation, allowing gradual curvature correction. This periodic expansion process corrects spinal shape progressively without requiring repeated surgical interventions, thereby reducing overall recovery time.
3Device complexity
If a fixed-length rod is used in scoliosis correction, then surgical procedure is simplified, but the construct cannot accommodate spinal growth
Solution Approach 1:
The rod transitions from a fixed-length design to a dynamic expandable structure. The inner and outer rods can slide relative to each other, allowing the construct to grow with the patient's spine while maintaining a relatively simple surgical implantation procedure.
Solution Approach 2:
The expandable rod system provides self-adjustment capability through non-invasive magnetic actuation. The rod automatically expands to accommodate spinal growth without requiring additional surgical intervention, making the construct adaptable while keeping the overall procedure simple.
4Manufacturing precision
If invasive surgery is performed frequently to adjust the spinal construct, then correction precision is improved, but patient trauma and surgical risks increase
Solution Approach 1:
The system replaces invasive mechanical surgical adjustment with non-invasive magnetic actuation. An external magnetic field is used to expand the rod and correct spinal curvature, eliminating the need for repeated open surgeries while maintaining correction precision.
Solution Approach 2:
A magnetic field is introduced as an intermediary to transfer energy and force to the rod without direct physical contact or surgical intervention. This intermediary mechanism allows precise rod expansion and curvature correction while avoiding surgical trauma and associated risks.
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
Enables the non-invasive, gradual correction and growth of the spine, reducing the need for multiple surgeries and minimizing invasive interventions, thereby addressing the challenges of spinal curvature in juvenile patients.
Implementation Method 1
The system is preferably magnetically activated from outside of the patient's body utilizing a magnetic field without further surgery for expansion
Data Source
AI summary
A growing rod for mounting between attachment mechanisms that are secured to anatomical structures of a patient having scoliosis. The growing rod includes an outer housing and an inner housing disposed within the outer housing. The inner housing includes a magnet assembly including a magnet having a first pole and a second pole and a gear reduction mechanism coupled to the magnet. A first rod is secured to the inner housing and a second rod is secured to the outer housing. The gear reduction mechanism reduces an output rotation of the magnet to rotate a driver that operates to move the inner housing along a longitudinal axis with respect to the outer housing.