Integral Dual Rod Spinal Construct for Osteotomy Stability
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Solution Overview
Problem
Current spinal rods used in surgical procedures for immobilizing and stabilizing vertebral bodies often fail due to compromised strength during bending or excessive stress, particularly in procedures like pedicle subtraction osteotomy, leading to potential negative outcomes such as rod fracture.
Innovation Solution
A dual rod spinal fixation construct is introduced, comprising two parallel rods connected by integrally formed cephalad and caudal arms, constructed from rigid, non-absorbable biocompatible materials, which provides increased stiffness and fatigue strength while minimizing hardware and ease of implantation, reducing the risk of rod failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single spinal rod is used for fixation, then the device complexity is low, but the rod strength and stiffness are insufficient leading to rod failure
Solution Approach 1:
The patent combines two separate spinal rods into a single integrated dual-rod construct where the rods are connected by lateral arms at both cephalad and caudal ends. This merging approach provides the strength of two rods while presenting them as one unified implantable unit, resolving the contradiction between needing enhanced rod strength and maintaining device simplicity.
Solution Approach 2:
The dual rod construct is segmented into distinct functional components: a first rod, a second rod, cephalad lateral arms, and caudal lateral arms. This segmentation allows each component to be optimized independently while working together to provide enhanced overall strength and stiffness compared to a single rod.
2Strength
If multiple side-by-side rods connected by connectors are used to enhance strength, then the rod strength increases, but the hardware quantity and implantation complexity increase
Solution Approach 1:
Instead of using separate rods with independent connectors, the patent merges the rods and connectors into a single integrated construct. The lateral arms are formed as one piece with the rods, eliminating the need for separate connector hardware and reducing the total quantity of components while maintaining the strength enhancement.
Solution Approach 2:
The integrated lateral arms serve multiple functions simultaneously: they connect the two rods, provide structural rigidity, and act as the fixation interface with the vertebrae. This multi-functionality reduces the need for additional specialized hardware components.
3Stability of the object's composition
If pedicle subtraction osteotomy is performed to increase stability, then the surgical stability improves, but the stress on the rod increases leading to potential rod fracture
Solution Approach 1:
The dual rod construct merges two load-bearing rods into one integrated structure, distributing the stress from pedicle subtraction osteotomy across both rods and their connecting lateral arms. This combined structure has higher overall strength and stiffness, preventing rod fracture while maintaining the stability benefits of PSO.
Solution Approach 2:
The construct functions as a composite structural system where two rods work together with their lateral arm connections to create a unified load-bearing structure. This composite arrangement provides enhanced strength and fatigue resistance compared to a single rod, enabling the construct to withstand the stresses of PSO procedures.
Data Source
AI summary
An integral dual rod spinal construct for immobilizing and stabilizing vertebral bodies of the spine is described.