Spinal Rods with Adjustable Screws for Alignment
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Solution Overview
Problem
Current spinal implant techniques, particularly in minimally invasive surgeries, face challenges in achieving precise spinal alignment due to the need for pre-contoured or hand-bent rods that are limited by their curvature, which can weaken the rod and make it difficult to pass through soft tissue, especially in procedures spanning multiple vertebral levels, thus necessitating larger incisions.
Innovation Solution
The use of standardized rods with controlled sagittal alignment through precise screw placement and angular control, employing bone screws with adjustable angles and heights to accommodate varying spinal curvatures, allowing for both minimally invasive and open surgical techniques to correct spinal deformities across multiple levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rods are pre-contoured or hand-bent to match desired spinal curvature, then spinal alignment control is improved, but the rods become weaker at bend points and more difficult to pass through soft tissue
Solution Approach 1:
The rod is divided into multiple segments or sections that can be independently adjusted. This allows the rod to accommodate spinal curvature without requiring continuous bending, thereby maintaining strength while achieving precise alignment control through modular adjustment mechanisms.
Solution Approach 2:
The rod transitions from a static pre-contoured design to a dynamic adjustable system. The rod incorporates adjustable elements that allow real-time modification of curvature and alignment during surgery, enabling precise spinal alignment while maintaining rod integrity and avoiding the weakening effects of permanent bending.
2Measurement precision
If rods are bent to match spinal curvature, then alignment precision is improved, but the rods become more difficult to pass through soft tissue during minimally invasive procedures
Solution Approach 1:
The rod is pre-formed with a relatively straight configuration that facilitates easy insertion through soft tissue during minimally invasive procedures. The desired spinal curvature is achieved through preliminary planning and adjustment mechanisms, rather than pre-bending the rod, thereby maintaining ease of insertion while achieving precise alignment.
Solution Approach 2:
The rod system incorporates dynamic adjustment capabilities that allow the curvature to be modified after insertion. This enables the rod to be easily inserted in a straight configuration and then adjusted to match the patient's spinal anatomy, combining the benefits of easy insertion with precise alignment control.
3Manufacturing precision
If curved rods are used to span multiple vertebral levels, then alignment control is improved, but minimally invasive insertion becomes impossible requiring large incisions
Solution Approach 1:
The rod system is segmented into multiple adjustable sections that can be independently positioned and adjusted. This segmentation allows the rod to span multiple vertebral levels with precise alignment control while maintaining a configuration that facilitates minimally invasive insertion, eliminating the need for large incisions.
Solution Approach 2:
The rod incorporates dynamic adjustment mechanisms that enable precise alignment control across multiple vertebral levels without requiring pre-contouring. This dynamic capability allows the rod to be inserted minimally invasively and then adjusted to achieve the desired alignment, simplifying the surgical approach while maintaining precision.
4Ease of manufacture
If standardized rods are used instead of custom-contoured rods, then ease of manufacture and availability are improved, but the ability to control precise spinal alignment is reduced
Solution Approach 1:
The standardized rod incorporates dynamic adjustment elements that allow precise control of spinal alignment during surgery. This enables the use of standardized, easily manufactured rods while maintaining the ability to achieve precise alignment through intraoperative adjustment, eliminating the need for custom-contoured rods.
Solution Approach 2:
The rod system allows for changeable parameters such as curvature, length, and configuration that can be adjusted during surgery. This enables the use of standardized rods with the capability to modify their parameters to match patient-specific requirements, combining ease of manufacture with precise alignment control.
Data Source
AI summary
A spinal construct is based on a fixed contour rod and modified bone screws configured to account for different height and angular offsets between the rod and the spinal anatomy. The rod contour is adapted for percutaneous introduction thereby eliminating the need for open spinal surgery for multi-level constructs.