Adjustable Spinal Implant Receiver with Threaded Arms
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Solution Overview
Problem
Current spinal implant systems face challenges in adjusting the height of vertebral rods during surgery without fully reducing them relative to the implant receiver, which can be risky due to potential excessive force that may dislodge pedicle screws, especially in cases of degraded or weakened vertebrae.
Innovation Solution
A spinal implant system featuring an implant receiver with adjustable arms and a nut mechanism that allows for in situ adjustment of a longitudinally extending rod's height, using thread patterns on the arms and a set screw to securely position and lock the rod at various elevations, enabling incremental adjustments and reducing the risk of screw dislodgment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rod is fully reduced relative to the implant receiver to adjust height, then the adjustment range is improved, but the risk of dislodging pedicle screws increases due to excessive force
Solution Approach 1:
The implant receiver incorporates movable arms that can be dynamically adjusted between extended and retracted positions. This dynamic structure allows the rod height to be adjusted by moving the arms rather than fully reducing the rod, enabling height adjustment while maintaining rod engagement and avoiding excessive force on pedicle screws.
Solution Approach 2:
The implant receiver is divided into separate functional components: a base portion, movable arms with thread patterns, and a rod receiving cavity. This segmentation allows the arms to be adjusted independently to control rod height, separating the height adjustment function from the rod reduction process and reducing the risk of screw dislodgment.
2Measurement precision
If the rod is fully reduced to achieve height adjustment, then the precision of rod positioning is improved, but the complexity of the adjustment process increases
Solution Approach 1:
The movable arms provide a dynamic adjustment mechanism where the arm position directly controls rod height. This dynamic system allows precise rod positioning through simple arm movement rather than complex rod reduction procedures, maintaining precision while reducing process complexity.
Solution Approach 2:
The movable arms act as intermediaries between the rod and the implant receiver base. By adjusting arm position rather than directly manipulating the rod, the system achieves precise rod positioning through a simpler intermediate mechanism, reducing the complexity of the adjustment process.
3Stability of the object's composition
If the rod is securely fixed at a specific height, then the stability of the spinal construct is improved, but the adaptability for incremental adjustments is reduced
Solution Approach 1:
The movable arms can be positioned at multiple discrete locations along their length, each corresponding to a different rod height. This dynamic positioning capability allows the spinal construct to be securely fixed at any desired height while maintaining the ability to perform incremental adjustments by repositioning the arms.
Solution Approach 2:
The arms are segmented with thread patterns that engage with the rod at multiple discrete positions. This segmentation allows the rod to be securely fixed at specific heights through arm positioning while maintaining adaptability for incremental adjustments by moving to adjacent engagement positions.
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
This solution allows for precise adjustment and secure fixation of vertebral rods at desired elevations, reducing the risk of screw dislodgment and facilitating complex spinal deformity corrections by enabling incremental rod placement and alignment without excessive force.
Implementation Method 1
A nut may rotate along an outside thread pattern of the first arm and the second arm to adjust a height of the rod in the longitudinal direction from the base to the open end
Implementation Method 2
A set screw may be inserted into a set screw cavity in the base and engage with an inside thread pattern of the first arm and the second arm to secure the rod at a specific height
Data Source
AI summary
An implant system is disclosed. The system may include an implant receiver having a base and a first arm and a second arm extending from the base in a longitudinal direction towards an open end. The first arm and second arm may define a receiving cavity therebetween. The first and second arm may each include an outside thread pattern for rotatably supporting a nut movable in the longitudinal direction and an inside thread pattern for rotatably supporting a set screw movable in the longitudinal direction. A rod may be selectively positioned within the receiving cavity at an intermediate elevation between the base and the open end and the rod may be supported by the nut. The set screw may be tightened against the rod thereby locking the rod and nut at the intermediate elevation. In some embodiments, the first and second arms may include a plurality of breakoff locations.