Expandable SI Joint Anchors for Stable Rod-Integrated Fixation
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Solution Overview
Problem
Current sacroiliac joint (SIJ) fixation techniques, such as SAI and iliac screws, suffer from high revision rates due to screw loosening, leading to recurrent SIJ pain, and there is a need for improved fixation and fusion methods that integrate with long constructs while reducing motion.
Innovation Solution
The development of sacroiliac joint implants, including threaded and non-threaded anchors, expandable and adjustable designs, and various fixation mechanisms, which can be used with robotic and navigation systems to stabilize and fuse the SIJ, providing secure attachment to spinal rods and promoting bone integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional SAI and iliac screws are used for fixation, then additional stability is provided for long constructs, but screw loosening occurs leading to high revision rates
Solution Approach 1:
The fixation system is divided into separate components: an anchor device that engages the sacroiliac joint and a rod construct that provides spinal support. This segmentation allows the anchor to be optimized for joint fusion while the rod provides construct stability, addressing both fixation strength and reducing loosening through specialized function distribution.
Solution Approach 2:
The anchor device features a nested structure with an outer shell and inner components that can be sequentially inserted and locked together. This nested design provides progressive stabilization, ensuring secure engagement with the sacroiliac joint while maintaining integration capability with the spinal rod construct, thereby improving reliability.
2Strength
If SAI screws are used to support long constructs, then secure lumbosacral foundation is achieved, but SIJ pain recurs due to screw loosening
Solution Approach 1:
The anchor device is designed to pre-compress and stabilize the sacroiliac joint surfaces before final rod attachment. This preliminary stabilization action promotes initial joint fusion and reduces micro-motion that causes pain, while maintaining the strength needed for long construct support.
Solution Approach 2:
The anchor device serves as an intermediary element between the sacroiliac joint and the spinal rod construct. It mediates the mechanical loads and provides a stable interface that protects the joint from harmful loosening forces while maintaining construct integrity, thereby preventing pain recurrence.
3Strength
If threaded anchors are used for SIJ fixation, then secure attachment is achieved, but integration with long constructs is limited
Solution Approach 1:
The anchor device incorporates multiple functional elements: threaded engagement for secure attachment to bone, a receptacle for rod acceptance, and options for additional fixation methods. This multi-functionality allows the same anchor to provide both secure attachment and versatile integration with various long construct configurations.
Solution Approach 2:
The anchor design allows for dynamic adjustment and adaptation during surgery, with options to modify engagement depth, rod positioning, and additional fixation methods. This dynamic capability enables secure attachment while adapting to different construct requirements, enhancing versatility.
Data Source
AI summary
Bone anchor implants, assemblies, systems, instruments, and methods thereof. The bone anchors may be threaded or non-threaded, adjustable or expandable, stackable, or otherwise configured to promote fixation of the sacroiliac joint. The bone anchors may be used independently or may be configured to integrate with long rod constructs, for example, with a tulip or other suitable attachment interface, to fuse the sacroiliac joint.