Lateral and Posterior SI Implants for Compressive Interlocking Fusion
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Solution Overview
Problem
Existing SI joint fusion devices fail to provide adequate compression across the SI joint, requiring multiple implants and often made of materials that lack strength and promote insufficient bone ingrowth, complicating the fusion process.
Innovation Solution
A minimally invasive surgical method involving a lateral SI implant that transfixes the joint and a posterior SI implant inserted in the intra-articular region, with the lateral implant compressing the joint and interlocking with the posterior implant to enhance fixation, using implants with features like deployable wings and adjustable compression to improve stability and bone ingrowth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If typical SI joint fusion devices are used, then the joint can be stabilized, but adequate compression across the SI joint is not provided to enhance fusion
Solution Approach 1:
The patent combines a lateral SI implant and a posterior SI implant into a unified fusion system. The lateral implant provides compression across the joint while the posterior implant fills the intra-articular region, and the two implants interlock to work together as a single functional unit that achieves both compression and stabilization.
Solution Approach 2:
The fusion system is divided into two separate implants: a lateral SI implant for compression and stabilization, and a posterior SI implant for intra-articular filling and additional stabilization. This segmentation allows each implant to be optimized for its specific function while working together to achieve the overall fusion goal.
2Force
If multiple implants are inserted to provide adequate compression, then compression is improved, but device complexity increases
Solution Approach 1:
The lateral SI implant and posterior SI implant are designed to interlock and function as a unified system. The posterior implant features a window that receives the lateral implant, creating an integrated structure that provides adequate compression through the lateral implant while the posterior implant contributes to stabilization and intra-articular filling, reducing the need for additional separate compression devices.
3Ease of manufacture
If posterior SI implants are made of non-metal materials, then bone ingrowth is promoted, but strength is reduced
Solution Approach 1:
The patent employs different materials for different implant components based on their functional requirements. The posterior SI implant uses a metal alloy (such as titanium, cobalt-chromium, or stainless steel) to provide the necessary strength and structural integrity in the intra-articular region. The lateral SI implant uses a polymer material (such as polyethylene or polyether ether ketone) that promotes bone ingrowth and is radiolucent for imaging, while still providing adequate compression force.
4Force
If lateral SI implants are used, then compression across the joint is provided, but risk of contacting sacral nerves increases
Solution Approach 1:
The fusion system divides the compression and stabilization functions between two implants: the lateral SI implant provides compression across the joint while the posterior SI implant handles the intra-articular stabilization. This segmentation allows the lateral implant to be designed with features that reduce nerve contact risk, such as a reduced lateral profile or angled insertion path, while the posterior implant compensates for any gaps in stabilization.
Data Source
AI summary
Systems, methods, and devices for sacroiliac (SI) joint fusion are described. At least one posterior SI implant and at least one lateral SI implant may be implanted. The posterior SI implant may be placed in the intra-articular region, and the lateral SI implant may transfix the SI joint such that the lateral SI implant passes through the ilium, across the SI joint, and into the sacrum. The lateral SI implant may compress the SI joint. The lateral SI implant may be inserted through a window in the posterior SI implant to interlock the two implants.