Expandable Dowel for Sacroiliac Joint Stabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for immobilizing the sacroiliac joint, such as using simple threaded screws, often fail to provide sufficient stability due to variations in bone density and morphology, leading to instability and risk of device back-out during arthrodesis procedures.
Innovation Solution
The use of non-threaded dowels with non-circular cross-sectional profiles, such as flat or concave surfaces, and hollow designs with expandable features or radially expandable mesh, which are implanted singly or in multiples to provide enhanced rotational resistance and stability to the sacroiliac joint, allowing for bone growth and integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If simple threaded screws are used for joint immobilization, then the device complexity is low, but the reliability of joint stability is insufficient due to variations in bone density and morphology
Solution Approach 1:
The dowel employs a non-circular cross-sectional profile (e.g., flat or concave surfaces) instead of a symmetric circular profile. This asymmetric geometry provides enhanced rotational resistance and prevents the dowel from rotating within the joint, thereby improving joint stability and reliability without requiring complex threaded structures
Solution Approach 2:
The dowel incorporates expandable features or radially expandable mesh that can be deployed after insertion. This dynamic expansion allows the dowel to adapt to variations in bone density and morphology, improving reliability by ensuring secure fit in diverse anatomical conditions while maintaining a simple insertion procedure
2Reliability
If simple threaded screws are used, then the ease of manufacture is high, but the device fails to provide sufficient rotational resistance leading to back-out risk
Solution Approach 1:
The non-circular cross-sectional profile (flat or concave surfaces) inherently provides rotational resistance without requiring complex threading or anti-rotation mechanisms. This simple geometric modification is easy to manufacture using standard dowel fabrication processes while effectively preventing device back-out
Solution Approach 2:
The dowel utilizes curved or contoured surfaces (concave or flat profiles) instead of a circular cross-section. These curved geometries engage with the bone surfaces to provide rotational stability through surface contact and mechanical interlocking, achieving high rotational resistance with simple manufacturing
3Reliability
If non-threaded dowels with non-circular profiles and expandable features are used, then the joint stability is improved, but the device complexity increases
Solution Approach 1:
The expandable dowel is divided into distinct functional segments: a simple insertion body and deployable expansion elements (such as radially expandable mesh or separate expansion features). This segmentation allows the complex stabilization function to be added as a modular component rather than requiring complete redesign of the entire device
Solution Approach 2:
The dowel transitions from a static simple cylinder to a dynamic structure with deployable expansion features. The expansion mechanism activates after insertion to provide enhanced stability, allowing the device to maintain simplicity during insertion but gain complexity only when needed for stabilization
Data Source
AI summary
Methods and apparatus for immobilizing a synovial joint, such as a sacroiliac (SI) joint are disclosed. In one form, a multipiece fixation device, such as a dowel, includes multiple expandable fasteners that are configured to fix adjacent bones of a synovial joint with respect to one another. The expandable fasteners include expansion portions that are expanded radially via insertion of another expandable fastener or an expansion device to fix the expandable fasteners to the bone. The fixation device may be configured to provide for compression or distraction of the bones of the synovial joint while at the same time stabilizing the joint.