Stadium-Shaped Surgical Fixation Member for Facet Joint Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Facet joint implants, such as bone dowels, often migrate posteriorly out of the facet joint before fusion is achieved due to smooth passage walls or lack of anti-migration features, leading to instability and pain.
Innovation Solution
A stadium-shaped fixation member with a tapered, anti-migration section is used, providing a precision press fit within the facet joint to prevent posterior migration, with a variable width and height, and a stepped sidewall design that maximizes contact surface area and engagement with articular surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bone dowel is inserted into the facet joint, then bone fusion is achieved, but the dowel migrates posteriorly out of the joint
Solution Approach 1:
The fixation member features a stadium-shaped cross-section with semicircular ends that specifically engage the articular surfaces of the facet joint, creating localized high-contact-area regions at the anterior and posterior aspects of the joint that prevent posterior migration while maintaining bone fusion capability
Solution Approach 2:
The semicircular ends of the stadium-shaped cross-section conform to the curved articular surfaces of the facet joint, maximizing contact surface area and creating a precision press fit that prevents posterior migration through geometric interlocking rather than relying on friction alone
2Ease of operation
If the passage walls are smooth, then the insertion procedure is easier, but the dowel migrates posteriorly
Solution Approach 1:
The passage is pre-formed with a stadium-shaped cross-section that precisely matches the fixation member's geometry before insertion, ensuring that the smooth-walled passage provides both easy insertion and subsequent migration prevention through geometric compatibility rather than requiring rough surfaces
3Ease of manufacture
If the contact surface area between dowel and articular surfaces is small, then the insertion is simpler, but the dowel migrates posteriorly
Solution Approach 1:
The fixation member's stadium-shaped cross-section fundamentally changes the contact surface area parameter by providing semicircular ends that conform to the articular surfaces, maximizing the contact area to prevent posterior migration while maintaining a relatively simple cylindrical-like overall form that is easy to manufacture and insert
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
The solution effectively stabilizes the facet joint by preventing implant migration and facilitating bone fusion, reducing pain and the need for additional hardware, while allowing for minimally invasive procedures and accelerated rehabilitation.
Implementation Method 1
Stabilization is achieved by a precision press fit between the void and the fixation member, the fixation having a slight greater maximum circumference than the void. Thus, the pressure created by the opposing articular surfaces maintains the fixation member in place by an interference fit.
Data Source
AI summary
A method of stabilizing a facet joint by providing a fixation member with a substantially stadium-shaped cross-section, forming a void having a substantially stadium-shaped cross-section within the facet joint and inserting the fixation member into the void. The void is formed by engaging a first drill guide with the facet joint having two drill guide paths and drilling two spaced-apart or slightly overlapping passageways within the face joint, followed by engaging a second drill guide with the facet joint and drilling a third passageway between the two other passageways. The fixation member includes a tapered, anti-migration section configured for engaging the opposing articular surfaces of the joint.