Radio-Opaque Marker Alignment for Intramedullary Nails
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Solution Overview
Problem
Intramedullary rods used for bone fixation can deflect to conform to the natural curvature of bones, making accurate placement of fixation screws challenging due to the need for compensation for bone curvature.
Innovation Solution
An aiming arm with radio-opaque markers is used, which changes its radiographic image characteristics based on alignment with a radiographic source, allowing for precise alignment with intramedullary nails and ensuring accurate placement of screws through corresponding apertures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If intramedullary rods are used to stabilize fractured bones, then structural reinforcement is provided, but accurate placement of fixation screws becomes challenging due to deflection conforming to bone curvature
Solution Approach 1:
Radio-opaque markers are introduced as intermediary elements between the intramedullary rod and the radiographic imaging system. These markers provide visible reference points on radiographic images that indicate the precise orientation and position of the intramedullary rod, enabling accurate alignment of fixation screws despite the rod's deflection to match bone curvature.
Solution Approach 2:
The patent uses radio-opaque markers that create distinct radiographic image characteristics (visible contrast changes) to indicate the orientation and position of the intramedullary rod. The markers appear as radio-opaque structures on radiographic images, providing visual feedback that changes based on the rod's alignment relative to the radiographic source, thereby guiding precise screw placement.
2Reliability
If intramedullary devices are inserted into the medullary canal, then bone stabilization is achieved, but compensation for bone curvature becomes necessary for accurate screw placement
Solution Approach 1:
Radio-opaque markers serve as intermediary reference elements that mediate between the intramedullary device and the surgical practitioner. The markers provide direct visual indication of the device's orientation on radiographic images, eliminating the need for complex mental compensation for bone curvature and simplifying the screw placement operation.
Solution Approach 2:
The radio-opaque markers provide real-time visual feedback on the orientation and position of the intramedullary device relative to the radiographic source. This feedback mechanism allows the surgical practitioner to adjust the positioning and alignment of fixation screws based on the actual device orientation visible on radiographic images, rather than relying on pre-calculated compensations.
3Measurement precision
If radio-opaque markers are added to the aiming arm, then alignment precision is improved, but device complexity increases
Solution Approach 1:
The aiming arm is segmented into functional components: the main body structure and separate radio-opaque markers. This segmentation allows the markers to be added as discrete elements without fundamentally redesigning the entire device, thereby improving alignment precision while minimizing the increase in overall device complexity.
Solution Approach 2:
Radio-opaque markers are incorporated as simple radiopaque elements (such as wires, plates, or beads) that provide contrast on radiographic images. These markers are relatively simple in design and can be integrated into the aiming arm structure without adding significant complexity, while they dramatically improve alignment precision by providing clear visual reference points.
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
Enables accurate alignment and placement of screws relative to the intramedullary nail, ensuring proper anchoring and stabilization of the bone, even in bones with natural curvature.
Implementation Method 1
at least a pair of radio-opaque markers carried by the body, wherein when a radiographic image is taken of the aiming arm from a first viewpoint, the radio-opaque markers define a first radiographic image characteristic when the aiming arm is not aligned with a source of the radiographic image
Data Source
AI summary
An aiming arm can include at least a pair of radiographic markers that define a first radiographic image characteristic when a radiographic image source is not adequately aligned with the aiming arm, and a second desired radiographic image characteristic when the radiographic image source is adequately aligned with the aiming arm. Once the radiographic image source has been aligned with the aiming arm, the position of the aiming arm relative to an underlying implant can be visually inspected to determine whether the aiming arm is aligned with the underlying implant.