Acetabular Cup Positioning Device Using Fluoroscopic Alignment
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Solution Overview
Problem
Conventional methods for positioning the acetabular cup during hip surgery are inaccurate due to reliance on patient position under surgical drapes, which may be rotated or tilted, leading to malpositioning and complications such as dislocation, premature wear, and metallosis, and require invasive navigation systems with costly equipment and lengthy setup.
Innovation Solution
An intraoperative guidance device using X-rays fluoroscopy with metallic rods and a sliding mechanism to accurately align the acetabular cup at 45 degrees inclination and neutral anteversion, correlating anatomical landmarks with the cup inserter, allowing for precise positioning regardless of patient tilt or rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods relying on patient position under surgical drapes are used, then the surgical procedure can be performed, but the acetabular cup positioning accuracy deteriorates due to patient rotation or tilt
Solution Approach 1:
The patent introduces an intermediary positioning device consisting of a vertical shaft, horizontal shaft, and alignment rods that mediate between the surgeon's actions and the acetabular cup placement. This device serves as a mechanical reference frame that is independent of patient positioning, allowing accurate cup orientation even when the patient is rotated or tilted under drapes
Solution Approach 2:
The positioning device is segmented into multiple independent components: a vertical shaft for inclination control, a horizontal shaft for anteversion control, and alignment rods for reference. This segmentation allows each component to be adjusted and aligned independently, improving overall positioning accuracy while maintaining device manageability
2Measurement precision
If invasive navigation systems are used to improve positioning accuracy, then measurement precision improves, but device complexity and cost increase due to expensive monitoring devices and specialized equipment
Solution Approach 1:
The patent employs simple, inexpensive alignment rods and shafts made of basic materials like metal or radiopaque plastic, replacing expensive navigation systems. These components are straightforward mechanical elements that can be manufactured at low cost and disposed of after a single use, eliminating the need for costly monitoring equipment
Solution Approach 2:
The patent replaces complex electronic navigation systems with a purely mechanical positioning device. The alignment rods and shafts provide geometric references through their physical construction, eliminating the need for sensors, computers, and electronic monitoring equipment while achieving comparable or superior positioning accuracy
3Measurement precision
If invasive navigation systems with probes are used, then positioning accuracy improves, but patient trauma increases due to separate skin incisions and local skin irritations
Solution Approach 1:
The patent extracts the positioning function from the patient's body by using an external mechanical reference frame (alignment rods and shafts) that references anatomical landmarks visually or through simple contact, rather than inserting probes into the patient. This eliminates the need for separate skin incisions and reduces patient trauma
Solution Approach 2:
The alignment rods serve as intermediaries that reference anatomical landmarks without requiring invasive insertion. The rods can be positioned externally or with minimal contact to establish geometric references, avoiding the need for deep probe insertion and subsequent skin irritation
4Measurement precision
If computerized navigation is used, then positioning accuracy improves, but operation time increases due to lengthy registration process and sophisticated equipment setup
Solution Approach 1:
The positioning device is pre-configured with fixed geometric relationships (90-degree angles between shafts, specific rod orientations) that establish reference frames in advance. This preliminary setup eliminates the need for time-consuming intraoperative registration processes, as the geometric references are already built into the device structure
Solution Approach 2:
By replacing computerized navigation with a mechanical positioning device, the patent eliminates the need for sophisticated monitoring equipment and lengthy software-based registration processes. The mechanical geometry provides immediate visual or tactile references that can be aligned quickly during surgery
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 and precise acetabular cup positioning, reducing the risk of complications like dislocation and metallosis, while eliminating the need for invasive navigation systems and costly monitoring devices, by leveraging conventional X-ray technology for real-time alignment.
Implementation Method 1
The present invention describes a method for accurately positioning the acetabular cup during implantation. It utilizes X-rays fluoroscopy with image intensification that is readily available in every operating room
Data Source
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AI summary
Positioning an acetabular cup in a desired optimal alignment in relation to the patients pelvis using conventional fluoroscopic equipment readily available in operating rooms in conjunction with a metallic jig as guide. The device having inclination metallic rods at 45 degrees angle to the cup impactor and anteversion rod situated at a distance from the midline that correspond to the degree of inclination. When said inclination and anteversion shafts are aligned with central anatomical structures such as symphysis pubis and middle of first sacral vertebra will result in correct placement of the acetabular cup at the desired version.