Computer-Assisted Distal Locking of Intramedullary Nails
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Solution Overview
Problem
The process of distal locking in intramedullary nailing is complicated by nail deformation during insertion, requiring lengthy and radiation-exposed trial-and-error methods for accurately locating distal locking holes, with existing computer-assisted methods either cumbersome or time-consuming due to the need for multiple fluoroscopic images.
Innovation Solution
A method utilizing a single calibrated fluoroscopic image taken in a lateral-medial direction, independent of the orientation of the distal locking holes, which allows for the calculation of the nail axis and hole positions using an iterative closest projection point algorithm, minimizing X-ray exposure and apparatus rearrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional trial-and-error method with multiple fluoroscopic images is used to locate distal locking holes, then positioning accuracy is improved, but surgical time and radiation exposure increase
Solution Approach 1:
The method performs preliminary calculation of the nail axis and distal locking hole positions using image processing algorithms before the actual locking procedure. By pre-determining the geometric relationships and projecting them onto the image plane, the system eliminates the need for repeated trial-and-error positioning during surgery, thus reducing surgical time while maintaining accuracy.
Solution Approach 2:
The patent replaces the mechanical trial-and-error positioning method with a computer-assisted image processing system. Instead of physically adjusting the C-arm and taking multiple images to locate locking holes, the system uses algorithms to automatically calculate and project the nail axis and hole positions from a single image, substituting mechanical adjustment with computational geometry.
2Measurement precision
If multiple fluoroscopic images are acquired to determine nail axis and locking hole positions, then positioning accuracy is improved, but radiation exposure to surgeon and patient increases
Solution Approach 1:
The method extracts only the essential information needed for positioning from a single fluoroscopic image, rather than acquiring multiple images. By using image processing algorithms to calculate the nail axis and locking hole positions from one image, the system eliminates the need for repeated radiation exposure while maintaining the necessary positioning accuracy.
Solution Approach 2:
The system performs preliminary computational analysis of the single image to determine all necessary positioning parameters before any additional radiation is required. By pre-calculating the nail axis orientation and locking hole positions through geometric projection, the system avoids the need for multiple fluoroscopic images and thus minimizes radiation exposure.
3Loss of information
If C-arm of X-ray device is rotated from antero-posterior to lateral-medial direction to acquire multiple images, then complete positioning information is obtained, but device complexity and operation time increase
Solution Approach 1:
The patent makes the single fluoroscopic image serve multiple functions: it provides both the nail axis orientation information and the distal locking hole position information. By using image processing algorithms to extract both sets of parameters from one image, the system eliminates the need for separate imaging positions, thus reducing device rearrangement complexity while maintaining complete positioning information.
Solution Approach 2:
The patent replaces the mechanical rotation and rearrangement of the C-arm with a computational geometry system. Instead of physically repositioning the X-ray device to different angles to obtain complete positioning information, the system uses algorithms to calculate and project the nail axis and locking hole positions from a single image, substituting mechanical complexity with computational simplicity.
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
This approach reduces X-ray exposure and simplifies the positioning of the X-ray device, enabling accurate localization of distal locking holes with fewer images, thus shortening surgical time and minimizing radiation exposure for both surgeon and patient.
Implementation Method 1
acquiring one single image (IM) of the distal end section by means of the X-ray device
Data Source
AI summary
A method for computer assisted localization of the distal locking holes (11; 14) of an implanted intramedullary nail (2) having a nail axis (19) and a first and second distal locking hole (11; 14) by A) acquiring one single image IM of the distal end section (25) of said intramedullary nail by means of an X-ray device (9) whose optical axis (30) is oriented essentially perpendicular to the nail axis (19) but irrespective to the orientation of the distal locking holes (11; 14); and B) calculating the position of the first and second hole axis (23; 20) of the first and second distal locking hole (11; 14) with respect to a three-dimensional coordinate system A-COS (7) of the implanted intramedullary nail (2).