Lenticular Optical Markers for Spinal Screw Tracking
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Solution Overview
Problem
Current spinal correction surgeries face challenges in accurately tracking and visualizing pedicle screws due to occlusion and obstruction during open surgical procedures, leading to suboptimal rod pathing and mechanical wear, despite advancements in polyaxial screws and tracking systems like Bendini and Medtronic Stealth.
Innovation Solution
The development of trackable bone screws with extensions featuring lenticular arrays that provide orientation data, allowing for accurate screw location and orientation tracking through image analysis, and a system that includes a computing device to process pixel data from these markers to determine the global position and orientation of pedicle screws, enhancing visibility and precision in rod bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual rod bending is performed by the surgeon, then the rod can be shaped to fit the spine, but the process is time-consuming and leads to mechanical wear on the rod
Solution Approach 1:
The system performs computer-automated rod bending based on pre-acquired screw position and orientation data, eliminating the need for time-consuming manual bending during surgery. The rod is bent automatically according to the predetermined path calculated from the tracked screw locations.
Solution Approach 2:
The manual mechanical bending process performed by the surgeon is replaced with an automated mechanical bending system controlled by computer software, which calculates and executes the rod bending based on tracked screw positions and orientations.
2Measurement precision
If existing tracking systems like Medtronic Stealth are used, then screw location can be tracked, but the camera is obstructed by surgical tools and fluids
Solution Approach 1:
Optical markers are attached to the pedicle screws as intermediary tracking elements. These markers are tracked by the imaging system instead of tracking the screws directly, allowing accurate position determination even when the screws themselves are obscured by surgical tools, tissues, or fluids.
Solution Approach 2:
The system uses optical markers with distinctive visual characteristics that can be detected and differentiated by the imaging system. The markers provide high-contrast visual signals that remain detectable despite the presence of surgical tools, blood, or other obstructions in the surgical field.
3Adaptability or versatility
If polyaxial screws are used, then a larger range of rod-insertion angles is accommodated, but the manual bending process remains arduous and accuracy requirements are not reduced
Solution Approach 1:
The arduous manual bending process is replaced with automated computer-controlled rod bending. The system calculates the optimal bending path based on the polyaxial screw positions and orientations, and executes the bending automatically, eliminating the physical difficulty while maintaining adaptability to various insertion angles.
4Measurement precision
If Bendini Rod Bending System is used, then tracking capability is provided, but the system does not interface with proprietary driver shapes and reports incorrect screw locations
Solution Approach 1:
The tracking system is designed with universal compatibility to interface with multiple proprietary driver shapes and screw types. The system can recognize and accurately track different screw configurations through its imaging and recognition algorithms, eliminating the need for system-specific hardware interfaces while maintaining measurement accuracy.
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 achieves accurate screw location and orientation with an angular error of less than 5°, improving surgical precision and reducing mechanical wear by maintaining marker visibility and adjusting for occlusions, thereby facilitating more precise computer-automated rod bending.
Implementation Method 1
The optical marker can include a first and second lenticular array that each includes first and second major axes, respectively. In accordance with another aspect, the first and second lenticular arrays can be positioned in a coplanar arrangement on the marker support and the first and second major axes can be oriented perpendicularly.
Data Source
AI summary
Among the various aspects of the present disclosure is the provision of devices, systems, and methods for tracking the positions and orientations of at least one bone screw implanted within a surgical site. The disclosed device includes an extension that includes an extension base configured to couple to the bone screw, a marker arm coupled at one end to the extension base in a hinged arrangement, and an optical marker attached to a free end of the marker arm opposite the hinged attachment. The optical marker includes a pair of lenticular arrays in a coplanar arrangement in which the major axes of the lenticular arrays are mutually perpendicular. Each lenticular array is configured to display different hues at different viewing angles. The disclosed method includes transforming a single image of a surgical site containing at least one bone screw and extension into the global positions of each bone screw based on the pixel positions and hues corresponding to the lenticular arrays of each optical marker.