Hand-held Stereovision System for Spinal Navigation
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Solution Overview
Problem
Current surgical navigation systems for spinal surgery are cumbersome, radiation-intensive, and inefficient, particularly in accurately registering patient anatomy and compensating for intervertebral motion during lumbar fusion procedures.
Innovation Solution
A hand-held stereovision system that captures intraoperative images of the spine, reconstructs stereovision surfaces, and registers them nonrigidly with preoperative CT images to generate updated CT images, which are then used for surgical navigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preoperative CT scans and intraoperative fluoroscopic images are used for navigation, then surgical guidance is provided, but radiation exposure to patient and surgical team increases
Solution Approach 1:
The system creates a 3D surface copy of the patient's spine anatomy using optical stereovision cameras instead of ionizing radiation. Multiple 2D images from different angles are processed to generate an accurate 3D surface model that can be registered with preoperative CT data, providing navigation guidance without radiation exposure
Solution Approach 2:
The patent replaces the mechanical/radiological imaging system (fluoroscopy and CT) with an optical imaging system. Stereo cameras capture light reflected from the surgical field to create 3D surface models, substituting ionizing radiation-based imaging with non-ionizing optical imaging for real-time navigation
2Productivity
If one-time registration at start of surgery is performed, then initial navigation setup is completed, but intervertebral motion between supine and prone positions causes registration errors
Solution Approach 1:
The system transitions from static one-time registration to dynamic continuous registration. The stereovision system captures real-time 3D surface data throughout surgery, allowing the navigation system to update and adjust for intervertebral motion as the patient's spine changes position between supine and prone orientations
Solution Approach 2:
The system implements continuous feedback by repeatedly capturing 3D surface images of the spine during surgery. These images are compared with the preoperative CT-based navigation model, allowing real-time detection and correction of registration drift caused by patient positioning changes
3Ease of operation
If skin-affixed fiducials are used for registration, then registration process is simplified, but large registration errors occur in spinal surgery
Solution Approach 1:
Instead of using skin-affixed fiducials that create large registration errors, the system creates an optical copy of the actual bony spine surface geometry. The stereovision system captures the true 3D shape of exposed vertebral surfaces, providing accurate anatomical landmarks for registration without relying on skin-mounted markers
Solution Approach 2:
The system uses the exposed bony spine surface itself as an intermediary for registration. Rather than placing external fiducials on skin, the natural anatomical surface of the vertebrae serves as the registration interface, eliminating the discrepancy between skin and bone positions
4Measurement precision
If automated methods using intraoperative CT are employed, then registration accuracy is improved, but capital costs and radiation exposure increase significantly
Solution Approach 1:
The system creates accurate 3D surface copies using inexpensive optical stereovision cameras rather than expensive intraoperative CT scanners. The photogrammetric 3D models achieved through stereo imaging provide sufficient registration accuracy for spinal navigation without requiring capital-intensive radiological equipment
Solution Approach 2:
The system uses disposable or low-cost optical cameras and single-use sterile adhesive markers instead of expensive, reusable intraoperative CT equipment. This approach achieves comparable registration accuracy at a fraction of the capital cost and without the associated radiation exposure
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 system provides an efficient, accurate, and radiation-free method for improving the placement of pedicle screws, reducing surgical complications, and enhancing surgical outcomes by accurately accounting for vertebral posture and alignment changes.
Implementation Method 1
a handheld stereovision device, the HHS including a body, at least two cameras mounted to the body, the at least two cameras angled towards a center of a field of view, and having an overlapping region of view
Data Source
AI summary
This invention provides a hand-held stereovision (HHS) system that is an efficient, accurate, and radiation-free imaging device to acquire intraoperative profiles of the exposed spine in prone position. The reconstructed intraoperative stereovision surfaces (iSV) are registered with preoperative CT (pCT; supine position) in a nonrigid fashion to generate updated CT images (uCT) and correct for vertebral posture and alignment changes. Updated CT images are uploaded to a commercial navigation system for surgical navigation.