Ultrasonic Bone Motion Tracking via Volumetric Ultrasound
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Solution Overview
Problem
Current methods for tracking bone motion in computer-assisted surgery are invasive, inaccurate, or require large and complex imaging equipment, exposing patients to radiation, and are not suitable for non-operating room use due to their invasiveness and size.
Innovation Solution
A non-invasive method using a volumetric ultrasound transducer to acquire 3D image volumes of bone surfaces, combined with a 3D positioning measurement system to track the transducer's position and align image volumes for accurate bone motion analysis, allowing for real-time tracking without invasive markers or radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If invasive markers (pins or screws) are attached to the bone for tracking, then measurement precision is improved, but the patient experiences trauma, pain, and increased risk of fracture and infection
Solution Approach 1:
The patent introduces an intermediary layer of soft tissue between the bone and the tracking system. Skin-mounted markers serve as intermediaries that can be tracked optically, while their relationship to the underlying bone is established through pre-operative imaging and registration. This intermediary approach allows non-invasive tracking while maintaining measurement accuracy through computational registration of the skin-bone relationship.
Solution Approach 2:
The patent replaces the mechanical invasive system (pins and screws physically attached to bone) with an optical non-invasive system (skin-mounted markers tracked by optical cameras). This substitution eliminates mechanical trauma to the bone while using optical fields to achieve the same tracking function through image processing and coordinate transformation.
2Ease of operation
If skin-mounted markers are used for non-invasive tracking, then patient comfort is improved, but measurement precision deteriorates due to skin and soft-tissue motion relative to the bone
Solution Approach 1:
The patent performs preliminary actions during pre-operative imaging to establish the relationship between skin-mounted markers and underlying bone structures. CT or MRI scans are acquired before surgery with markers in place, creating a registered dataset that maps the skin-bone relationship. This preliminary registration allows the system to compensate for soft tissue motion during surgery by referencing the pre-established anatomical relationships.
Solution Approach 2:
The patent creates a virtual copy of the bone structure and its relationship to skin markers through pre-operative imaging. The registered CT or MRI data provides a digital model that replicates the anatomical relationships, allowing the system to infer bone position from skin marker position through computational transformation rather than direct mechanical attachment.
3Object-affected harmful factors
If fluoroscopy and image registration techniques are used for non-invasive bone tracking, then invasiveness is reduced, but device complexity and cost increase due to large imaging apparatuses
Solution Approach 1:
The patent extracts the essential tracking function from the complex fluoroscopy system. Instead of using full fluoroscopic imaging apparatuses, the invention isolates and uses only the optical tracking of skin-mounted markers combined with pre-operative image registration. This extraction eliminates the need for large, expensive, radiation-producing fluoroscopy equipment while retaining the core capability of non-invasive bone position measurement.
Solution Approach 2:
The patent creates simplified optical copies of the tracking function rather than using the original complex fluoroscopy system. Optical cameras capture images of skin markers, and software processes these images to determine bone position through registration algorithms. This copying approach replicates the essential measurement capability while eliminating the complexity and radiation hazards of the parent fluoroscopy technology.
4Measurement precision
If pre-operative CT or MRI scans are used to construct 3D models for fluoroscopy registration, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the pre-operative imaging data serve multiple functions. The same CT or MRI scans are used both for surgical planning and for establishing the registration framework between skin markers and bone structures. This multi-functional use of the imaging data eliminates the need for separate registration imaging procedures, reducing overall system complexity while maintaining measurement precision through the dual-purpose utilization of the acquired images.
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 robust non-invasive tracking of bone motion, decomposing joint motion into specific components, measuring kinematics, instability, and range of motion, suitable for both surgical and non-surgical settings without exposing patients to radiation.
Implementation Method 1
acquiring a first reference image volume I0 of a bone surface with a volumetric ultrasound imaging transducer
Data Source
AI summary
A computerized bone motion tracking system according to one exemplary embodiment is configured to: provide a non-invasive means for accurate measurement and tracking of the motion of a bone using a volumetric ultrasound transducer and a three dimensional position measurement system; provide relative measurements of one bone relative to another bone of a joint; decompose relative joint motion into specific components; and measure joint instability and range of motion.