Inertial Sensor Cup Implanting Device for Pelvic Alignment
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Solution Overview
Problem
Current methods for orienting an acetabular cup implant in computer-assisted surgery are invasive, costly, and lack precise quantitative assessment, often resulting in inaccurate cup positioning which can lead to premature wear and improper gait.
Innovation Solution
A computer-assisted surgery system utilizing inertial sensors to determine the precise three-axis orientation of the acetabular cup implant relative to the pelvis, with a rotation indicator providing visual guidance for accurate alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical navigation is used for computer-assisted surgery, then navigation accuracy is improved, but operative time increases and invasiveness increases due to pinning reference
Solution Approach 1:
The patent replaces optical navigation systems with inertial measurement units (IMUs) that use accelerometers and gyroscopes to track the position and orientation of surgical instruments. This substitution eliminates the need for optical cameras and reflective markers, thereby reducing operative time while maintaining measurement precision through trigonometric calculations based on gravitational reference
Solution Approach 2:
The patent extracts and eliminates the reference pinning step from the navigation process. By using the gravity vector as a natural reference frame, the system removes the need to attach physical references to the patient's anatomy, thereby reducing invasiveness while preserving navigation accuracy
2Measurement precision
If optical navigation with reference pinning is used, then navigation capability is improved, but invasiveness of the procedure increases
Solution Approach 1:
The patent replaces the mechanical reference pinning system with an inertial sensing system that uses the gravity vector as a natural reference. This substitution eliminates the need to penetrate the patient's skin and bone to attach references, thereby reducing invasiveness while maintaining navigation capability through trigonometric orientation calculations
Solution Approach 2:
The patent utilizes the Earth's gravity field as a free, naturally available reference frame that requires no attachment to the patient. The IMU sensors self-calibrate using the gravity vector, eliminating the need for external reference structures and reducing procedural invasiveness
3Measurement precision
If C-arm validation equipment is used, then validation capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces bulky C-arm imaging equipment with compact inertial measurement units that can be directly attached to surgical instruments. This substitution dramatically reduces device complexity while maintaining validation capability through real-time trigonometric calculations of instrument orientation relative to the pelvis
Solution Approach 2:
The patent creates a virtual copy of the anatomical reference frame through software processing of IMU sensor data. Instead of using physical imaging equipment to visualize anatomy, the system reconstructs spatial relationships through trigonometric calculations, reducing hardware complexity while preserving validation capability
4Ease of operation
If manual reference guides are used, then ease of operation is improved, but positioning accuracy deteriorates due to not accounting for patient position on operative table
Solution Approach 1:
The patent implements a dynamic reference system where the IMU sensors continuously track the gravity vector to determine the patient's actual position on the operative table. This dynamic adaptation maintains ease of operation while correcting for positional variations, thereby preserving positioning accuracy that static manual guides cannot achieve
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 enables cost-effective, minimally invasive, and precise orientation of the acetabular cup implant, reducing the risk of premature wear and improving surgical outcomes by providing real-time orientation data.
Implementation Method 1
a CAS processing unit including at least one inertial sensor unit connected to the cup implanting device, the inertial sensor unit outputting three-axes readings
Data Source
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AI summary
A computer-assisted surgery (CAS) system comprises a cup implanting device including a shaft having a tooling end and a handle end with a handle for being manipulated, the shaft having a longitudinal axis, the tooling end adapted to support a cup for being received in an acetabulum of a patient, and a rotation indicator having a visual guide representative of a device plane, wherein the device plane is in a known position and orientation relative to a center of the cup on the tooling end. A CAS processing unit includes at least one inertial sensor unit connected to the cup implanting device, the inertial sensor unit outputting three-axes readings and having a virtual preset orientation related to a reference axis of a pelvis of the patient, the virtual preset orientation being based on pre-operative imaging specific to the pelvis of the patient, the reference axis of the pelvis passing through a center of rotation of said acetabulum of the pelvis and through a reference landmark of the pelvis, wherein an instant three-axis orientation of the longitudinal axis of the cup implanting device is trigonometrically known relatively to the reference axis when the cup is in the acetabulum of the patient and the device plane passes through the reference landmark via the visual guide, the instant three-axis orientation used for calibrating the inertial sensor unit on the cup implanting device relative to the pelvis.