Bone Model Registration Using Adaptive Soft Tissue Thickness
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Solution Overview
Problem
Existing bone model registration methods in orthopaedic surgical procedures often require piercing or contacting soft tissue to register with bone, leading to increased surgical time and variability, and may not accurately account for local soft tissue variations.
Innovation Solution
A method and system that registers a three-dimensional bone model by capturing point positions on soft tissue surfaces using a registration tool, estimating soft tissue thickness, and optimizing the model's transformation to align with anatomical landmarks without direct bone contact, utilizing a computing device and robotic surgical assistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing bone model registration methods contact or pierce soft tissue to register with bone, then registration can be performed, but surgical time increases and variability increases
Solution Approach 1:
The patent uses an intermediary mathematical model (soft tissue thickness model) to bridge the gap between the registration tool contacting soft tissue and the underlying bone model. Instead of directly contacting bone, the system models soft tissue thickness at each point and uses this model to transform soft tissue contact points into corresponding bone surface points, enabling indirect registration that is both accurate and time-efficient
Solution Approach 2:
The patent replaces the mechanical approach of directly contacting or piercing bone with a computational approach. A mathematical model calculates soft tissue thickness based on point cloud data and anatomical landmarks, then uses this model to perform the registration transformation computationally, eliminating the need for physical bone contact while maintaining registration accuracy
2Measurement precision
If existing bone model registration methods contact or pierce soft tissue to register with bone, then registration can be performed, but variability increases
Solution Approach 1:
The patent changes the parameter being measured from direct bone contact points to soft tissue surface points with associated thickness values. By modeling soft tissue thickness as a variable parameter at each point in the point cloud, the system transforms the registration problem into one that accounts for soft tissue variability, thereby reducing registration variability and improving reliability
Solution Approach 2:
The soft tissue thickness model serves as an intermediary that systematically accounts for soft tissue variations. This model transforms each soft tissue contact point into its corresponding bone surface point through computational adjustment, eliminating the need for direct bone contact and the variability associated with manual tissue piercing or contact methods
3Device complexity
If existing bone model registration methods do not account for soft tissue variations, then the process is simpler, but registration accuracy decreases
Solution Approach 1:
The patent applies local quality by calculating soft tissue thickness individually at each point in the point cloud rather than using a uniform thickness value. The system identifies anatomical landmarks and calculates localized thickness measurements that vary across different regions of the bone surface, thereby improving registration accuracy while maintaining a manageable process through automated computational methods
Data Source
AI summary
Systems and methods for planning and assisting orthopaedic surgical procedures include a computing device and a robotic surgical device. The computing device defines a surgical coordinate system relative to a bone of a patient and captures a plurality of point positions in the surgical coordinate system. The plurality of point positions includes a first point position representing a location on a soft tissue surface covering a portion of the patient's bone. The computing device identifies an estimated soft tissue thickness value for each of the plurality of point positions and registers a three-dimensional model of the patient's bone in the surgical coordinate system based on the plurality of point positions and the estimated soft tissue thickness values. The computer system may control the robotic surgical device according to the registered bone model.