Knee Implant Planning via Articular Feature Regression
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Solution Overview
Problem
Current methods for selecting implants in joint arthroplasty, such as knee arthroplasty, face challenges in accurately determining pre-operative joint geometry and prioritizing anatomical features, leading to potential strain or dysfunction of soft tissues due to improperly sized implants, and often rely on indirect measurements and simplified assumptions about joint mechanics.
Innovation Solution
A pre-operative planning technique involving the generation of computer models of the femur and tibia, establishment of mechanical reference frames, and prioritization of articular features through control points to optimize implant size and placement, accounting for disease states and the natural kinematic function of the joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If pre-operative imaging is used to determine joint geometry, then the planning process can be performed before surgery, but difficulty in accurately locating particular bone features and inaccurate characterization of articular features reduces measurement precision
Solution Approach 1:
The patent introduces a planning tool as an intermediary device that interfaces with the patient's bone structures during surgery. This tool incorporates indicators that directly reference specific bone features (such as the sulcus of the medial condyle) and provides real-time guidance for implant positioning, thereby achieving both time efficiency and measurement precision simultaneously
Solution Approach 2:
The patent replaces traditional mechanical measurement methods (such as gap balancing tools requiring multiple implants to be trialled) with a pre-configured planning tool that has predetermined indications for implant positioning. This substitution eliminates the need for iterative mechanical measurements while maintaining accuracy through pre-calculated reference points
2Reliability
If gap balancing tools and multiple implant trials are used, then implant selection can be guided by indirect indicia, but these approaches require specialized tools to be inserted into the open joint and add time to each procedure
Solution Approach 1:
The patent applies preliminary action by pre-determining implant positioning parameters before the surgical procedure. The planning tool is manufactured with pre-calculated indications for implant placement based on the patient's specific anatomy, eliminating the need for time-consuming intraoperative trial procedures while maintaining reliable implant selection
Solution Approach 2:
The patent creates a physical or digital copy of the patient's joint geometry through pre-operative scanning and modeling. This copy is used to determine optimal implant positioning, allowing accurate planning to be performed outside the operating room and transferred to the surgical procedure without requiring multiple physical implant trials
3Ease of operation
If anatomical features are given equal weight in selecting implants, then the selection process is simplified, but this approach leaves the ligaments surrounding the joint outside of an acceptable tension range and causes the joint to deviate from natural kinematic function
Solution Approach 1:
The patent applies local quality by differentiating the importance of various anatomical features in implant selection. The planning tool provides different indications for different bone features based on their relative importance to joint function and ligament tension, allowing the selection process to account for local variations in anatomical significance rather than treating all features equally
Data Source
AI summary
Articular features in a joint may be characterized by fitting equations to a series of control points representative of one or more articular features on a bone of the joint. The equations may be fit to the control points by use of a regression, such as a least squares regression. The fit equations may be used to create best fit curves for the articular features. Disease states may be accounted for in deriving the best fit curves from the fit equations. An articular implant may be constructed or selected to match the best fit curves.