Modular Knee Prosthesis Coupler for Bowed Canal Alignment
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Solution Overview
Problem
Current knee prostheses lack the ability to accommodate individual anatomical variations, particularly in bone bowing and kinematic alignment, leading to improper positioning and potential pain during knee replacement surgeries.
Innovation Solution
A modular prosthesis system with a coupler that allows for variable alignment, including offset and angular adjustments, to match specific patient anatomy, using a kit of couplers with different configurations selected based on patient-specific measurements or computer-assisted surgical systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed V/V angle is used for the stem, then manufacturing and implantation are simplified, but the prosthesis cannot accommodate variations in patient bone anatomy
Solution Approach 1:
The prosthesis is divided into modular components including a stem, a coupler, and a tray that can be independently configured and assembled. The coupler acts as an intermediate segment that provides angular adjustment capability between the stem and tray, allowing customization to match patient-specific bone anatomy while keeping each individual component relatively simple in design
Solution Approach 2:
The coupler incorporates dynamic angular adjustment capability, allowing the V/V angle to be varied within a range (e.g., 0-15 degrees) rather than being fixed. This enables the prosthesis to adapt to different bone anatomies by selecting appropriate angular configurations during implantation, thereby improving versatility without requiring completely different prosthesis designs for each patient
2Ease of operation
If the stem is rigidly fixed at a set position, then implantation is straightforward, but optimal positioning relative to the intramedullary canal cannot be achieved in bowed bones
Solution Approach 1:
The rigid connection between stem and tray is segmented by introducing a movable or adjustable coupler interface. This allows the stem and tray to be positioned independently and connected at an optimized angle, maintaining implantation simplicity while achieving precise positioning accuracy for bowed intramedullary canals
Solution Approach 2:
The coupler enables change in the angular parameter (V/V angle) between stem and tray to accommodate variations in bone anatomy. By adjusting this parameter within a defined range, the system achieves optimal stem positioning accuracy in bowed bones without complicating the overall implantation procedure
3Adaptability or versatility
If offset is provided in the knee implant, then implantation is facilitated, but there is no uniformity as each patient is different
Solution Approach 1:
A single modular prosthesis design with adjustable coupler serves multiple patient anatomies by varying the angular configuration. The coupler's ability to adjust within an angular range (e.g., 0-15 degrees V/V) allows one universal implant design to accommodate diverse bone anatomies, eliminating the need for multiple specialized implant variants
Data Source
AI summary
A knee prosthesis (10, 20) is disclosed. In one example of an embodiment, the knee prosthesis includes a load bearing component (12, 22) and a stem (14, 24) arranged and configured to be coupled within an intramedullary canal of a patient's bone. In some embodiments, the knee prosthesis may also include a coupler (16) for coupling the stem to the load bearing component. In use, the stem is offset from and angled relative to the load bearing component to facilitate reception of the stem in a bowed or angled intramedullary canal of a patient's tibia or femoral bone. In one example of an embodiment, the coupler may include first (32) and second (34) ends, the central longitudinal axis (33) of the first end and the central longitudinal axis (35) of the second end are offset from one another, non-parallel to one another, and do not intersect or cross each other's path at any point.