Modular Femoral Knee Stem Extender with Adjustable Threaded Junction
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Solution Overview
Problem
Existing modular knee prostheses have limited adjustment capabilities and complex attaching mechanisms, making it difficult to achieve a precise fit for anatomical variations and increasing assembly time.
Innovation Solution
A prosthetic device with a modular junction system that allows the stem to be adjustably fixed to the femoral component in an infinite number of positions along the anterior-posterior direction using a single threaded engagement, eliminating the need for complex fastening mechanisms and reducing inventory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If modular components are used to accommodate different anatomical variations, then adaptability is improved, but device complexity increases due to multiple fixed attachment locations
Solution Approach 1:
The patent transforms the static, fixed attachment locations into a dynamic, adjustable system. The stem can be rotated to any angle within a range (e.g., 0-30 degrees) relative to the femoral component, allowing continuous adaptation to different anatomical variations rather than being limited to discrete pre-set positions. This dynamic adjustment mechanism reduces the need for multiple specialized components.
Solution Approach 2:
The patent creates a universal interface where a single stem design can accommodate various anatomical configurations through rotational adjustment. Instead of requiring different stem designs for different valgus angles, one universal stem can be adjusted to fit various angles, reducing inventory complexity while maintaining adaptability.
2Adaptability or versatility
If multiple fixed attachment locations are provided, then adaptability to different anatomical variations is improved, but assembly time increases due to complex fastening mechanisms
Solution Approach 1:
The dynamic rotational capability allows the stem to be adjusted to the correct angle during assembly rather than requiring pre-configured fixed positions. This eliminates the time-consuming process of selecting and installing different pre-positioned attachment locations, as the single stem can be rotated to any required angle using a simple mechanism.
Solution Approach 2:
The patent changes the attachment parameter from fixed discrete positions to continuous angular adjustment. The stem can be rotated to any angle within a range, allowing the surgeon to adjust the angle during the procedure to match the patient's anatomy, eliminating the need to time-consuming selection and installation of multiple pre-configured options.
3Ease of manufacture
If fixed attachment locations are used, then manufacturing simplicity is maintained, but precision of fit for unique anatomical structures is reduced
Solution Approach 1:
The patent maintains manufacturing simplicity by producing a single stem design rather than multiple fixed configurations. The dynamic rotational adjustment mechanism allows this single manufactured component to achieve precise fit for unique anatomical structures by being rotated to the exact required angle, combining ease of manufacture with high precision.
Solution Approach 2:
The patent transitions from fixed manufacturing positions to adjustable parameters. The stem is manufactured at a standard position but can be rotated to any required angle during assembly, allowing precise adaptation to unique anatomical structures without requiring complex precision manufacturing for each possible configuration.
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 precise fitting and simplified assembly of knee prostheses for various anatomical configurations, reducing assembly time and inventory needs while accommodating different valgus angles and bone sizes.
Implementation Method 1
a single threaded engagement
Data Source
AI summary
A knee prosthesis includes a femoral component and a stem for implanting in a femur. A modular junction is provided for attaching the stem to the femoral component. The femoral component may include a boss having a slot for receiving the components of the modular junction. A portion of the modular junction may be placed within the slot and the modular junction may be tightened in place on the boss by threading the stem into engagement with a portion of the modular junction. Accordingly, the stem may be connected to the femoral component by a single threaded engagement and the position of the stem may be adjusted to any desired location along the anterior-posterior direction on the femoral component.