Stylus Assembly Locking Mechanism for Surgical Jig Positioning
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Solution Overview
Problem
Existing stylus assemblies for positioning cutting guides in joint replacement surgery often result in inaccurate positioning due to unintentional movement during removal, as they rely on damaged areas for reference, leading to misdirected incisions.
Innovation Solution
A stylus assembly with a C-shaped body, adjustable stylus, and a locking mechanism that allows loose insertion and secure locking with minimal handling, referencing from the less worn posterior femoral condyle, utilizing a cam-based locking system for precise and backlash-free positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the stylus is freely adjustable relative to the cutting guide, then the stylus can be positioned accurately, but the cutting guide may move unintentionally when the stylus is removed
Solution Approach 1:
The stylus assembly transitions from a static rigid connection to a dynamic adjustable connection. The stylus can be adjusted relative to the body through the retaining member and locking mechanism, allowing dynamic positioning while maintaining stability when locked. This resolves the contradiction by enabling both adjustment capability and position stability through controlled dynamics.
Solution Approach 2:
The locking mechanism acts as an intermediary between the stylus and the body. It mediates the connection by allowing the stylus to be adjusted during positioning, then securing it in place when needed. This intermediary component enables the system to switch between adjustable and stable states, resolving the contradiction between positioning accuracy and guide stability.
2Reliability
If the stylus is rigidly fixed to the cutting guide, then the cutting guide remains stable, but the stylus cannot be adjusted for optimal positioning
Solution Approach 1:
The connection between stylus and body is made dynamic through the locking mechanism. The stylus can be adjusted freely when the locking mechanism is in the unlocked state, then secured when locked. This dynamic design allows the system to adapt between adjustability and stability based on operational needs, resolving the contradiction between these two requirements.
Solution Approach 2:
The stylus is pre-adjusted to the desired position before final locking. The locking mechanism is designed to lock in place after adjustment is complete, ensuring both adjustability during setup and stability during use. This preliminary adjustment followed by secure locking resolves the contradiction between ease of operation and position stability.
3Measurement precision
If the stylus assembly requires multiple components for adjustment and locking, then positioning precision is improved, but the device complexity increases
Solution Approach 1:
Multiple functions are merged into integrated components. The retaining member combines the stylus support function with the locking function. The locking mechanism integrates both the adjustment control and the securing action. This merging reduces the total number of separate components while maintaining positioning precision, resolving the contradiction between precision and complexity.
Solution Approach 2:
The locking mechanism serves multiple functions: it secures the stylus to the body, maintains positioning precision, and enables easy adjustment when unlocked. This multi-functionality reduces the need for separate components for each function, thereby reducing overall device complexity while maintaining high positioning precision.
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 accurate and reliable positioning of cutting guides by minimizing handling and movement during stylus removal, reducing the risk of misdirection and improving surgical precision.
Implementation Method 1
utilizing a cam-based locking system for precise and backlash-free positioning
Data Source
AI summary
A stylus assembly is adapted to be attached to a surgical jig. The stylus assembly comprises a body having first and second arms with a space therebetween for receiving a portion of the surgical jig, a stylus adjustably mounted relative to the body, and a locking member in use, actuation of the locking member from an unlocked to a locked position enables locking of the body to the surgical jig and locking of the stylus relative to the body.