Acetabular Rim Cutter with Spring-Biased Guide Element
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Solution Overview
Problem
Surgeons face difficulties in accurately locating and cutting the rim of an acetabulum to create a predetermined annular seating surface for a flanged acetabular cup, as existing rotary cutters lack precision in alignment and depth control.
Innovation Solution
An acetabular rim cutter with a rotatable carrier and a part-spherical guide element for precise alignment, combined with a depth cutting control system and radial cutting teeth, allows for accurate cutting and reaming of the acetabulum, featuring a modular design for different sizes and depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotary cutter is used to cut the acetabulum rim, then the cutting operation can be performed, but the surgeon has difficulty in locating the cutter with sufficient accuracy
Solution Approach 1:
A guide element is introduced as an intermediary component between the surgeon and the cutter. The guide element locates on the acetabulum and guides the cutter to the correct position, eliminating the difficulty of direct cutter location while maintaining cutting functionality
Solution Approach 2:
The guide element extends beyond the cutter in the axial dimension, providing an additional locating point that projects further into the acetabulum. This dimensional extension enables more precise location without compromising the cutting operation
2Manufacturing precision
If the rim is cut to create an annular seating surface, then the cup can be seated, but it is difficult to ensure the seating surface is at a predetermined distance from the base and the cup bearing surface is at the desired depth
Solution Approach 1:
The guide element is designed with a predetermined length that corresponds to the desired depth of the seating surface from the base. By positioning the guide element correctly on the acetabulum before cutting, the cutter automatically achieves the correct depth without requiring complex depth control systems
Solution Approach 2:
The guide element serves dual functions: it locates the cutter axially and simultaneously controls the depth of the cut. The predetermined length of the guide element self-regulates the seating surface depth, eliminating the need for separate depth control mechanisms
3Adaptability or versatility
If a fixed design cutter is used, then the structure is simple, but it cannot adapt to different acetabulum sizes and depth requirements
Solution Approach 1:
The cutter system is divided into separate modular components: the guide element and the cutter can be used in combination, and different guide elements with varying lengths can be selected based on the specific acetabulum size and depth requirements. This segmentation enables adaptability while maintaining relative structural simplicity of each component
Solution Approach 2:
The guide element serves multiple functions: it provides axial location for the cutter, controls the depth of the seating surface, and can be selected in different lengths to accommodate various acetabulum sizes. This multi-functionality achieves versatility without proportionally increasing device complexity
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
The solution enables precise alignment and cutting of the acetabulum rim, ensuring correct positioning and depth of the annular seating surface, facilitating the secure seating of a flanged acetabular cup and allowing for modular adaptation to various acetabulum sizes and surgical needs.
Implementation Method 1
The guide element is axially movable with respect to the shaft of the drive axis and is spring-biased against the acetabulum
Data Source
AI summary
An acetabular rim cutter has an annular cutting face provided on a rotatable carrier. A coupler is provided for attaching the carrier to a rotational power source. A guide element is axially aligned with the cutting face to locate and align the cutting face on the acetabulum with which it is to be used. Preferably, the guide element is axially movable in relation to the cutting face and a resilient element is provided for biasing it axially away therefrom.