Artificial Hip Joint Stem Concave Part Design
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Solution Overview
Problem
The existing artificial hip joint stem implantation process faces difficulties in driving the stem into the medullary cavity due to limited directional control, which can result in biting and damage to the stem and inserter, especially in surgical procedures like the direct anterior approach where the abdomen obstructs the driving path.
Innovation Solution
The artificial hip joint stem features a concave part with a decreasing distance between inner and outer wall portions, allowing the inserter to be inclined and rotated, enabling stem insertion from various angles and reducing the risk of biting, while also including a screw hole for conventional inserter use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the stem is driven only from immediately above along the longitudinal direction, then the structure is simple, but the driving performance deteriorates and the stem and inserter may bite each other
Solution Approach 1:
The concave part allows the inserter to approach and drive the stem not only from the longitudinal direction but also from oblique directions. By introducing multi-directional driving capability (changing from one-dimensional to multi-dimensional approach), the patent resolves the contradiction between structural simplicity and driving performance, enabling the surgeon to select optimal driving angles while maintaining a relatively simple overall structure.
2Adaptability or versatility
If the stem is driven from an oblique direction, then the driving flexibility improves, but the stem and inserter may bite each other causing damage
Solution Approach 1:
The concave part acts as an intermediary structure between the inserter and the stem body. It provides a controlled interface that guides the inserter's movement and maintains proper alignment during oblique driving, preventing direct contact between the inserter's sharp edges and the stem body that would cause biting and damage.
Solution Approach 2:
The concave part's geometry is designed to prevent biting and damage before they can occur. By creating a predetermined path and contact surfaces within the concave part, the structure proactively counteracts the potential harmful effects of oblique driving, ensuring that the inserter and stem do not bite each other even when driven from oblique directions.
3Ease of manufacture
If a conventional column-shaped inserter is used for screw fixation, then the制造 simplicity is maintained, but the driving control is limited
Solution Approach 1:
The inserter is divided into functionally distinct segments: a column-shaped main body for simple manufacturing and grip, and a separate concave part (or modular attachment) that provides enhanced driving control. This segmentation allows each component to be optimized independently - the main body remains simple to manufacture while the concave part delivers superior operational control.
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(b)
Figure 3
AI summary
In an artificial hip joint stem of the present invention, a distance between an inner wall portion and an outer wall portion is decreased as separating from an opening part in a sectional view that is parallel to a stem central axis and includes the inner wall portion and the outer wall portion, and both a front wall portion and a rear wall portion have a planar region in a sectional view that is parallel to the stem central axis and includes the front wall portion and the rear wall portion. A stem inserter of the present invention includes a disk-shaped front end part. The present invention also provides an artificial hip joint system including the artificial hip joint stem and the stem inserter, and an artificial hip joint including the artificial hip joint stem.