Sonotrode with Transverse Perforations for Bone Cutting
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Solution Overview
Problem
Ultrasonic surgical instruments are less suitable for cutting through bone material due to the high-frequency vibrations causing bone structure breakdown, which prevents the instrument head from penetrating deeper and results in the accumulation of dissolved bone material, limiting their effectiveness in surgical operations.
Innovation Solution
The sonotrode features a longitudinally extending instrument head with transverse openings that provide elastic mobility, allowing for the removal of dissolved bone material and enabling deeper penetration, combined with a cutting surface design that includes recesses for efficient bone processing and protection of soft tissue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-frequency vibrations are used to break down bone structure, then bone material is dissolved effectively, but the instrument head cannot penetrate deeper due to accumulation of dissolved bone material
Solution Approach 1:
The instrument head is segmented by providing multiple openings (e.g., 3-10 openings) that divide the solid structure into regions separated by thin walls. This segmentation allows dissolved bone material to be channeled through the openings while maintaining structural integrity for penetration.
Solution Approach 2:
The instrument head is designed with a porous-like structure featuring multiple openings with cross-sectional areas between 0.1-2.0 mm². This porous configuration enables the head to maintain rigidity for penetration while allowing dissolved bone material to pass through, preventing accumulation.
2Strength
If the instrument head is made rigid for structural stability, then it maintains strength for cutting, but it lacks elastic mobility to remove dissolved bone material effectively
Solution Approach 1:
Different regions of the instrument head have different properties: the overall structure maintains rigidity for strength, while localized regions (walls between openings) are designed with specific thickness (0.2-1.0 mm) to provide elastic mobility. This allows the head to exhibit both strength and adaptive movement.
Solution Approach 2:
The instrument head transitions from a purely rigid structure to a dynamic structure with controlled elasticity. The openings create flexible zones that allow the head to move adaptively during cutting, enabling elastic mobility while maintaining overall structural strength through the remaining material framework.
3Adaptability or versatility
If openings are added to the instrument head to enable elastic mobility, then dissolved bone material can be removed, but the structural rigidity may be compromised
Solution Approach 1:
The structural parameters of the instrument head are optimized: opening cross-sectional area is controlled at 0.1-2.0 mm², wall thickness is maintained at 0.2-1.0 mm, and the number of openings is limited (3-10). These parameter constraints ensure that elastic mobility is achieved while structural rigidity is preserved.
Solution Approach 2:
The instrument head effectively becomes a composite structure combining rigid and flexible zones. The solid material provides rigidity while the openings create flexible regions, resulting in a composite structure that exhibits both rigidity for stability and elasticity for mobility.
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 sonotrode effectively cuts through bone by superimposing high-frequency vibrations with manual sawing movements, allowing for deeper penetration and efficient bone material removal while minimizing the risk of damaging soft tissues, thus enhancing the instrument's suitability for surgical bone cutting.
Implementation Method 1
A high-frequency mechanical vibration is generated with an ultrasonic transducer. The sonotrode is connected to the ultrasonic converter and is made to oscillate by the ultrasonic converter. When the cutter of the sonotrode is brought into contact with the tissue, the tissue is severed by the high frequency vibration.
Implementation Method 2
In contrast to the high-frequency vibrations of the ultrasonic transducer, however, the instrument head with the openings is given an elastic inherent mobility. Because the openings are aligned transversely to the longitudinal direction of the instrument head, the instrument head performs a movement within itself, which is superimposed on the high-frequency vibration driven by the ultrasonic transducer.
Data Source
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Figure 3~4
AI summary
The invention relates to a sonotrode for an ultrasonic surgical instrument. The sonotrode comprises an instrument head (17), which is equipped with a cutting device (18) extending longitudinally. According to the invention, the instrument head (17) is provided with a plurality of perforations (20) extending in the transverse direction through the instrument head (17). The perforations (20) have an oblong shape in cross section, wherein the largest cross-sectional extent of the perforations (20) and the longitudinal direction of the instrument head (17) enclose an angle of between 30° and 80°. By means of the perforations according to the invention, the instrument head (17) is given an intrinsic elastic mobility, by means of which the removal of the broken-up bone is taken care of.