Convex Shank Geometry for Surgical Scissors Beam Strength
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Solution Overview
Problem
Surgical instruments, such as scissors and forceps, face challenges in maintaining complete closure and grasping force when extended in length, due to reduced force transmission and flexibility issues, which are critical in delicate medical and dental procedures where reduced bulk and increased length are necessary.
Innovation Solution
Increasing beam strength in the shank and handle portions by creating convexity in these areas through stamping of heat treatable or non-heat treatable steel, ensuring that the entire force applied at the handle is transmitted to the blades or platforms, allowing for complete closure and effective manipulation in tight spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the length of the surgical instrument is increased to reduce bulk and reach tight operative fields, then the ability to access reduced openings is improved, but the flexibility of the flat handle and shanks causes flexing upon closure which prevents complete closure of the blades
Solution Approach 1:
The patent applies curvature to the shank portions by creating convexities in their configuration. This curvature transforms the flat, flexible shanks into arched structures that resist flexing during closure. The convex shape acts as a structural reinforcement that maintains rigidity while allowing the instrument to achieve complete blade closure despite its extended length.
2Ease of operation
If the length of the scissors or forceps is increased with narrower flat shanks and handles, then the ability to manipulate in tight openings is improved, but the force applied at the handle results in less force at the working end
Solution Approach 1:
The convexities created in the shank portions provide structural reinforcement that reduces energy loss through flexing. This curved geometry acts as a beam-strengthening feature that efficiently transmits applied force from the handle to the working end, maintaining adequate cutting or grasping force despite the instrument's extended length and narrow profile.
3Strength
If beam strength is increased in the shank and handle portions to ensure complete closure, then the force transmission is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent creates convexities in the shank portions through a stamping process, which is a relatively simple manufacturing method. This stamping technique forms the curved, beam-strengthening geometry in a single forming operation, avoiding the need for complex multi-step machining or assembly processes. The convexities are integrated into the stamping die design, making the strengthened structure economical to produce.
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 surgical instruments to maintain complete closure and grasping force even at extended lengths, enhancing their usability in delicate procedures while being more economical to manufacture, with the added benefit of using softer steel that can be heat-treated for optimal beam strength.
Implementation Method 1
A manufacturing benefit is derived by fabricating the present instrument out of softer, heat treatable steel, and then heat treating to harden.
Data Source
AI summary
A surgical scissors or forceps for use where the operative field is greatly reduced and the instrument is elongated with a low profile and having convexity of the shanks in order to measurably increase the beam strength of the device. The instrument is further provided with interchangeable handle inserts that provide additional weight at the back end of the instrument.