Surgical Instrument Tendon Preload-and-Locking Mechanism
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Solution Overview
Problem
Current laparoscopic and endoscopic surgical instruments face challenges in providing precise control over the tensile force of tensile members, which affects the responsiveness and tactile feedback during surgical procedures, leading to potential declines in instrument performance over time due to tension losses.
Innovation Solution
A preload mechanism with ring-shaped guides is introduced to adjust the tensile force in the tensile member by varying its lateral distance, allowing for increased tension and improved control through longitudinal or rotational movement of a movable guide, thereby maintaining optimal instrument performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tensile member is used to control the end effector, then the surgeon can manipulate the instrument, but the tensile force may decrease over time leading to loss of control and tactile feedback
Solution Approach 1:
The preload mechanism applies preliminary tensile force to the tensile member before surgical use through longitudinal movement of the movable guide, which increases the lateral distance and pre-tensions the member. This preliminary action compensates for expected tension losses during surgery, maintaining reliable control throughout the procedure.
Solution Approach 2:
The system allows dynamic adjustment of the tensile force parameter by moving the movable guide longitudinally or rotating it about the longitudinal axis. This changes the lateral distance between guides, thereby adjusting the tensile force to compensate for degradation over time and maintain optimal control characteristics.
2Ease of operation
If the tensile force is increased to improve responsiveness, then tactile feedback is enhanced, but the device complexity increases due to the preload mechanism
Solution Approach 1:
The movable guide serves multiple functions: it acts as a structural support element, a tensioning mechanism through longitudinal movement, and an adjustment knob through rotational movement. This multi-functionality allows the system to enhance responsiveness without adding separate dedicated components for each function.
Solution Approach 2:
The movable guide acts as an intermediary between the surgeon's manual adjustment actions and the tensile member tensioning. By providing a simple rotational or longitudinal interface, it mediates the complex interaction between the surgeon's input and the internal tensile force adjustment, simplifying the user interface while maintaining precise control.
Data Source
AI summary
A surgical instrument includes a handle, an elongated shaft and an end effector extending distally from the shaft. A tensile member is preloaded with a tensile force and extends at least partially through the shaft. A preload mechanism for adjusting the tensile force includes first and second guides in contact with the tensile member to restrain the tensile member at respective first and second lateral distances from a longitudinal axis. A third guide is disposed longitudinally between the first and second guides and is in contact with the tensile member to restrain the tensile member at a third lateral distance from the longitudinal axis. The third guide is movable to vary the third lateral distance and a corresponding length of the tensile member disposed longitudinally between the first and second guides to thereby vary the tensile force.