Adjustable Surgical Limb Support With Locking Gas Cylinder
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Solution Overview
Problem
Existing leg stirrups for surgical tables lack a full range of motion adjustment, particularly in supination/pronation direction, and are cumbersome to manipulate, making it inconvenient for physicians to adjust patient limb positions during procedures.
Innovation Solution
A stirrup-type leg holder with a single control mechanism allowing independent adjustment in lithotomy, abduction/adduction, and supination/pronation dimensions, featuring a ball-and-socket arrangement and a cable-operated release mechanism for easy adjustment at the distal end, enabling movement along three axes of rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional leg stirrup with proximal attachment mechanism is used, then the stirrup can be attached to the surgical table, but the adjustment is cumbersome and requires direct manipulation near the procedure site
Solution Approach 1:
The patent inverts the traditional attachment mechanism location from proximal (near the patient's hip) to distal (at the foot end of the stirrup). This allows the physician to manipulate the adjustment mechanism at the distal end, which is more convenient and accessible during surgery, while the actual attachment point remains at the proximal end to the surgical table.
Solution Approach 2:
The patent introduces a cable-operated release mechanism as an intermediary between the physician's manual input and the clamping assembly. The cable transmits force from the distal control mechanism to the proximal clamping assembly, enabling easy adjustment without direct manipulation near the procedure site.
2Adaptability or versatility
If a leg stirrup with limited adjustment range is used, then the device structure remains simple, but it lacks full range of motion adjustment particularly in supination/pronation direction
Solution Approach 1:
The patent employs a ball-and-socket arrangement where a spherical ball member interfaces with a socket in the clamping assembly. This spherical geometry naturally provides multi-directional rotation capability, enabling adjustment in lithotomy, abduction/adduction, and supination/pronation dimensions without requiring complex mechanical linkages for each degree of freedom.
Solution Approach 2:
The ball-and-socket joint serves multiple functions simultaneously: it provides attachment to the surgical table, enables multi-axis adjustment, and allows full range of motion in three dimensions. This universal joint design eliminates the need for separate mechanisms for each adjustment direction.
3Reliability
If a locking mechanism is added to hold the limb support position, then position stability is improved, but the mechanism becomes more complex and harder to operate
Solution Approach 1:
The spring-loaded clamping assembly automatically engages and locks the ball-and-socket joint when the release mechanism is not activated. The spring force maintains constant clamping pressure on the ball, providing self-locking capability that holds the limb support position without requiring additional locking components or complex mechanisms.
Solution Approach 2:
The patent replaces complex mechanical locking systems with a spring-loaded friction-based clamping mechanism. The spring provides continuous holding force, and the friction between the clamped components maintains position stability, eliminating the need for screws, clips, or other complex locking hardware.
Data Source
AI summary
A limb holder comprising: a mounting bracket for attachment to a surgical table; a mounting element comprising a spheroidal surface for attachment to said mounting bracket; a clamping assembly for providing a clamping engagement about said spheroidal surface of said mounting element, said clamping assembly comprising an upper jaw and a lower jaw, wherein said upper jaw and said lower jaw are biased towards one another so as to provide said clamping engagement about said spheroidal surface of said mounting element; a limb support element mounted to said clamping assembly via a support rod; a release mechanism mounted to said support rod and connected to said clamping assembly for selectively releasing said clamping engagement of said clamping assembly about said spheroidal surface of said mounting element, whereby to allow said limb support element to be repositioned relative to said mounting element and hence repositioned relative to the surgical table; anda locking gas cylinder having a first end and a second end, said second end being biased away from said first end, wherein said first end of said locking gas cylinder is mounted to said mounting bracket and said second end of said locking gas cylinder is mounted to said support rod, whereby to bias said support rod away from said mounting bracket, and further wherein said second end is selectively lockable relative to said first end.