Patient Limb Positioning Cradle for Operating Table
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Solution Overview
Problem
Existing devices for angular positioning of a patient's limb on an operating table, such as those used during knee operations, face issues with lateral torque leading to deterioration, malfunctions, and lack of precision due to tilting of the patient's pelvis, hindering surgical accuracy and access for surgeons.
Innovation Solution
A device with a cradle positioning system that includes a sole, clevis, arm-holder, slide, and shaft, allowing secure mounting on either side guide rail, with motorized rotation and adjustable length to maintain vertical alignment and distribute force uniformly, avoiding excessive compression on the thigh and knee joint, and optionally incorporating a laser beam generator for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a cylinder with a rod supporting a transverse axis carrying a cradle is used for limb positioning, then the limb can be supported at an angle, but significant lateral torque is applied to the cylinder head and rod causing deterioration and malfunction
Solution Approach 1:
The patent extracts the harmful lateral torque from the cylinder by introducing a separate support structure (first support means) that carries the cradle and position the rotation axis away from the cylinder rod. This separates the positioning function from the support function, eliminating the torque problem while maintaining angular positioning capability.
Solution Approach 2:
The patent introduces a second support means as an intermediary structure that carries the rotation axis and cradle independently of the cylinder rod. This intermediary structure absorbs the lateral loads and prevents them from being transmitted to the cylinder, resolving the contradiction between positioning capability and cylinder durability.
2Ease of operation
If the positioning device is mounted on a side edge of the operating table, then angular positioning is achieved, but the patient's pelvis tilts causing the knee to move outside a vertical plane parallel to the longitudinal axis of the operating table
Solution Approach 1:
The patent moves the positioning mechanism from a side-mounted configuration to a top-mounted configuration on the operating table. By positioning the cradle and rotation axis above the patient's knee in a vertical plane, the system eliminates pelvic tilting and ensures the knee moves precisely in the required vertical plane, achieving both positioning capability and vertical alignment precision.
Solution Approach 2:
The patent creates an asymmetric support structure where the first support means is attached to the top surface of the operating table rather than the side edge. This asymmetric positioning allows the cradle to be positioned directly over the patient's limb, eliminating the lever arm that causes pelvic tilting while maintaining angular positioning capability.
3Length of moving object
If a long axis is used to carry the cradle to reach the patient's limb, then positioning reach is improved, but lateral torque increases causing cylinder deterioration
Solution Approach 1:
The patent extracts the cradle and rotation axis from the cylinder rod structure and places them on a separate support structure. This allows the use of a longer positioning arm to reach the patient's limb without the long arm being attached to the cylinder rod, thereby eliminating the lateral torque problem while maintaining extended reach capability.
4Stability of the object's composition
If the positioning device is rigidly mounted to provide stable support, then structural stability is improved, but the device cannot adapt to different operating table widths and patient morphologies
Solution Approach 1:
The patent introduces adjustable and movable elements into the support structure, including adjustable support means that can be positioned at different locations on the operating table and adjustable cradles that can accommodate different patient anatomies. This dynamic design maintains structural stability while providing adaptability to various configurations.
Solution Approach 2:
The patent designs the support structure with universal mounting capabilities that can be attached to operating tables of different widths and configurations. The adjustable support means and cradle positioning allow a single device design to serve multiple patient morphologies and surgical scenarios, achieving both stability and versatility.
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 device ensures precise angular positioning of the patient's limb, reducing tilting and compression, enhancing surgical precision and access, and accommodating various operating table widths and patient morphologies, thus improving the conduct of surgical operations.
Implementation Method 1
an arm-holder, rotatably mounted around said rotation shaft and actuated in rotation in a plane perpendicular to said sole by a motorization
Implementation Method 2
a slide, mounted integral with the aforesaid arm-holder, on the side opposite to the aforesaid motorization, and able to guide a slider in a plane perpendicular to said sole
Implementation Method 3
a hub, whose axis is located in a plane parallel to said sole and perpendicular to the longitudinal axis of the operating table, and able to slide through said arm along the main axis of said arm
Implementation Method 4
a shaft, rotatably and translatable mounted in the aforesaid hub, whose axis is collinear with the aforesaid axis of the hub, and supporting at one of its ends the aforesaid cradle
Implementation Method 5
the aforesaid rotation shaft, located close to the upper part of said yoke, allowing the arm holder to pivot, may include a bore, in order to be able to accommodate a laser beam generator, of small size and low power or any another light beam generator, to allow the surgeon precise visual positioning of the axis of the aforesaid shaft of rotation with respect to the coxo-femoral joint
Data Source
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AI summary
The invention relates to a device for angularly positioning a member of a patient lying on an operating table (TO), comprising means for positioning a cradle (Be) supporting the member of the patient relative to lateral guide rails (RG1, RG2) of the operating table (TO). Said positioning means comprise: means (MS1, MS2, MS3) for fixing the cradle positioning means (Be) on either of the two lateral guide rails (RG1, RG2) of the operating table (TO), and; means for positioning this cradle (Be) along an axis (?3) contained in a plane parallel to that defined by the operating table (TO), and perpendicular to the principal axis (?) of the operating table (TO).