Surgical Retractor Arm Mechanism for Controlled Force Feedback

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Solution Overview

Problem

Existing surgical retractors, such as the Finochietto retractor, lack force-feedback, apply uneven forces due to rotational mechanisms, and expose surgical sites to potential damage from moving parts, while being inflexible in accommodating surgeon preferences and patient needs.

Innovation Solution

A surgical retractor device with pivotable arms and handles that operate in the same plane, providing force-feedback through mechanical or hydraulic mechanisms, ensuring controlled opening and closing with interchangeable parts and minimizing exposure to surgical equipment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a hand-cranked lever mechanism is used to open the retractor arms, then the device can be operated manually, but the force applied is uneven and the opening speed is not linearly controllable

Engineering Contradiction:
Improvemanual operationVSAvoidopening speed control
Core Design Contradiction:
Ease of operationVSProductivity

Solution Approach 1:

The patent replaces the hand-cranked lever mechanism with a mechanical or hydraulic actuator system that provides linear, controlled movement of the retractor arms. This substitution eliminates the non-linear rotational motion of the crank and replaces it with a system that allows for more precise and uniform control of the opening speed and force application.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If metal-on-metal parts are used in the Finochietto retractor, then the structure is durable, but lubrication is required to function optimally

Engineering Contradiction:
Improvestructural durabilityVSAvoidmaintenance requirement
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent employs a disposable design where the entire retractor device or its critical components are discarded after a single use. This eliminates the need for lubrication and maintenance of metal-on-metal parts, as the device is sterilized and disposed of rather than reused. The disposable nature ensures optimal function without requiring post-sterilization lubrication.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If the lever transverses with the device during rotation, then the opening mechanism functions, but greater momentum is applied causing potential damage

Engineering Contradiction:
Improveopening mechanism functionVSAvoidmomentum-induced damage
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent removes the transversing lever mechanism entirely and replaces it with a system where the actuator applies force directly in line with the device's axis of operation. This extraction of the problematic lever component eliminates the transverse displacement and associated momentum that could damage bones or tissue, while still achieving the desired arm opening function through direct linear actuation.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If the bar with notches is exposed in the open state, then the mechanism is accessible, but surgical equipment may be hindered or damaged

Engineering Contradiction:
Improvemechanism accessibilityVSAvoiddamage to surgical equipment
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent designs the actuator and its components to be nested within the retractor housing when not in use. The bar with notches or other mechanical components are retracted into the device body, leaving only the essential gripping surfaces exposed. This nesting approach maintains mechanism functionality while preventing exposed components from interfering with or damaging surgical equipment such as tubes and cords.

Inventive Principle:
Principle #7Nested doll (Nesting)

5Device complexity

If classical retractors have few interchangeable parts, then the device is simple, but it does not cater to specific surgeon preferences or patient needs

Engineering Contradiction:
Improvenumber of partsVSAvoidcustomization capability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent divides the retractor device into modular segments that can be interchanged. The gripping surfaces, arm configurations, and actuator types can be selected and attached based on specific surgical requirements, surgeon preference, or patient anatomy. This segmentation allows for customization while maintaining overall device simplicity through standardized connection interfaces.

Inventive Principle:
Principle #1Segmentation

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 allows precise control of force application, reduces patient morbidity, and facilitates rapid closure, while protecting surgical equipment and enhancing user comfort and efficiency.

Implementation Method 1

The device further comprises a hydraulic actuator configured to apply a force to the first and second press arms

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Data Source

PatentEP4297657B1Surgical retractor device
Publication Date: 2026.03.18 VIKING ARM MEDICAL AS
  • EP4297657B1 patent drawingFigure 1~2
  • EP4297657B1 patent drawingFigure 3~4
  • EP4297657B1 patent drawingFigure 5~6

AI summary

The invention relates to a surgical retractor device comprises a housing (7), a first press arm (2) pivotably coupled to the housing, and a second press arm (3) pivotably coupled to the housing, said first and second arm having a rotational movement in a first plane. Each press arm comprises a gripping member (4a, 4b) pivoting around an axis at a right angle with the first plane, at the outer end of each press arm, and an attachment means at the inner end of the arm, wherein the housing comprises an opening and closing mechanism. The housing (7) comprises an opening and closing mechanism (6), the mechanism comprising a rotatable first and second press arm attachment structure (10a, 10b) for attaching the attachment means (5a, 5b) of the press arms, symmetrically positioned a distance away from a centerline of the surgical device, to the housing (7), and; rotatable first and a second handle attachment structure (13a, 13b), and; a transfer mechanism to transfer rotation from said first and second handle attachment structure (13a, 13b) to said first and second press arm attachment structure (10a, 10b). The device further comprises a first and a second handle (8, 9) for operating the opening and closing mechanism (6). The first and second handle (8, 9) comprises a handle attachment means (14a, 14b) at the inner end of the handle for attaching said handles to the first and second handle attachments structures (13a, 13b), respectively, and; a handle structure operable by a user. The first and second handle (8, 9) having a rotational movement in the first plane and being symmetrically positioned a distance away from the centerline of the surgical device (1).