Weightless traction system
Inventors
Assignees
Smith and Nephew Orthopaedics AG • Smith and Nephew Asia Pacific Pte Ltd • Smith and Nephew Inc
Publication Number
US-12364639-B2
Publication Date
2025-07-22
Expiration Date
2039-06-12
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Abstract
A system for translating a constant traction load to an object such as a medical device or a patient includes a plurality of independently rotatable, coaxially aligned spools, each housing a constant force spring fixed at respective ends to the spool and to a rigid member, a plurality of flexible biasing members each coupled on their respective first ends to a spool and at least partially wound around the spool. A plurality of connectors are connected to the respective other ends of the biasing members, which may comprise wire rope. The connectors are configured to quickly couple to and decouple, directly or indirectly, from the object to which the traction load is being delivered. A guide provides a partial path for one or more of the biasing members to the object. A selected load may be applied by coupling one or more of the reversible couplers tensioned by the constant force springs to the object, without use of gravitational loading.
Core Innovation
The invention provides a system and method for translating a constant traction load to an object requiring traction, such as a medical device or a portion of a patient's anatomy, without the use of gravitational loading. This system employs a plurality of independently rotatable, coaxially aligned spools, each housing a constant force spring fixed at respective ends to the spool and to a rigid member. A plurality of flexible biasing members, like wire ropes, are each coupled on one end to the spool and at least partially wound around it, with connectors at their other ends configured for quick coupling and decoupling to the object. A guide provides a partial path for the biasing members to the object, allowing the application of a selected load by coupling one or more of the reversible couplers tensioned by the constant force springs to the object.
The system is designed to maintain a generally constant tractive force during movement or repositioning of the object or patient, overcoming the limitations of traditional traction devices that rely on adjustable weights or threaded displacement devices. Traditional devices are often cumbersome, difficult to assemble and adjust, and may experience fluctuations in force due to limb stretching or slippage. This invention solves the problem by providing constant traction force via constant-force springs housed in spools that unwind or wind the biasing members, thus maintaining an approximately constant force as the object moves.
Additionally, the system includes a vertical support and an adjustable arm pivotably attached to it, enabling positioning of the traction load from virtually any location or direction. The casing housing the spools is rigidly affixed to the vertical support and includes slots to allow the biasing members to extend and retract. This design provides discrete adjustment of the traction load by selectively coupling or uncoupling the reversible couplers without repositioning the object, facilitating ease of use and safety in medical and surgical environments.
Claims Coverage
The patent includes one independent claim that defines the system features for translating a constant load via constant force springs and associated components. The main inventive features are:
Spools with constant force springs coaxially aligned about a rigid member
A plurality of independently rotatable, coaxially aligned spools rotatable about a same rigid member that is independent from the spools, each spool housing a constant force spring fixed to the spool inner circumferential wall at one end and to the rigid member at the other.
Flexible biasing members coupled to spools and partially wound thereon
A corresponding plurality of relatively inelastic, flexible biasing members, each coupled on a first end to an exterior contact point on the exterior surface of one spool and at least partially wound around the associated spool.
Connectors with reversible couplers for quick coupling and decoupling
A corresponding plurality of connectors attached to the second end of the biasing members, each including reversible couplers configured to quickly couple and decouple from the object requiring traction.
Guide mounted on vertical support providing a partial path for biasing members
A guide mounted on a vertical support including slides extending between the vertical support and the object, providing a partial path for the biasing members to the object.
Discrete load adjustment via selective coupling of reversible couplers
Selective coupling of one or more of the reversible couplers to the object applies a desired load such that repositioning the object results in negligible change in the load translated through the system.
Casing forming a closed body housing multiple spools rigidly affixed to vertical support
All spools are housed in the same casing rigidly affixed adjacent to the slides on the vertical support, with the casing outer surface defining multiple slots permitting extension and retraction of the biasing members without allowing connectors to enter the casing.
The claims cover a system that applies constant adjustable traction loads by using multiple coaxially aligned constant force spring spools, biasing members with quick connectors, and a guide assembly mounted on an adjustable vertical support, all housed in a casing permitting discrete load adjustments without gravitational loading.
Stated Advantages
Provides constant traction force without requiring gravitational loads, reducing weight and size of the system.
Enables adjustments to the position of the device or patient without changing the applied traction load.
Simplifies assembly and disassembly compared to traditional weight-based traction devices.
Reduces health and safety risks to surgical staff that might arise from handling suspended weights.
Allows discrete adjustment of traction load by selectively coupling or uncoupling biasing members while maintaining traction.
Facilitates ease of use through table-mounting or stand-alone configurations and adjustable arm positioning.
Documented Applications
Applying traction or suspension loads to a patient's limb or anatomical region during orthopaedic surgery.
Use in therapeutic and/or exercise situations involving medical devices requiring controlled traction.
Maintaining constant traction forces during open or arthroscopic surgery to distract bones of limb joints such as wrist, ankle, elbow, knee, shoulder, or hip.
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