Variable pitch tapered compressing screw for dynamic compression
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Publication Number
US-12256968-B2
Publication Date
2025-03-25
Expiration Date
Abstract
A bone screw is provided with a resilient component that enables a surgeon to measure the amount of compression effected by the bone screw during installation and dynamically maintain that compression across the provided bone screw during fracture healing. The provided bone screw includes a leading component, a trailing component, and a resilient component that may be compressed between the leading and trailing components and which is arranged such that the bone screw's axial rigidity is maintained. The leading and trailing components may be engaged together or independently by a driving instrument. Advancing or receding only the leading component or only the trailing component alters a compression force effected by the bone screw between two bone fragments, enabling a surgeon to set a desired compression force. A measurement tool is also provided that may be used to measure an amount of compression force effected by an installed bone screw.
Core Innovation
The disclosed invention relates to a bone screw for dynamic fracture compression that uses independently rotatable leading and trailing exteriorly threaded components. A longitudinally compressible resilient component is positioned around a portion of the leading component and within the trailing component, and is configured to be longitudinally compressed between the leading component and the trailing component and between first and second ends.
A first end of the resilient component is fixedly attached to one of the leading component or the trailing component in both a compressed state and a non-compressed state. This attachment causes the resilient component to rotate with the fixedly attached one of the components when only that component is rotated relative to the other, while the resilient component does not rotate with the other component when only the other component is rotated.
The other component includes a ridge in contact with, but not fixedly attached to, a second end of the resilient component in the compressed state, which allows rotation between the leading component and the trailing component without twisting the resilient component. The ridge is configured to prevent axial movement in at least one direction of the second end of the resilient component relative to the other component, and the document further describes measuring compression force by measuring displacement between leading and trailing interfaces and converting displacement to compression force via a spring constant.
Claims Coverage
The document includes three independent claims. The independent claims cover a bone screw structure, a system for compressing a bone fracture, and a method for preparing a bone hole, inserting the screw, measuring compression force, and adjusting the compression force.
Independently rotatable leading and trailing threaded components with fixed rotation behavior
A bone screw comprising a leading component including a first exteriorly threaded region and a second exteriorly threaded region; a trailing component including a third exteriorly threaded region; and a resilient component positioned around a portion of the leading component and within the trailing component, wherein a first end of the resilient component is fixedly attached to one of the leading component or the trailing component in each of a compressed state and a non-compressed state so that the resilient component rotates with the fixedly attached component when only that component is rotated relative to the other, but does not rotate with the other component when only the other component is rotated relative to the one.
Ridge contact arrangement preventing twisting and axial movement of resilient end
The other of the leading component or the trailing component comprises a ridge in contact with, but not fixedly attached to, a second end of the resilient component when the resilient component is in the compressed state, which allows the leading component and the trailing component to rotate relative to one another without twisting the resilient component, wherein the ridge is configured to prevent axial movement in at least one direction of the second end of the resilient component relative to the other.
System compression using leading and trailing driver features
A system for compressing a bone fracture comprising a bone screw including a leading component with a first driver feature and a trailing component with a second driver feature, and a resilient component positioned around a portion of the leading component and within the trailing component, together with a first driving component configured to engage both the first driver feature of the leading component and the second driver feature of the trailing component, and a second driving component configured to engage either only the first driver feature of the leading component or only the second driver feature of the trailing component.
Method for fracture compression with measuring and adjusting compression force
A method for compressing a bone fracture comprising preparing a bone hole to receive a bone screw; inserting the bone screw into the prepared bone hole via a first driving component configured to engage both the first driver feature of the leading component and the second driver feature of the trailing component; measuring a compression force effected by the inserted bone screw; and adjusting the compression force effected by the inserted bone screw via a second driving component configured to engage either only the first driver feature of the leading component or only the second driver feature of the trailing component.
Overall, the claim set centers on a bone screw that longitudinally compresses a resilient component between independently rotatable leading and trailing threaded components while enabling relative rotation without twisting through a ridge in contact with a resilient end. The independent system and method claims add driver-feature engagement for compressing a bone fracture, including measuring compression force and adjusting it by selectively driving either the leading component or the trailing component.
Stated Advantages
Enables each of the leading component and the trailing component to rotate relative to one another without twisting the resilient component.
Prevents axial movement in at least one direction of the second end of the resilient component relative to the other of the leading component or the trailing component.
Allows measuring compression force effected by the inserted bone screw and adjusting the compression force effected by the inserted bone screw.
Supports dynamic fracture compression and addresses stress relaxation and fixation failure modes.
Documented Applications
Compressing a bone fracture using the disclosed bone screw, including measuring and adjusting compression force effected by the inserted bone screw.
Dynamic fracture compression across a fracture during fracture healing, in the context of failure modes such as pullout and screw stripping.
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