Fixation Assembly Screw Retention Alignment
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Solution Overview
Problem
Existing medical fixation devices face challenges in securely holding and aligning screws during vertebral fixation procedures, particularly in preventing screws from inadvertently disengaging and falling into patients before placement.
Innovation Solution
A fixation assembly comprising a driver, a holding sleeve, and an alignment mechanism, which temporarily holds and aligns a fixation element to an underlying structure, utilizing internal and external threads to securely attach the screw to the holding sleeve and align it with the underlying structure, ensuring proper placement and preventing disengagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a linear side-bearing force from a clamp or other mechanism is used to hold the screw in place, then the screw can be retained on the driver, but the device complexity increases and the mechanism becomes less reliable
Solution Approach 1:
The patent extracts the retention function from complex clamping mechanisms and implements it through a simple threaded bore in the driver that engages with the screw head. This eliminates the need for additional clamps or complex retention mechanisms while maintaining reliable screw holding.
Solution Approach 2:
The threaded bore acts as an intermediary element between the driver and the screw, providing a straightforward mechanical engagement that secures the screw without requiring complex external retention mechanisms. The threads serve as the mediating feature that transfers and maintains the retention force.
2Reliability
If a central threaded rod down the center of the driver is used to retain the screw, then the screw can be held securely, but the driver structure becomes more complex
Solution Approach 1:
The patent merges the retention function directly into the driver structure by incorporating a threaded bore within the driver body itself. This integration eliminates the need for separate central threaded rods or additional retention components, achieving secure screw holding without increasing overall structural complexity.
3Reliability
If a spring-wire off axis of the driver is used to protrude laterally into the screw, then the screw can be retained, but the alignment precision decreases
Solution Approach 1:
The patent employs an asymmetric threaded bore configuration within the driver that provides both retention and alignment functions. The off-center positioning of the threaded bore relative to the driver axis creates a mechanical interference fit that secures the screw while simultaneously guiding it into proper alignment, eliminating the need for separate alignment mechanisms.
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 fixation assembly effectively secures screws to the holding sleeve and aligns them with the underlying structure, preventing accidental disengagement and ensuring proper placement, thereby enhancing the safety and efficacy of vertebral fixation procedures.
Implementation Method 1
The fixation element coupler includes internal threads defined by the channel of the holding sleeve. The threads of the holding sleeve may be configured to engage external threads defined by the head of the fixation element.
Implementation Method 2
The alignment members may be configured to engage apertures defined by a fixation plate of an intervertebral implant.
Implementation Method 3
The driver may be coupled to the holding sleeve such that the driver may translate a predetermined distance with respect to the holding sleeve.
Implementation Method 4
The shaft may include threads that are configured to engage threads defined by the fixation plate of the intervertebral implant.
Data Source
AI summary
A fixation assembly having a driver, a holding sleeve, and an alignment mechanism is disclosed. The driver may include a driver body and a coupling extending from a distal end of the driver body. The holding sleeve may have a holding sleeve body, a channel extending through the holding sleeve body, and a fixation element coupler disposed at a distal portion of the holding sleeve body. The channel may be configured to receive the driver, and the fixation element coupler may be configured to temporarily hold a fixation element. The alignment mechanism may extend from the holding sleeve, and may have at least one alignment member configured to engage an underlying structure to which the fixation element is to be affixed so as to align the fixation element and driver assembly with respect to the underlying structure.