Non-threaded Bone Anchor Securing Mechanism
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Solution Overview
Problem
Existing anchors with threaded set screws often experience thread stripping, improper tightening, and loosening, leading to instability in securing elongated members to bones, requiring revision procedures.
Innovation Solution
A non-threaded securing mechanism comprising a receiver with a channel and a shaft, utilizing an outer and inner member with compressible extensions that axially move and expand to securely attach the elongated member without rotational movement, ensuring stable engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a threaded set screw design is used to secure the elongated member, then the securing mechanism can be manufactured with standard threading components, but the threads may be stripped on the receiver and/or set screw due to improper tightening
Solution Approach 1:
The patent removes the threaded set screw component entirely and replaces it with a non-threaded securing mechanism. The outer member engages with the receiver through a groove without requiring threads, eliminating the risk of thread stripping while maintaining the securing function.
Solution Approach 2:
The patent replaces the threaded mechanical engagement system with a non-threaded interference fit system. The outer member's exterior surface engages with the receiver's groove through compressible extensions that create friction and mechanical interlocking without threads, substituting the threading mechanism with an alternative mechanical engagement approach.
2Ease of manufacture
If a threaded set screw is used, then the securing mechanism can be assembled with standard parts, but the set screw may bind within the receiver preventing further tightening
Solution Approach 1:
The patent eliminates the threaded set screw that causes binding during tightening. The non-threaded outer member engages with the receiver through a groove without the rotational binding issue, allowing straightforward axial insertion and securing of the elongated member.
Solution Approach 2:
Instead of using rotational threading to create engagement, the patent inverts the approach by using axial insertion with a non-threaded interface. The outer member is inserted axially into the receiver and secured through the groove engagement, reversing the traditional threading mechanism's approach to engagement.
3Ease of manufacture
If a threaded set screw is used, then the securing mechanism can be manufactured with standard components, but the set screw may apply outward force on the arms causing them to splay apart
Solution Approach 1:
The patent removes the threaded set screw that generates outward radial force on the receiver arms. The non-threaded outer member engages with the groove without creating this splaying force, maintaining the receiver arms in a stable, spaced-apart configuration throughout the securing process.
Solution Approach 2:
The patent converts the potential harm of arm splaying into a benefit by designing the outer member to engage with the groove in a way that maintains the arms' spaced-apart configuration. The groove engagement naturally holds the arms in their intended positions without the harmful outward force that would cause them to splay.
4Ease of manufacture
If a threaded set screw design is used, then the securing mechanism can be assembled with standard parts, but false impression of full tightening may occur leading to loosening
Solution Approach 1:
The patent eliminates the threaded set screw that creates false tightening indications. The non-threaded outer member engages with the receiver through a groove without the visual or tactile feedback that creates false impressions of full tightening, providing more reliable indication of actual engagement status.
Solution Approach 2:
The patent improves the feedback mechanism by using the groove engagement to provide clear, unambiguous indication of proper engagement. The outer member's position relative to the groove and receiver arms provides direct feedback on whether the elongated member is securely engaged, eliminating the false feedback associated with threaded connections.
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 non-threaded securing mechanism provides a stable and reliable attachment of elongated members to bones, preventing loosening and thread stripping, thus reducing the need for revision procedures and enhancing surgical reliability.
Implementation Method 1
The second member may also include a compressible extension that is sized to fit within the bore when the extension is moved in the bore and to expand to a width greater than the bore when the second member extends outward beyond the bore
Data Source
AI summary
A device to attach an elongated member to a bone in a patient with the device including a receiver with arms that are spaced apart that form a channel sized to receive the elongated member, and a groove on an inner surface of at least one of the arms. A shaft may be operatively connected to the receiver and configured to attach to the bone. A securing mechanism is attached to the receiver that includes an outer member and an inner member. The outer member may include a bore and a non-threaded exterior that may be configured to engage with the groove to attach the securing mechanism to the receiver. The second member may be sized to fit in the bore and move axially along the bore in a non-rotational manner. The second member may also include a compressible extension sized to fit in the bore when the extension is moved in the bore and to expand to a width greater than the bore when the second member extends outward beyond the bore.