Expandable Distal End for Bone Screw Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Small bone anchors, particularly small bone screws, often become disengaged from driving instruments during insertion or removal, leading to potential loss within a patient due to existing retention mechanisms that increase the diameter of the instrument or obscure the surgical view.
Innovation Solution
A locking screwdriver with a shaft featuring a distal end that expands within the bone anchor's driving opening, utilizing a sliding member and actuator to create a secure, releasable lock, preventing disengagement and ensuring the bone screw remains attached during procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retention sleeves or locking structures are mounted on the shaft of the driving instrument, then the bone screw can be secured and prevented from becoming disengaged, but the diameter of the shaft becomes too large for desired application and the surgical view is obscured
Solution Approach 1:
The driving instrument is divided into separate functional components: a shaft, a distal end with driving features, and a sliding member with locking features. This segmentation allows the locking function to be added without permanently increasing the shaft diameter, as the locking structures are contained within the distal end and sliding member assembly.
Solution Approach 2:
The sliding member is received within the shaft, and the distal end is received within the bone anchor's driving opening. The locking structures are nested within these components, allowing the retention function to be achieved without increasing the overall external dimensions of the driving instrument.
2Reliability
If retention sleeves or locking structures are mounted on the shaft of the driving instrument, then the bone screw can be secured, but the surgical view of the bone screw and target location is obscured
Solution Approach 1:
The locking and retention functions are extracted from the main shaft body and concentrated into a separate distal end assembly with a sliding member. This allows the shaft to maintain a slender profile for surgical access while the locking mechanisms are contained within the distal end, minimizing obstruction of the surgical view.
Solution Approach 2:
The locking structures are localized to the distal end of the shaft rather than being distributed along the entire shaft. This local concentration of locking features allows the majority of the shaft to remain slender and non-obtrusive, maintaining surgical visibility while providing secure retention at the critical interface with the bone anchor.
3Reliability
If a sliding member is added to create a releasable lock, then the bone screw can be securely attached, but the device complexity increases
Solution Approach 1:
The sliding member combines multiple functions into a single component: it provides the locking interface with the distal end, guides the distal end within the bone anchor's driving opening, and enables the releasable lock mechanism. This merging reduces the need for separate locking components and simplifies the overall device structure.
Solution Approach 2:
The sliding member serves multiple purposes: it acts as a locking element, a guide for the distal end, and a mechanism for secure attachment. This multi-functionality reduces the total number of components needed in the driving instrument, offsetting the added complexity of the releasable lock mechanism.
Data Source
AI summary
An interlock driving instrument is configured to be releasably lockable to a fastener, such as a bone anchor. A bone anchor can be locked to the interlock driving instrument by inserting an expandable distal end of the shaft of the interlock driving instrument into the driving opening of the bone anchor and expanding the distal end within the driving opening by translating an expansion member into the expandable distal end. Alternatively, the bone anchor can be locked to the interlock driving instrument by inserting the distal end of the shaft of the interlock driving instrument into the driving opening of the bone anchor and translating a sliding member along a sloped surface defined in a channel extending into the shaft.