Bone Anchor Handling Instrument Threadless Insertion Mechanism
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Solution Overview
Problem
Existing handling instruments for bone anchors in spinal surgery are not designed for comfortable use, as they require the inner housing part to be screwed over its entire adjustment path, which can be cumbersome and inefficient.
Innovation Solution
The outer housing part features a threadless section with a radial recess, allowing the inner housing part to be inserted translationally and then screwed in, with a swivel joint decoupling the distal section from rotary movement, enabling easier assembly and distribution of forces through diametrically opposite unthreaded sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner housing part is screwed over its entire adjustment path to join with the outer housing part, then a secure connection is achieved, but the assembly process becomes cumbersome and inefficient
Solution Approach 1:
The patent introduces a threadless section at the distal end of the outer housing part's internal thread. This allows the inner housing part to be preliminarily inserted translationally into the outer housing part before screwing begins. The threaded section of the inner housing part engages with the threaded portion of the outer housing part, enabling initial positioning without requiring the full screwing travel, thus improving assembly efficiency while maintaining connection stability.
2Reliability
If the external thread of the inner housing part is continuous in the circumferential direction, then complete engagement is possible, but translational insertion without rotation is prevented
Solution Approach 1:
The patent segments the external thread of the inner housing part by introducing a threadless section that extends circumferentially. This creates a gap in the threaded portion, allowing the inner housing part to be inserted translationally into the outer housing part in a suitable rotational position without requiring continuous rotation. The segmented thread design enables the translational insertion movement while still providing sufficient threaded engagement for secure connection.
3Ease of operation
If a threadless section is created by removing material from a circumferential internal thread, then translational insertion is enabled, but manufacturing complexity increases
Solution Approach 1:
The patent creates the threadless section in the outer housing part's internal thread by providing a radially extending, outwardly projecting recess in its wall. This recess can be produced, for example, while the outer housing part is still flat, such as by a simple punching operation, before the threading process. This preliminary creation of the threadless section simplifies the overall manufacturing process compared to forming complete threads and then removing material.
Data Source
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AI summary
The invention relates to a handling instrument (2) for connecting to a bone anchor (14), comprising a first outer (4) and a second inner sleeve-shaped housing part (6) with a respective longitudinal direction (8), a first housing part internal thread (26) which extends in the respective longitudinal direction, and a second housing part external thread (38). The handling instrument is characterized by a threadless section (30) of the first housing part in the region of the internal thread, said section extending distally from a proximal longitudinal end (28) of the internal thread in the longitudinal direction and in a circumferential direction (10), and the handling instrument is characterized in that the outer thread of the second housing part is formed only in the region of the extension of the threadless section such that the second housing part can be plugged into the first housing part in the longitudinal direction in a translational manner at a suitable rotational position and can subsequently be screwed into the internal thread of the first housing part.