Hollow Bone Screw with Internal Indentation for Height Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bone screws used in spinal osteosynthesis devices are not adjustable in height after initial assembly, requiring complete disassembly to adjust the longitudinal position, which is inconvenient for surgeons and can lead to premature screw rupture during manipulation.
Innovation Solution
A bone screw design featuring a hollow pin with an internal indentation for screwdriver access, allowing for permanent accessibility and adjustability, even after assembly, through a recess that remains functional even after the pin is broken at its line of least resistance, enabling repositioning of the screw within the bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the pin is made long to facilitate insertion of connector and nut, then ease of operation is improved, but after assembly the pin protrudes excessively which is inconvenient for the patient
Solution Approach 1:
The pin is designed with a breakable portion that has a line of least resistance, allowing it to be segmented into two parts: a longer initial length for facilitating insertion of the connector and nut, and a shorter final length after breaking that is convenient for the patient. The breakable portion includes an indentation that provides access for a screwdriver to enable controlled breaking at the desired location.
2Adaptability or versatility
If the pin is made adjustable in height after assembly, then adaptability is improved, but the assembly becomes more complex requiring additional access mechanisms
Solution Approach 1:
The indentation is positioned inside the hollow pin, creating a nested structure where the access mechanism for adjustment is contained within the pin itself. This allows the screwdriver to access the breakable portion from the interior space of the pin, enabling height adjustment without requiring external mechanisms or disassembly of the connector-nut assembly.
Solution Approach 2:
The pin structure itself provides the adjustment mechanism through its breakable portion and internal indentation. The pin is self-contained with all necessary elements for both initial insertion and subsequent height adjustment, eliminating the need for additional external adjustment mechanisms or complex assembly procedures.
3Ease of operation
If the pin remains accessible after assembly for adjustment, then ease of operation is improved, but the connector-nut assembly becomes more complex to accommodate permanent access
Solution Approach 1:
The indentation for screwdriver access is merged with the hollow interior space of the pin, creating a unified structure that provides permanent access without requiring separate external mechanisms. The connector and nut assembly remain simple and conventional, while the pin itself contains the access feature, eliminating the need for complex integrated adjustment mechanisms.
Data Source
Figure 1~6
Figure 7~9
AI summary
The invention relates to a bone screw (1) comprising a lower bone anchor part provided with a thread (2), an upper part consisting of a pin (3) with a threaded outer surface for receiving a nut (12), and a seat (10) for receiving a connector (6) which is used to connect the screw (1) to a rod (20) of an osteosynthesis device and is held against the seat (10) by the nut (12), said bone screw being characterised in that said pin (3) is hollow and has an inner space (24) opening up at the upper end (25) thereof, the lower part of said inner space (24) ending with an impression (26) for receiving a screwdriver. The invention also relates to an assembly formed by such a bone screw (1), a connector (5) for connecting the screw (1) to a rod (20) of an osteosynthesis device, and a nut (12; 22) for holding the connector (5) against the seat (10) of the screw (1). The invention further relates to a kit comprising at least one such assembly and a screwdriver for engaging with said impression (26) ending the lower part of the inner space (24) of the pin (3).