Surgical Instrument Jaw Thread Integration
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Solution Overview
Problem
Existing instruments for connecting a bone screw to a spinal rod face challenges in precision and ease of assembly due to complex internal and external threading, leading to significant play and increased production complexity.
Innovation Solution
The instrument features a housing with a single internal thread jaw and a pivotable jaw for gripping the bone screw head, where the internal thread jaw projects beyond the other jaw, forming a sleeve-shaped section, allowing for precise guidance of the adjustment tool and simplifying assembly, with a rotatable adjustment tool section preventing accidental loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal thread is designed as two halves provided on the inner sides of the jaws, then the adjustment tool can be screwed into the housing, but the production becomes relatively complex and there is significant play between the internal thread and external thread
Solution Approach 1:
The patent merges the internal thread functionality into a single jaw structure rather than distributing it across two separate jaws. The first jaw incorporates the internal thread directly in its body, eliminating the need for two separate threaded halves and reducing assembly complexity while maintaining secure connection stability.
Solution Approach 2:
The patent extracts the threading function from the pivotable jaw and assigns it exclusively to the fixed first jaw. This separation allows the pivotable second jaw to focus solely on gripping functionality while the first jaw handles both structural support and threading operations, simplifying the overall design.
2Ease of operation
If the two jaws are connected in an articulated manner via a transverse axis, then the bone screw can be gripped, but there is a relatively large amount of play between the internal thread of the jaws and the external thread of the setting tool
Solution Approach 1:
The patent introduces the first jaw as an intermediary structural element that provides a precise, fixed reference for the internal thread. This intermediary structure eliminates play by establishing a stable foundation that maintains accurate thread alignment even when the second jaw pivots for gripping operations.
Solution Approach 2:
Instead of having both jaws contribute to the threading function, the patent inverts the approach by making only the first jaw threaded and fixed, while the second jaw remains pivotable and unthreaded. This inversion eliminates the play problem by removing the moving thread component that caused misalignment.
3Reliability
If the internal thread is provided on both inner sides of the jaws, then the adjustment tool can be secured, but the assembly requires multiple internal and external threads to be screwed together
Solution Approach 1:
The patent combines multiple threading functions into a single integrated structure on the first jaw. The internal thread is provided only on the first jaw, which consolidates what would otherwise require multiple separate threaded components, thereby simplifying manufacturing while maintaining reliable tool retention.
Solution Approach 2:
The first jaw serves multiple functions simultaneously: it provides structural support, incorporates the internal thread for tool insertion, and acts as the fixed reference for the pivotable second jaw. This multi-functionality reduces the number of separate components needed, simplifying both manufacture and assembly.
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
This design enhances precision and ease of assembly, ensuring secure gripping and preventing accidental loosening of the bone screw, while allowing for gentle axial displacement of the spinal rod into the fork head.
Implementation Method 1
the adjustment tool has an external thread on one section and is screwed into an internal thread of the housing
Implementation Method 2
the two jaws having a gap between the distal and proximal ends lying, orthogonal to the longitudinal axis of the housing extending pivot axis are articulated and not crossing each other, so that a compression of the proximal ends of the jaws causes an opening of the distal ends of the jaws
Data Source
Figure 1~3
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AI summary
Instrument (10) for connecting a bone screw (12) to a spinal rod (20), wherein the instrument (10) comprises a substantially cylindrical and hollow housing (22) and an adjusting tool (24) axially penetrating the housing, which has an external thread (54) on a section (56) and is screwed into an internal thread (52) of the housing, and wherein the housing is designed in a pincer-like manner and has a first and a second jaw (30, 34) which each have a proximal and a distal end (42, 44, 46, 48) facing the user and the distal ends (46, 48) engage the head (16) of the bone screw, wherein the two jaws are pivotally connected to each other via a pivot axis (40) located between the distal and proximal ends and extending orthogonally to the longitudinal axis (38) of the housing, wherein the internal thread of the housing is located at a proximal end (42) is provided for a single cheek (30).