Orthopedic Lock Screw Pre-Assembly for Spinal Rod Fixation
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Solution Overview
Problem
Current orthopaedic devices for stabilizing the spine require increased surgical workload due to the need to thread a lock screw through a top opening after the ball-shaped rod end is introduced, which can lead to accidental unscrewing and increased complexity during assembly.
Innovation Solution
The orthopaedic device features a pre-assembled lock screw with a proximal face and distal end designed to fit through a lateral opening, allowing it to be introduced and screwed into a top opening before the rod is inserted, ensuring secure locking and preventing accidental extraction, thereby reducing surgical workload through pre-tensioning and alignment with the screw thread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lock screw is threaded into the top opening after the ball-shaped rod end is introduced, then the assembly can be completed, but the surgical staff's workload increases and the risk of accidental unscrewing increases
Solution Approach 1:
The lock screw is pre-threaded into the top opening of the connecting element before the ball-shaped rod end is introduced into the socket. This preliminary action allows the screw to be positioned and secured in advance, reducing the workload during surgery and preventing accidental unscrewing since the screw is already engaged with the threaded opening.
2Ease of operation
If the lock screw is accessible from outside the connecting element, then it can be threaded in during surgery, but it may be accidentally unscrewed or extracted
Solution Approach 1:
The lock screw is pre-positioned and threaded into the top opening before the rod assembly is completed. This preliminary engagement ensures the screw is secured in place and cannot be accidentally unscrewed or extracted during subsequent handling or vibrations.
Solution Approach 2:
Instead of making the lock screw accessible from outside for threading during surgery, the design inverts the approach by having the screw engage from the inside through the top opening, with the proximal face presenting the screw drive accessible from outside while the distal end remains engaged within the connecting element.
3Reliability
If the distal end of the lock screw is shaped to prevent extraction through the top opening, then security is improved, but pre-tensioning capability may be limited
Solution Approach 1:
The distal end of the lock screw is given a specific shape (such as a rounded or enlarged end) that prevents extraction through the top opening while still allowing pre-tensioning. This local modification to the screw's geometry provides both security against accidental extraction and the capability for pre-tensioning before final assembly.
Data Source
AI summary
Orthopedic devices including a connecting element suited for receiving at least part of a first rod, and a lock screw. The connecting element includes an anchor for securing the connecting element to a bone, in particular a vertebra, a first lateral opening, and a top opening with a first inner screw thread. The lock screw is received within the top opening and includes a proximal face presenting a screw drive, accessible from outside the connecting element, a distal end for locking the first rod within the connecting element, and wherein the lock screw is adapted to fit through the first lateral opening to be subsequently introduced into the top opening with the proximal face leading.