Orthopedic Locking Screw Dual-Thread Removal
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Solution Overview
Problem
Existing orthopedic locking screws often break during installation or use, leading to bone damage when attempting to remove the broken screw, as current removal devices require significant bone tissue removal.
Innovation Solution
An orthopedic locking screw with a thread pattern section featuring intersecting threads allows for secure fastening and easy removal without damaging bone tissue, utilizing a functional thread that interacts with the implant's internal thread and a counter thread to facilitate shearing off during removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional locking screws are used, then secure fastening is achieved, but bone damage occurs when the screw breaks and needs removal
Solution Approach 1:
The screw thread is segmented into two distinct systems: a first thread system for secure fastening with the implant, and a second thread system for removal. The second thread is superimposed on the first thread, creating intersecting thread paths that allow the removal device to engage and extract the broken screw without damaging surrounding bone tissue.
Solution Approach 2:
The locking screw incorporates dual functionality through superimposed threads: it serves both as a fastening element (first thread) and as a removable element (second thread). This multi-functionality allows the same screw structure to provide secure fixation during use and enable easy removal when needed, eliminating the need for separate fastening and removal mechanisms.
2Ease of operation
If removal devices with tapered openings are used, then broken screws can be gripped, but considerable bone loss occurs
Solution Approach 1:
The second thread system acts as an intermediary mechanism between the broken screw and the removal device. Instead of requiring the removal device to directly grip the broken screw (which causes bone loss), the second thread provides a dedicated engagement path that mediates the removal process, allowing the device to thread onto the superimposed second thread and extract the screw without contacting or removing bone tissue.
3Device complexity
If a single thread system is used, then simple structure is maintained, but removal of broken screw damages bone tissue
Solution Approach 1:
Two distinct thread systems are merged into a single superimposed thread pattern on the screw shaft. The first and second threads are combined in space, with the second thread superimposed on the first, creating an integrated structure that provides both fastening and removal functionality without requiring separate components or increasing overall device complexity.
Data Source
AI summary
An orthopedic locking screw arranged in a bore of an orthopedic implant enables easy removal of a broken locking screw out of the implant. The orthopedic locking screw for a cooperation with a thread in the orthopedic implant comprises a longitudinally extending shaft. The shaft comprises a thread pattern section extending at least partially along the shaft. The thread pattern section comprises a first thread with a first direction, which is a functional thread configured for the cooperation with the thread in the orthopedic implant. The thread pattern section further comprises a second thread with a second direction opposite to the first direction of the first thread. The second thread is superimposed on the first thread and intersects the first thread. An orthopedic locking system comprises the orthopedic locking screw and the orthopedic implant. The locking screw is manufactured by applying the thread pattern section to the longitudinally extending shaft.