Bone Fixation Plate Locking Disc for Screw Backout Prevention
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Solution Overview
Problem
Existing bone fixation systems face issues with screws loosening and separating from bone plates postoperatively due to insufficient thread purchase or screw stripping, necessitating invasive repairs or replacements.
Innovation Solution
A bone plate fixation system featuring a locking disc or cap mechanism that inhibits screw backout by allowing resilient deflection in the insertion direction while resisting deflection in the opposite direction, using a groove or track configuration with tactile, auditory, and visual feedback for secure locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bone screw is used to secure a bone plate, then the bone plate can be fixed to the bone, but the screw may loosen and separate from the plate postoperatively due to insufficient thread purchase or screw stripping
Solution Approach 1:
The hole in the bone plate is segmented into multiple functional zones: a chamfered entrance zone for screw guidance, a cylindrical middle zone for thread engagement, and a flared exit zone for locking disc reception. This segmentation allows each zone to perform its specific function optimally, improving screw fixation reliability while maintaining ease of insertion
Solution Approach 2:
A locking disc is introduced as an intermediary component between the bone screw and the bone plate hole. The locking disc engages with the flared exit zone of the hole to prevent screw backout and loosening, thereby improving fixation reliability without increasing insertion difficulty
2Ease of operation
If the plate hole is chamfered to facilitate screw insertion, then ease of operation improves, but the hole structure becomes more complex
Solution Approach 1:
Multiple functional features (chamfered entrance, cylindrical middle section, flared exit) are merged into a single continuously varying hole geometry. This integration achieves ease of screw insertion while avoiding the complexity of separate adjustable components or multiple processing steps
3Reliability
If a locking disc is inserted into the hole to prevent screw backout, then screw fixation reliability improves, but the device complexity increases
Solution Approach 1:
The locking disc is designed to be inserted through the bone plate along with the screw in a single operation. The disc automatically engages with the flared exit zone of the hole to prevent screw backout, providing self-locking functionality without requiring additional steps or complex adjustment mechanisms
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
The system effectively prevents screw backout, providing secure fixation of bone plates to bones with tactile and visual confirmation, reducing the need for invasive procedures and enhancing surgical reliability.
Implementation Method 1
the locking disc is operatively associated with the wall to resist resilient deflection of the locking disc in the insertion direction of the bone screw less than the locking disc resists resilient deflection of the locking disc in a direction opposite the insertion direction
Implementation Method 2
The wall of the bone plate hole can have a groove configured and dimensioned to receive the locking disc. The locking disc can be cooperatively received in the groove such that the groove permits resilient deflection of the locking disc in only the insertion direction of the bone screw
Implementation Method 3
a bone screw for fixing the bone plate with respect to a bone. The bone screw is insertable through the hole into bone in an insertion direction to fix the bone plate to the bone
Data Source
AI summary
A fastener, for example a bone screw, is sized to pass through a hole of an implant, for example a bone plate, the fastener having a shaft or anchor portion engageable with body tissue, and a head portion. A locking cap secures to the bone plate and covers the head to block the head and inhibit screw back out. Alternatively, or additionally, a locking disc located in the plate hole resiliently deflects downward to allow screw insertion, but is blocked to limit or prevent upward deflection so that screw back out is inhibited.