Variable-Angle Locking Construct With Relief Holes for Orthopedic Plates
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Solution Overview
Problem
Existing bone screw and plate systems in orthopedics often require threaded or tapered holes, limiting the ability to lock screws at variable angles, which can lead to inefficiencies in biomechanical load transfer and compromise the stability of osteotomies or fractures.
Innovation Solution
A variable angle locking screw and plate system that eliminates the need for threaded or tapered holes, allowing for efficient biomechanical load transfer by using a bone anchor with a tapered head and a plate with reliefs and projections that enable locking at various angles without shearing or creating burrs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded or tapered holes are used in the plate, then the screw can be locked to the plate, but the ability to lock at variable angles is limited and manufacturing complexity increases
Solution Approach 1:
The plate hole is designed with an asymmetric geometry featuring a relief portion that creates a locking surface at a specific angle. This dynamic geometry allows the screw to lock at variable angles relative to the plate, transforming the static threaded/tapered hole design into an adaptable locking mechanism that maintains reliability while enabling angle variability.
Solution Approach 2:
The invention changes the geometric parameters of the plate hole by introducing a relief portion that creates a non-circular, asymmetric cross-section. This parameter change eliminates the need for threads or tapers while providing a locking surface that can engage the screw at variable angles, thus improving adaptability without sacrificing locking reliability.
2Reliability
If threaded or tapered holes are used in the plate, then screw locking is achieved, but the system requires more complex manufacturing processes
Solution Approach 1:
The invention extracts the threading or tapering process from the plate manufacturing by eliminating these features entirely. Instead of manufacturing complex threaded or tapered holes, the plate is created with a simple asymmetric hole geometry featuring a relief portion, significantly simplifying the manufacturing process while maintaining screw locking reliability through the asymmetric locking surface.
Solution Approach 2:
Rather than creating complex internal thread or taper structures within the plate hole, the invention inverts the approach by creating an asymmetric geometry with a relief portion on the plate that complements the screw geometry. This inversion simplifies manufacturing by avoiding difficult internal threading operations while achieving reliable locking through the asymmetric engagement surface.
3Ease of manufacture
If standard non-locking screw/plate systems are used, then manufacturing is simpler, but biomechanical load transfer efficiency is reduced
Solution Approach 1:
The invention applies local quality by creating a specific asymmetric geometry with a relief portion at the plate hole location where locking is needed. This localized asymmetric feature provides enhanced load transfer efficiency through positive locking engagement, while the rest of the plate maintains simple manufacturing characteristics, thus balancing strength improvement with manufacturing ease.
Data Source
AI summary
An embodiment includes a bone fixation system comprising: a bone anchor with a tapered head, the head being threaded; and a plate that includes a void, the void including one of a counterbore or a countersink; wherein: (a) no portion of the void is threaded; (b) the void includes an inner wall; (c) the inner wall includes reliefs along its perimeter. Other embodiments are described herein.