Variable Angle Bone Plate with Segmented Threaded Holes
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Solution Overview
Problem
Conventional bone plates with fixed screw trajectories limit the angular orientation of locking screws, restricting the range of possible angles at which bone screws can be securely fixed, which can compromise the stability and flexibility of bone fixation systems.
Innovation Solution
The development of a bone plate with variable angle locking holes that include internal threads and recesses, allowing bone screws to be inserted at various angles within a range (up to 30 degrees) to securely engage with the plate, enhancing the range of angular orientations for screw fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional bone plates with fixed screw trajectories are used, then the structural simplicity is maintained, but the angular orientation range for locking screws is limited
Solution Approach 1:
The fixation hole is segmented into multiple functional zones: a first region with threads extending from the inner surface, a second region with recesses that divide threads into columns, and a third region providing additional thread engagement. This segmentation allows the hole to accommodate screws at multiple angular orientations while maintaining structural integrity.
Solution Approach 2:
The invention transitions from a conventional single-axis fixation hole to a multi-dimensional variable angle hole with threads and recesses arranged in three-dimensional space. The recesses create columns of thread segments that are offset along the transverse direction, enabling angular adjustment while maintaining secure engagement.
2Adaptability or versatility
If variable angle holes with recesses are introduced, then the flexibility of screw insertion angles is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention modifies the geometric parameters of the fixation hole by introducing recesses at specific depths and angles. The recesses divide the threads into columns with varying circumferential lengths that increase axially inward, creating a controlled three-dimensional structure that accommodates angular variation while being manufacturable using standard bone plate fabrication techniques.
3Reliability
If multiple columns of thread segments are created, then the thread engagement reliability is improved, but the structural complexity of the fixation hole increases
Solution Approach 1:
Different regions of the fixation hole are given different local qualities: the first region provides initial thread engagement, the second region with recesses creates multiple columns of thread segments for enhanced engagement, and the third region provides additional securement. Each zone is optimized for its specific function, with thread segments having circumferential lengths that increase axially inward to maximize engagement reliability.
Data Source
AI summary
A bone plate having at least one variable angle locking hole is described. The variable angle locking hole allows a bone anchor having a threaded head to be driven into underlying bone while oriented at an angle with respect to a central hole axis of the hole that is within a range of angles at which the head is configured to threadedly mate with the at least one thread of the bone plate. Accordingly, the bone anchor can be driven into the underlying bone until the threaded head threadedly purchases with the bone plate inside the variable angle locking hole.