Bone Fixation Locking Member with Ratcheting Stem
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Solution Overview
Problem
Existing bone fixation devices often irritate surrounding tissue and have undesirable cosmetic effects due to their profile, and they lack an effective mechanism to prevent the outer disk from translating opposite to the insertion direction, which can compromise the stability of the bone flap or implant.
Innovation Solution
A bone fixation device featuring a toothed stem with a biasing member that engages locking teeth on the outer member, preventing reverse translation and ensuring secure fixation of anatomical structures, made from biocompatible materials like PEEK or PEKK, with a design that minimizes tissue irritation and enhances cosmetic outcomes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ratcheting member is used as the locking mechanism, then the stability and reliability of the bone fixation device is improved, but the profile relative to the surrounding skull increases causing tissue irritation and undesirable cosmetic effects
Solution Approach 1:
The patent extracts the ratcheting mechanism from the traditional disk configuration and relocates it to a separate stem component. The stem includes locking teeth that engage with complementary teeth on the outer disk, allowing the ratcheting function to be distributed. This extraction allows the outer disk to have a reduced profile while maintaining the stabilizing ratcheting mechanism through the stem's engagement features.
2Ease of operation
If the outer disk is made slidable along the stem, then the ease of operation for securing bone flap is improved, but the risk of unintended translation in opposite direction increases compromising fixation stability
Solution Approach 1:
The patent implements a dynamic locking system where the stem and outer disk transition from a movable state during insertion to a locked state after positioning. The stem includes locking teeth that initially allow sliding movement for easy operation, then engage with complementary teeth on the outer disk to prevent unintended translation. This dynamic transition enables both ease of operation and fixation stability.
Solution Approach 2:
The locking teeth on the stem act as an intermediary mechanism between the outer disk and the stem body. These teeth engage with complementary teeth on the outer disk to mediate the transition from movable to fixed state. The intermediary locking mechanism allows the outer disk to slide during insertion while preventing reverse translation, thus maintaining both ease of operation and reliability.
3Device complexity
If a traditional locking mechanism like rivet or frictional fit is used, then the device complexity is reduced, but the reliability and stability of the fixation is compromised
Solution Approach 1:
The patent replaces traditional mechanical locking systems (rivets, frictional fits) with a toothed engagement mechanism. The stem includes locking teeth that mesh with complementary teeth on the outer disk, creating a ratcheting effect. This mechanical substitution provides reliable fixation stability while maintaining relative simplicity, as the toothed engagement is integrated into the basic structure of the stem and outer disk components.
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 device provides stable and secure fixation of bone flaps or implants while reducing tissue irritation and cosmetic issues, ensuring effective anatomical structure alignment and stability.
Implementation Method 1
a biasing member that extends into the stem receiving slot and is configured to bias the stem toward the surface
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A locking member for a bone fixation device can include a locking body that defines an outer surface, an opposed bone contacting surface, and a slot that extends from the bone contacting surface to the outer surface. The locking member can further include at least one locking tooth that extends into the slot and a biasing member that extends into the slot and defines an abutment surface that faces the at least one locking tooth. The slot can be configured to receive a toothed member along an insertion direction and the biasing member can be configured to bias the toothed member toward the at least one locking tooth such that at least one tooth of the toothed member engages the at least one locking tooth of the locking member so as to prevent the toothed member from translating through the slot along a direction that is opposite the insertion direction.