Bone Staple Inserter Trigger Camming Mechanism
Solution Overview
Problem
Existing bone staple inserters face challenges in single-handed use, reliable deformation of superelastic staples, and efficient deployment in bone fixation procedures, particularly in orthopedic trauma fixation, where they need to be quick, reliable, and cost-effective.
Innovation Solution
A disposable inserter with a trigger-activated camming assembly that constrains and expands the staple legs from a converging to a transverse position, utilizing cylindrical expander pins and a scissoring mechanism to induce superelastic properties, allowing for easy and secure deployment of staples with two, three, or four legs, suitable for various bone fixation procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional bone staple inserter design is used, then the staple can be inserted into bone, but the device is difficult to operate with one hand and requires complex manual manipulation
Solution Approach 1:
The inserter features a spring-loaded automatic release mechanism that automatically deploys the staple from the device once the compression force is applied to the trigger. The spring automatically pushes the staple off the expander pins after deployment, eliminating the need for additional manual manipulation steps and enabling true single-handed operation.
Solution Approach 2:
The device incorporates a dynamic trigger mechanism with cam surfaces that automatically transitions from a loading state to a deployment state when activated. The cam surfaces convert the compression force applied by the user into automatic staple release, reducing the complexity of manual manipulation required.
2Ease of operation
If the staple legs are spread to transverse position for insertion, then the staple can be implanted in bone, but the superelastic properties must be induced through deformation
Solution Approach 1:
The staple is pre-formed in a compressed configuration with legs at angles of 60-88 degrees relative to the bridge member. The inserter is pre-assembled with the staple in this non-activated state, with expander pins positioned to engage the inner corners of the bridge member. When deployed, the spring automatically spreads the legs to transverse position, reliably inducing the superelastic properties through controlled deformation.
3Reliability
If the staple is held constrained on the inserter, then the staple position is controlled, but the mechanism must reliably hold and then release the staple
Solution Approach 1:
The securing mechanism uses removable expander pins that engage the inner corners of the bridge member to hold the staple in a constrained position. These pins are automatically extracted by the spring-loaded release mechanism when the trigger is activated, providing reliable holding during insertion and automatic release for deployment without complex locking systems.
4Ease of manufacture
If the inserter is designed for disposable use, then cost considerations are met and manufacturing is simplified, but the device must still be sufficiently strong to reliably deform and deploy the staple
Solution Approach 1:
The inserter is designed as a disposable device with a simplified construction that eliminates the need for complex, expensive, reusable components. The spring-loaded mechanism and cam surfaces are engineered to provide sufficient strength for reliable staple deformation and deployment while using materials and manufacturing methods suitable for cost-effective mass production of single-use devices.
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
Enables quick, reliable, and efficient single-handed deployment of superelastic staples across bone segments, minimizing user interaction and reducing the risk of over-spreading or misalignment, while accommodating different anatomical regions like the foot and hand, with a design suitable for mass production and economic manufacturing.
Implementation Method 1
The staple has a bridge member that extends a length along an axis and which joins legs spaced apart along the axis. The staple is fabricated in a closed (converging legs) shape and is mechanically deformed or 'activated' by the inserter during use to induce the superelastic shape memory properties in the staple so as to compress bone segments
Implementation Method 2
The mechanism uses a trigger activated camming assembly which draws apart a pair of pivoting arm members. The staple is held on the inserter on cylindrical expanders and the inserter has a mechanism to spread the expanders which opens the legs so that the superelastic properties are induced and the legs are spread into transverse positions for implantation
Data Source
AI summary
The invention is an inserter for a staple having a bridge member and opposing open legs and the inserter holds the staple between a pair of cylindrical expanders which splay apart in response to a camming mechanism having a pair of followers that carry the expanders. The followers are activated as they are drawn over the camming ramp in response to a trigger action. The ramp also includes a detent which alerts the user that the staple is engaged in an activated position, and a safety that keeps the followers from returning to the un-loaded position.