External Fixation Clamp Trigger Mechanism
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Solution Overview
Problem
Conventional external fixation clamping systems face variability in spring force, requiring adjustments and trial-and-error for inserting fixation elements, and lack consistent clamping action independent of tightening nut position, leading to inefficiencies and potential loosening during fracture reduction.
Innovation Solution
An external fixation clamp with a latch assembly that stores higher energy before insertion, releasing energy upon insertion to provide consistent clamping and provisional load, decoupling latching and clamping functions, allowing easy insertion and adjustment without tools, and maintaining fixation without dependent positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring force is increased to provide stronger provisional clamping, then the fixation element is retained more securely, but the insertion of the fixation element becomes mechanically prohibited
Solution Approach 1:
The latch is preliminarily positioned in the engaged position before fixation element insertion, and the spring is pre-compressed to store energy. When the fixation element is inserted, it triggers the latch to disengage, allowing the stored spring energy to rapidly close the jaws and provide provisional clamping. This preliminary preparation resolves the contradiction by ensuring both easy insertion (latch disengaged) and secure retention (spring energy released).
Solution Approach 2:
The latch assembly acts as an intermediary mechanism between the spring force and the fixation element. It decouples the spring force application from the insertion process, allowing the spring to be compressed without immediately applying clamping force during insertion. The latch mediates by holding the jaws open during insertion, then releasing to allow spring-driven closure for provisional clamping.
2Reliability
If the nut is threaded into the clamping apparatus to increase spring force, then provisional clamping is improved, but the clamping apparatus complexity increases
Solution Approach 1:
The provisional clamping function is extracted from the nut-threading mechanism and assigned to a dedicated latch assembly with a spring. The nut is removed from the provisional clamping function entirely, serving only for final locking. This extraction simplifies the overall apparatus by separating the two functions into distinct mechanisms: latch/spring for provisional clamping and nut for final locking.
Solution Approach 2:
The clamping function is segmented into two independent stages: provisional clamping handled by the latch and spring mechanism, and final locking handled by the nut. This segmentation allows each component to be optimized for its specific function without the complexity of a unified mechanism, reducing overall apparatus complexity while maintaining reliable provisional clamping.
3Force
If the latch assembly uses a spring with high stored energy to ensure strong clamping, then the clamping force is sufficient, but the energy release during insertion becomes uncontrolled
Solution Approach 1:
The latch assembly incorporates a trigger mechanism that provides feedback control for energy release. The fixation element itself acts as the trigger, and when inserted, it automatically activates the latch to release the spring energy. This feedback mechanism ensures that the high stored energy is released only under the correct condition (fixation element insertion), providing controlled and reliable energy release while maintaining sufficient clamping force.
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 clamp achieves predictable and efficient fixation with reduced turns for locking, independent of element position, ensuring stable provisional retention and easy adjustment before full locking, enhancing surgical efficiency and reducing variability.
Implementation Method 1
The latch may be configured to translate linearly relative to one of the inner and outer jaws, and the latch biasing member may have a first higher level of stored energy when the inner and outer jaws are in the open position and a second lower level of stored energy when the inner and outer jaws are in the closed position. In one aspect, the change in stored energy is a result of un-compressing the latch biasing member element during the linear translation of the latch.
Data Source
AI summary
An external fixation clamp for receiving a fixation element includes an inner jaw and an outer jaw movable between an open position that permits the fixation element to be placed between the inner and outer jaws and a closed position that restricts removal of the fixation element from between the inner and outer jaws. A latch assembly may cooperate with the inner and outer jaws to secure the jaws in a closed position. The latch assembly may comprise a latch and a latch biasing member. The latch may be configured to translate linearly relative to one of the inner and outer jaws, and the latch biasing member may have a first higher level of stored energy when the inner and outer jaws are in the open position and a second lower level of stored energy when the inner and outer jaws are in the closed position.