Constant Force Tensor Balancer Clock Spring Mechanism
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Solution Overview
Problem
Current surgical tensor/ligament balancers require surgeons to manually adjust and measure force to accurately determine gaps between resected bones, leading to variability and potential inaccuracies in knee joint stability assessments during prosthetic replacements.
Innovation Solution
A constant force tensor/ligament balancer with a spring housing and clock spring mechanism that applies a consistent force to move a second paddle relative to a first paddle, allowing for precise measurement of gaps in flexion and extension without requiring manual adjustment of output force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a surgeon manually adjusts the force on the tensor/ligament balancer to measure the gap in flexion and extension, then the measurement can be performed, but the measurement accuracy is compromised due to variability in manual force application
Solution Approach 1:
The tensor/ligament balancer applies its own constant force through a spring mechanism to move the second paddle, eliminating the need for the surgeon to manually adjust and monitor force levels. The device self-regulates the measurement force, ensuring consistency while reducing operational complexity.
Solution Approach 2:
The patent transforms the variable manual force parameter into a constant force parameter through the spring mechanism. This parameter change ensures that the measurement force remains consistent across different measurements, directly improving measurement precision.
2Measurement precision
If the surgeon pays close attention to the amount of force used during measurement, then measurement accuracy may be maintained, but the operational complexity and time required increase
Solution Approach 1:
The device automatically maintains constant force through its spring mechanism, eliminating the need for the surgeon to continuously monitor and adjust force levels. This reduces procedural complexity while maintaining high measurement accuracy.
3Measurement precision
If a constant force mechanism is implemented in the tensor/ligament balancer, then measurement accuracy is improved, but the device complexity increases due to additional components
Solution Approach 1:
A spring mechanism is introduced as an intermediary element between the surgeon's input and the measurement system. This spring acts as a force-regulating mediator that automatically maintains constant force, improving measurement precision while adding only a single mechanical component.
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
Ensures consistent and accurate measurement of gaps between resected bones, reducing complexity and improving measurement accuracy by maintaining a constant output force, thus enhancing knee joint stability assessments during prosthetic procedures.
Implementation Method 1
The tensor/ligament balancer can include a spring housing coupled to the trigger and constrained to move in one direction relative to the body based on the movement of the trigger between the first, actuated position and the second, released position. The spring housing can be received within the slot of the body and can include at least one measurement indicia such that the movement of the spring housing relative to the slot enables measurement of the gap. The tensor/ligament balancer can include a clock spring disposed in the spring housing and coupled to the trigger.
Implementation Method 2
The clock spring can be operable to be wound by the trigger when the trigger is pivoted into the first, actuated position, and can be operable to unwind when the trigger pivots into the second, released position.
Data Source
AI summary
A tensor/ligament balancer for use in measuring a gap existing between an anatomy is provided. The tensor/ligament balancer can include a first paddle. The tensor/ligament balancer can also include a second paddle movable relative to the first paddle. The tensor/ligament balancer can further include a biasing member operable to apply a substantially constant force on the second paddle to move the second paddle relative to the first paddle. At a first position, the second paddle can be substantially adjacent to the first paddle. The second paddle can be automatically movable away from the first paddle to a second position by applying the substantially constant force to the second paddle.