Mechanical Joint Balancer for Knee Surgery Force Measurement
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Solution Overview
Problem
Current methods for balancing joints, particularly during total knee replacement surgery, lack precision in measuring and adjusting the relative forces between the lateral and medial sides, leading to potential instability and the need for improved mechanical devices and methods.
Innovation Solution
A joint balancer device comprising a handle, a gauge, and a mechanical link system that translates displacement of the upper plate into a proportional movement of the gauge, allowing for accurate measurement and adjustment of force imbalances between the lateral and medial sides of a joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional spacer blocks or distractor tools are used to assess joint balancing, then the relative stiffness can be evaluated, but the measurement precision is insufficient to detect subtle force imbalances between lateral and medial sides
Solution Approach 1:
The patent replaces traditional mechanical assessment tools (spacer blocks, distractor tools) with a mechanical linkage system that converts subtle displacement into magnified gauge readings. The linkage mechanism includes levers and pointers that amplify small movements of the upper plate relative to the lower plate, transforming imperceptible force imbalances into clearly visible gauge deflections that can be read with precision.
Solution Approach 2:
The patent introduces a mechanical linkage system as an intermediary between the joint structures and the measurement gauge. This intermediary mechanism (comprising levers, pointers, and connection elements) translates the subtle relative displacement between lateral and medial sides into magnified movements that the gauge can accurately detect and display, thereby enabling precise measurement without requiring complex instrumentation.
2Measurement precision
If the upper plate displacement is measured directly without magnification, then the device structure remains simple, but the displacement magnitude is too small to provide clear measurement indication
Solution Approach 1:
The patent employs a mechanical linkage system with levers and pointers that magnifies the small displacement of the upper plate. The linkage mechanism converts subtle movements into amplified gauge pointer deflections, enabling clear visual measurement of force imbalances that would otherwise be imperceptible with direct measurement approaches.
Solution Approach 2:
The patent transforms the small linear displacement between plates into a magnified rotational movement of the gauge pointer through the mechanical linkage system. This dimensional transformation converts an难以观测的小位移 into a clearly visible angular deflection on the gauge scale, providing precise measurement indication without requiring complex electronic or optical systems.
3Difficulty of detecting and measuring
If no mechanical magnification system is used, then the device complexity is reduced, but the ability to detect and measure relative force differences between joint sides is insufficient
Solution Approach 1:
The patent replaces direct observation methods with a mechanical linkage and gauge system that automatically magnifies and displays relative force differences. The linkage mechanism (including levers, pointers, and connection elements) converts subtle displacement caused by force imbalances into amplified gauge readings, making detection and measurement straightforward without requiring complex instrumentation.
Solution Approach 2:
The patent introduces a mechanical linkage system as an intermediary that facilitates the detection and measurement of relative force differences. This intermediary mechanism translates the subtle mechanical effects of force imbalances into clearly visible gauge deflections, thereby reducing the difficulty of detection and measurement while maintaining relatively simple device architecture.
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 enables precise measurement and adjustment of force imbalances, facilitating better joint stability and alignment during surgical procedures by providing a clear indication of relative differences in force, thereby improving the accuracy of joint balancing.
Implementation Method 1
the mechanical link magnifies displacement of the upper plate such that the gauge displays the magnified displacement
Data Source
AI summary
The present invention relates to devices and methods for balancing joints, including knee joints. The devices convert unequal forces at a joint to a rotation or displacement of a pointer or gauge. The devices are able to display the relative difference in force between the lateral and medial sides of a joint from flexion to extension. In certain aspects, the devices are useful for balancing the knee during total knee surgery. The devices can be inserted between the trial femoral and tibial components of the knee and measures whether one condyle experiences more force than the other.