Knee Joint Gap Balancing With Digital Ligament Tension Modeling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current state-of-the-art gap balancing devices for total knee arthroplasty are complex, difficult to use, and do not enable proper balance with the patella in place, particularly when working with different knee implant systems.
Innovation Solution
An instrumented tensioner-balancer is used to measure bone and soft tissue parameters by applying a distraction force within the knee joint, collecting data, and deriving a digital geometric model to achieve balanced flexion and extension gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current state-of-the-art gap balancing devices are used, then gap measurement capability is provided, but device complexity increases and ease of operation deteriorates
Solution Approach 1:
The gap balancer is divided into separate functional modules: a distractor component for applying distraction force, a measurement component for measuring gap dimensions, and a balancing component for adjusting ligament tension. This segmentation allows each module to perform its specific function independently, reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The gap balancer is designed as a universal device that can measure and balance gaps for different knee implant systems and configurations. The device incorporates adjustable components that adapt to various implant sizes and types, eliminating the need for multiple specialized devices and thereby reducing complexity.
2Measurement precision
If current gap balancing devices are used, then gap measurement is enabled, but ease of operation worsens due to difficulty in use
Solution Approach 1:
The gap balancer incorporates self-aligning features and intuitive adjustment mechanisms that allow the surgeon to operate the device without extensive training. The distractor automatically positions itself to apply force along the correct axis, and the measurement indicators provide direct visual feedback, eliminating complex操作流程.
Solution Approach 2:
The device uses visual indicators and mechanical feedback mechanisms as intermediaries between the surgeon's actions and the gap balancing outcome. These intermediaries translate complex mechanical adjustments into simple visual cues that are easy to interpret and adjust.
3Measurement precision
If current gap balancing devices are used, then gap measurement capability is provided, but adaptability deteriorates when working with different knee implant systems
Solution Approach 1:
The gap balancer is designed with universal interfaces and adjustable components that accommodate various knee implant systems, sizes, and configurations. The device can be adapted to different implant types through interchangeable attachment mechanisms and adjustable measurement scales.
Solution Approach 2:
The device allows adjustment of measurement parameters and distraction forces to match the specific requirements of different implant systems. By changing physical parameters such as distraction force magnitude and measurement scale, the same device can accurately measure gaps for various implant configurations.
4Measurement precision
If complex gap balancing devices are used, then measurement capability is improved, but productivity deteriorates due to time consumption
Solution Approach 1:
The gap balancer is pre-configured with standard measurement scales and distraction forces that are appropriate for common implant sizes. This preliminary setup eliminates the need for time-consuming adjustments during surgery, allowing the surgeon to immediately begin measurement and balancing procedures.
Solution Approach 2:
The device replaces complex mechanical adjustment systems with simpler mechanisms that provide direct mechanical measurement and indication. This substitution reduces the number of steps required to achieve accurate gap measurement and balancing, thereby improving surgical efficiency.
Data Source
AI summary
A method of evaluating a knee joint which includes a femur, a tibia, and ligaments, includes: inserting into a lateral or medial compartment of the joint a tensioner-balancer having apparatus for applying distraction force; moving the joint within its range of motion; maintaining a predetermined distraction load range or a predetermined distraction height range; collecting distraction height and force data of the femur relative to the tibia; deriving ligament displacement and load data from the height and force data; processing the data to produce a digital geometric model of the joint, the model including a ligament force versus displacement characterization curve for each of a plurality of flexion angles of the femur relative to the tibia; using a software application, evaluating the digital geometric model and selecting a portion of the curve that represents a predetermined desired level of ligament tautness; and storing the digital geometric model.