Virtual Ligament Balancing for Knee Implant Positioning
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Solution Overview
Problem
Traditional knee replacement surgery methods rely on intraoperative gap balancing, which only considers flexion and extension gaps, neglecting mid-flexion laxity and requiring corrective procedures, whereas a preoperative 'virtual' gap balancing method is preferable to ensure proper prosthetic implant placement and soft tissue stabilization.
Innovation Solution
A method involving imaging to determine bone density ratios and ligament tension, using reference populations to predict ligament laxity and generate a correction plan for prosthetic implant positioning, balancing vertical, horizontal forces, and moments, allowing for preoperative virtual ligament balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional intraoperative gap balancing is performed considering only flexion and extension gaps, then the surgical procedure is simpler and faster, but mid-flexion laxity is neglected leading to improper soft tissue stabilization
Solution Approach 1:
The patent performs virtual gap balancing preoperatively using imaging data and computational models to determine optimal prosthetic component positioning before surgery. This preliminary action allows the surgeon to plan the procedure with precise gap balancing considerations for flexion, extension, and mid-flexion positions, eliminating the need for complex intraoperative adjustments and ensuring proper soft tissue stabilization from the start
Solution Approach 2:
The patent creates a virtual copy of the patient's knee joint using imaging data (CT or MRI scans) to build a digital model. This virtual replica allows for simulation and optimization of gap balancing in different flexion positions without affecting the actual patient, enabling comprehensive soft tissue stabilization planning before the surgical procedure begins
2Productivity
If gap balancing is performed only after initial cuts are made intraoperatively, then the surgical workflow is streamlined, but corrective procedures must be performed on the spot increasing surgery time and complexity
Solution Approach 1:
The patent performs virtual gap balancing and determines optimal prosthetic component positioning preoperatively using imaging data and computational models. This preliminary planning allows the surgeon to proceed with the surgical workflow efficiently without needing to perform time-consuming corrective procedures intraoperatively, as the initial cuts and component placement can be made according to the pre-determined optimal positions
Solution Approach 2:
The patent uses virtual simulation feedback from the digital knee model to optimize component positioning before surgery. The computational model provides feedback on how different positioning options affect gap balancing in various flexion positions, allowing the surgeon to make informed decisions preoperatively and avoid intraoperative trial-and-error adjustments
3Reliability
If preoperative virtual gap balancing is performed to determine optimal prosthetic component positioning, then soft tissue stabilization is improved, but additional preoperative planning time and computational resources are required
Solution Approach 1:
The patent creates a virtual copy of the patient's knee joint using standard imaging data (CT or MRI scans) that is already available from diagnostic workup. This virtual model allows for comprehensive gap balancing analysis without requiring additional imaging procedures or excessive computational resources, making the preoperative planning process efficient while maintaining high accuracy in prosthetic implant placement
Solution Approach 2:
The patent optimizes prosthetic component positioning by adjusting key parameters such as component orientation, positioning, and sizing in the virtual model. By focusing computational efforts on these critical parameters rather than exhaustive analysis, the system achieves high accuracy in predicting soft tissue stabilization while minimizing preoperative planning time and computational resource requirements
Data Source
AI summary
A method of generating a correction plan for a knee of a patient includes obtaining a ratio of reference bone density to reference ligament tension in a reference population. A bone of the knee of the patient may be imaged. From the image of the bone, a first dataset may be determined including at least one site of ligament attachment and existing dwell points of a medial femoral condyle and lateral femoral condyle of the patient on a tibia of the patient. Desired positions of contact in three dimensions of the femoral condyles of the patient with the tibia of the patient may be obtained by determining a relationship in which a ratio of bone density to ligament tension of the patient is substantially equal to the ratio of reference bone density to reference ligament tension.