Knee Resection Instruments Flexion-First Gap Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current orthopedic procedures for knee arthroplasty face challenges in reducing surgical complexity and minimizing anterior femoral notching, while accurately matching flexion and extension gaps without preliminary cuts or patella reduction.
Innovation Solution
The use of a flexion-first surgical technique and specialized components, including a first assembly with a tibial resection guide, a second assembly with an intramedullary rod and tool for creating a flexion gap, and a third assembly with shims for matching the extension gap, allows for precise adjustments and tensioning of the knee joint, maintaining the medial femoral joint-line and reducing notching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional knee arthroplasty procedures are performed with preliminary cuts and patella reduction, then the surgical process can be completed, but surgical complexity increases and anterior femoral notching risk increases
Solution Approach 1:
The patent applies the inversion principle by performing flexion gap balancing before extension gap balancing, which is the reverse of the traditional sequence. This 'flexion-first' approach allows the surgeon to establish the correct flexion gap and ligament tension before addressing the extension gap, thereby eliminating the need for preliminary cuts and patella reduction that traditionally were required to control femoral positioning. The intramedullary rod with flexion guide is inserted first to establish flexion gap, and only afterward is the extension gap addressed, inverting the conventional surgical sequence.
Solution Approach 2:
The patent applies preliminary action by using the intramedullary rod with integrated flexion guide and tensioning tool to pre-establish the correct flexion gap and ligament tension before any femoral resections are performed. The rod is inserted into the femoral canal and used to tension the ligaments and create the flexion gap between tibia and femur, thereby pre-determining the appropriate femoral component size and positioning before actual bone cutting occurs. This preliminary positioning action eliminates the need for subsequent re-cuts to correct femoral notching.
2Manufacturing precision
If traditional procedures make preliminary cuts to establish extension gap, then extension gap can be created, but flexion and extension gaps often do not match requiring re-cuts
Solution Approach 1:
The patent applies preliminary action by establishing the flexion gap first using the intramedullary rod with tensioning capability, before addressing the extension gap. The rod is inserted and used to tension the ligaments and create the flexion gap, thereby pre-determining the appropriate femoral component size and positioning. Only after the flexion gap is established does the surgeon proceed to create the extension gap, ensuring that both gaps will match without requiring re-cuts.
Solution Approach 2:
The patent applies feedback by using the intramedullary rod with integrated tensioning tool to actively tension the ligaments and measure the resulting flexion gap, providing real-time feedback on the correct femoral component size and positioning. The surgeon adjusts the tensioning and measures the gap, then uses this feedback information to guide the subsequent extension gap creation, ensuring both gaps match. This feedback loop eliminates the need for trial components and re-cuts.
3Object-affected harmful factors
If femoral component is sized without flexion-first technique, then sizing can be performed, but notching occurs and patella reduction is required
Solution Approach 1:
The patent applies the inversion principle by sizing the femur based on flexion gap measurements obtained through ligament tensioning with the intramedullary rod, rather than traditional extension gap measurements. This reversed sequencing allows the surgeon to determine the correct femoral component size before any resections, ensuring proper positioning that avoids anterior notching. The flexion-first sizing approach eliminates the need for patella reduction that would otherwise be required to accommodate notching.
Solution Approach 2:
The patent applies preliminary action by using the intramedullary rod to tension the ligaments and establish the correct femoral component size and positioning before any femoral resections are performed. The rod is inserted into the femoral canal and used to create the flexion gap, thereby pre-determining the appropriate sizing parameters. This preliminary sizing action ensures that when the femur is subsequently resected and the component implanted, there will be no anterior notching requiring patella reduction.
Data Source
AI summary
Methods, systems and apparatuses including apparatuses that can be used in knee replacement procedures are disclosed. According to one example, a method is disclosed that can include determining a desired flexion space between a tibia and a femur with the patient's knee joint oriented in flexion, referencing a tibia resection guide along the tibia a distance from the desired flexion space, resecting a proximal end portion of the tibia with the tibia resection guide, inserting an intramedullary rod into the femur with the patient's knee joint in flexion, tensioning the patient's knee joint to create a flexion gap by separating the tibia and the femur, sequent to tensioning the patient's knee joint, reorienting the femur into extension relative to the tibia and re-tensioning the patient's knee joint to create an extension gap that substantially matches the flexion gap.