Force-Indicating Retractor With Strain Gauges for Joint Tension
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Solution Overview
Problem
Existing orthopedic implants, particularly for joints like knees and hips, face challenges in achieving a proper fit due to inconsistent measurement of soft tissue tension and laxity, leading to variable sizing and potential misalignment during surgical procedures.
Innovation Solution
A force-indicating retractor device with strain gauges and pressure sensors is used to measure and standardize the application of forces between joint articular surfaces, providing data to a robotic surgical system for precise implant sizing and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual or z-retractor methods are used to apply varus/valgus stress to the knee, then the procedure can be performed with simple equipment, but the amount of force applied is not standardized leading to inconsistent soft tissue tension measurements
Solution Approach 1:
The patent replaces manual mechanical force application with an instrumented retractor that uses sensors (strain gauges, pressure sensors) to objectively measure soft tissue tension. This substitution transforms subjective manual assessment into quantifiable mechanical data, resolving the contradiction between measurement precision and device complexity by introducing specialized sensing equipment.
Solution Approach 2:
The instrumented retractor acts as an intermediary device between the surgeon and the joint, providing standardized force application and simultaneous measurement. This intermediary function allows consistent force delivery while capturing accurate soft tissue tension data, addressing both the need for standardization and the requirement for precise measurement.
2Manufacturing precision
If visual estimates and hand measurements are used to determine implant size, then the surgical procedure is simple and quick, but the implant fit varies from too loose to too tight
Solution Approach 1:
The system incorporates real-time feedback through force indicators and sensors that provide objective data on soft tissue tension during surgery. This feedback loop allows the surgeon to adjust implant sizing decisions based on quantifiable measurements rather than visual estimates, improving implant fit precision while integrating measurement capabilities into the surgical workflow.
Solution Approach 2:
The patent replaces subjective visual estimation with objective mechanical measurement systems including strain gauges and pressure sensors. This substitution provides precise quantitative data on soft tissue tension that directly informs implant sizing, resolving the contradiction between surgical simplicity and implant fit accuracy.
3Measurement precision
If standardized force application is implemented using instrumented retractors, then soft tissue tension can be accurately quantified, but the device complexity and cost increase
Solution Approach 1:
The instrumented retractor serves as a specialized intermediary tool that combines force application with embedded sensors. This design consolidates multiple functions (retraction, force application, measurement) into a single device, addressing the measurement precision requirement while containing device complexity within a focused surgical instrument rather than requiring complex external systems.
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 accurate quantification of soft tissue tension, enhancing the precision of orthopedic implant placement by standardizing the application of forces, thereby improving the fit and stability of implants.
Implementation Method 1
The retractor includes one or more strain gauges that may be positioned at the insertion end, the base end, or both ends of the retractor.
Implementation Method 2
The force indicators may include one or more pressure sensors positioned at the insertion end of the retractor.
Data Source
AI summary
Devices, systems, and methods for measuring a force applied to a joint during a surgical procedure are disclosed. The device includes an insertion tool, a handle, and one or more force indicators. The insertion tool includes an insertion end and a base end. The one or more force indicators may be attached to the insertion tool and the handle. The insertion end of the device may be inserted into a joint during a surgical procedure and used to apply a force to the joint and/or measure the force using the one or more force indicators when the force is applied.