Novel approach to dynamic knee laxity measurement using capacitive strain gauges

Area of Science:

• Biomedical Engineering
• Orthopedics
• Biomechanics

Background:

• Severe knee trauma, including anterior cruciate ligament tears, can lead to significant joint instability and laxity.
• Accurate quantification of knee joint laxities is crucial for diagnosis and guiding treatment decisions.
• Current methods for assessing knee laxity may have limitations in accuracy or ease of use.

Purpose of the Study:

• To introduce polydimethylsiloxane (PDMS) strain gauges as a novel, non-invasive method for quantifying knee joint laxities.
• To demonstrate the feasibility of using PDMS strain gauges for measuring anterolateral and rotational knee laxities during active and passive motion.
• To present proof-of-concept measurements and a prototype device for knee laxity assessment.

Main Methods:

• Development and testing of a prototype polydimethylsiloxane (PDMS) strain gauge system.
• Utilized a custom-designed knee test rig to simulate isolated knee joint instabilities.
• Conducted measurements during active and passive motion using a motor-controlled human knee model.

Main Results:

• Determined the absolute sensitivity of an exemplary sensor to be 2.038 [Formula: see text] and relative sensitivity to be 1.121 [Formula: see text].
• Identified optimal sensor positions for capturing projected bone-to-bone displacement on the skin.
• Demonstrated the capability of PDMS strain gauges to measure bone-to-bone displacements via skin surface measurements.

Conclusions:

• Polydimethylsiloxane (PDMS) strain gauges are effective for measuring bone-to-bone displacements on the skin surface.
• The study presents a novel and feasible approach for in vitro assessment of knee joint laxities using an artificial knee test rig.
• This technology holds potential for improved diagnostics and management of knee instabilities.