A Reconfigurable Multiplanar In Vitro Simulator for Real-Time Absolute Motion With External and Musculotendon Forces

Area of Science:

• Biomechanics
• Musculoskeletal modeling
• Robotics

Background:

• Computational biomechanics research requires realistic experimental data.
• Current limitations exist in simulating physiological loading conditions in real-time.
• Accurate measurement of joint forces and muscle activation is crucial for understanding movement.

Purpose of the Study:

• To present the design, configuration, capabilities, accuracy, and repeatability of the University of Texas at El Paso Joint Load Simulator (UTJLS).
• To validate the UTJLS's performance using cadaver knee specimens under simulated squat maneuvers.
• To establish a novel platform for real-time musculoskeletal biomechanics research.

Main Methods:

• The UTJLS utilizes two robotic manipulators and eight musculotendon actuators.
• A custom control system manages position, force, and hybrid control, collecting data at 2000 Hz.
• Four cadaver knee specimens underwent 47 real-time tests, including squat variations with and without simulated muscle forces.

Main Results:

• Musculotendon actuator accuracy and repeatability were within 8 N and 5 N, respectively.
• Ground reaction force (GRF) accuracy and repeatability were within 30 N and 13 N.
• Ground reaction moment accuracy and repeatability were within 4.4 N·m and 1.9 N·m.

Conclusions:

• The UTJLS is a unique musculoskeletal simulator capable of real-time, multiplanar motion simulation.
• Its design and control system offer flexibility for various testing scenarios and future research.
• The system's accuracy and repeatability support its use in advancing computational musculoskeletal biomechanics.