Effects of a Passive Back-Support Exoskeleton on Knee Joint Loading during Simulated Static Sorting and Dynamic...

Area of Science:

• Biomechanics
• Ergonomics
• Wearable Technology

Background:

• Back-support exoskeletons (BSEs) are designed to reduce spinal load.
• The load-shifting mechanisms may have unintended consequences on other joints, such as the knee.
• Understanding knee joint loading during exoskeleton use is crucial for assessing potential side effects.

Purpose of the Study:

• To evaluate the effects of using a back-support exoskeleton (BSE) on knee joint loading during simulated occupational tasks.
• To investigate how different working tasks and body postures influence knee joint forces when using a BSE.
• To determine if BSE use alters tibiofemoral forces.

Main Methods:

• Twenty-nine healthy subjects performed simulated static sorting and dynamic lifting tasks (stoop, squat, varied trunk rotation).
• Kinematic and kinetic data were collected using force plates, motion sensors, and exoskeleton-integrated sensors.
• An inverse quasi-static biomechanical model was used to calculate horizontal and vertical tibiofemoral forces.

Main Results:

• BSE use variably affected median horizontal tibiofemoral forces (HOR50) depending on task and posture.
• Generally, median vertical tibiofemoral forces (VERT50) increased with BSE use, irrespective of task or posture.
• 90th percentile forces (HOR90, VERT90) were not significantly affected by the exoskeleton.

Conclusions:

• The investigated back-support exoskeleton can alter knee joint loading, with effects varying by work task and user posture.
• Increased vertical tibiofemoral forces suggest a potential side effect of BSE use on knee joints.
• Future research should examine the contribution of these altered knee loads to cumulative work-related knee exposures.