Lumbar segment-dependent soft tissue artifacts of skin markers during in vivo weight-bearing forward–Backward bending

Frontiers in Bioengineering and Biotechnology, 2022 · DOI: 10.3389/fbioe.2022.960063 · Published: August 17, 2022

Simple Explanation

This study investigates how skin markers used in motion capture systems are affected by soft tissue movement when measuring lumbar spine motion during forward and backward bending. The researchers compared measurements from skin markers to virtual bone markers derived from dual fluoroscopic images to quantify the errors (soft tissue artifacts or STAs) in different directions. The study found that STAs vary depending on the direction of movement, the location of the marker on the lumbar spine, and whether the spine is in flexion or extension.

Study Duration

Not specified

Participants

Six pain-free female adults

Evidence Level

Original Research

Key Findings

1
STAs continuously increased in the anterior/posterior (AP) direction during the bending cycle.
2
The proximal/distal (PD) direction exhibited a reciprocal pattern during lumbar extension and flexion.
3
During flexion, the STA at the lower lumbar region was significantly higher than that at the upper lumbar region in the PD direction.

Research Summary

This study quantified soft tissue artifacts (STAs) of skin markers on the lumbar spine during weight-bearing forward-backward bending using dual fluoroscopy. The results showed that STAs are dependent on anatomical direction, marker location, lumbar segment, and bending phase. The findings suggest that these patterns can help clinicians assess kinematic errors and improve the accuracy of lumbar joint kinematic measurements.

Practical Implications

Improved Kinematic Models

The findings can be used to develop location- and direction-specific weighting factors for global optimization algorithms to minimize the effects of STAs on lumbar joint kinematic calculations.

Clinical Assessment

Clinicians and physical therapists can use the STA patterns to better assess kinematic errors in patients with low back pain during functional activities.

Personalized Treatment

Credible and valid lumbar spine kinematic results are important for future studies aiming to provide personalized clinical management for LBP.

Study Limitations

1
The study included only young women with relatively low BMI.
2
The study focused on flexion-extension, lacking data on other degrees of freedom.
3
The study used quasi-static images, not representing instantaneous dynamic positions.

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