Associations Between Hip Mobility and Pain in Chronic Low Back Pain Using IMU and Markerless Motion Capture

Area of Science:

• Biomechanics
• Rehabilitation Medicine
• Musculoskeletal Disorders

Background:

• Chronic non-specific low back pain (CNLBP) is often linked to impaired hip mobility and altered lumbopelvic mechanics.
• Understanding the relationship between hip movement and low back pain is crucial for effective treatment strategies.

Purpose of the Study:

• To investigate the association between improvements in pain-provoking hip flexion and reduction in low back pain.
• To evaluate the agreement and consistency between Inertial Measurement Units (IMUs) and markerless motion capture systems for assessing hip flexion in CNLBP patients.

Main Methods:

• A longitudinal study involving 36 CNLBP patients undergoing a 6-week physiotherapy protocol.
• Active hip flexion was measured using both IMUs and a markerless system during the symptomatic limb's movement.
• Pain and disability were quantified using the Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI).

Main Results:

• Moderate correlations were found between improved hip flexion and decreased pain (markerless: r = -0.52; IMU: r = -0.57).
• Negligible associations were observed between hip flexion improvements and disability scores.
• High correlation (r = 0.87) between IMUs and markerless systems, though markerless systems showed consistent underestimation (-3.67° bias).

Conclusions:

• Enhancements in symptom-specific hip mobility are associated with pain reduction in CNLBP patients, underscoring the importance of lumbopelvic biomechanics.
• IMUs provide greater consistency for movement assessment, while markerless systems offer a more accessible, clinically relevant alternative.