Occupational Low Back Pain at RIC

Sitting and occupational LBP in office workers

It is widely accepted that prolonged static sitting and disturbed lumbar spine alignment in sitting are etiological factors for occupational LBP. Sitting Biomechanics lab is working to provide sitting solutions for limiting such risk factors of LBP in office workers.

Sitting Biomechanicslab proposed a new sitting posture to prevent or to relieve occupational LBP. This new sitting concept, defined as WO-BPS posture, and the dynamic sitting between a regular posture and this WO-BPS posture, have been evaluated in Sitting Biomechanics lab under the support of NIOSH. The evaluation consists of three major parts:

Part I: Laboratory evaluation on sitting load, sitting pressure and muscle activity

Part II: Radiographic evaluation on lumbar spine alignment

Part III: Clinical evaluation of 12 weeks in subjects’ work environment for the dynamic sitting

Findings and Conclusions

WO-BPS posture:

• Reduced the load on lumbar spine
• Reduced back muscle activities in the lumbar region
• Forwardly rotated the sacrum
• Maintained lumbar lordosis
• Increased ventral side lumbar intervertebral disc heights

Dynamic sitting:

• Improved office workers’ sitting tolerance and comfort and relieved established LBP

Conclusions:

• The proposed sitting concept is beneficial in preventing and treating occupational sitting related LBP.

Pressure Distribution of a regular sitting posture and the WO-BPS posture

Upper row:interface pressure between the backrest and the back. Lower row: interface pressure between the seat cushion and the buttock-thighs. Left column: interface pressure recorded in Normal sitting posture. Right column: interface pressure recorded in the WO-BPS sitting posture.

Finding highlight: WO-BPS posture shifts sitting load from rear part of buttocks to thighs and the upper back, decreasing sitting load on lumbar spine.

Back Muscle Activity

In a one-hour sitting, posture changes induced muscle activity changes. N — Normal posture; W — WO-BPS posture; R—Right side; L—Left side.

Finding highlight: WO-BPS posture reduces back muscle activities in lumbar region.

Radiographic Evaluation of Lumbar Spine Alignment

Representative lateral radiographs from one subject in the Standing (A), Normal (B), and WO-BPS (C) postures. Measurement of the sacral inclination (a) and the lumbar lordosis are shown.

Finding highlight:

• WO-BPS posture restores lumbar lordosis close to that of standing.

• WO-BPS posture opens ventral side of lumbar spine.