Pelvic belt effects on pelvic morphometry, muscle activity and body balance in patients with sacroiliac joint dysfunction

Abstract

Introduction: The sacroiliac joint (SIJ) is frequently involved in low back and pelvic girdle pain. However, morphometrical and functional characteristics related to SIJ pain are poorly defined. Pelvic belts represent one treatment option, but evidence still lacks as to their pain-reducing effects and the mechanisms involved. Addressing these two issues, this case-controlled study compares morphometric, functional and clinical data in SIJ patients and healthy controls and evaluates the effects of short-term pelvic belt application.

Methods: Morphometric and functional data pertaining to pelvic belt effects were compared in 17 SIJ patients and 17 controls. Lumbar spine and pelvis morphometries were obtained from 3T magnetic resonance imaging. Functional electromyography data of pelvis and leg muscles and center of pressure excursions were measured in one-leg stance. The numerical rating scale was used to evaluate immediate pain-reducing effects.

Results: Pelvic morphometry was largely unaltered in SIJ patients and also by pelvic belt application. The angle of lumbar lateral flexion was significantly larger in SIJ patients without belt application. Muscle activity and center of pressure were unaffected by SIJ pain or by belt application in one-leg stance. Nine of 17 patients reported decreased pain intensities under moderate belt application, four reported no change and four reported increased pain intensity. For the entire population investigated here, this qualitative description was not confirmed on a statistical significant level.

Discussion: Minute changes were observed in the alignment of the lumbar spine in the frontal plane in SIJ patients. The potential pain-decreasing effects of pelvic belts could not be attributed to altered muscle activity, pelvic morphometry or body balance in a static short-term application. Long-term belt effects will therefore be of prospective interest.

Fig 1. Summary of the experimental setup.

Fig 2. Morphometrical measurements.

On basis of 3 Tesla magnetic resonance imaging, angles and spatial relations were compared at the lumbar spine. ASIS = anterior superior iliac spine, ax = axial plane, co = coronal plane, cd = caudal, cr = cranial, d = dorsal, l = left, MRI = magnetic resonance imaging, PSIS = posterior superior iliac spine, r = right, S _1,2,etc. = first (second, etc.) sacral vertebral body, sa = sagittal plane, Th ₁₂ = twelfth thoracic vertebral body, v = ventral, ∡ = angle.

Fig 3. Morphometrical measurements.

On basis of 3 Tesla magnetic resonance imaging, angles and spatial relations were compared at the pelvis. ASIS = anterior superior iliac spine, ax = axial plane, co = coronal plane, cd = caudal, cr = cranial, d = dorsal, l = left, MRI = magnetic resonance imaging, PSIS = posterior superior iliac spine, r = right, S _1,2,etc. = first (second, etc.) sacral vertebral body, sa = sagittal plane, Th ₁₂ = twelfth thoracic vertebral body, v = ventral, ∡ = angle.

Fig 4. Morphometrical measurements.

On basis of 3 Tesla magnetic resonance imaging, angles and spatial relations were compared at the sacroiliac joint. ASIS = anterior superior iliac spine, ax = axial plane, co = coronal plane, cd = caudal, cr = cranial, d = dorsal, l = left, MRI = magnetic resonance imaging, PSIS = posterior superior iliac spine, r = right, S _1,2,etc. = first (second, etc.) sacral vertebral body, sa = sagittal plane, Th ₁₂ = twelfth thoracic vertebral body, v = ventral, ∡ = angle

Fig 5. Pelvic belt application.

A SacroLoc belt (Bauerfeind AG, Zeulenroda-Triebes, Germany) is applied to a female volunteer under moderate tension, as recommended by the manufacturer.

Fig 6. 11-point Numerical rating scale (NRS) data on pain intensity.

Fig. 6A: Non-significantly altered pain intensity was observed in sacroiliac joint pain patients with belt application under moderate tension, while maximum tension slightly increased pain intensity. Fig. 6B: Comparison to the condition without pelvic belt (Δ NRS) revealed that moderate tension tended to change pain intensity more effectively than maximum tension in patients with sacroiliac joint pain on a non-significant level.