The measurements of sacroiliac joint stiffness with colour Doppler imaging: A study on healthy subjects

Rationale and objectives: Primary peripartum pelvic and low back pain is a common complaint of females. The etiologic relation between pain and pelvic stability has been shown in previous studies, but at present there is no objective clinical testing method to evaluate pelvic stability. Methods: In this study, a dynamic measurement method using sonoelasticity to assess the sacroiliac joint (SI) stiffness was tested in vivo in 14 healthy female volunteers. With the subjects in supine position vibrations were unilaterally applied to the anterior iliac spine. The vibrations were registered by a Colour Doppler Imaging (CDI) transducer over the ip-silateral SI joint. Since the threshold level of the apparatus has a direct relation with the power of the vibrations, the intensity of the vibrations (sonoelasticity) on the sacrum and ilium was measured indirectly in threshold units. The differences between the threshold values were accepted as the power loss of vibrations through the SI joint. One-way analysis of variance-test and T-test for paired samples were applied on the measurement results ( P < 0.05). Results: Statistically, the results showed a satisfactory intra-individual reproducibility and inter-individual variability. There was no significant difference between the data derived from the left SI joint and right SI joint. Conclusions: Based on the promising results on healthy female volunteers, this method will be specifically used in future studies on patients with peripartum pelvic pain.