2011 Annual Conference

Kunder, Karina Amani

Rehabilitative ultrasound imaging (RUSI) has been shown to be a reliable and valid method of assessing the morphology of spinal stabilizers, such as the multifidus, in adults without scoliosis. It is hypothesized that spinal stability in adolescent idiopathic scoliosis (AIS), the most common type of scoliosis, may be reduced due to structural changes from spinal deformity. However, RUSI has not been used to examine the multifidus in adolescents with and without scoliosis. The purpose of this cross-sectional study is to determine the reliability of ultrasonographic measurements of the lumbar and thoracic multifidus muscles in both healthy adolescents and adolescents with IS.

Twenty 10-12 years old adolescents, 10 with AIS and 10 age-matched controls, completed the study. The participants with AIS had curves of 15-24° and Risser 0-1.

An ultrasound machine with a curved array transducer with a frequency range of 1 to 4 MHz was used to capture the image of the multifidus muscle. The parasagittal method was used to determine muscle thickness of the multifidus at both sides of T8, L1, and L4 vertebral levels. The transducer was placed centrally and longitudinally over the spinous process and then moved laterally with a 30-45° angle toward the spinous processes to locate the zygapophyseal joints. Images were taken in the relaxed prone and standing positions for two sessions on the same day. Muscle thickness was measured from the zygapophyseal joints to the inner edge of the fascia between the multifidus and superficial tissue.

Intraclass Correlation Coefficients (ICC_3,3) were used to calculate intrarater reliability.

Ultrasonographic measurements of multifidus thickness had good intrarater reliability (ICC = 0.83 - 0.99) at T8, L1, and L4 in the relaxed prone and standing positions for both groups. Reliabilities were similar between the relaxed prone (ICC = 0.83 – 0.99) and standing positions (ICC = 0.88 – 0.99) in both groups. The ICC was higher in the control group (ICC = 0.94 – 0.99) than the scoliosis group (ICC = 0.83 – 0.98) in the relaxed condition.

The results demonstrate that RUSI is reliable in measuring the thoracic and lumbar multifidus in adolescents with and without IS. However, RUSI is more reliable in adolescents without IS.

RUSI imaging may provide a reliable and objective method for further understanding of the pathophysiology of AIS. Nonoperative treatments for scoliosis such as bracing and exercise may be improved with a clearer understanding of muscle mass and strength changes in scoliosis, especially in adolescents with a high likelihood of progression.