Association of sagittal spinal alignment in the standing position with the masses and amounts of intramuscular non-contractile tissue of the trunk and lower extremity muscles in patients with Parkinson's disease.

Background: We examined the association of sagittal spinal alignment in the standing position with the masses and amounts of intramuscular non-contractile tissue of multiple trunk and lower extremity muscles, such as the hip joint muscles, measured using an ultrasound imaging device in patients with Parkinson's disease (PD).

Methods: The participants were 10 patients with PD. Sagittal spinal alignment (thoracic kyphosis, lumbar lordosis, and sacral anterior inclination angles) in the standing position was measured using a Spinal Mouse. Muscle thicknesses and echo intensities of the trunk and lower extremity muscles, including the hip joint muscles, were also measured in the prone or supine position using an ultrasound imaging device.

Findings: Partial correlation analysis with body height and weight as control variables showed that a low lumbar lordosis angle in the standing position was significantly associated with low thicknesses of the trunk extensor muscles (lumbar erector spinae and multifidus). Partial correlation analysis also revealed that a high sacral anterior inclination angle in the standing position was significantly associated with low lumbar multifidus muscle thickness. However, the thicknesses and echo intensities of the trunk flexor and hip joint muscles were not significantly related to thoracic kyphosis, lumbar lordosis, or sacral anterior inclination angles.

Interpretation: The results of this study suggested the association between a low lumbar lordosis angle in the standing position and low lumbar erector spinae and multifidus muscle thicknesses and between a high sacral anterior inclination angle in the standing position and low lumbar multifidus muscle thickness in patients with PD.