A validity study of phase velocity measurements in spinal cord injury.

We measured a cross-section of able-bodied (AB) men (n = 175) and men with chronic spinal cord injury (SCI) (n = 33) residing in the community, 14 to 65 years old, to identify associations between dietary factors, physical activity, health status, and mechanical properties of long bones assessed by phase velocity measurement of flexural waves in the tibia during the second to seventh decades. This study (1) evaluated the influence of different types of osteoporosis risk factors on measured phase velocity of tibia bone as measured by Bone Stiffness Measurement Device (BSMD)-Swing in AB men and in men with long-standing SCI and (2) estimated the construct validity of phase velocity measurements by assessing the discriminatory capability of the BSMD-Swing. Linear regression analysis suggests a direct relationship between health status, tibia length, age, and phase velocity (R(2) = 23%). An analysis of variance results in significant differences in phase velocity values between AB controls and individuals with SCI with and without pathologic fracture history. Phase velocity measurements in the tibia shaft provide useful information about bone status in populations at risk for low-trauma fractures and seems well suited for assessing tibia bone status in SCI.