The importance of coupling-path correction for velocity measurements of the heel

Clinical devices for measuring bone with ultrasound use apparent velocity to assess bone fragility and risk of osteoporotic fracture. The magnitude of the artifacts resulting from failure to correct the velocity measurement for the effects of propagation through intervening media is estimated, and a method for correcting for such artifacts in human subjects is tested. Failure to measure the bone width and correct for the paths through water and soft tissue yields deceptively high reproducibility, masking intrapatient variability. Uncorrected velocity has a strong dependence on bone width. The results demonstrate the importance of the velocity correction