Whole-Body Vibration During Passive Standing in Individuals With Spinal Cord Injury: Effects of Plate Choice, Frequency, Amplitude, and Subject's Posture on Vibration Propagation

Publication year: 2012
Source:PM&R

Milad Alizadeh-Meghrazi, Kei Masani, Milos R. Popovic, Beverley Catharine Craven

Background To date, few pharmacologic or rehabilitation interventions for sublesional osteoporosis (SLOP) or low bone mass of the hip and knee regions after spinal cord injury (SCI) have produced significant or sustained increases in lower extremity bone mineral density. Whole body vibration (WBV) is a potential intervention for the prevention and/or treatment of SLOP. Objective The objective of this study was to identify the optimal WBV conditions (ie, plate, frequency, amplitude, and subject posture) among men with chronic SCI during passive standing. A priori, the “optimal WBV condition” was defined as the combination of WBV parameters that facilitates lower extremity vibration absorption while minimizing vibration propagation to the head. Design This phase 0 device development study assessed the lower extremity propagation characteristics of WBV in men with and without SCI by using a variety of a priori specified plates, frequencies, amplitudes, and postures. The study's aim was to facilitate the implementation and future evaluation of the efficacy of WBV and passive standing for prevention and treatment of men with SCI and SLOP. Setting A tertiary SCI rehabilitation center in Toronto, Canada. Participants Healthy men with chronic paraplegia (n = 5) and those without SCI (n = 7), ages 20-50 years, weighing 68-113 kg, and having a height of 168-188 cm. Interventions An EasyStand standing frame was fitted onto 2 commercially available vibration platforms: WAVE and Juvent. Accelerometers were attached to the participants' forehead, hip, knee, and ankle to measure vibration propagation. Vibration parameters evaluated were posture (knee angles of 140°, 160°, and 180° [180° for Juvent only]), vibration frequency (25 Hz, 35 Hz, and 45 Hz), and vibration amplitude (0.6 mm and 1.2 mm [WAVE only]). The subjects were exposed to all combinations of posture, frequencies, and amplitudes during the experiments (total parameter combinations: 12 WAVE and 9 Juvent). Main Outcome Measurements Peak-to-peak vibration and transmissibility of vibration were recorded and computed for each accelerometer at the tested locations. Results Variations in frequency generated the most noticeable changes in propagation characteristics, followed by variations in knee angle and amplitude. Conclusions WBV therapy delivered with use of the WAVE platform with a knee angle of 140°, plate frequency of 45 Hz, and amplitude of 1.2 mm met our a priori criteria for the “optimal WBV condition.” Future studies should evaluate the therapeutic efficacy of the WAVE platform by using these parameters to maintain or augment bone mass among persons with SCI and SLOP.

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