Low-Level, High-Frequency Mechanical Signals Enhance Musculoskeletal Development of Young Women With Low BMD

Authors

  • Vicente Gilsanz MD,

    Corresponding author
    1. Department of Radiology, Childrens Hospital of Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California, USA
    2. Department of Orthopedics, Childrens Hospital of Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California, USA
    • Childrens Hospital Los Angeles, Department of Radiology, MS #81, 4650 Sunset Boulevard, Los Angeles, CA 90027, USA
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  • Tishya AL Wren,

    1. Department of Radiology, Childrens Hospital of Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California, USA
    2. Department of Orthopedics, Childrens Hospital of Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California, USA
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  • Monique Sanchez,

    1. Department of Radiology, Childrens Hospital of Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California, USA
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  • Frederick Dorey,

    1. Department of Pediatrics, Childrens Hospital of Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, California, USA
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  • Stefan Judex,

    1. Department of Biomedical Engineering, State University of New York, Stony Brook, New York, USA
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  • Clinton Rubin

    1. Department of Biomedical Engineering, State University of New York, Stony Brook, New York, USA
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    • Dr Rubin is an inventor of the technology evaluated in this manuscript. He is also a founder of and consultant to Juvent, Inc. All other authors state that they have no conflicts of interest.


Abstract

The potential for brief periods of low-magnitude, high-frequency mechanical signals to enhance the musculoskeletal system was evaluated in young women with low BMD. Twelve months of this noninvasive signal, induced as whole body vibration for at least 2 minutes each day, increased bone and muscle mass in the axial skeleton and lower extremities compared with controls.

Introduction: The incidence of osteoporosis, a disease that manifests in the elderly, may be reduced by increasing peak bone mass in the young. Preliminary data indicate that extremely low-level mechanical signals are anabolic to bone tissue, and their ability to enhance bone and muscle mass in young women was investigated in this study.

Materials and Methods: A 12-month trial was conducted in 48 young women (15–20 years) with low BMD and a history of at least one skeletal fracture. One half of the subjects underwent brief (10 minutes requested), daily, low-level whole body vibration (30 Hz, 0.3g); the remaining women served as controls. Quantitative CT performed at baseline and at the end of study was used to establish changes in muscle and bone mass in the weight-bearing skeleton.

Results: Using an intention-to-treat (ITT) analysis, cancellous bone in the lumbar vertebrae and cortical bone in the femoral midshaft of the experimental group increased by 2.1% (p = 0.025) and 3.4% (p < 0.001), respectively, compared with 0.1% (p = 0.74) and 1.1% (p = 0.14), in controls. Increases in cancellous and cortical bone were 2.0% (p = 0.06) and 2.3% (p = 0.04) greater, respectively, in the experimental group compared with controls. Cross-sectional area of paraspinous musculature was 4.9% greater (p = 0.002) in the experimental group versus controls. When a per protocol analysis was considered, gains in both muscle and bone were strongly correlated to a threshold in compliance, where the benefit of the mechanical intervention compared with controls was realized once subjects used the device for at least 2 minute/day (n = 18), as reflected by a 3.9% increase in cancellous bone of the spine (p = 0.007), 2.9% increase in cortical bone of the femur (p = 0.009), and 7.2% increase in musculature of the spine (p = 0.001) compared with controls and low compliers (n = 30).

Conclusions: Short bouts of extremely low-level mechanical signals, several orders of magnitude below that associated with vigorous exercise, increased bone and muscle mass in the weight-bearing skeleton of young adult females with low BMD. Should these musculoskeletal enhancements be preserved through adulthood, this intervention may prove to be a deterrent to osteoporosis in the elderly.

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