Neurophysiological assessment of bone mechanosensitivity using the bone myoregulation reflex

Mechanical loading is essential for bone growth, development, and skeletal integrity, and these effects are mediated primarily by osteocytes, the principal mechanosensory cells of bone. Aging and osteoporosis can impair osteocytes and the lacunocanalicular system, leading to bone loss, reduced biomechanical quality, and increased fragility. The bone myoregulation reflex may offer a noninvasive means of evaluating bone mechanosensitivity and quality.

This study aimed to evaluate the applicability of a noninvasive neurophysiological method based on the bone myoregulation reflex as a tool for determining bone mechanosensitivity and quality.

The mechanical threshold was defined as the minimum force required to activate osteocytes, which are the sensory receptors of the bone myoregulation reflex, and was estimated using a cumulative averaging method. Thresholds were measured first in healthy young adults during whole-body vibration and then in older adults with primary osteoporosis to assess the ability of the method to detect bone loss-related changes in mechanosensitivity.

In healthy young adults, the normalized mechanical thresholds ranged from 2.9 to 4.7% of the peak-to-peak vibration loading force, depending on the vibration frequency. In contrast, participants with osteoporosis exhibited significantly higher thresholds, ranging from 9.0 to 15.5%.

This proof-of-concept study demonstrates the feasibility of a neurophysiological method for assessing bone mechanosensitivity using the bone myoregulation reflex. The higher thresholds observed in patients with osteoporosis suggest impaired osteocyte function and provide a basis for future clinical validation. Such validation should consider BMI and sex and include both young and older non-osteoporotic controls to distinguish osteoporosis from age-related effects.