Repair and remodeling of partial-weightbearing, uninstrumented long bone fracture model in mice treated with low intensity vibration therapy

Background: While vibration therapy has shown encouraging results across many fields of medicine in the last decade, its role as originally envisioned for bone health remains uncertain. Especially regarding its efficacy in promoting fracture healing, mixed and incomplete outcomes suggest a need to clarify its potential. In particular, the definitive effect of vibration, when isolated from the confounding mechanical inputs of gait and stabilizing instrumentation, remains largely unknown. Methods: Four cohorts of C57BL/6 male mice underwent single-leg, open fibula fracture. Vibration was applied at 0.3 g to two groups for 20 min/d. At 3 and 6 weeks, fibulae were harvested for microcomputed tomography and 3-point bending to failure. Findings: In bone volume and tissue volume, the groups at each healing time point were statistically not different. At 3 weeks, however, the ratio of bone-to-tissue volume was lower for the vibrated group than control. Likewise, while bone mineral density did not differ, tissue volume density was lowest with vibration. At 6 weeks, mean differences were nominal. Biomechanically, vibration consistently trended ahead of control in strength and stiffness, but did not achieve statistical significance. Interpretation: At this stage of therapeutic development, vibration therapy in isolation does not demonstrate a clear efficacy for bone healing, although further treatment permutations and translational uses remain open for investigation.