A Study of Bone Formation Subsequent to Intramedullary Fluid Pressure Fluctuations in Young and Old Rats

Osteoporosis is a major health care concern. In addition to medication, mechanical loading (e.g., exercise) can augment bone mass to alleviate or delay osteoporosis. Reports in the literature indicate that the stimuli initiating bone remodeling with mechanical loading are fluctuations in intramedullary pressure and interstitial fluid flow. Methodologies designed to altered intramedullary pressure and fluid flow involve infection susceptible and external oscillatory equipment. We report preliminary data indicating enhanced bone formation in rat femora by use of polydimethylsiloxane (PDMS) based pressure modulating micropump, which alters intramedullary pressure. These pressure alterations are sensed and recorded via a wireless pressure sensor system for real-time measurement of bone intrameduallry pressure. With only 10 minutes of pressure fluctuation and 7 days of recovery, new bone volume formation in the rats tended (p=0.09) to be higher in femora receiving pressure modulation vs. the contralateral control bone. These results suggest that our system may be efficacious in augmenting bone mass.