In vivo measurement of bone deformations using strain gauges

Quantifying the mechanical input to bone is an important step in understanding the form and function of the skeleton. The forces applied to bone at the organ level must be translated to the cellular level and in some way play a role in the maintenance and adaptation of bone tissue. Determining the deformations that a bone normally experiences should help elucidate this mechanotransduction mechanism in bone. To date, the strain gauge, a device that measures the deformations of the material to which it is attached, has been the method used to quantify in vivo bone strains. While the strain gauge suffers from limitations, especially when used in the harsh environment of the body, this device has provided many useful measurements of bone deformations. This chapter covers the development of strain gauges for use with bone and tabulates the in vivo strain measurements recorded over the years to quantify the mechanical loading environment of the skeleton. While strain gauges have been used for many applications using in vitro bone specimens and human cadavers, this chapter will focus on the use of strain gauges to measure in vivo bone strains.