Measurements of In Vivo Strains in the Rat Tail Vertebra

The study of bone adaptation is important in understanding the etiology of age-related bone fractures, developing optimal designs for total joint replacements, and preventing bone loss during prolonged space flight. Numerous studies have attempted to quantify the relationship between mechanical loading and bone adaptation [1,2,3,4]. An in vivo rat tail vertebra model has been developed for trabecular bone adaptation studies where a controlled mechanical load can be applied to a whole vertebra [3]. The load levels applied in vivo were selected using in vitro strain gage measurements on cadaveric rat tails, resulting strains in the cortical shell of tail vertebrae within the physiological range. However, it is not clear what the physiological strain level in the rat tail vertebrae in vivo during normal cage activities is. In addition, the in vivo strain in the rat tail vertebra subjected to mechanical loads has not been quantified.