Long-term measurement of bone strain in vivo: the rat tibia.
Despite the importance of strain in regulating bone metabolism, knowledge of strains induced in bone in vivo during normal activities is limited to short-term studies. Biodegeneration of the bond between gauge and bone is the principle cause of this limitation. To overcome the problem of bond degeneration, a unique calcium phosphate ceramic (CPC) coating has been developed that permits long-term attachment of microminiature strain gauges to bone. Using this technique, we report the first long-term measurements of bone strain in the rat tibia. Gauges, mounted on the tibia, achieved peak or near peak bonding at 7 weeks. Measurements were made between 7-10 weeks. Using ambulation on a treadmill, the pattern and magnitude of strain measured in the tibia remained relatively constant between 7-10 weeks post implantation. That strain levels were similar at 7 and 10 weeks suggests that gauge bonding is stable. These data demonstrate that CPC-coated strain gauges can be used to accurately measure bone strain for extended periods, and provide an in vivo assessment of tibial strain levels during normal ambulation in the rat.
Rabkin
B A
BA
NASA-Ames Research Center, Moffett Field, California, USA.
Szivek
J A
JA
Schonfeld
J E
JE
Halloran
B P
BP
D000818:Animals; D001696:Biomechanical Phenomena; D001703:Biophysics / Q000295:instrumentation; D001843:Bone Cements; D002130:Calcium Phosphates; D002516:Ceramics; D008297:Male; D008422:Materials Testing; D051381:Rats; D011916:Rats, Inbred F344; D013977:Tibia / Q000502:physiology*; D013997:Time Factors
D001843:Bone Cements; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous