The objective of this study was to compare bone mineral density and content measurements by dual-energy x-ray absorptiometry with bone stiffness measurements as indicators of the load-bearing capacity of regenerating bone during distraction osteogenesis.
The study analyzed ex vivo a set of 26 sheep bone specimens after distraction osteogenesis. Bone mineral density and bone mineral content were measured by dual-energy x-ray absorptiometry. Biomechanical parameters such as torsional, compressive, and bending stiffness were determined using a material testing system. The maximum torsional moment applied at fracture is used to determine the load-bearing capacity of the bone.
The correlation between stiffness measurements and the load-bearing capacity of a bone is significantly greater than the correlation between load-bearing capacity and bone mineral density and content measurements by dual-energy x-ray absorptiometry.
The results of this ex vivo study indicate that stiffness measurements are a better quantitative indicator of the load-bearing capacity of a bone and thus of bone healing than bone mineral density and content measurements by dual-energy x-ray absorptiometry. The results of the current study do not confirm previous work that showed that there is a significant correlation between bone material quality obtained by dual-energy x-ray absorptiometry and bone strength.
From the Department of Orthopaedic Surgery, Hannover Medical School, Hannover, Germany.
Accepted for publication July 14, 2009.
Fixator parts, used in this study, were a generous gift of Smith + Nephew, Hamburg, Germany. Parts of this study were supported by Wyeth, Cambridge, MA.
Reprints: Thilo Floerkemeier, MD, Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 1-7, 30625 Hannover, Germany (e-mail: Thilo.Floerkemeier@annastift.de).