Bone Load Estimation for the Proximal Femur Using Single Energy Quantitative CT Data

Abstract

A density-based load estimation method was applied to determine femoral load patterns. Two-dimensional finite element models were constructed using single energy quantitative computed tomography (QCT) data from two femora. basic load cases included parabolic pressure joint loads and constant tractions on the greater trochanter. An optimization procedure adjusted magnitudes of the basic load cases, such that the applied mechanical stimulus approached the ideal stimulus throughout each model. Dominant estimated load directions were generally consistent with published experimental data for gait. Other estimated loads suggested that loads at extreme joint orientations may be important to maintenance of bone structure. Remodeling simulations with the estimated loads produced density distributions qualitatively similar to the QCT data sets. Average nodal density errors between QCT data and predictions were 0·24 g/cm³ and 0·28 g/cm³. The results indicate that density-based load estimation could improve understanding of loading patterns on bones.

Keywords:

• Bone load estimation
• density distribution
• bone adaptation simulation
• finite element analysis
• optimization

Additional information

Notes on contributors

KENNETH J. FISCHER

Current address: Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pittsburgh Pittsburgh. PA 15213. U.S.A

CHRISTOPHER R. JACOBS

Current address: Musculoskeletal Research Laboratory. Department of Orthopaedics. Pennsylvania Stale University School of Medicine, Hershey, PA 17033, U.S.A.

MARC E. LEVENSTON

Current address: Continuum Electromechanics Laboratory, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, U.S.A.