1. Department of Medicine (A.C., E.M.S., D.J.M., H.F.R., E.S.), Columbia University, New York, New York 10032
2. Bone Bioengineering Laboratory, Department of Biomedical Engineering (X.S.L., X.E.G.), Columbia University, New York, New York 10032
3. Creighton University (J.L., R.R.R., J.M.L.), Omaha, Nebraska 68131