[1] BETH ISRAEL HOSP, DIV GERONTOL, BOSTON, MA 02215 USA
[2] HARVARD UNIV, SCH MED, BOSTON, MA USA
[3] BETH ISRAEL HOSP, CHARLES A DANA RES INST, BOSTON, MA 02215 USA
[4] BETH ISRAEL HOSP, DEPT ORTHOPAED SURG, ORTHOPAED BIOMECH LAB, BOSTON, MA 02215 USA