The researchers used an x-ray technique called dual-energy x-ray absorptiometry (DEXA) scanning to test the strength of the bones (known as bone mineral density, or BMD) at 3 different sites in the body: the spine (lower back), the hip, and the upper part of the thigh bone (femur). The scans were done before transplantation. Each participant was then randomly (completely by chance) assigned to receive either the test drug (zoledronic acid) or placebo (saltwater) by intravenous injection. Each patient received 5 injections of either zoledronic acid or placebo over the next 12 months. Hospital pharmacists, who were not involved in analyzing the results of the study, prepared the solutions for injection so that neither the researchers who were conducting the study nor the participants were aware of whether zoledronic acid or placebo was being administered. All participants (in both groups) received calcium and vitamin D supplements as well as medication to prevent rejection of the transplanted liver. Dual-energy x-ray absorptiometry was repeated at 3, 6, and 12 months after transplantation to evaluate what was happening to BMD over time.