A triple-tracer nuclear medicine study that incorporates (99m)Tc-sulfur colloid, (111)In-labeled leukocytes, and (99m)Tc-methylene diphosphonate can be useful for the diagnosis of aseptic loosening in a patient after total-knee arthroplasty, as demonstrated in this case study. The triple-tracer technique takes less time and is more accurate than a bone scan alone.