Acute osteomyelitis: advantage of white cell scans in early detection

Acute osteomyelitis was induced in 18 rabbits after direct injection of a solution of Staphylococcus aureus culture into a proximal tibial metaphysis. Serial plain radiographs and radionuclide studies with indium-111 oxide labeled while blood cells and technetium-99m methylene diphosphonate were performed over the next 4 weeks. Visual and quantitative analysis by measuring the isotope activity of 111In and 99mTc over the infected tibias as compared with the opposite bones revealed that the white blood cell scans were positive in 15 (83%) of the 18 rabbits during the first week after injection of the microorganism. During the same period, the 99mTc bone scans were positive in only 22% of the animals (p less than 0.005). In the animals that survived, both white blood cell and bone scans were positive during the second week, and thereafter, the bone scans revealed consistently higher activity than was observed with white blood cell scans. Computed tomography performed in six rabbits revealed an increased attenuation coefficient of the medullary cavities in the infected bones of four animals during the first week and of one more during the second week. Plain radiographs became positive after the 12th day. Results indicate that in patients with suspected acute osteomyelitis, white blood cell scans and probably computed tomography can detect the disease earlier than 99mTc bone scans and plain radiographs.