Bone density of the ulna: comparisons of different radiologic methods for in situ estimation.

Actual mineral content of 32 ulnae was determined by weighing the defatted and dehydrated bones and measuring their volume pycnometrically. The physical density of the distal cancellous part of the bone was calculated and the radiographic density of the distal cancellous part of the bone was determined using silver analysis of roentgen film and densitometry. The results were compared with those obtained earlier by a simple measurement of cortical thickness. The best results were obtained from densitometric scanning of the distal part of the bone but simple cortical measurement gave practically the same accuracy. Because none of the local measurement methods furnish a reliable estimate of mineral content in single cases, a simple cortical measurement is recommended in comparisons of large populations since the other local methods do not give more information in spite of their complexities.