Roentgen stereophotogrammetry for determination of bone growth. Comparison with the tetracycline method

Two different methods for determination of leg growth, the tetracycline method and roentgen stereophotogrammetry, were applied simultaneously in 41 young rabbits and compared 1 and 2, and 21 and 22 days after insertion of pins or balls of tantalum as markers. The tetracycline method gave slightly higher values than the other method, the difference varying between 77 and 6 micrometer/d on the first 2 days after marker insertion and between 32 and 1 micrometer/d after 3 weeks. When ball markers were used, agreement between the two methods was obtained 3 weeks after insertion. The difference between the methods used is due to that the two methods did not measure growth in precisely identical regions.