[Functional adaptation of the bones. Animal experiment studies on rats]

The authors wanted to study the effect of non-physiologic muscular forces on growing rat bones. 35 animals were submitted to a total extirpation of the femur, 40 animals served as control group. They were killed immediately, six, twelve, or 24 weeks later, respectively. The results determined by macroscopic X-ray and fluorescence microscope examination are identical. As opposed to the control tibiae, the tibiae exposed to a greater load showed an increased bone density, increased ventral and lateral annexes, above all within the proximal third, and a torsion apparent in the cross-section. The less loaded tibiae showed a smaller bone density, increased medial and lateral annexes, above all within the proximal third, and a torsion apparent in the cross-section. The results are explained by the varying action of pressure and muscular forces and compared to those achieved by other authors.