Changes in composition and metabolic activity of the skeletal parts of the extremity of the adult rat following below-knee amputation.

Below-knee amputation in adult male rats resulted in characteristic quantitative and qualitative changes of the tibia stump and of the femur in the amputated leg. These changes were followed for periods of 1 to 32 weeks after the amputation. The femur of the amputated leg underwent a significant reduction of its total bone mass and a significant decrease of its percentage ash content, whereas its percentage water and organic contents increased significantly. The bone specific activity was initially decreased and began to increase after the 10th week post surgery with a positive linear regression. The amputated tibia underwent a significant, though declining, increase of its percentage water and organic contents and a likewise significant decrease of its percentage ash content. The specific activity of the amputated tibia was significantly higher than that of the tibia from the non-amputated leg, the difference showing a negative linear regression. The specific activity of the femur was decreased initially and increased later on.