Age-dependent decreases of phosphorus and magnesium in human Achilles' tendons

To elucidate changes of human tendons with aging, the authors studied age-r elated changes of elements in human Achilles' tendons by inductively couple d plasma-atomic emission spectrometry. The subjects consisted of seven men and seven women, ranging in age from 61 to 97 yr. It was found that the con tent of calcium increased progressively with aging in the Achilles' tendons , whereas the contents of phosphorus and magnesium decreased gradually with aging. The previous investigations demonstrated that the content of calciu m and phosphorus increased progressively with aging in most, but not all, h uman tissues, except for the bones. In ligaments, such as the anterior cruc iate ligament and the ligament of the head of the femur, which are histolog ically similar to the Achilles' tendon, it was previously found that both t he contents of calcium and phosphorus increased with aging in the ligaments . It should be noted that the content of phosphorus in the Achilles' tendon s decreased during the aging process. In addition, it was found that there was a very high direct correlation between phosphorus and magnesium content s in the tendons, but not between calcium and phosphorus contents.