Your entire skeleton replaces itself roughly every 10 years through continuous bone renewal.

The human skeleton is not a static structure but a dynamic organ that undergoes continuous renewal through bone remodeling, a metabolic process driven by two primary cell types: osteoclasts and osteoblasts. Osteoclasts break down and dissolve old or damaged bone mineral through a process called bone resorption. Once the old bone is removed, osteoblasts move in to secrete new bone matrix, which eventually mineralizes into hard tissue.According to the National Institutes of Health, approximately 10% of the adult skeleton is replaced every year. Over roughly a decade, this cumulative process results in an entirely new skeleton. Remodeling is essential for maintaining calcium homeostasis in the blood and repairing micro-fractures caused by daily physical stress. Without this constant replacement, bones would become increasingly brittle and prone to failure.The rate of replacement varies across the body. Spongy trabecular bone in the spine renews faster than the dense cortical bone found in the shafts of long bones. As humans age, the balance between bone removal and formation can shift. After age 30, bone resorption often begins to outpace formation, leading to a gradual loss of bone density. Maintaining adequate intake of vitamin D and calcium, combined with weight-bearing exercise, helps support osteoblasts in their lifelong task of rebuilding the skeletal frame.