Wolff’s Law is a simple ideology that states that the natural bone of a healthy animal or person will adapt to the stress under which it is placed. This law was developed in the 19th century by German surgeon and anatomist Julius Wolff. He posited that if the load under which a bone is placed is increased, the bone naturally reconstructs itself to become stronger and withstand the additional strain. These changes are remarkable and include both primary changes to trabeculae architecture and secondary adaptive changes to external cortical bone, which may become thicker. The opposite is also true; if the strain on a bone decreases, the bone weakens over time due to the lack of stimulation needed to keep bones strong and healthy. Bone strength and density often decreases after a prosthesis is placed as a result of stress shielding, or the transfer of load from bone to prosthetic.