Total knee replacement may be done on people, usually over 55, whose knees have been damaged by arthritis, trauma, or other destructive diseases of the joint resulting in severe limiting knee pain and significant stiffness, instability (constant giving way) and deformity (lock-knees or bowlegs) of the knee.
The Mexican government has a Federal District, which houses the federal government. The Federal District is a physical place and a territory, bordering Mexico City, which is the country's capital city. This is not counted as one of the states, and is much like the United States' District of Columbia.
Mexico is an ethnically diverse nation, and the Mexican constitution defines the country to be multicultural. Most Mexicans are Mestizos, people of mixed European (White) and Native American background. They account for 60-80% of the Mexican population (between 67 up to 90 million in 2010).