A hip fracture is a break in the top quarter of the thighbone, usually treated with surgery. Each year about 300,000 Americans, most of them over age 65, suffer hip fractures. It happens more often to women than men because they fall more often and are more likely to have osteoporosis, a disease that weakens bones. Other factors that increase the risk of hip fracture include long-distance running and ballet dancing, which can cause thin cracks called stress fractures in the hips. If untreated, these cracks can grow larger. Hip fractures cause severe pain in the hip or groin and may prevent walking. The skin around the injury may swell, redden, or bruise. Some people with hip fractures can still walk but may feel vague pain in the hip, buttocks, thighs, groin, or back. Doctors will ask about recent injuries or falls, perform a physical exam, and take X-rays if a hip fracture is suspected. If X-rays are unclear, an MRI or bone scan may be needed. During a bone scan, a small amount of radioactive dye is injected into a vein, traveling through the blood to the bones to reveal fractures. Hip fractures can damage surrounding muscles, ligaments, tendons, blood vessels, and nerves. If not treated promptly, they can affect long-term mobility and cause complications. Surgery is usually needed, with the type depending on the fracture, age, and overall health. Pre-surgery tests may include blood and urine tests, chest X-rays, and an electrocardiogram. Keeping bones strong and healthy is the best prevention. Doctors may recommend drugs that enhance estrogen activity and improve bone density, known as selective estrogen receptor modulators. The FDA has approved hip protector garments for elderly people with osteoporosis, which may help prevent hip fractures.