Distal Femur Thighbone Fracture
Article by Dr. Darren R Keiser MD
A fracture is a broken bone. Fractures of the thighbone that occur just above the knee joint are called distal femur fractures. The distal femur is where the bone flares out like an upside-down funnel. Distal femur fractures most often occur either in older people whose bones are weak, or in younger people who have high energy injuries, such as from a car crash. In both the elderly and the young, the breaks may extend into the knee joint and may shatter the bone into many pieces.
Distal femur fractures vary. The bone can break straight across (transverse fracture) or into many pieces (comminuted fracture). Sometimes these fractures extend into the knee joint and separate the surface of the bone into a few (or many) parts. These types of fractures are called intra-articular. Because they damage the cartilage surface of the bone, intra-articular fractures can be more difficult to treat.
Distal femur fractures can be closed — meaning the skin is intact — or can be open. An open fracture is when a bone breaks in such a way that bone fragments stick out through the skin or a wound penetrates down to the broken bone. Open fractures often involve much more damage to the surrounding muscles, tendons, and ligaments. They have a higher risk for complications and take a longer time to heal.
When the distal femur breaks, both the hamstrings and quadriceps muscles tend to contract and shorten. When this happens the bone fragments change position and become difficult to line up with a cast.
Fractures of the distal femur most commonly occur in two patient types: younger people (under age 50) and the elderly.
Distal femur fractures in younger patients are usually caused by high energy injuries, such as falls from significant heights or motor vehicle collisions. Because of the forceful nature of these fractures, many patients also have other injuries, often of the head, chest, abdomen, pelvis, spine, and other limbs.
Elderly people with distal femur fractures typically have poor bone quality. As we age, our bones get thinner. Bones can become very weak and fragile. A lower-force event, such as a fall from standing, can cause a distal femur fracture in an older person who has weak bones. Although these patients do not often have other injuries, they may have concerning medical problems, such as conditions of the heart, lungs, and kidneys, and diabetes.
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Article URL: http://orthoinfo.aaos.org/topic.cfm?topic=A00526&webid=2FDDE053