→ a break in one or more of the bones that make up the knee.
The knee is the meeting place for four leg bones: the kneecap (patella), the thighbone (femur), the shinbone (tibia) and the calf bone (fibula). Damage to any of these bones can result in a fracture. Doctors categorise fractures in several different ways. In a non-displaced fracture, the broken pieces remain in contact with each other, or just a fraction apart, leaving most of the bone intact and in its correct position. In a displaced fracture, the pieces break and are no longer properly aligned. A comminuted fracture is where the bone breaks into many pieces. Open or closed fractures denote whether the bone has broken through the surface of the skin (open) or not (closed).
Knee fractures are usually caused either by a powerful impact (for example when the kneecap hits the car dashboard during an accident) or if you fall heavily onto your knee joint. People who suffer from weakened bones due to osteoporosis, or a bone infection, can be at higher risk of fractures following minor injuries. These types of breaks are known as pathologic fractures.
Typical signs that you may have fractured your knee include pain, bruising, or swelling that happens soon after an injury. It may be painful to move the knee, either by bending it or simply by putting weight on the affected leg. You may find it difficult to straighten the leg fully or to walk without pain. In some cases you may feel a grinding sensation in the knee as the broken pieces of bone rub against each other. The area may also appear visibly deformed or misaligned.
Diagnosing a fracture starts with a physical examination by your doctor. You will be asked about the circumstances of the injury and when you first experienced the symptoms. Some fractures are clearly visible in the examination. Others will need to be confirmed with an x-ray. The consultant will also check for signs of hemarthrosis, which is where damaged blood vessels bleed into the joint spaces, potentially causing swelling, stiffness or more serious complications.
Fracture treatment varies depending on the severity of the injury. Simple fractures are usually treated with a cast or splint, which keeps the knee straight and restricts movement while the bone heals naturally. More severe fractures may require surgery. Screws, pins or wires can be used to bind and fix large pieces of bone to restore alignment. Smaller bone fragments may have to be removed if they are too small to pin. Treatment for hemarthrosis varies depending on the cause of the damage, from simple rest and icing at home to aspiration (where fluid is drawn from the joint to reduce swelling and prevent further damage) and surgery.