Fractures, Bursa Inflammation, and Patellar Injuries
Fractures of the bones of the knee are relatively common. The patella, or kneecap, may fracture due to a fall directly onto it or in car accidents when the knee is driven into the dashboard. If the bone is displaced (pulled apart), surgery may be required for repair, but if the bone is in a good position, a knee immobilizer and watchful waiting may be all that is required.
The head of the fibula on the lateral side of the knee joint can be fractured either by a direct blow or as part of an injury to the shin or ankle. This bone usually heals with little intervention, but fractures of this bone can have a major complication. The peroneal nerve wraps around the bone and can be damaged by the fracture. This will cause a foot drop, so do not be surprised if the physician examines your foot when you complain of knee problems.
With jumping injuries, the surface of the tibia can be damaged, resulting in a fracture to the tibial plateau. The mechanism of injury is jumping and landing on a fully extended, straightened knee. Since the femoral condyle sits on the tibial plateau to make the knee joint, it must heal with the most even joint surface as possible to prevent future arthritis and chronic pain. For that reason, after plain X-rays reveal this fracture, a CT scan may be done to make certain that there is no displacement of the bones. This type of fracture may require surgery for repair.
Fractures of the femur require significant force, but in people with osteoporosis, less force is needed to cause a fracture of this large bone. In people with knee replacements who fall, there is a potential weakness at the site of the knee replacement above the femoral condyle, and this can be a site of fracture. The decision to operate or treat by immobilization with a cast will be made by the orthopedist.
Housemaid's knee (prepatellar bursitis) is due to repetitive kneeling and crawling on the knees. The bursa or space between the skin and kneecap becomes inflamed and fills with fluid. It is a localized injury and does not involve the knee itself. Treatment includes padding the knee and using ibuprofen or naproxen as an anti-inflammatory medication. This injury is commonly seen in carpet installers and roofers. On occasion, if the skin is damaged or torn, this bursa may become infected.
The kneecap sits within the tendon of the quadriceps muscle, in front of the femur, just above the knee joint. It is held in place by the muscles of the knee.
The patella can dislocate laterally (toward the outside of the knee). This occurs more commonly in women because of anatomic differences in the angle aligning the femur and tibia. Fortunately, the dislocation is often returned to the normal position by straightening out the knee, usually resulting in the kneecap popping back into place. Physical therapy for muscle strengthening may be needed to prevent recurrent dislocations. Patellar dislocations are not knee dislocations, which require tearing of three to four major ligaments of the knee. Knee dislocations are uncommon and are a surgical emergency.
The patellofemoral syndrome occurs when the underside of the patella becomes inflamed if irritation develops as the underside of the kneecap rubs against the femoral condyle with each flexion and extension of the knee. This inflammation can cause localized pain, especially with walking downstairs and running. Treatment includes ice, anti-inflammatory medication, and exercises to balance the quadriceps muscle. More severe cases may require arthroscopic surgery to remove some of the inflamed cartilage and realign parts of the quadriceps muscle.