Patellar dislocation is a painful knee injury that most commonly affects adolescents. It generally occurs during physical activities, so athletic teens are most at risk. With appropriate diagnosis and treatment, most people recover without further issue or recurrence. Strengthening and stretching the muscles and ligaments around the knee and in the leg can help prevent kneecap dislocation. Appropriate first aid and immediate medical attention are essential, and doctors often recommend ongoing rehabilitation and physical therapy.
Patella is the medical term for the kneecap, the part that sticks out of the front of the knee that one can usually maneuver slightly when the knee is relaxed. When the leg is bent and straightened, the patella stays in pretty much the same position. A patellar dislocation occurs when the patella slips out of this position.
A patellar dislocation occurs when something exerts excessive force on the knee joint, often due to a sudden change in direction that causes a sideways twisting motion in the joint. Direct trauma to the knee joint can also cause the dislocation. The type of movements that result in kneecap dislocation most commonly occur when a person plays a sport involving rotation of the knee, such as gymnastics, soccer, and hockey. Weakness or tightness in the surrounding tissues can contribute, as can malformations in the knee joint.
Patellar dislocation most commonly occurs in people aged ten to 17 years, with similar rates of occurrence in males and females. It is fairly uncommon, making up only two percent of knee injuries. There seems to be a genetic factor -- 24% of people who experience this injury have a relative who has also had a dislocation.
When the patella dislocates, it is generally noticeable as out of position, usually at the outside of the knee instead of the front, giving the appearance of a deformation. When one flexes or tightens the hamstring muscle, the leg bends. In a person with a patellar dislocation, the leg will often bend, even without the flexing of the leg muscle. It may be impossible for the injured individual to straighten his or her leg. Other symptoms include pain in the knee and kneecap, bruising, and swelling. The knee may give way when the individual attempts to stand. The patella may be hyper-mobile, meaning it will slide around the front of the knee joint.
Some basic first aid will improve the comfort of a person who has had a patellar dislocation. After calling an ambulance, caregivers can encourage the individual to straighten his or her leg or help with this motion. This will return the kneecap to the correct position, reducing pain. The individual should sit in this position until medical assistance arrives. Applying ice can help reduce swelling. People who have experienced dislocation before may be able to correct the situation without emergency care.
Because patellar dislocation occurs when the patella slips out of position, it is simple to diagnose through observation of the symptoms. A medical practitioner may test the patella by moving it back and forth while the patient flexes the knee. He or she may also ask the patient to perform squats or bend and straighten the knee while lying down. X-rays can confirm the diagnosis and reveal the extent of the injury.
Paramedics will splint the patient’s leg and transport them to the nearest accident and emergency department. If the kneecap remains out of position, a doctor can perform a reduction to manipulate the patella back into the correct position. The leg is then splinted in a straight position for several weeks, usually with a removable leg brace. Surgery is uncommon for knee dislocations, but the attending physician may enlist a surgeon if a piece of bone snaps off within the joint, or if there are multiple dislocations. Physiotherapy will reduce the chance of reoccurrence.
The patella is held in position by several ligaments and tendons. Patellar dislocation more often occurs when there is a weakness or tightness in these tissues that prevents them from supporting the knee joint properly. Athletes should perform regular exercises to stretch the tissues around the knee joint and strengthen the surrounding muscles. Exercises may include squats, hamstring curls, and thigh stretches.
Most people who suffer a patellar dislocation will not experience a subsequent event -- reoccurrence rates are about 30%. Without physiotherapy, the risk of reoccurrence can increase.
Bone or ligament damage may occur when a person has a patellar dislocation. People who experience this complication may require surgery. X-rays can confirm the extent of the injuries and determine whether the patient needs such measures.
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