Knee hyperextension occurs when pressure is placed on the knee that bends it backward, past its normal straightened position, according to MayoClinic.com. Common causes of knee hyperextension include sports, dance, falls and car accidents. Treatment options range from over-the-counter painkillers to surgery, depending on the degree of injury.
Mayo Clinic rehabilitation specialist Dr. Edward Laskowski says knee hyperextension is a common injury in gymnastics, basketball and volleyball. While hyperextension injuries can damage ligaments, cartilage and other structures that help stabilize the knee, Laskowski says many sports-related injuries are more limited. You might just notice some pain when you try to straighten your knee and some bruising and swelling. Athletes who suffer a very forceful hyperextension commonly tear a knee ligament called the anterior cruciate ligament, or ACL. If the injury is severe enough to require surgery, Laskowski says you may have to wait six to nine months before returning to sports.
Some knee hyperextension can occur naturally, and some in the dance world think it may even complement the look of a leg with a pointed foot. The Harkness Center for Dance Injuries notes that trouble occurs when dancers “lock” back into the knee and put more stress on the knee joint and lower leg. Dancers with knee hypertension may suffer from a muscle imbalance in the thigh, “shin splints” or stress fractures in the tibia. The Harkness Center notes that home exercise plans may help dancers prevent a recurrence of pain from knee hyperextension and dance instructors should encourage those dancers not to lock their knees.
Knees can also become hyperextended if you take a hard fall or get injured in a car accident. Laskowski says car accidents can cause particularly severe knee injuries because the impact often occurs when the leg is straight and tense. In extreme cases, the knee can become dislocated and several knee ligaments may be torn or detached from surrounding bones and muscles. He recommends immediately consulting a doctor any time a hyperextension injury causes joint swelling, instability or impaired motion or pain. Rest and some physical therapy may be ordered.