A hyperextended knee occurs when the knee is bent backward, often as a result of landing wrong after a jump. A hyperextended knee can damage ligaments, cartilage and other stabilizing structures in the knee.
Young children have softer bones because they're still growing, so a hyperextended knee can result in a chip of bone being pulled away from the main bone when the ligaments stretch too far. In older children and adults, forceful hyperextension may tear one of the knee ligaments, particularly the anterior cruciate ligament (ACL).
If the knee injury is severe enough to cause swelling, pain or instability, see a doctor immediately. Even if the injury doesn't need surgical repair, physical therapy may be needed to help restore leg strength and stability.
May 20, 2015
- Mencio GA, et al. Skeletal trauma in young athletes. In: Skeletal Trauma in Children. 5th ed. Philadelphia, Pa.: Saunders Elsevier; 2015. http://www.clinicalkey.com. Accessed April 24, 2015.
- DeLee JC, et al. Knee injuries in skeletally immature athletes. In: DeLee & Drez's Orthopaedic Sports Medicine: Principles and Practice. 4th ed. Philadelphia, Pa.: Saunders Elsevier; 2015. http://www.clinicalkey.com. Accessed April 24, 2015.
- Marx JA, et al. Knee and lower leg. In: Rosen's Emergency Medicine: Concepts and Clinical Practice. 8th ed. Philadelphia, Pa.: Mosby Elsevier; 2014. http://www.clinicalkey.com. Accessed April 24, 2015.
- Brooks GP, et al. Treatment of knee injuries in the young athlete. http://www.uptodate.com/home. Accessed April 24, 2015.