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How to Treat a Dislocated Kneecap


No one will have to tell you when you’ve suffered—and suffered is the right word—a dislocated kneecap. It is a serious, painful injury that needs immediate medical attention. The long-term consequences are not that dire, but getting through the initial stages is an ordeal for any athlete and those who are nearby when it happens.

The kneecap (patella) sits in a groove at the bottom of thighbone. It stays in this groove when the knee is bent and acts as a support for the quadricep muscles that stabilize the leg when it is extended. Any physical activity that involves the lower extremities requires a stable kneecap.

The good news: In 90 percent of the cases, the kneecap returns to its groove spontaneously. There might still be pain and damage to supporting structures, so don’t try to walk it off or put weight on it immediately. More good news: Getting the kneecap back into its proper position is safe and simple when performed by a health care professional.

How a Dislocated Kneecap Happens

When the kneecap partially moves out of its position, doctors call the condition a subluxation. A partially dislocated kneecap can be the result of a previous dislocation or an inherited tendency for the kneecap to slide to the outside. There could be tenderness under the kneecap and pain when the person twists the knee or climbs stairs. A feeling of the knee’s instability is a common complaint. This is because the muscles and ligaments are unable to keep the patella in the femoral groove.

When the kneecap moves all the way out, usually to the outside of the leg, it has been dislocated. The injury can result from a blow to the knee, but it happens more commonly when an athlete performs some kind of twisting motion or change of direction.

“Often the patella can be prone to dislocating because of a tight TFL [tensor fascia latae muscle] and lateral quadriceps,” says Athletes’ Performance physical therapist Anna Hartman. These muscles can increase the lateral pull on the patella, causing the medial (inside) structures to be under stress and continued strain. Also, weak glute (buttocks) muscles can result in poor control of the femur, the bone on which the patella sits. This can cause the patella to sit more on the outside and be prone to dislocation.”

Dislocated Kneecap by the Numbers

Percentage of people who suffer a dislocated kneecap after having had the injury previously

The age group most susceptible to dislocated kneecap injuries

The number of knee dislocations per 100,000 adults

The number of knee dislocations per 100,000 adolescents

Who’s at Risk for a Dislocated Kneecap

Sports that require the foot to be planted and the body to change directions, such as basketball, are associated with a high incidence of dislocated kneecap, as are soccer, skiing and football. This injury happens in women more often than in men, in younger rather than older athletes, and in exercisers who are overweight. It's also more prevalent in those who have anatomical features that predispose them to the injury.

Dislocated Kneecap Symptoms

When the kneecap is completely out of the groove:

  • Severe pain, tenderness
  • Immediate swelling
  • The kneecap is visibly displaced, usually to the outside of the knee joint
  • A kneecap that can be moved excessively from side to side (but don’t try it)
  • A feeling that your weight cannot be supported
  • Inability to straighten your leg

Initial Treatment

  • Do not try to treat yourself or another athlete when a dislocation has occurred other than to immobilize the knee with a splint with the leg in a straightened position, if possible.
  • Get medical help immediately.
  • A physician can manually move the kneecap back into position when the leg is straightened.
  • Ice packs can be used 15-20 minutes, 3-4 times a day to reduce swelling.
  • If not treated, the episodes become less painful and result in less disability, but the damage to the knee joint remains until it is treated.

Dislocated Knee Versus Dislocated Kneecap

“A dislocated knee (as opposed to a kneecap) is one of the most challenging sports injuries in terms of recovery,” says Joshua Hackel, MD, the director of Primary Care Sports Medicine at the Andrews Institute in Gulf Breeze, Florida. “When the knee is dislocated, damage to the peroneal nerve is possible and a condition called drop foot (or foot drop) is the result. The person cannot lift the foot during normal walking; the toes drag on the ground. This makes running very difficult. It is not a common problem, but we see it two or three times a year in football or soccer players.”

Comeback Strategy

Return to sports will be determined by how soon your knee recovers, not by how many days or weeks it has been since your injury has occurred. The goal of rehabilitation is to return you to your normal activities as soon as is safely possible. If you return too soon, you may worsen your injury. Long-term treatment usually involves immobilizing the knee for an average of three weeks, followed by rehabilitation exercises that focus on restoring range of motion.

The University of Michigan Health System says that you may safely return to your activities when, starting from the top of the list and progressing to the end, each of the following is true:

  1. Your injured knee can be fully straightened and bent without pain.
  2. Your knee and leg have regained normal strength compared to the uninjured knee and leg.
  3. Your knee is not swollen.
  4. You are able to bend, squat, and walk without pain.
  5. Wear a brace to immobilize the knee during rehabilitation.

Prehab to Strengthen and Stretch

  1. Foam Roll - (for the lateral quad and tenor fascia latea) 
  2. Sidelying Hip Rotation
  3. Half-Kneel Quad Hip Flexor Stretch

Expect to return to participation within four to six weeks after the injury, but aggressive treatment may shorten that time period. Surgery is rarely required, but when it is, six to eight weeks might be needed before the knee is strong enough to resume sports activities.

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How to Avoid a Dislocated Kneecap

It is impossible to prevent all kneecap dislocations, but there are some steps you can take to make the injury less likely to occur or reoccur.

  • Use proper technique when exercising or playing sports.
  • Warm up by jogging or doing other activity to raise the body temperature enough to break a sweat.
  • Warm up by going through the movements—starting slowly and gradually increasing the speed—required in your sport.

These following exercises can strengthen the muscles that support the knee joint, enhance flexibility, and reduce your chances of a dislocated kneecap. Include them in your movement prep (warm-up) routine.

  1. Foam Roll - (for the lateral quad and tenor fascia latea)
  2. Glute Bridge Double Leg with Pad
  3. Forward Lunge Elbow to Instep

Jim Brown, Ph.D. has written 14 books on health, medicine, and sports. His articles have appeared in the Washington Post, New York Post, Sports Illustrated for Women and Better Homes & Gardens. He also writes for the Duke School of Medicine, UCLA School of Medicine, Cleveland Clinic and Steadman-Hawkins Research Foundation.

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Tags: Knee, Injury Prevention, Injury, Knee Pain, Lower Body


  1. Anna J. Hartman, MS, ATC, CSCS, Manager, Performance Physical Therapy Services, Athletes’ Performance, Phoenix, Arizona
  2. American Journal of Roentgenology