A patellar dislocation occurs when the kneecap slides out of place. The patella is the bone more commonly known the kneecap. It fits securely in a V-shaped groove in front of the knee so that the patella can move up and down when the leg is bent or straightened.
Patellar dislocation is very common. Treatment includes nonsurgical manipulation of the patella, immobilization, medications, and physical therapy. In some cases, surgery may be required to repair damage caused by the dislocation.
Excess pronation of the feet—inward roll of the feet when walking or running
Other factors that can create instability in the patella include:
Weak thigh muscles
A patella that sits too high on the thigh bone
Weakened and stretched ligaments from a previous patellar dislocations
Patellar dislocation may cause:
Extreme pain and swelling at the knee
Buckling under your own weight
Abnormal appearance of the knee
Your doctor will ask about your symptoms and medical history. A physical exam will be done. This will include a thorough exam of your patella to check for tenderness and swelling. If possible, your doctor will have you walk. Your doctor may be able to make the diagnosis based on your symptoms.
Images may be taken of your knee. This can be done with:
If the patella did not return to the V-shaped groove on its own, the doctor will manipulate it back into place.
The knee will be immobilized in a brace for stability and support. A brace may be needed for up to 4 weeks. Activities will be limited until the knee is stable again.
Medications will be given to help reduce swelling and reduce pain.
Physical therapy may be recommended to:
Stretch and condition the quadriceps and hamstring muscles
Maintain muscle strength, flexibility, and endurance
Improve balance and range of motion
Improving leg strength may help prevent future dislocations.
Electrical stimulation treatments may be used to send gentle electrical pulses through the skin into local tissue. These may include:
Electrical muscle stimulation (EMS)—to help rehabilitate muscles
Transcutaneous electrical nerve stimulation (TENS)—to help manage pain
Surgery may be needed for recurrent patellar dislocation or dislocations with severe injuries to soft tissue. It may also be needed for those who don’t recover with standard medical therapy. Surgical procedures include:
of damaged cartilage, or to realign ligaments or tendons that stabilize the patella
Reconstruction of medial patellofemoral ligament to help with stability and prevent recurrent dislocations
To help reduce your chance of patellar dislocation, keep quadriceps and hamstring muscles strong with strengthening and stretching exercises.
Panni AS, Vasso M, et al. Acute patellar dislocation: What to do? Knee Surg Sports Traumatol Arthrosc. 2013;21(2):275-278.
Unstable kneecap. Ortho Info—American Academy of Orthopaedic Surgeons website. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00350. Updated August 2007. Accessed November 13, 2017.
8/4/2014 DynaMed Plus Systematic Literature Surveillancehttp://www.dynamed.com/topics/dmp~AN~T116461/Acute-patellar-dislocation: Cincinnati Children's Hospital Medical Center. Evidence-based care guideline for conservative management of lateral patellar dislocations and instability in children and young adults aged 8-25 years. Cincinnati (OH): Cincinnati Children's Hospital Medical Center; 2014 Mar 18.
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