Dislocation vs Subluxation of the Knee

It is very common as an Athletic Trainer to hear athletes to say “I dislocate my knee all the time”. Do you though? There is a substantial difference between a knee dislocation and a patellar subluxation. The more common of the two injuries is the patellar dislocation.

Patellar, or kneecap, dislocations/subluxations occur when the patella moves out of its groove. Patellar subluxations occur with more regularity and the younger the athlete, the more common it is. Most of the dislocations occur laterally due to the anatomical structure of the knee. Causes can be from both contact and non-contact mechanisms and typically happen when the foot is planted and a rapid change of direction or twisting occurs. A dislocation due to a direct blow usually causes severe damage to the restraining ligaments. These ligaments are not able to dissipate the forces and typically rupture or tear. Signs and symptoms of a lateral patellar dislocation are: acute swelling, extreme pain until relocation occurs, continued pain along the medial ligaments, discoloration medially at site of ligament injury, and sense of instability or apprehension that another subluxation will occur.

Treatment for a patellar subluxation/dislocation is usually handled non-operatively. The knee is immobilized for about seven to 10 days to allow time for edema control and establishing full range of motion. Once full range of motion is established, strength and proprioception exercises are introduced. It takes around three to six weeks to get back to full activity. If patellar subluxations are a common occurrence, then additional rehab is needed. Bracing can also be an option to decrease the frequency of patellar subluxations/dislocations. If subluxations/dislocations continue, then surgery may be necessary. Studies show that after a first subluxation/dislocation, there is a 40 percent chance of another subluxation/dislocation. However, after surgery and effective rehab, the chance of additional subluxation/dislocation is reduced to only 10 percent.

A total knee dislocation is a lot different then a patellar subluxation/dislocation. When a total knee dislocation happens it becomes a medical emergency. A knee dislocation typically occurs with a major trauma or force, and is when the femur and tibia are forced out of alignment; causing significant damage to the ligaments and boney structures of/around the knee. A total knee dislocation is serious because if there is delayed or incorrect treatment, the person can lose their leg. If the knee is dislocated, the joint will look deformed and there will be severe pain. Occasionally, there can be instances where the athlete has no feeling below the knee at all. Additional symptoms that may be found include loss of pulse, feeling or movement below the knee.

At the hospital, X-rays and an arteriogram (an x-ray of the artery) are taken to ensure that the popliteal artery is not severed and there are no fractures. The three steps for treatment after a dislocation are: reduction of the dislocation, immobilization to keep it stable and prevent further damage and lastly a referral to an orthopedic surgeon to discuss the surgery options. After surgery, results for athletes returning to play sports have been good.

Interesting Links

http://orthopedics.about.com/cs/patelladisorders/a/kneecapdisloc.htm

http://www.youtube.com/watch?v=h9wKLHLWmXk&feature=fvwp

http://www.emedicinehealth.com/knee_dislocation/article_em.htm

http://www.wheelessonline.com/ortho/traumatic_dislocations_of_the_knee

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2 thoughts on “Dislocation vs Subluxation of the Knee

  1. Hi,

    This is a great review, thanks for blogging.

    Here is an interesting recent article on patellar dislocation that I co-authored:

    Magnetic resonance imaging of acute patellar dislocation in children: patterns of injury and risk factors for recurrence.

    Best regards,

    Brian Sabb
    http://www.linkedin.com/in/briansabb

  2. Pretty nice post. I just stumbled upon your blog and wanted to say that I’ve truly loved surfing around your blog posts.
    After all I’ll be subscribing in your feed and I am hoping
    you write once more soon!

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