Patellar Subluxation or Dislocation

A patellar dislocation refers to when the patella- the kneecap- moves out of its normal groove in the front of the knee and slides to one side. A subluxation- or a partial dislocation- occurs when the patella partially slides out of its normal groove and slides back in on its own. Patellar dislocations most often happen laterally, or toward the outside of the knee/body, but it is possible for them to also dislocate medially, or toward the midline of the body.

 

Symptoms

• Extreme pain

• Rapid swelling

• Obvious deformity

• Pain particularly on the medial- or inside toward the midline- aspect of the knee

• Instability

• Apprehension to move or loss of movement of the knee

• Feeling like the patella is “out”

• Hearing or feeling a loud “pop”

 

Causes

• Contact with another person or an object

• Non-contact injury when foot is planted and there is a rapid change of direction or twist

• Direct blow to the knee

• Shallow groove or uneven groove that the patella sits in

• Weak or unbalanced muscles of the quadriceps

 

Risk Factors

• Young women with undeveloped muscles

• Ligamentous laxity

• Cerebral palsy

• Down syndrome 

• Tight illiotibial (IT) band

• Muscle imbalance

 

Prevention

• Training for muscle balance

• Quadricep strengthening

• Bracing or taping

 

Diagnosis

• Physician will check range of motion and inquire about mechanism of injury

• X-ray to check for fracture

• MRI to assess ligamentous and soft tissue damage

• Physician will assess groove that patella normally sits in

 

Treatment Options

Non-surgical:

• Reduction of dislocation (self or manual)

• Immobilization for 7-10 days followed by slow gradual mobilization

• Non weight-bearing on crutches for 3-4 weeks

• Physical therapy for hip and thigh strengthening 

• Non-steroidal anti-inflammatory drugs for pain and inflammation

• Full recovery in 3-6 weeks if there is no ligament or other soft tissue damage

 

Surgical:

• Arthroscopic repair of medial patellofemoral ligament if torn or damaged

• Lateral release surgery to decrease lateral tension and tighten the medial side