Patella dislocation, also known as kneecap dislocation, is when the patella (or kneecap) slips out of the groove it normally glides in. The patella may partially or completely dislocate and can be recurrent in those with patella instability. This is more common in younger athletes who undertake rapid changes in direction or twisting movements, it also less frequently results from a direct blow to the knee.
Normal knee joint (Left) and Patella or Kneecap dislocation (Right)
Risk factors for patella dislocation
- Twisting injury
- Direct blow or trauma to the knee
- Previous or known patellar instability
- Ligamentous laxity
- Leg malalignment conditions – such as, knocked knees (genu valgum), inward rotation of the femur (femoral anterversion) or abnormal outward rotation of the leg with walking (external tibial torsion, out-toeing gait)
- Certain bone or muscle structural abnormalities.
Symptoms of patella dislocation
- Popping sensation
- Knee pain, can be extreme until relocation occurs, and usually persists along the inner knee after relocation.
- Swelling of the knee
- Unable to weight bear
- Unable to straighten the knee
- Knee instability or apprehension
Diagnosis of Patella dislocation
Your doctor or surgeon will take a history, conduct a physical examination, and likely order an x-ray reviewing the patella and the groove it glides in. Sometimes an MRI is also ordered to further assess the local structures.
Management of patella dislocation
Often the patella will pop back into place itself, however if it does not the patient should attend the emergency department or seek urgent medical review.
Initial management should also include the RICE principles – Rest, Ice, Compression and Elevation. Once the initial pain and swelling improves, rehabilitation with a physiotherapist should be commenced.
Usually a review with the surgeon will involve a physical examination looking for ongoing swelling, ongoing instability and other risk factors for instability.
Depending on the examination findings an MRI may be necessary.
In essence there are 3 things that keeps the kneecap in joint:
- The strength of the muscles
- The strength of the Medial Patellofemoral Ligament (MPFL)
- The shape of the bones that makeup the joint
Treatment will focus on one or all of these areas.
- Medications such as anti-inflammatories
- Activity modification
- Knee bracing
Surgery may occasionally be needed if the kneecap keeps dislocating. Commonly the required procedure is a medial patellofemoral ligament (MPFL) reconstruction or a Tibial Tubercle Transfer (TTT) depending on the underlying pathology driving the instability.
If you or your child has experienced patella dislocation and you would like further advice and assistance in management, please contact us and book an appointment to discuss this further.