What is patella instability?
The patella (kneecap), which rests in a groove at the end of the femur (thigh bone), protects the knee joint and helps with knee extension.
Patella dislocations usually happen when the knee is extended and twisted. Direct collisions to the knee (such as in football) can also cause a dislocation.
How to spot patella instability
Symptoms of a patellar dislocation include pain and swelling in the front of the knee. You may also notice your child’s patella is positioned on the outside of the knee, or the knee has an abnormal appearance.
How we diagnose patella instability
During an examination, your physician will assess range of motion, check stability and mobility and pinpoint any tender areas. X-rays of your child’s knee will be taken to show the alignment of the patella and to check for fractures of the patella or femur. Additional imaging, including MRI or CT scan, may be used to check for injuries to the bone or cartilage, tears of the medial patellofemoral ligament or to measure overall limb alignment.
How we treat patella instability
After a dislocation, the patella may spontaneously go back to its normal position, or your doctor may need to put it back in place.
Initial treatment usually includes over-the-counter anti-inflammatory medications (such as aspirin or ibuprofen), restricting activity and immobilization or bracing. Physical therapy is also prescribed to strengthen quadriceps as well as hip and core mechanics.
If your child injures the cartilage over the knee joint (articular cartilage), which can cause loose fragments of bone or cartilage within the joint, surgery may be recommended. Children with recurrent patellar dislocations may need surgery to repair structures (bone, muscle, tendons, or ligaments) on the inside of the knee, release tight structures on the outside of the knees, or modify the alignment of the leg.
Recurrent patellar dislocations occur more commonly in children than in adults. This is often a result of abnormal anatomy that increases the likelihood for children to dislocate the patella.
Unlike adults, children have open growth plates to allow for continued bone growth. When considering surgical options for recurrent patellar dislocations, treatment options and timing may vary based on whether the child has open or closed growth plates.