Sports Medicine: Patellar Dislocation
What is a patellar dislocation?
The patella (kneecap) normally sits in a groove at the end of the femur called the trochlea. When the knee bends and straightens the patella slides up and down in this groove. A patellar dislocation happens when the patella shifts out of this groove, usually towards the outer side of the knee. This can cause damage to the patella, femur and surrounding ligaments.
What causes a patellar dislocation?
Patellar dislocations may result from a direct blow to the inner side of the patella, forcing it outwards. However, patellar dislocations most often occur without contact as the athlete decelerates and plants their foot to change direction. Athletes that suffer from patellar dislocations often have multiple factors that predispose them to patellar dislocations, including:
- A wide pelvis
- Shallow femoral grooves (trochlea)
- Flat (pronated) feet
- Quadriceps weakness
- Patellas that are flat
- Patellas that sit higher on the knee
- Patellas that tilt to the outer side of the knee
What are the symptoms of a patellar dislocation?
Patellar dislocations generally cause a complete loss of function of the knee until the patella is restored to its normal position. The athlete will experience significant pain and swelling. The athlete may feel a “clunk” when the patella dislocates or when it relocates back into the groove. The pain is often felt on the inner side of the patella due to damage of the ligamentous tissues that hold the patella in place.
How is a patellar dislocation diagnosed?
Patellar dislocations that do not go back into place on their own should be reduced by a physician that is trained to minimize the damage that could occur when the patella is relocated. X-rays and an MRI may also be recommended to determine any damage that may have occured to the bones, cartilage and ligaments as a result of the dislocation.
What is the treatment for a patellar dislocation?
In most new cases of a patellar dislocation, the physician will choose to treat the injury with rehabilitation. The athlete will be put in a brace for comfort and improved patellar motion, and the athlete will begin anti-inflammitory treatments. Once the swelling has improved, the athlete will begin to work on knee range of motion and quadriceps strength. The athlete will gradually return to sports specific activity once the physician has determined that the injury has fully recovered.
In cases where there are recurring patellar dislocations or other damage as a result of the dislocation, the athlete may require surgery. The surgery may involve repair or reconstruction of ligaments around the patella, changing the bony alignment of the knee, or a combination of soft tissue and bone reconstruction. Rehabilitation after surgery will be similar to the rehab in non-surgical cases.
What is the long term outlook for a patellar dislocation?
With proper treatment and rehabilitation, the long term outlook for a patellar dislcoation is usually good. It is important for any athlete that suffers a patellar dislocation to continue to strengthen their quadriceps, long after they return to activity.