You can dislocate your patella (kneecap) by twisting your leg, awkwardly falling to your knees or receiving a blow inside of your knee. Remember from our knee anatomy lesson that movement of kneecap (up and down like an elevator) is controlled by the quadriceps muscles. This means that when you are forcefully twisting your leg your quadriceps muscles are contracting and can force the kneecap to move outside of its normal movement range.
Remember that the kneecap moves up and down along the femoral groove. Patella dislocation happens mostly towards the outside (laterally) of the knee. Both runner’s knee and patella dislocation are more common in females because of their wider angle of the hip joint. This is sometimes referred to as the Q angle and is one of the risk factors that can cause injuries like patella dislocation and patella femoral syndrome.
Another risk factor is a malformed patella or femoral groove which makes the kneecap more prone to dislocate as was the case also with patella femoral syndrome. To explain how the patella or femoral groove can be malformed we can imagine the bottom of the patella as an inverted mountain and the femoral groove as a valley between two mountains. In this case if the mountain is not high enough nor the valley deep enough then the patella can be more easily dislocated.
Symptoms
Most likely your kneecap will move back to its normal position when you straighten your leg. But sometimes it will not return and has to be surgically treated in order to return the kneecap to a normal position. Although the kneecap might have returned to its normal range, this injury may damage the tissues, ligaments of the patella and even the cartilage of the bone. Most likely there will be almost instant swelling of the knee and severe pain. You may also feel that your knee is unstable because lateral dislocation of patella may also cause a tear of the medial patellar ligament.
Treatment
Keep your knee in an elevated position, apply ice and compression to reduce the pain and swelling and rest the injured knee.
Usually surgery is not needed provided the kneecap has returned to its normal position. An Orthopedist will send you for an X-ray and sometimes also for a MRI (magnetic resonance image) to determine the severity of the injury. Most likely your doctor will tell you to rest your knee or sometimes using a knee brace is needed in order to keep the kneecap in a fixed position. From a few weeks to one month is usually enough recovery time needed for damaged tissues and/or torn ligaments to repair. Of course recovery time depends on the extent of the damage caused by a patella dislocation.
Untreated patella dislocation will most likely lead to repetitive dislocation of patella, which in turn will increase the risk of developing osteoarthritis of the knee joint. Therefore it is extremely important to follow your doctor’s orders and let your injured knee recover before returning to your previous level of activity. In case the medial patellar ligament is torn, surgery is sometimes needed in order to prevent future dislocations. In conclusion, a patella dislocation is a serious injury and must always be treated.
