Unstable Kneecap (Patella Instability)- Recuurent knee cap dislocation
The Knee cap or patella, is the bone that you feel at the front of the knee. This bone, normally, stays in a groove at the bottom of the thigh bone. It also has the thickest cartilage of any other bone in the body.As long as your kneecap (patella) stays in its groove in the knee, you can walk, run, sit, stand, and move easily. When the kneecap slips out of the groove, problems and pain often result.
What causes instability of the knee-cap?
The knee-cap, in a way, connects the muscles in the front of the thigh to the shinbone (tibia). As you bend or straighten your leg, the kneecap is pulled up or down. The thighbone (femur) has a V-shaped notch (femoral groove) at one end to accommodate the moving kneecap. In a normal knee, the kneecap fits nicely in the groove. But if the groove is uneven or too shallow, the kneecap could slide off, resulting in a partial or complete dislocation. A sharp blow to the kneecap, as in a fall, could also pop the kneecap out of place. Some peoples bodies are built in a certain way, which makes them prone to getting knee cap instability. When the dislocation of the knee cap happens after an acute injury, there is a sprain or a tear of a cord like ligament that holds the knee cap in place, called the Medial Patello-Femoral Ligament (MPFL). This ligament may need reconstruction if surgical intervention is carried out.
What are the symptoms?
Knee buckles and can no longer support your weightKneecap slips off to the sideKnee catches during movementPain in the front of the knee that increases with activityPain when sittingStiffnessCreaking or cracking sounds during movementSwelling of the knee and fluid collection.
What are the treatment options?
The treatment depends on whether the injury is acute or of a chronic prolonged nature. If it has happened recently, it is important to make sure that the knee cap has returned to its normal position in the groove. If it has not, then it has to be manually pushed back. This is called reduction.
In a chronic instability situation, further investigations like MRI scan may be necessary to rule out any associated injuries, as,a dislocation often damages the underside of the kneecap and the end of the thighbone, which can lead to additional pain and arthritis.
The initial treatment is with exercises (Physiotherapy) and braces. Exercises will help strengthen the muscles in your thigh so that the kneecap stays in place. Cycling is often recommended as it helps to strengthen the muscles and is a non-impact activity.
If the problem of instability persists inspite of non-surgical measures or if there are any associated injuries to the knee joint, then arthroscopic surgery of the knee may be required to correct the problem. The surgery involves having a look inside the knee with arthroscopy and may also need reconstruction of a vital ligament to keep the knee cap in place and to prevent it from slipping out of the groove.
Further information can be obtained from your doctor.
Dr Vinod Kumar Abu Dhabi
Sports surgeon Abu Dhabi
Shoulder surgeon Abu Dhabi
NMC Royal Hospital