The kneecap (patella) forms a very important part of your knee joint. It sits in a groove on the front of your femur (thigh bone). On its under surface, the patella has a thick layer of cartilage that allows your kneecap to glide smoothly as you bend and straighten your knee.
The thigh muscle (quadriceps) is attached to the kneecap, which is then attached to the top of the shin bone (tibia) by the patella tendon.
The groove that the kneecap sits in is called the trochlea. Normally, it sits snugly in the centre of this groove, and as the knee bends and straightens, it should travel straight up and down the trochlea.
In people with an unstable patella, the kneecap doesn’t travel in a straight line. Instead it travels unevenly in the trochlea or rides out of it.
Other names
- patella subluxation
- patella maltracking
Symptoms
Some things you may notice are:
- Kneecap slides to the side
- Knee buckles and can no longer support your weight
- Knee catches during movement and may lock in place
- Pain in the front of the knee that increases with activity
- Pain when sitting
- Stiffness
- Creaking or cracking sounds during movement
- Swelling
Causes
Causes for an unstable patella include:
- An uneven or shallow groove for the patella causing the patella to slide off
- A wider pelvis
- An abnormal gait
- A sharp force to the kneecap, maybe via a fall, causing the patella to pop out of place
Risk Factors
The main risk for Unstable Patella is anatomical variation in the patella and the patella groove. Also weak thigh muscles can cause your patella to be unstable
Investigations
The doctor will most likely ask you to have a x-ray done of your knee to determine the presence of an unstable patella.
Complications
The problems associated with an unstable patella can be mild to severe. For some it is just an inconvenience, but for others the pain can be so severe they may be bed bound.
The major complication that may arise is a dislocated patella. As your kneecap is unstable it is much more prone to dislocation, and when this occurs it is associated with unbearable pain. It usually happens after a twisting force or a large impact force is applied to the knee joint.
Treatment
Treatment first involves determining if the patella is dislocated. After this is excluded via examination and x-ray there are a few methods of improving an unstable patella.
- Physical therapy can strengthen the muscles that stabilise the kneecap. One exercise therapy that may be recommended is is cycling.
- Bracing and taping the knee can relieve the pain. There are a number of different braces available which suit the severity of your condition.
- Better footwear can help control your gait while running and so relieve pressure on the patella.
- In a chronic condition surgery may be suggested. This surgery usually involves realigning, releasing or increasing the tensions of certain surrounding ligaments and tendons to result in less pressure placed on the kneecap.
Seeking Advice
Your Family Doctor (GP)
Your Family Doctor will be able to diagnose and help treat your problem. He or she will be able to
- tell you about your problem
- advise you of the best treatment methods
- prescribe you medications
- and if necessary, refer you to Specialists (Consultants) for further treatment
Prevention
A general way you can prevent this from happening is engaging in regular exercising which involves your legs (eg. cycling and swimming), but avoid activities which overuse and overload the knee.. To prevent it from getting worse you can wear a brace which works by stabilising the knee. Also before and after activity stretch your hips and legs well.
F.A.Q. | Frequently Asked Questions
Why do kneecap dislocations become a recurrent problem?
In an unstable kneecap once it comes out of place and dislocates, ligaments that were holding it in place are torn. Once it is torn it usually doesn’t heal with proper tension and so it subsequently dislocates more easily. Who gets an Unstable Patella?
It seems to affect women more than men, and teenagers get it more than people in older and younger age groups. It also has a higher tendency in athletes and manual workers.
Is there any medicine I can take for it?
To reduce pain and swelling you can take NSAIDS eg. Aspirin.