Bipartite Patella.  Ever heard of it?

Anatomy
The Patella, or knee cap, is that floating bone that sits on the anterior (front) side of your knee joint.  Unlike most bones in your body, your patella isn’t attached to other bones by ligaments (sinu that attaches bone to bone).  Instead it is enveloped within the distal quadriceps (or patella) tendon (attaching muscle to bone), literally floating within it.  Note that the distal quadriceps tendon is the tendon that attaches the quadricep muscles to the tibia (large lower leg bone).  When your quadricep is relaxed you will notice that you can quite easily move your patella about with little force.  When you contract your quadricep group however, you will notice that the patella becomes almost impossible to move.  This is due to the contracting quadricep loading the quadricep tendon which in turn pulls on the tibia.  The tension within the quadriceps tendon at this time keeps the patella firm in place.

Further anatomical considerations
A bipartite patella is a congenital condition where the patella develops from 2 boney centres that results in a main and accessory bone. The main and accessory bones are connected by fibrocartilaginous (jointy) tissue. The incidence is around 3-5% of the population – with males 8 times more likely to have the anomalie. Forty three percent of cases are bilateral. The superolateral pole (upper outside) of the patella is the most common location of the accessory bone (75%).  In rare cases some people may even have three patellas!  A very well known elite distance runner was born with such a condition, eventually having one of these bones removed to alleviate pain it was causing.  Any guesses?  A certain ‘toilet roll’ author also has such an anomaly, although he has anomalies scattered all over him. 
Many people would not realise they have this anomalie.  It is not always visually obvious.  Most are found on X-ray. 

Incidence/Pathologies/Injury
In 15% of children, two or more ossification (boney) centers of the patella may be seen at the same time during development. These centers usually fuse to form a single bone (patella). In cases of bipartite patella the accessory (extra) center remains separated from the main bone of the patella by fibrocartilaginous (jointy) tissue. This fibrocartilaginous interface may weaken the patella. Subsequent direct or indirect trauma to the interface between the two pieces of bone may result in a fracture or inflammation at this site. In the case of a fracture, a non-union fracture (the two bones don’t heal – they remain separated) may develop between the 2 fragments because cartilaginous (jointy) tissue has limited ability to repair. The mobility between the main bone and the accessory bone is assumed to be the cause of symptoms.  In less aggressive conditions the cartilaginous surface between the two bones may become inflamed producing similar symptoms.
Pain is centered over the joint line (where the two bones meet) and can often be palpated (usually the upper outside portion of the patella).
Treatment
Treatment to this pathology varies from conservative soft tissue work through to surgical excision. 
If the quadricep is applying undue load onto the patella then the two portions of the bipartite patella can be pulled with different forces, shearing one on the other and causing an irritation of the surface or joint between the two bones, or in severe cases a fracture. Treatment of this can be as simple as soft tissue work to the tight portions of the quadricep.  What may also be causing a biomechanical anomaly to the bipartite patella is a pelvic anomaly.  Treatment of this condition would involve a full assessment of your pelvis, focusing on pelvic positions that may be torsioning (twisting) your femur and causing uneven loading of the bipartite patella.  Running will need to be modified, especially hills and stairs.
In severe cases where the surface between the two bones becomes chronically irritated, or highly mobile, and injections such as cortisone has not settled the condition, the extra bone may be excised (cut out).  There are other options within surgery such as releasing the lateralis tendon (outside quadricep tendon) or a lateral retinacular (lateral piece of connective tissue that pulls the extra piece of patella laterally) release.  All have been shown to have good results short and long term.

The key to assessing this condition is palpable pain over the lateral aspect of the patella where the two bones join.  Once irritated, the joint will become worse with hill or stair running and when severely aggravated, just about any form of running.

Self Treatment
Stretching of the quadricep muscles is imperative as is self massage.  Most of the focus should be on the lateral aspect of the quadricep, especially the distal (towards the end) portion just above the knee.

Summary
Although not a common knee injury in runners, it certainly exists.  If pain is centered about the lateral aspect of your patella, gets worse with hills or stairs and is palpably sore over the lateral upper patella, consider it.

Happy running.

Stretching of the quadricep muscles is imperative as is self massage, it is really good thing that you can do on your own.

Last year i had patella problem and i got proper treatment and now my pain is no more, that happen when i fell down from stairs and got hurt on exact position that time i was going for my testking 350-018 certification exams but i missed them due to this incident.

Treatment to this pathology varies from conservative soft tissue work through to surgical excision. If the quadricep is applying undue load onto the patella then the two portions of the bipartite patella can be pulled with different forces, shearing one on the other and causing an irritation of CISSP exam the surface or joint between the two bones, or in severe cases a fracture. Treatment of this can be as simple as soft tissue work to the tight portions of the quadricep.  What 1z0-042 exam may also be causing a biomechanical anomaly to the bipartite patella is a pelvic anomaly.  Treatment of this condition would involve a full assessment of your pelvis, focusing on pelvic positions that may be 70-238 exam torsioning (twisting) your femur and causing uneven loading of the bipartite patella.  Running will need to be modified, especially hills and stairs.