In most patients with<unk>  an examination of their history will highlight a precipitating event that caused the injury. Changes in activity patterns such as excessive increases in running mileage, repetitions such as running up steps and the addition of strength exercises that affect the<unk>  joint are commonly associated with symptom onset. Excessively worn or poorly fitted footwear may be a contributing factor. To prevent recurrence the causal behaviour should be identified and managed correctly. The medical cause of<unk>  is thought to be increased pressure on the<unk>  joint. There are several theorized mechanisms relating to how this increased pressure occurs: * Increased levels of physical activity * Malalignment of the patella as it moves through the femoral groove * Quadriceps muscle imbalance * Tight anatomical structures, e.g. retinaculum or iliotibial band. Causes can also be a result of excessive genu valgum and the above-mentioned repetitive motions leading to abnormal lateral patellar tracking. Individuals with genu valgum have larger than normal Q-angles causing the weight-bearing line to fall lateral to the centre of the knee causing overstretching of the MCL and stressing the lateral meniscus and cartilages. The cause of<unk>  and dysfunction often results from either abnormal forces (e.g. increased pull of the lateral quadriceps retinaculum with acute or chronic lateral PF subluxation/dislocation) or prolonged repetitive compressive or shearing forces (running or jumping) on the PF joint. The result is synovial irritation and inflammation and subchondral bony changes in the distal femur or patella known as "bone bruises". Secondary causes of PF<unk>  are fractures, internal knee derangement, osteoarthritis of the knee and bony tumors in or around the knee.
Patellofemoral pain syndrome
Chondromalacia patellae
Patellar subluxation syndrome
Patellar tendinitis
Greater trochanteric pain syndrome
Infrapatellar fat pad syndrome
Anterior compartment syndrome
Infrapatellar bursitis