I think I should have posted this long ago.

Patella Dislocation

Patella dislocations occur in 2 ways:

* Direct blow to the kneecap knocking the patella out of place
* Awkward twisting motions of the knee (Dath et al., 2006).

Sports commonly associated with patellar dislocation include soccer, gymnastics and ice hockey. The patella wobbles out of the patellofemoral groove, usually to the lateral side of the knee (away from the middle of the body) (Dath et al., 2006). This occurs when the quadriceps tendons and other ligament stabilizers attached to the borders of the patella contract forcefully as the knee is rotating, pulling the patella out of place (Dath et al., 2006).

Predisposing Factors

1) Demographics

Age:
• Average age of occurrences for patellar dislocation is 16–20 yrs old (Atkin et al., 2000)
• Primarily due to increased participation in sports and recreation

Gender:
• Female are more susceptible to patellar dislocation

Athletic Population (Atkin et al., 2000):
• Particularly in sports with twisting, rotational motion of the knee
• Direct trauma to the knee

2) Positive Family History
• Related up to 24% of patellar dislocation incidences (Dath et al., 2006)

3) Anatomical FactorsExcessive Q-angle
• Angle greater than 25 degrees between the patellar tendon and quadriceps muscle (Buchner et al., 2005)

Misalignment of the patella on the knee joint
• Due to malformed patella/knee joint, patella situated abnormally higher on the knee than normal (Buchner et al., 2005)

Insufficient Vastus Medialis Obliquus Muscle (VMO) (Dath et al., 2006)
• Normal function is to keep patella in stable position
• If function is decreased, will result in instability of the patella


Quoted from wikipedia