Patellar fractures are generally caused by a direct blow to the front of the knee although they can also be caused by an over-energetic contraction of the quadriceps muscle during sporting activities. The knee swells up rapidly, especially at the front of the knee over the kneecap. Walking is normally impossible and in most cases it will prove impossible to straight leg raise.
Most significant patellar fractures will require accurate reconstruction and fixation.
Patello-femoral arthritis may occur following a patellar fracture.