Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


(pă-tel′ă, pă-tel′e, pă-tel′′ī″) pl. patellae, patellas [L. patella, a small pan] A lens-shaped sesamoid bone situated in front of the knee in the tendon of the quadriceps femoris muscle. SYN: kneecap. SEE: osteochondritis dissecans.

p. alta A high-riding patella (high positioning of patella). When a person is standing, the patella rests in a more superior position than normal.

p. baja A low-riding patella (low positioning of patella). When a person is standing, the patella rests in a more inferior position than normal.

bipartite p. The developing patella that matures from two centers rather than one. This usually congenital condition causes no symptoms but may be mistaken for a fracture.

fracture of p. A break in the continuity of the kneecap. Treatment may consist of suturing the bone fragments. A long-leg immobilizer is applied for 6 to 8 weeks. Following removal of the brace, gradual exercise may be started and weight placed on the leg for a few weeks, after which the patient may walk.


(pă-tel′ăr) Pert. to the patella.


(păt″ĕ-lĕk′tō-mē) [″ + Gr. ektome, excision] Surgical removal of the patella.


(pă-tel′ĭ-form″) [patella + -form] Shaped like the patella.


(pă-tĕl″ō-fĕm′ō-răl) Pert. to the patella and femur.

patellofemoral pain syndrome

Pain in the knee that occurs with exertion, e.g., walking upstairs, and is associated with stiffness after prolonged sitting and tenderness when the patella is compressed on the femoral condyle or when it is moved laterally. SEE: patellofemoral instability.


(pā′tĕn-sē) [L. patens, open] The state of being freely open.


(pat′ĕnt (senses 1, 2), pāt′ (senses 2, 3)) [L. litterae patentes, open letters] ABBR: pat. 1. Protected by trademark or trade name; patented. SEE: proprietary (3).

2. Evident; accessible. 3. Having or offering free, unobstructed passage.

patent ductus arteriosus

SEE: patent ductus arteriosus.

Patent foramen ovale

ABBR: PFO. Incomplete closure of the foramen ovale after birth. PFOs are common. They are present in about 25% of the population. In some individuals they are a cause of cryptogenic stroke.

PREVALENCE: Approximately one fourth of the general population has a patent foramen ovale.


(pă-tĕr′năl) [L. paternis, fatherly] Pert. to or inherited from the father.


(pă-tĕrn′ăl-ĭzm) In health care, a type of decision making in which only health care professionals have authority over patients. When ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.