patella (pa-tel'a) (-tel'e, -tel'i?) plural.patellaeplural.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. Synonym: kneecap
See: osteochondritis dissecans
A high-riding patella (high positioning of patella). When a person is standing, the patella rests in a more superior position than normal.
A low-riding patella (low positioning of patella). When a person is standing, the patella rests in a more inferior position than normal.
ballotable patellaFloating patella.
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.
Displacement of the patella from its normal position in the femoral trochlea. Most patellar dislocations are marked by obvious deformity and occur laterally. They result in the tearing or stretching of the medial patellar retinaculum and the oblique fibers of the vastus medialis muscle. The patella may spontaneously reduce as the patient attempts to straighten the knee.
A patella that rides up from the condyles owing to a large effusion in the knee. Synonym: ballotable patella
fracture of patella
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.
Excessive medial and/or lateral motion of the patella. A medially hypermobile patella can be moved greater than 75% of its width medially. A laterally hypermobile patella can be moved greater than 75% of its width laterally. See: hypomobile patella
; apprehension test
Increased medial patellar hypermobility can result from laxity of the lateral patellar retinaculum. Lateral patellar hypermobility indicates laxity of the medial patellar retinaculum and/or weakness of the oblique fibers of the vastus medialis.
Increased motion of the patella within the femur's trochlea can lead to chondromalacia patellae, producing pain in weight-bearing activities, esp. squatting or climbing or descending stairs. Lateral patellar hypermobility is a predisposition to patellar dislocation or subluxation.
Treatment and rehabilitation consists of strengthening the muscles on the side opposite the hypermobility. Neuromuscular reeducation may be needed to restore the normal recruitment sequence of the oblique fibers of the vastus medialis and the vastus lateralis.
Lack of normal medial and/or lateral motion of the patella. A medially hypomobile patella cannot be moved more than 25% of its width medially. A laterally hypomobile patella cannot be moved more than 15% of its width laterally. See: hypermobile patella
Medial hypomobility often results from adhesions of the lateral patellar retinaculum or tightness of the iliotibial band. Lateral hypomobility can result from tightness of the medial patellar retinaculum or hypertrophy or spasm of the oblique fibers of the vastus medialis.
The patient will complain of pain and demonstrate decreased strength during weight-bearing activities. Improper tracking of the patella as the result of hypomobility can lead to chondromalacia patellae.
Physical agents such as moist heat and/or ultrasound and manual therapy techniques can be used to encourage the elasticity of the offending tissues. A surgical release of the patellar retinaculum may be required.
rider's painful patella
Tenderness and pain in the patella from horseback riding.
A condition in which the patella appears to be pointing inward when the patient is standing; caused by excessive femoral anteversion.
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