The kneecap, or patella, rides along a trough or groove at the end of the thighbone (femur), much like a bobsled down a track. The patella is attached to the strong thigh muscles on one end, and is attached via the patellar tendon to the front of the shinbone (tibia) on the other end. Thus, when the thigh muscles contract, they pull on the patella, and the leg straightens. The undersurface of the patella has a thick layer of smooth cartilage, and rides nearly friction free. Damage to the cartilage undersurface of the patella is termed Chondromalacia Patella.
May be due to direct trauma, such as a fall on a flexed knee. Abnormal cartilage wear may develop due to chronic maltracking or subluxation of the patella (see patellar instability). Weight gain, or other increased load on the knee can cause symptoms. Also frequently seen in adolescent girls.
Pain in the front of the knee. Worsened with going up and down stairs, climbing, squatting or kneeling, and prolonged standing.
Tenderness in the front of the knee, with a positive patellar compression test. Findings are often unimpressive.
Diagnosis is made by history and physical examination. X-rays are useful to rule out other injury.
Anti-inflammatory medication, rest, physical therapy and possible patellar stabilizer knee bracing are the mainstays of treatment for this condition.
Generally not indicated.
Most cases resolve with appropriate treatment.