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Condition/Disorder Synonyms

  • Infrapatellar bursitis

  • Housemaid's knee

ICD-9-CM Code

  • 726.65 Prepatellar bursitis

ICD-10-CM Code

  • M70.40 Prepatellar bursitis, unspecified knee

Preferred Practice Pattern

Key Features


  • Localized inflammation of the prepatellar bursa

  • Bursa fills with blood and serous fluid as response to either acute or repeated microtrauma.

  • Presents as pronounced, local swelling isolated to the anterior knee.

Essentials of Diagnosis

  • When acute, result of single episode of trauma or repeat trauma to the anterior knee when in a flexed position.

  • Bursitis is commonly related to occupation or specific activity that causes rubbing or pressure on the anterior knee from a hard surface.

  • Swelling is contained to bursa that results in the visualization of a swollen appearance on both sides of the patella tendon.

  • Patients often note focal pain to palpation of swollen bursa, decreased ROM, or inability to bear weight on the flexed knee.

  • Differential diagnosis is essential due to presence of infections to this area.

  • Exquisite swelling, marked tenderness, and redness or heat may be indicative of differential diagnosis.

  • When chronic, often associated with occupation (maid) or prolonged activity (tile installer) that places flexed knee on hard surface.

  • When acute, often associated with acute blow when the knee is flexed (athletes).

General Considerations

  • Full history of symptoms and medical history screening will ensure appropriate diagnosis.

  • Isolated diagnosis related to acute or chronic activity (pressure to the anterior flexed knee by a hard surface) and focal swelling/pain.

  • Marked tenderness or swelling with acute onset may signal underlying fracture.

  • Redness or heat may be indicative of infection.

  • Septic bursitis if fluid has neutrophil count greater than 1500 cells/μL.2

  • Septic arthritis if fluid has a neutrophil count greater than 50,000 cells/μL.3


  • Occurs primarily in adults but can occur in children and athletes of any age.

Clinical Findings

Signs and Symptoms

  • Point tenderness to the anterior knee.4

  • Focal swelling.

  • Swelling in multiple joints may indicate arthritis.1

  • Stiffness with flexion.

  • Pain with rubbing or light pressure to the anterior knee.

  • Pain with focal pressure.

  • Knee ROM (usually flexion) can be reduced.

  • Pain and swelling can be either insidious or acute.

    • Occasionally, swelling can be spontaneous and without pain.

  • Possible reduction in strength due to pain and inflammation.

  • Pain in anterior knee.

  • Increased swelling throughout the day.

  • Tenderness changes position with tendon movement during extension.

  • Thickening of the tendon.

  • Decreased extension strength.

Functional Implications

  • Inability to climb stairs or ladder

  • Inability to push off during ambulation


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