Knee (Prepatellar) Bursitis - Arthritis-health

What Causes Bursitis in the Knee?

To understand what causes knee bursitis, it is helpful to know more about the prepatellar bursa and bursae in general:

• A bursa is a thin, slippery, fluid-filled sac that serves as both a cushion and a lubricant between kneecap and skin.
• The prepatellar bursa is normally just 0.1 inch thick—about the thickness of 2 quarters stacked on top of each other—and 1.5 inches in diameter.2Aguiar RO, Viegas FC, Fernandez RY, Trudell D, Haghighi P, Resnick D. The prepatellar bursa: cadaveric investigation of regional anatomy with MRI after sonographically guided bursography. AJR Am J Roentgenol. 2007 Apr;188(4):W355-8. doi: 10.2214/AJR.05.1466. PubMed PMID: 17377004.
• When inflamed, a bursa’s normally thin lining thickens and produces excess fluid. The excess fluid collects in the bursa sac, causing it to swell.
• When the prepatellar bursa is inflamed, it fills with fluid, causing the front of the knee to look swollen.

There are many reasons a prepatellar bursa may become inflamed, such as repeated irritation, an injury, or an underlying inflammatory condition. Repeated irritation from kneeling is the most common reason.

See Causes of Knee Bursitis (Prepatellar Bursitis)

Housemaid’s knee and other nicknames

Prepatellar bursitis has been called housemaid’s knee, carpet layer’s knee, coal miner’s knee, and carpenter's knee. These nicknames arose because people whose jobs require frequent kneeling are prone to knee bursitis.

Who Gets Knee Bursitis?

While anyone can get prepatellar bursitis, experts estimate about 80% of cases occur in men. Men aged 40 to 60 years are most likely to be affected.3Baumbach SF, Lobo CM, Badyine I, Mutschler W, Kanz KG. Prepatellar and olecranon bursitis: literature review and development of a treatment algorithm. Arch Orthop Trauma Surg. 2014 Mar;134(3):359-70. doi: 10.1007/s00402-013-1882-7. Epub 2013 Dec 5. PMID: 24305696.

How Long Does Knee Bursitis Last?

With rest and home treatment, the swelling and other symptoms caused by knee bursitis may go away in a couple of weeks. Medical treatment may be necessary if symptoms persist longer than 2 or 3 weeks after beginning rest and home treatment.

Knee bursitis that does not go away or comes and goes repeatedly is considered chronic bursitis. When knee bursitis is chronic it is more challenging to treat.

What Does Knee Bursitis Feel Like?

When pressed, the lump at the front of the knee may feel like a water balloon. The knee may also feel tender, stiff, and painful.

Interestingly, prepatellar bursitis is not always painful.4Williams CH, Sternard BT. Bursitis. [Updated 2020 Aug 15]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513340/ Little or no pain is especially likely when prepatellar bursitis has become chronic.5Khodaee M. Common Superficial Bursitis. Am Fam Physician. 2017 Feb 15;95(4):224-231. PMID: 28290630.

See Prepatellar Bursitis Symptoms

Knee pain, along with skin that is warm to the touch, may be a sign of infection. An infected bursa (septic bursitis) is a serious condition and requires immediate medical attention.