Infra-patellar bursitis (clergyman's knee)
Infra-patellar bursitis (clergyman's knee) is inflammation of the bursa, a fluid-filled sac that reduces friction, just below the kneecap.
Remember
Localise kneeling-related swelling by position: below the kneecap is infra-patellar bursitis (clergyman's knee), while over the kneecap is pre-patellar bursitis (housemaid's knee).
Memory aid
The housemaid kneels forwards to scrub, so the bursa in front of the patella is affected; the clergyman kneels upright, so the bursa below it is affected.
Compare how the housemaid and the clergyman kneel to see which bursa is affected.
A bursa is a small, fluid-filled sac that sits where skin or tendon rubs over bone, and it reduces friction there. Bursitis is inflammation of one. The infra-patellar bursa lies just below the patella (kneecap), around the patellar tendon, the thick cord between the kneecap and the tibia (shinbone). Anatomy texts divide it into a superficial part, between the skin and the tendon, and a deep part, between the tendon and the tibia. The superficial part, between the skin and the tendon, matches the localised swelling that follows repeated kneeling.
Infra-patellar bursitis is also known as clergyman's knee. The cause is repeated micro trauma (many tiny injuries). Upright kneeling is often the trigger, classically in the clergy. It presents as a painful, often red swelling below the knee joint. A bursa is a separate sac and not part of the joint lining, so the joint itself is not primarily affected and movement can remain largely preserved.
When a swelling follows kneeling, the key skill is to localise it by position. A swelling over the kneecap is pre-patellar bursitis (housemaid's knee), which is linked with kneeling forwards. A swelling above the kneecap means the suprapatellar bursa, which communicates with the knee joint and often goes with an effusion (excess fluid inside the joint).
Rest, ice, elevation and simple painkillers are the usual first treatment. If infection is suspected, fluid can be drawn off the bursa with a needle and tested, and antibiotics are given if it is infected.
Key facts
- Site
- the bursa just below the patella, around the patellar tendon.
- Cause
- repeated micro trauma, often from upright kneeling (classically in the clergy).
- Presents as
- a painful, often red swelling below the knee joint.
- Joint
- the bursa is separate from the joint lining, so movement can remain largely preserved.
- Look-alike
- pre-patellar bursitis (housemaid's knee) is a swelling in front of the kneecap.
- Usual treatment
- rest, ice, elevation and simple painkillers.
Exam traps
- The bursa in front of the kneecap can become inflamed after kneeling too, but it gives swelling over the kneecap, not below it.
- The synovial membrane (the thin lining of the joint) makes lubricating fluid, and irritation gives excess fluid in the joint (an effusion) with general swelling around the knee, not a tender lump beneath the kneecap.
- A load-related tendon problem seen with jumping (patellar tendinopathy, or jumper's knee) fits activity-related tendon pain, not a swelling that follows kneeling.
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