Prepatellar Bursitis (Housemaid's Knee)
Summary
Prepatellar bursitis is inflammation of the prepatellar bursa, a fluid-filled sac located anterior to the patella. It presents as a localised swelling over the front of the kneecap, typically caused by repetitive kneeling (hence "Housemaid's knee", "Carpet layer's knee", "Clergyman's knee"). The condition may be aseptic (sterile, due to friction/trauma) or septic (infected, usually with Staphylococcus aureus). The key clinical distinction is from a knee joint effusion — in bursitis, swelling is in front of the patella, whereas knee effusion is behind the patella. Aseptic bursitis is managed conservatively; Septic bursitis requires aspiration, cultures, and antibiotics (flucloxacillin).
Key Facts
- Anatomy: Bursa anterior to patella
- Cause: Repetitive kneeling (occupational)
- Types: Aseptic (friction), Septic (S. aureus)
- Presentation: Fluctuant swelling over patella; Not inside knee joint
- Distinguish From: Knee effusion (behind patella)
- Treatment: Rest, Knee pads; Flucloxacillin if septic
Clinical Pearls
"In Front vs Behind": Prepatellar bursitis = swelling IN FRONT of patella. Knee effusion = swelling BEHIND patella (fills suprapatellar pouch).
"S. aureus = Septic Bursitis": Most common organism. Always consider infection if there is overlying cellulitis or fever.
"Knee Pads Prevent It": Occupational prevention is key — advise knee pads for those who kneel frequently.
"Aspiration Distinguishes Aseptic from Septic": Send for microscopy, culture, and crystal analysis.
Incidence
- Common
- Higher in occupations requiring kneeling
Demographics
- All ages
- M > F
Risk Factors / Occupations
| Occupation | Notes |
|---|---|
| Carpet layers | |
| Plumbers | |
| Cleaners | |
| Gardeners | |
| Clergy | (Kneeling for prayer) |
| Roofers |
Anatomy
- Prepatellar bursa lies between skin and patella
- Reduces friction during knee flexion
Causes
| Type | Mechanism |
|---|---|
| Aseptic (Traumatic) | Repetitive friction from kneeling; Direct trauma |
| Septic | Bacterial infection (usually S. aureus); Often via skin break |
Septic Bursitis
- 80% caused by S. aureus
- May follow minor skin trauma (abrasion, puncture)
- Overlying cellulitis common
Symptoms
| Feature | Aseptic | Septic |
|---|---|---|
| Swelling | Yes | Yes |
| Pain | Mild | Moderate-severe |
| Warmth | +/- | Yes |
| Erythema | +/- | Yes (often cellulitis) |
| Fever | No | Yes |
| Skin break | No | Often |
Key Finding
Inspection
- Discrete swelling over patella
- Erythema and warmth (septic)
Palpation
- Fluctuant
- Tender (especially if septic)
- NOT in communication with knee joint
Movement
- Knee ROM usually preserved
- Pain at end of flexion (bursa compressed)
Aspiration (If Septic Suspected)
| Test | Purpose |
|---|---|
| Microscopy and Culture | Identify organism |
| WCC in aspirate | >000 cells/μL suggests infection |
| Gram stain | Rapid identification |
| Crystal analysis | Exclude gout/pseudogout |
Blood Tests
| Test | Findings |
|---|---|
| WCC, CRP | Raised in septic bursitis |
| Blood cultures | If systemic sepsis |
Imaging
- Usually not required
- USS: Confirms bursal swelling
- MRI: If diagnostic uncertainty
Management Approach
┌──────────────────────────────────────────────────────────┐
│ PREPATELLAR BURSITIS MANAGEMENT │
├──────────────────────────────────────────────────────────┤
│ │
│ ASEPTIC BURSITIS: │
│ • Rest — Avoid kneeling │
│ • Ice │
│ • NSAIDs │
│ • Knee pads for prevention │
│ • Aspiration (if tense — for symptom relief) │
│ • Compression bandage │
│ │
│ SEPTIC BURSITIS: │
│ • Aspiration for culture (before antibiotics) │
│ • Antibiotics: │
│ - Flucloxacillin 500mg-1g QDS (or IV if severe) │
│ - Duration: 10-14 days │
│ • Serial aspiration may be needed │
│ • Incision and drainage if refractory │
│ • Hospital admission if systemically unwell │
│ │
│ CHRONIC / RECURRENT: │
│ • Bursectomy (surgical excision) │
│ • Only if conservative measures fail │
│ │
└──────────────────────────────────────────────────────────┘
Of Septic Bursitis
- Abscess formation
- Cellulitis spread
- Sepsis
- Osteomyelitis (rare)
Of Treatment
- Aspiration: Re-accumulation, Infection (if sterile)
- Bursectomy: Scarring, Wound complications
Aseptic
- Resolves with rest and activity modification
Septic
- Good outcome with early antibiotics
- May need repeated aspiration or surgery
Key Resources
- NICE CKS: Bursitis
Key Evidence
Aspiration + Antibiotics
- First-line for septic bursitis
What is Prepatellar Bursitis?
Prepatellar bursitis is swelling of a small fluid-filled sac (bursa) at the front of the kneecap. It's sometimes called "Housemaid's knee" because it's caused by kneeling for long periods.
What Causes It?
- Kneeling a lot (e.g., laying carpets, cleaning, gardening)
- Direct injury to the knee
- Infection (if bacteria get in)
What Are the Symptoms?
- Swelling at the front of the knee
- Pain and tenderness
- If infected: Redness, warmth, fever
How is It Treated?
- Rest and avoid kneeling
- NSAIDs for pain
- Knee pads to prevent it coming back
- If infected: Antibiotics and draining the fluid
When Should I See a Doctor?
See a doctor if you have:
- Fever
- Redness spreading around the knee
- Severe pain
Primary Resources
- NICE Clinical Knowledge Summaries. Bursitis.
Key Studies
- McAfee JH, Smith DL. Olecranon and prepatellar bursitis. Am Fam Physician. 1988;37(4):119-125. PMID: 3279576