Pre-patellar bursitis

• Pre-patellar bursitis:

  • Pre-patellar bursa = closed, fluid filled sac that lies between the anterior surface of the patella and the skin
  • Bursitis occurs when the bursa is irritated causing thickening of the bursa wall and increased fluid production causing swelling
  • Due to its association with overuse and certain occupations it is also known as housemaid's knee or carpet layers knee
• Can be classified as:

  • Non-septic
  • Septic - around 30% of cases are septic
• Non-septic causes:

  • trauma - either acute or chronic from repetitive pressure/overuse
  • Crystal deposition - gout or pseudogout
  • Systemic inflammatory conditions e.g. RA
  • Other systemic conditions e.g. SLE
• Septic causes:

  • When bacteria enter from trauma or direct spread from surrounding infection
  • Most cases due to staphylococcus aureus
  • Predisposing factors: trauma, pre-existing bursal disease, prior aspiration of bursa, immunocompromised
• More common in:

  • Men aged 40-60
  • Occupation that involves prolonged kneeling
  • Play sports involving repetitive movement of knees/direct impact to knees
  • Septic more common in children or immunocompromised people
• Presentation:

  • Pain, swelling, erythema
  • Difficulty kneeling or walking
  • Fever in septic bursitis
• Examination:

  •Localised swelling and erythema overlying the patella

  •May be warm even in non-septic cases

  •Often tender- but may be painless in chronic bursitis

  •Fluctuant (movable and compressible)

  •Range of motion of knee shouldn't be affected- although may be some discomfort at extreme flexion of knee

  *Suspect alternative diagnosis if generalised joint swelling or range of knee movement limited and painful*
• Assess for signs of infection:

  •Fever, tachycardia, hypotension

  •Increased tenderness or painful, red, hot, swelling of bursa which is progressively worsening

  •May be local cellulitis

  •May be abrasion or laceration over the bursa
• Investigations:

  • Bloods for infection and comorbidities - FBC, CRP/ESR, uric acid, HbA1c, autoantibodies
  • X-ray if bony pathology suspected
  • Bursal aspiration (can be done in GP)- can relieve pain, send for gram staining, culture and crystal analysis
• Appearance of fluid can give clue to nature of bursitis:

  •Pus/turbid- indicates infection

  •Straw coloured – infection less likely

  •Blood stained – trauma, infection, inflammatory causes (gout or RA)

  •Milky fluid – gout or pseudogout
• Management of non-septic:

  • Conservative - rest, ice, activity modification and knee pads, simple analgesia (topical or systemic)
  • Most will respond to conservative management but reattend if worsening/signs of infection
  • Consider bursal aspiration for comfort if large effusion
  • If no response consider steroid injections (if confident not septic)
  • If no response after 2 months refer to specialist
• Septic bursitis management:

  • Aspirate fluid and treat empirically with oral antibiotics
  • First line = flucloxacillin, clarithromycin if penicillin allergic
  • Conservative management for symptom relief
  • Review every few days to monitor response to treatment - may been antibiotics for 1-4 weeks
  • Admit/refer if response inadequate or complications suspected
• Admit if:

  •Septic bursitis with severe infection/systemically unwell or immunocompromise

  •Any suspicion of septic joint (limited range of movement, joint pain etc)

  •Extensive cellulitis

  •Bursa requires I+D e.g. signs of pointing abscess (come to a head) or not responding to antibiotics
• Refer if:

  •Inadequate response to antibiotics in septic bursitis

  •Aspiration required but unable to do in primary care

  •Recurrent septic bursitis – may require surgical excision of bursa

  •Non septic bursitis but no response to conservative management after 2 months