Infected Hemiarthroplasty

Clinical image

Girdlestone situation after removal of an infected hip prosthesis. Source: Wikimedia Commons — Mehlauge; CC BY-SA 3.0. Image binary is embedded locally in this package; original source and licence are retained.

Key points

Talking the talk

• This is the supine AP front view of the left hip showing a modular bipolar hemiarthroplasty.
• What concerns me is the radiolucencies seen in the Gruen zones 1,2,4, and 7. There appears to be a cortical break below the lesser trochanter. The acetabulum is porotic but head size not under or over sized. I would like to see the immediate post operative X-ray to know whether the stem has sunk and latest lateral view of left hip.

What do you think?

• The prosthesis appears loose. It was inserted only 3 years back. The radiographs are highly suggestive of infection until proven otherwise.
• I would take a thorough history covering the reason for the procedure, any leaking wound after surgery, UTI, chest infection or dental extraction, immunosuppressive comorbidities and smoking. I wound examine for signs of inflammation, health of the scar and do Full blood count, ESR and CRP
• I will aspirate the hip if the pretest probability is high, especially if ESR and CRP are elevated.

How good is ESR and CRP

• IL 6 more accurate than ESR and CRP (Berbari, JBJS am, 2010)

How useful is aspiration?

• Image guided aspiration is highly sensitive and specific with high negative predictive value (all around 90%, but 67% PPV), especially with clinical features suggestive of infection or when ESR and CRP elevated. Spangehl JBJS Am, 1999

If aspiration negative

• Bone scan T99 M Low specificity
• Indium Leukocyte-more specific and sensitive
• FDG-PET- Sensitive, does not diff infection from aseptic loosening

What would you do

• I will sit with the patient and fully discuss what her problems and expectations are.
• We have to reach an agreement on whether she would wish to proceed with revision surgery taking on board the potential risks and complications of surgery weighted against the probable benefits.
• Proceed with 2 stage revision

Tsukayama Classification

• Early Postoperative
• Late Chronic
• Haematogenous
• Intraoperative

Prerequisites of 1 stage procedure

• Known organism , sensitive to Ab
• No pus
• Elderly/patients with multiple medical problems
• Success rate 0f 80% if antibiotic loaded cement used against 60% if not (Hanssen and Rand, JBJS 1998)

Advantages and Disadv of 2 stage procedure

• More versatile: cemented/ uncemented/ bonegraft
• Allows assessment of response to antibiotics
• Difficult nursing
• Difficult second surgery due to scarring, shortening and atrophy
• PROSTALAC spacer is costly, can dislocate and fracture

Duration of antibiotics

• No clear guideline
• Wait for at least 6 week looking for good response
• Most surgeons do 2nd stage at 3 months, 6 weeks antibiotics and further 6 weeks with out, monitoring CRP and ESR
• Some aspirate before the procedure

5/6 of my last operations got infected

Theatre design

Principles

• Stop operating and investigate
• Find out whether organism was same: Staph aureus then nasal carrier-take swabs an appropriate treatment
• Look for breakdown of theatre sterility: Microbiology investigate for laminar flow system
• Fischer index :
  • at rest:<9 cfm /dm2/h
  • in activity: < 90/dm2/h
• Instrument sterilisation and packing
• Intra operative precautions breakdown
  • too much movement
  • opening and closing door

Theatre sterility

• Operation theatre quality
  • Structure:
    • clean, sterile and dirty areas clearly demarcated
    • Surfaces easy to clean
  • Contamination controlled airflow system (HVAC system) ;Controls temperature, humidity and airflow
    • Involves: Ventilation, pressurisation, filtration and air distribution
    • HEPA filter 99.97% reduction of particles above 0.3 microns
    • Ventilation
• Water supply
• Procedural and Behavioural factors
  • Attire
  • Preparation in another room
  • Use correct plenum
  • Limiting needless activity
  • WHO check list

Ventilation

• Unidirectional
  • LAF
    • Horizontal
    • Vertical
    • Exponential
• Turbulent
• Mixed

Classic studies

• Charnley: 7% reduced to 0.5% with
  • Unidirectional flow
  • High pressure
  • Exhaust suit
  • High rate of air exchange
• Lidwell: Further reduction in infection with ultra clean air
• A meta-analysis encompassing 26 studies could not ultimately confirm the role of LAF in surgery
• Some recent studies have even indicated an increase in SSI after hip prosthesis with procedures performed under LAF (Christian Brandt, germany)