Infection

incidence

· current rate is 1% over lifetime of prosthesis

· increased risk with high-risk patients (2%)

· rheumatoid arthritis

· steroids

· diabetes

· increased risk with revision (2%)

classification

Early postoperative

· acute fulminating infection

· develops within 1 month of surgery

· wound infection or infected haematoma that has progressed to deep infection

· typically

· febrile patient

· red swollen discharging wound

Late chronic

· more indolent

· develop more than 1 month from surgery

· typically

· well patient

· healed wound

· worsening of pain

· never pain-free interval

Acute haematogenous

· acute onset of clinical symptoms

· can occur several years after surgery

· typically

· well patient

· previously well functioning hip

Treatment

Goals

· eradication of infection

· restoration of function

Techniques

Debridement

· excision of necrotic and infected tissue

· removal of

· cement

· wires

· plates and screws

· sutures

· removal of prosthesis if not well-fixed

Intrapelvic cement

· must be removed

· may rarely require additional retroperitoneal exposure

· may require

· CT scan with contrast

· angiogram

· cystogram

· should consult

· vascular surgeon

· urologist

Antibiotics

· if organism identified on previous aspiration or operation

· appropriate antibiotics

· on induction

· if organism not identified

· cephalosporin

· after tissue obtained for culture

· consultation with infectious diseases specialist

· appropriate antibioitic

· monitoring safety and efficacy

Duration

· 4 to 6 weeks

· can choose dose

· empirically

· based on serum bacteriocidal titre of at least 1:8

Superficial infection

Minor

· superficial cellulitis treated with

· oral antibiotics

· local wound care

Major

· significant infection with haematoma or drainage treated with

· systemic antibiotics

· surgical evacuation and debridement

alternatives

Antibiotic suppression

Indications

· patient refused or unfit for surgery

· highly sensitive or low virulence organism

· no loosening of prosthesis

· asymptomatic infection

Technique

· prolonged oral antibiotics (6 mths)

Results

· success defined as no clinical, laboratory or radiographic evidence of infection

· successful in 12 of 19 patients

Retention of components

Indications

· short duration of symptoms (<1 day to 1 mth)

· G+ organism

· no loosening of prosthesis

Technique

· early intensive debridement

· 6 wks of antibiotics

· 1 wk systemic

· 5 wks oral

Results

· ultimate failure rate of 40%

Two-stage reimplantation

· procedure of choice

Advantages

· high rate of success

· two opportunities for debridement

Disadvantages

· two surgical procedures required

· surgery more difficult

· scar formation

· shortening

· distortion of anatomy

· increased hospitalisation cost

· patient inconvenience

Technique

· operative debridement

· may insert antibiotic-loaded cement beads or spacer

· rehabilitation

· varying period of traction

· mobilisation easier with cement spacer

· parenteral antibiotics

· usually 6 weeks

· period off antibiotics

· to assess response

· clinical, laboratory and aspiration

· delay

· at least 6 wks and up to 1 yr

· depends on virulence of organism and response to antibiotics

· reimplantation

· Gram stain and frozen section performed at time of surgery

· procedure abandoned if signs of infection

· replacement of implant with antibiotic-loaded cement

Results

· 91% incidence of success

One-stage reimplantation

· controversial

Indications

· highly sensitive organism

· healthy patient with no risk factors for infection

· rheumatoid arthritis

· diabetes

· chronic infection (skin lesions, respiratory, UTI)

· adequate bone and soft tissue to support revision

· elderly infirm patient who will not tolerate two procedures

Contraindications

· severe infection with necrotic tissue and draining sinuses

· multiple previous operations

· inadequate debridement with retention of old cement

· virulent or multiple organisms

Advantages

· fewer operations

· less cost

· less inconvenience to patient

Disadvantages

· increased failure with recurrent sepsis

· may be due to

· no opportunity for repeated debridement

· no period without prosthesis for antibiotic

Technique

· operative debridement

· removal of implant

· replacement of implant with antibiotic-loaded cement

· 6 weeks of antibiotics

Results

· best results are from Buchhoz

· 77% success

· increased to 90% when failures revised with 1-stage procedure

· 2% mortality, 2% amputation, 3% Girdlestone

Resection arthroplasty

Indications

· patient refusal or unfit for second operation

· high-risk patient (steroid-dependent RA)

· poorly sensitive or highly virulent organism

· inadequate bone or soft tissue to support revision

Advantages

· effective control of infection

Disadvantages

· inferior function

· pain

· limp

· walking aid

· shoe lift

· increased energy expenditure

Amputation

Technique

· hip disarticulation

Indications

· life-threatening infection

· severe loss of soft tissue and bone stock

· vascular injury

Incidence

performed in 0.1%