Posterior (Moore/Southern) approach - preserves abductors, allows an Extended Trochanteric Osteotomy if needed | advanced
- MSIS CRITERIA: confirm a chronic PJI with 2 or more major criteria - (1) sinus tract communicating with the prosthesis, (2) synovial WBC over 3000 or PMN percentage over 80%, (3) serum ESR over 30 AND CRP over 10, (4) 2 or more positive cultures with the same organism, (5) histology showing over 5 PMN per high-power field.
- TWO-STAGE OUTCOMES: infection eradication 85-90%, but higher complications than primary THA - 10-20% reinfection at 2 years, 10-15% dislocation, 10-15% aseptic loosening at 10 years, and lower patient satisfaction.
- ARTICULATING SPACER PREFERRED: maintains limb length, offset and ROM, allows weight-bearing, makes Stage 2 easier, and gives similar infection control to a static spacer; its 13-15% dislocation rate is an acceptable trade-off.
- HANSSEN HIGH-DOSE CEMENT: 4g vancomycin plus 2.4g tobramycin per 40g cement (3 times standard dosing), achieving around 200 times the MIC locally with minimal systemic toxicity.
- ANTIBIOTIC HOLIDAY at BOTH stages: stop antibiotics 2 weeks before Stage 1 (lifts culture yield from 60% to 80%) and 2 weeks before Stage 2 (lifts aspiration sensitivity from 40% to 75%).
- FROZEN SECTION at Stage 2: over 5 PMN per high-power field means abort reimplantation and place a new spacer (sensitivity around 80%, specificity around 95%). DUAL MOBILITY at reimplantation cuts dislocation from 10-15% to 2-3%.
When & Why
Indication. A chronic periprosthetic joint infection (symptoms over 4 weeks, or a sinus tract, or an indolent presentation with raised inflammatory markers) of a total hip arthroplasty that is confirmed on the MSIS/ICM criteria. Two-stage exchange is the global benchmark for chronic PJI because it delivers the most reliable infection eradication (around 85-90%) by completely removing the biofilm-harbouring implant and cement, then reimplanting once the host is controlled. Confirm the diagnosis first (MSIS major criteria - need 2 or more). A single sinus tract is pathognomonic and stands alone; otherwise combine the laboratory and culture data:
- Detail
- Communicating with the prosthesis - pathognomonic, a stand-alone major criterion
- Detail
- Over 3000 cells per microlitre OR PMN percentage over 80%
- Detail
- ESR over 30 mm per hour AND CRP over 10 mg per litre (both required)
- Detail
- Two or more separate samples growing the same organism
- Detail
- Over 5 polymorphonuclear leukocytes per high-power field at 400x in 5 separate fields
The benchmark for chronic PJI. Radical debridement with implant and cement removal, an antibiotic spacer interval, then reimplantation. Infection eradication around 85-90%.
A single operation for selected patients - known organism, good soft tissues, adequate bone. Less morbidity, but less reliable for virulent or polymicrobial infection.
Indefinite oral antibiotics for the patient unfit for surgery, accepting an infected implant to suppress symptoms. Not definitive treatment.
Pre-operative essentials. Image the bone stock (AP pelvis, lateral hip, Judet views, and a CT to grade acetabular and femoral loss by the Paprosky classification and to detect pelvic discontinuity). Order antibiotic-cement components (vancomycin 4g vials, tobramycin 2.4g) and the revision implants you might need (augments, cages, modular stems, dual mobility). Consent specifically for an Extended Trochanteric Osteotomy (ETO), sciatic nerve injury, recurrent infection, and salvage procedures (Girdlestone, arthrodesis, amputation). Note that a cell saver is contraindicated in infection because it disseminates bacteria. Involve Infectious Diseases early.
The Operation
The goal across both stages is the same: eradicate the biofilm by removing every foreign body and all infected tissue, then restore a stable, painless hip. The exposure is the posterior (Moore/Southern) approach - it preserves the abductors, gives extensile access, and permits an ETO when the stem is well-fixed. Laid out below, it is the heart of the procedure.
Operative sequence
- Lateral decubitus, affected side up, pelvis held perpendicular to the floor with anterior support at the ASIS and posterior support at the sacrum; pad all bony prominences and place an axillary roll under the dependent axilla.
- Pelvic perpendicularity is critical - obliquity causes systematic cup malposition in inclination and anteversion; confirm with a positioning rod or fluoroscopy.
- Prep the entire leg from iliac crest to toes with a wide circumfermonary field so you can extend for an ETO if needed.
- Use the previous posterior scar (typically 8-15cm), extending proximally toward the PSIS or distally 5cm beyond the greater trochanter as required; anticipate indurated scar from prior surgery and infection.
- Deepen through subcutaneous tissue (often fibrous) and incise the fascia lata in line with the femur.
- Split gluteus maximus bluntly in the line of its fibres - this is the internervous plane between the superior and inferior gluteal nerves.
- Find the sciatic nerve early by blunt finger dissection; in revision it may be adherent in scar or displaced medially by a subsided stem.
- Protect it throughout with a finger or Hohmann retractor - it is the structure most at risk, with a 2-5% injury rate in revision versus 0.2% in primary THA.
- The posterior capsule and short external rotators are usually scarred and thickened; release them from the posterior trochanter to the femoral neck insertion.
- Excise the thickened posterior capsule completely (it harbours biofilm) and tag the rotators for later repair.
- Dislocate the hip posteriorly with flexion, adduction and internal rotation.
- Take 5-6 tissue samples from different sites (capsule or pseudocapsule, femoral interface membrane, acetabular interface membrane, femoral bone, acetabular bone, and a soft-tissue quadrant) using a separate instrument for each, before any debridement, to avoid contamination.
- Send for aerobic and anaerobic culture with a 14-day hold (slow growers such as Cutibacterium), fungal culture if immunosuppressed, and 1-2 samples for frozen and permanent histology.
- Multiple samples are crucial: a single culture is about 70% sensitive versus 94% with multiple samples; two or more positive cultures with the same organism is a major MSIS criterion.
- Pass curved osteotomes around the cup-bone interface circumferentially, starting at the superior dome and working a full 360 degrees.
- Lever the cup out with a broad osteotome, preserving as much bone stock as possible for reimplantation.
- If the stem is cemented or well-fixed, perform an Extended Trochanteric Osteotomy rather than risk cortical perforation - attempting cement removal without an ETO carries about a 30% perforation risk.
- Mark the anterolateral femur for an 8-10cm length, taking one-third of the circumference and preserving the posterior two-thirds with the vastus lateralis attachment (its blood supply from the lateral circumflex femoral artery).
- Three saw cuts - anterior vertical, distal horizontal, and posterior vertical-oblique - create a fragment that hinges open like a book with the abductors still attached, exposing the stem and cement for removal.
- Remove all cement with an ultrasonic cement removal system or a high-speed burr with long thin carbide bits, working systematically proximal to distal; keep a finger in the anterior joint to detect any breakthrough.
- Perform a radical debridement: complete synovectomy, excision of the entire interface membrane (biofilm harbour), removal of all PMMA, metal and polyethylene debris, and excision of any sinus tract.
- Debride non-viable bone to a healthy bleeding bed (the "paprika sign"), reaming acetabulum and femoral canal to bleeding bone - inadequate debridement causes about 50% of recurrent infections.
- Irrigate with a minimum of 9 litres of body-temperature normal saline - high-pressure pulse lavage first, then low pressure - reaching every recess.
- Use no additives (no Betadine, chlorhexidine or hydrogen peroxide): they are cytotoxic to osteoblasts and impair bone healing; mechanical removal is what works.
- After lavage, change gloves, gowns and instruments and use fresh implant sets for the spacer - simulating a new operation to lower the bacterial load further.
- Insert an articulating spacer (preferred over static): it maintains limb length, offset and ROM, prevents soft-tissue contracture, allows weight-bearing, and makes Stage 2 easier, with similar infection control to a static spacer. Reserve a static spacer for severe instability or abductor deficiency.
- Use the Hanssen high-dose cement: 4g vancomycin plus 2.4g tobramycin per 40g of Palacos or Simplex cement (3 times standard dosing) - it achieves around 200 times the MIC locally with minimal systemic toxicity; vancomycin covers Gram-positive (including MRSA) and tobramycin covers Gram-negative.
- Insert the acetabular spacer first (2-3mm larger than native), then the femoral component with a metal head, reduce the hip, and ensure the construct is stable but retrievable, avoiding excess cement keying into the canal.
- If an ETO was made, reduce the trochanteric fragment anatomically and fix it with a minimum of 3 cerclage cables passed around intact femur proximal and distal to the osteotomy, tightened sequentially for compression; test stability by pulling on the abductors (90% union if rigidly fixed).
- Repair the posterior capsule remnants and short external rotators to restore posterior soft-tissue restraint, then close gluteus maximus, fascia lata, subcutaneous tissue and skin.
- Give organism-specific IV antibiotics for a minimum of 6 weeks (extend to 12 for difficult organisms): vancomycin for MRSA, flucloxacillin if sensitive, a fluoroquinolone or third-generation cephalosporin for Gram-negatives.
- For all staphylococcal PJI, add rifampicin 300-450mg twice daily after the wound has healed (day 5-7), paired with fusidic acid or a fluoroquinolone - rifampicin penetrates biofilm and is bactericidal but must never be given as monotherapy.
- Monitor CRP and ESR weekly - CRP should roughly halve each week; a plateau or rise suggests persistent infection.
- Maintain a minimum 6-8 week interval, then stop all antibiotics for a 2-week holiday before Stage 2 to unmask persistent infection (aspiration sensitivity rises from 40% to 75%).
- Return through the same posterior scar expecting a harder dissection than Stage 1 - dense scar, distorted anatomy from spacer subsidence, and a sciatic nerve encased in scar (highest risk).
- Protect the nerve early with blunt dissection, excise the pseudocapsule, dislocate posteriorly, and remove the spacer head, acetabular component and femoral component.
- Remove every fragment of spacer cement (it is a biofilm substrate), then lightly re-debride any residual membrane and ream acetabulum and femoral canal back to bleeding bone.
- Before reimplantation, take 5-6 fresh tissue samples for culture (14-day hold) and permanent histology, and send capsule or interface tissue for frozen section.
- Over 5 PMN per high-power field means persistent infection: abort reimplantation, place a new antibiotic spacer, give extended IV antibiotics for 12 weeks, and reconsider suppression or salvage. The test is about 80% sensitive and 95% specific.
- If the frozen section is negative (under 5 PMN per high-power field) and the tissues look clean, proceed to reimplantation.
- Reconstruct by the Paprosky classification (detailed in Background and Evidence), aiming for at least 50% host bone contact and biologic fixation, with multiple screws in the safe zones (avoid the 3 and 9 o'clock positions over the external iliac vessels).
- Most prefer cementless components (no biofilm substrate); if cement is needed in poor bone, use low-dose antibiotic cement (1g vancomycin per 40g - not the high-dose spacer mix).
- If an ETO was used, leave it open until the stem is inserted, then reduce and cable (3 or more cables), bypassing the osteotomy site by two cortical diameters (about 10cm).
- Use a dual mobility cup as the first-choice stability strategy - it cuts dislocation from 10-15% down to 2-3% with a lower revision rate than a constrained liner (no dissociation risk). Reserve a constrained liner for severe abductor deficiency or salvage.
- Repair the posterior capsule and short external rotators meticulously, restore offset and soft-tissue tension, and confirm stability on trial (Shuck test, flexion to 90 degrees with internal rotation and adduction) before final implantation.
- Insert the final acetabular and femoral components, reduce the hip and recheck stability, then repair any ETO with 3 or more cables in compression.
- Give a final 3-litre pulse lavage and close the fascia lata, subcutaneous tissue and skin; give intra-operative IV antibiotics (vancomycin 1g plus cefazolin 2g, or an organism-specific agent).
Identify it early with blunt dissection and protect it with a finger throughout. The nerve sits 2-3cm posterior and inferior to the posterior acetabular rim, and may be displaced medially by a subsided stem or encased in scar. Avoid limb lengthening over 4cm (a nerve-stretch injury); a complete palsy warrants nerve exploration by a peripheral nerve surgeon. Also protect the superior gluteal neurovascular bundle (avoid dissection above piriformis, 5cm above the trochanter), the femoral vessels anteriorly (keep a finger in the joint during reaming or cement removal), and the thin quadrilateral plate medially.
Inadequate debridement causes about half of recurrent infections. Remove all cement, all interface membrane and all non-viable bone - retained cement is a biofilm reservoir that defeats even high-dose antibiotics. Balance aggressive debridement against preserving enough bone stock for a stable reimplantation.
An articulating spacer maintains length, offset and ROM, allows weight-bearing, and makes Stage 2 dramatically easier than a static block - with the same 85-90% infection control. Its 13-15% dislocation rate is acceptable and manageable with reduction, precautions and an abduction brace. Reserve a static spacer for severe instability, abductor deficiency, or the non-compliant patient.
More than 5 PMN per high-power field, or gross purulence, means abort reimplantation: place a new high-dose spacer and extend IV antibiotics to 12 weeks. Reimplanting through active infection drops success from 85-90% to under 50%. The test is about 80% sensitive and 95% specific - a negative result still warrants final culture-directed antibiotics if Stage 2 cultures grow.
Location: 2-3cm posterior and inferior to the posterior acetabular rim, possibly displaced medially or encased in scar. Protection: early blunt identification, finger protection, gentle retraction, avoid lengthening over 4cm. Injury rate 2-5% in revision versus 0.2% in primary.
Location: exits the greater sciatic notch above piriformis, about 5cm above the greater trochanter. Protection: avoid dissection superior to piriformis and stay anterior to the notch; injury denervates the abductors and causes a Trendelenburg gait.
Location: anterior to the joint, along iliopsoas medial to the proximal femur. Protection: keep a finger in the anterior joint during reaming or cement removal and control reamer depth; a breach is catastrophic bleeding - immediate vascular consult.
Location: insertion of gluteus medius (lateral facet) and minimus (anterior facet). Protection: if an ETO is made, fix with 3 or more cables and protect weight-bearing 6-8 weeks; non-union (5-10%) causes Trendelenburg gait.
Location: the thin medial acetabular wall separating the joint from the iliac vessels and obturator neurovascular bundle. Protection: recognise a deficient medial wall pre-operatively (Kohler line, teardrop) and use gentle technique medially; an intrapelvic breach with bleeding needs immediate laparotomy.
Aftercare & Complications
Antibiotic protocol - Stage 1 onwards: organism-specific IV antibiotics for a minimum of 6 weeks (extend to 12 for difficult organisms). Add rifampicin 300-450mg twice daily once the wound has healed (day 5-7), paired with fusidic acid or a fluoroquinolone for all staphylococcal PJI.
- After Stage 2: debated and without RCT consensus. Most surgeons give at least 6 weeks of organism-specific IV antibiotics if Stage 1 cultures were positive (even if Stage 2 cultures are negative); some centres advocate chronic oral suppression (for example doxycycline 100mg twice daily), which observational data suggest lowers reinfection from 10-20% to 5-10%. Reserve suppression for high-risk patients (immunosuppressed, prior PJI) and balance against C. difficile, resistance and tendon rupture. Rehabilitation | Phase | Timing | Weight-bearing | Therapy | |-------|--------|----------------|---------| | 1 | 0-6 weeks | If ETO: toe-touch or 20kg partial until union; if no ETO and cementless: WBAT | Gentle ROM within precautions; hip precautions strict (no flexion over 90 degrees, no adduction, no internal rotation) | | 2 | 6-12 weeks | Progress to full weight-bearing once ETO unites (usually 6-8 weeks) | Progressive abductor strengthening, gait training | | 3 | 3-6 months | Full | Functional exercises, normalise gait | Abduction brace for the first 6 weeks in high-risk patients. Occupational therapy for hip-precaution education and adaptive equipment (raised toilet seat, sock aid, reacher). Surveillance. Radiographs at 6 weeks, 3, 6 and 12 months, then annually lifelong, looking for loosening, osteolysis, ETO union, fracture and heterotopic ossification. Check CRP and ESR at every visit for the first 2 years, then annually lifelong; a CRP over 10 or ESR over 30 warrants aspiration and possibly FDG-PET or CT. Recurrence can appear 5-10 or more years later from late haematogenous seeding or dormant biofilm. Dental prophylaxis is debated between national societies: AAOS/ADA (US) and NICE (UK) do not recommend routine antibiotic prophylaxis before dental work for most prosthetic joints, but many surgeons still cover high-risk patients (immunosuppressed, prior PJI) or those within 2 years of reimplantation, and after a treated PJI a lower threshold to cover and to treat dental sepsis promptly is common practice.
- Recognition
- Rising CRP/ESR, pain, wound drainage, positive aspiration culture, positive PET/CT
- Prevention
- Radical Stage 1 debridement, high-dose antibiotic cement, adequate 6-8 week interval, antibiotic holiday, frozen section at Stage 2, organism-specific antibiotics 6-12 weeks
- Management
- Aspiration and culture - same organism: repeat two-stage (60-70% success) or chronic suppression; new organism: treat as acute PJI; multiple failures: Girdlestone, arthrodesis or amputation
- Recognition
- Acute pain, limb shortening, unable to weight-bear, confirmed on X-ray
- Prevention
- Optimise spacer size and offset, meticulous soft-tissue repair, hip precautions
- Management
- Closed reduction under sedation, abduction brace, precautions; if recurrent, revise to a static spacer or expedite Stage 2
- Recognition
- Sudden pain, unable to weight-bear, cement fracture on X-ray
- Prevention
- High-fatigue cement (Palacos or Simplex), avoid excessive loading, proceed to Stage 2 before cement fatigues
- Management
- Late fracture means proceed to Stage 2; early fracture means revise the spacer and investigate cause
- Recognition
- Acute pain, limb shortening and rotation, unable to weight-bear, confirmed on X-ray
- Prevention
- Dual mobility cup (reduces to 2-3%), meticulous soft-tissue repair, optimise offset and length, 12-week precautions
- Management
- Closed reduction, abduction brace; if recurrent, revise to dual mobility or constrained liner or open soft-tissue repair
- Recognition
- Persistent trochanteric pain, Trendelenburg gait, lucency or fragment migration on X-ray
- Prevention
- Minimum 3 cables (preferably 4-5), compression, protected weight-bearing 6-8 weeks, smoking cessation, control infection
- Management
- Asymptomatic: observe; symptomatic: ORIF with plate, cables and bone graft, protected weight-bearing 12 weeks
- Recognition
- Immediate foot drop, posterolateral leg numbness; delayed progressive pain and weakness
- Prevention
- Early identification, blunt dissection, finger protection, avoid lengthening over 4cm
- Management
- Reduce tension immediately (flex knee and hip), explore if traction suspected, AFO for foot drop; most recover partially over 12-18 months
- Recognition
- Progressive start-up or activity-related pain, progressive radiolucent lines over 2mm, migration, osteolysis
- Prevention
- Preserve bone stock at debridement, biologic fixation with 50% bone contact, optimise bone health
- Management
- Rule out infection first (aspiration, CRP/ESR, PET/CT), then revise addressing bone defects with augments, graft or cage
- Recognition
- Intra-operative loss of resistance or subsidence; post-operative acute pain and X-ray fracture
- Prevention
- Gentle technique, avoid over-press-fit, recognise weak bone, bypass ETO by two cortical diameters
- Management
- Vancouver B1 stem stable: plate and cables; B2 stem loose: long stem plus ORIF; B3 poor bone: long stem and strut grafts; C below stem: ORIF plate
- Recognition
- Persistent pain despite healed wound, normal X-rays and negative infection workup
- Prevention
- Meticulous technique, optimised component position, adequate infection treatment, realistic counselling
- Management
- Rule out infection and mechanical causes; multimodal analgesia, physiotherapy, pain psychology; refractory: consider Girdlestone
- Recognition
- Uneven gait, need for a shoe lift, back pain; pelvic obliquity on exam
- Prevention
- Pre-operative templating, intra-operative limb-length checks, prioritise stability over length
- Management
- Under 2cm and stable: accept, most adapt; 2-4cm: shoe lift; over 4cm and symptomatic: consider revision
Salvage procedures if two-stage fails - Repeat two-stage revision - for the young patient with good bone stock and a first failure; success about 60-70% (lower than the first two-stage).
- Chronic antibiotic suppression - indefinite oral antibiotics (doxycycline 100mg twice daily or a fluoroquinolone) for the elderly or poor surgical candidate; accepts an infected implant to suppress symptoms.
- Girdlestone (excision arthroplasty) - remove all implants, cement and infected tissue, leaving a pseudarthrosis; pain relief about 60-70% but major shortening (3-5cm) and lifelong walker use, for the low-demand patient unfit for further reconstruction.
- Arthrodesis - fuse the hip in 25 degrees flexion, neutral abduction and rotation; excellent infection control (over 95%) and pain relief but loss of ROM and later back pain, for the young active patient after multiple failures.
- Amputation - last resort, for life-threatening sepsis or a non-functional painful limb after multiple failures; rare (under 1% of PJI cases).
Viva & Exam Focus
SPACERSPACER - antibiotic spacer requirements at Stage 1
RIFAMPINRIFAMPIN - the staphylococcal PJI antibiotic strategy
Clinical Decision Scenarios
Practise clinical reasoning and management decisions out loud
“A 68-year-old woman presents 18 months after primary THA with 6 weeks of progressive hip pain, CRP of 45 and ESR of 65. Hip aspiration shows a WBC of 8500 with 92% PMN and grows MRSA. How would you diagnose and manage this?”
“You are performing Stage 1 two-stage revision for chronic PJI. The femoral stem is a well-fixed cemented stem. Describe your approach to cement removal and femoral component extraction.”
“Explain the articulating versus static antibiotic spacer decision - advantages, disadvantages, and when you would choose each.”
MSIS criteria (need 2 or more major)
- Sinus tract (pathognomonic)
- Synovial WBC over 3000 or PMN over 80%
- ESR over 30 and CRP over 10 (both)
- Two or more cultures, same organism
- Histology over 5 PMN per high-power field at 400x
Pre-operative essentials
- Antibiotic holiday 2 weeks (culture yield 60% to 80%)
- Aspiration culture with aerobic, anaerobic and fungal holds
- Image bone stock with X-ray and CT (Paprosky)
- Order high-dose antibiotic cement: vancomycin 4g plus tobramycin 2.4g
- Cell saver contraindicated - it disseminates bacteria
- Consent for ETO, nerve injury, recurrence, salvage
Stage 1 critical steps
- Five to six tissue samples before debridement, 14-day hold
- Radical debridement: complete synovectomy, all interface membrane
- ETO if cemented or well-fixed: 8-10cm, one-third circumference, 3 or more cables, 90% union
- Complete cement removal with ultrasonic or burr, finger anteriorly
- Minimum 9-litre irrigation, no additives, change all instruments
- Articulating spacer, Hanssen high-dose cement, 13-15% dislocation
- IV antibiotics 6-12 weeks, add rifampicin after wound healed
- Interval 6-8 weeks, then a 2-week holiday before Stage 2
Stage 2 critical steps
- Frozen section mandatory: over 5 PMN per high-power field means abort
- Remove all spacer cement, ream to bleeding bone
- Reconstruct by Paprosky, aim for 50% host bone contact
- Dual mobility preferred: dislocation 10-15% down to 2-3%
- ETO repair: 3 or more cables, protected weight-bearing
- Meticulous capsule and short-rotator repair
- Post-Stage 2 antibiotics 6 weeks if Stage 1 positive (debated)
Hanssen high-dose cement
- 4g vancomycin plus 2.4g tobramycin per 40g cement (3 times standard)
- Around 200 times the MIC locally, minimal systemic toxicity
- Vancomycin covers Gram-positive, tobramycin Gram-negative
- Use Palacos or Simplex (high fatigue strength)
Danger zones
- Sciatic nerve (2-5% in revision): early identification, finger protection, avoid lengthening over 4cm
- Superior gluteal nerve (5cm above trochanter): avoid dissection above piriformis
- Femoral vessels (anterior): finger in joint during reaming or cement removal
- Abductor attachment: ETO needs 3 or more cables and protected weight-bearing
- Quadrilateral plate: gentle medial technique, breach needs laparotomy
Complications and salvage
- Recurrent infection 10-20% at 2y: repeat two-stage (60-70%) or suppression
- Spacer dislocation 13-15%: reduction, brace; recurrent means revise or expedite Stage 2
- Post-Stage 2 dislocation 10-15%: dual mobility to 2-3%
- Sciatic injury 2-5%: reduce tension, AFO, most recover partially
- Salvage: repeat two-stage, chronic suppression, Girdlestone, arthrodesis, amputation (under 1%)
High-yield pearls
- Success 85-90%, but reinfection 10-20%, dislocation 10-15%, loosening 10-15% at 10y, lower satisfaction
- Antibiotic holiday at both stages (60-80% cultures, 40-75% aspiration)
- Rifampicin for staph PJI: biofilm penetration, never monotherapy, start after wound healed
- Articulating spacer: maintains ROM and length, allows weight-bearing, similar control
- Frozen section over 5 PMN per high-power field means abort reimplantation
- Dual mobility reduces dislocation to 2-3%, lower revision than constrained
- Lifelong surveillance: CRP and ESR for 2 years then annually; recurrence can be years later
Background & Evidence
Epidemiology. Periprosthetic joint infection complicates roughly 1-2% of primary total hip arthroplasties and a higher proportion of revisions. It is driven by biofilm-forming organisms: Staphylococcus aureus (including MRSA) and coagulase-negative staphylococci predominate, with Cutibacterium (Propionibacterium) causing about 10% of PJI and requiring extended 14-day culture. Gram-negatives, enterococci and streptococci make up the remainder, and fungal infection is rare but difficult. Pathophysiology - why two stages works. Bacteria on an implant live in a biofilm: a sessile, metabolically quiescent community that is highly resistant to both host defences and antibiotics, and that anchors to the implant surface and cement. Systemic antibiotics suppress planktonic bacteria and control symptoms but cannot eradicate the biofilm, which is why antibiotics alone relapse and why culture yield drops while the patient is on antibiotics (the rationale for the holiday). Eradication requires mechanical removal of the biofilm - explanting all metal and cement and debriding the membrane - followed by a local high-dose antibiotic depot (the spacer), and biofilm-active systemic therapy. Rifampicin is uniquely able to penetrate staphylococcal biofilm and kill slow-growing organisms, but resistance emerges within days as monotherapy, so it must always be paired with a second agent. These principles underpin every step of the two-stage protocol. Paprosky classification of bone loss guides both acetabular and femoral reconstruction at Stage 2.
- Features
- Intact rim, minimal migration, intact teardrop and Kohler line
- Features
- Superior-medial wear, intact rim, Kohler line intact
- Features
- Superior migration under 3cm, medial wall intact, ischial lysis
- Features
- Medial wear, Kohler line disrupted, intact columns
- Features
- Severe superior migration over 3cm, under 50% host bone contact
- Features
- Pelvic discontinuity, severe medial or global deficiency
- Features
- Minimal metaphyseal bone loss, intact diaphysis
- Features
- Extensive metaphyseal damage, intact diaphysis
- Features
- Metaphyseal damage, 4cm or more diaphyseal contact available
- Features
- Extensive metaphyseal and diaphyseal damage, under 4cm contact
- Features
- Extensive damage, non-supportive isthmus, scarce diaphyseal contact
References
The 2018 Definition of Periprosthetic Hip and Knee Infection: An Evidence-Based and Validated Criteria
- Multi-institutional study: 684 PJI and 820 aseptic cases, externally validated on 422 patients
- Two positive cultures or a sinus tract remain stand-alone major criteria (diagnostic of PJI)
- Weighted scoring of serum CRP, D-dimer, ESR and synovial WBC, PMN%, leukocyte esterase, alpha-defensin and synovial CRP; aggregate score of 6 or more equals infected
- New criteria sensitivity 97.7% versus 79.3% (2011 MSIS) and 86.9% (ICM), with specificity 99.5%
Role of Rifampin for Treatment of Orthopedic Implant-Related Staphylococcal Infections: A Randomized Controlled Trial (Foreign-Body Infection Study Group)
- Randomized, double-blind, placebo-controlled trial of 33 patients with staphylococcal implant infection after debridement
- Ciprofloxacin-rifampin cured 12 of 12 (100%) versus 7 of 12 (58%) for ciprofloxacin-placebo (P equals 0.02)
- Established rifampin as essential for biofilm-active therapy of staphylococcal device infection
- Rifampin must be combined with a partner agent (here ciprofloxacin) to prevent emergence of resistance
Two-Stage Uncemented Revision Hip Arthroplasty for Infection
- 50 consecutive infected THAs treated with a standardised two-stage uncemented protocol
- Reinfection rate 8% (4 of 50) at mean follow-up 5.8 years
- Two reinfections were salvaged with a further successful two-stage revision
- Radical first-stage debridement, antibiotic-loaded cement or beads, and 3 months of organism-specific antibiotics underpinned success
Practical Applications of Antibiotic-Loaded Bone Cement for Treatment of Infected Joint Replacements
- Low-dose antibiotic cement (1g or less per batch) is for prophylaxis; high-dose (more than 1g per batch) is for treatment of established infection
- High-dose antibiotic cement requires hand-mixing by the surgeon to allow elevated doses and multiple agents
- Commercially available antibiotic cements are low-dose only (tobramycin or gentamicin)
- Spacers (static or articulating) deliver local antibiotic, stabilise soft tissues and facilitate easier reimplantation
Diagnosis and Management of Prosthetic Joint Infection: Clinical Practice Guidelines by the Infectious Diseases Society of America (IDSA)
- Evidence- and opinion-based recommendations for DAIR, resection with staged reimplantation, one-stage exchange and amputation
- Recommends multiple intra-operative cultures and withholding antibiotics before sampling where feasible
- Endorses organism-specific antibiotics, with rifampin combinations for staphylococcal infection
- Frames two-stage exchange as the option with the most reliable infection eradication for chronic PJI
Further reference citations 1. Younger ASE, Duncan CP, Masri BA, McGraw RW. The outcome of two-stage arthroplasty using a custom-made interval spacer to treat the infected hip. J Arthroplasty. 1997;12(6):615-623. doi:10.1016/S0883-5403(97)90034-2 2. Masri BA, Panagiotopoulos KP, Greidanus NV, Garbuz DS, Duncan CP. Cementless two-stage exchange arthroplasty for infection after total hip arthroplasty. J Arthroplasty. 2007;22(1):72-78. doi:10.1016/j.arth.2006.02.156 3. Gomez MM, Tan TL, Manrique J, Deirmengian GK, Parvizi J. The fate of spacers in the treatment of periprosthetic joint infection. J Bone Joint Surg Am. 2015;97(18):1495-1502. doi:10.2106/JBJS.N.00958 4. Choi HR, Kwon YM, Freiberg AA, Nelson SB, Malchau H. Periprosthetic joint infection with negative culture results: clinical characteristics and treatment outcome. J Arthroplasty. 2013;28(6):899-903. doi:10.1016/j.arth.2012.10.022 5. Trampuz A, Zimmerli W. Diagnosis and treatment of infections associated with fracture-fixation devices. Injury. 2006;37(Suppl 2):S59-S66. doi:10.1016/j.injury.2006.04.010 6. Beswick AD, Elvers KT, Smith AJ, Gooberman-Hill R, Lovering A, Blom AW. What is the evidence base to guide surgical treatment of infected hip prostheses? Systematic review of longitudinal studies in unselected patients. BMC Med. 2012;10:18. doi:10.1186/1741-7015-10-18