The Management of Infected Total Knee Arthroplasty

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By Fares S. Haddad, BSc, MCh(Orth), FRCS(Orth); Ademola Adejuwon, MRCS(Eng)
ORTHOPEDICS 2007; 30:779

September 2007

Up to 2% of total knee arthroplasties (TKAs) are complicated by infection. This leads to dissatisfied patients with poor function, and has social and economic consequences. The challenge is the eradication of infection, restoration of full function, and prevention of recurrence.

A number of therapeutic strategies exist for the management of infected TKA with the accepted gold standard being two-stage revision arthroplasty combined with intravenous antibiotic therapy. This usually is associated with long periods of hospitalization, difficult mobility, pain, and financial ramifications. As a result novel and less aggressive approaches are being attempted. Prosthesis sparing early aggressive debridement in the acutely infected knee, antibiotics, and single-stage knee revision should be considered.

Aggressive early debridement
The main goal is eradicating the infection while preserving the implant. Twenty-nine cases of acutely infected knees (18 primaries and 11 revisions) that occurred within 6 weeks of the index operation were reviewed. Microbiology confirmed bacterial colonization in all cases with 20 early postoperative infections and 9 cases of acute hematogenous spread. All patients underwent aggressive open debridement, a thorough synovectomy, and a change of insert. Systemic antibiotics were continued until inflammatory markers and the plasma albumin concentration returned to within normal limits. A year following cessation of treatment we had a 72% infection control rate.

The evidence suggests that a role exists for early aggressive open debridement in acute knee infections with possible prosthesis salvage. This is only appropriate in selective cases where infection occurs within the first 4 to 6 weeks after the onset of acute postoperative or acute hematogenous infection, and in the absence of any prosthetic loosening.1 An aggressive and complete debridement must be performed and systemic antibiotic administration is imperative for success.

Combating TKA Infections With Antibiotics
The profile of bacterial infections colonizing joints has changed over the past 10 years showing increasing drug resistance as demonstrated by the emergence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus epidermidis (MRSE).2 The choice of antibiotic is based on the culture sensitivities from specimens obtained from the infection site. It usually is continued for six weeks following debridement before a decision to discontinue is made based on clinical findings and inflammatory markers.

Combination antibiotic regimens such as rifampicin and ciprofloxacin have shown good results at eradicating periprosthetic infections.3 Linezolid is good for combating resistant organisms such as MRSA and MRSE.4 With good pharmacokinetics its oral bioavailability is close to 100% allowing for an alternate mode of administration.5 As a result of significant side effects of aplastic anemia and peripheral neuropathy, the typical course of linezolid is limited to 28 days. In our center we used linezolid for 26 periprosthetic infections (hips and knees). Two cases were observed of pancytopenia and one neuropathy associated with the drug; however fewer re-infections were noted in these patients than expected from our previous experience.

Antibiotic suppression therapy alone should only be considered under special circumstances as it may not successfully eradicate deep infection. In a multi-center study, 40 (18%) of 225 infected TKAs had antibiotic suppression.6 Our criteria for the use of antibiotic suppression therapy alone are:

 

• the patient is too infirm to undergo a surgical procedure,

• a pathogen of low virulence that is susceptible to oral antibiotics, and

• the prosthesis is not loose.

Revision Arthroplasty

The choice of optimal management depends on duration and pathogenesis of infection, stability of the implants, antimicrobial susceptibility of the pathogens, and the condition of the soft tissues. Once chronic deep infection is established, revision arthroplasty is required.

Thorough open debridement with retention of the prostheses, particularly in the early postoperative stages or after hematogenous acute infection remains an integral part of our armamentarium. Adjuvant prolonged antibiotic therapy is necessary often up to 1 year. The use of rifampicin and ciprofloxacin has proved invaluable in this regard.

Single stage exchange has been reserved for infirm patients who cannot tolerate two-stage procedures. An aggressive bony and soft-tissue resection is combined with appropriate antibiotic therapy that is continued until inflammatory and nutritional markers normalize. Two-stage exchange remains the gold standard and is used in >70% of our patients.

The treatment program is influenced by a number of factors, and decision making is undertaken in a multidisciplinary setting with the support of infectious diseases physicians and microbiologists.

The role for single-stage revision in knees is unclear.7 Having seen excellent results with one-stage hip revisions for infections we have instituted a protocol for revising the infected knee in the nonimmunocompromised patient. The new protocol involves re-prepping and re-draping the patient between prosthesis removal and reimplantation. Antibiotics are continued until inflammatory markers return to within normal limits. Data currently is being collected to clarify a role for single-stage TKA revision.

The two-stage revision with depot antibiotic loaded cement in the interval period remains the accepted treatment with success rates of >90%.8,9 Antibiotic loaded cement allows for higher effective concentrations than can be achieved parenterally.5 Vacuum mixing of the cement is avoided to allow for a porous mix to elute antibiotic. Antibiotic choice is based on sensitivities from aspirations; however, some do not work well in cement, such as chloramphenicol and rifampicin. In the absence of an organism, vancomycin (3 g/40 g of cement) and gentamicin (2 g/40 g of cement) are used in high dosages. There is no concern over the systemic safety of the doses involved6; however, when performing second-stage reconstruction <5% per mass of cement should be used.

We administer intravenous teicoplanin intraoperatively and continue administration until culture sensitivities are obtained. Antibiotics are stopped after 6 weeks and re-implantation is performed between 8 to 12 weeks.

Between stages a mobile antibiotic spacer is used to maintain joint alignment and prevent soft-tissue contractures. With a mobile articulating spacer during second-stage surgery, less extensile exposures are required and a greater range of movement compared to patients in whom a static spacer was used.

The timing of the second stage is based on clinical response. Antibiotics are continued after the reimplantation until culture results are obtained. If there is no growth on enrichment culture, antibiotics are stopped after five days, otherwise appropriate antibiotic therapy is continued until the inflammatory markers normalize.

Conclusion

Infection of a TKA is a catastrophic complication for which we have yet to achieve optimal outcomes. The undeniable gold standard management of two-stage revision is associated with multiple morbidities and large expenditure.

Prosthesis sparing, aggressive early open debridement works for acute infections within 4 to 6 weeks of the index operation or of hematogenous seeding.

The role of single-stage revision is unclear, but with the success of one-stage hip revisions we have started to consider the single-stage knee revision in a highly selected cohort. For the two-stage revision arthroplasty antibiotic delivery can be improved by using antibiotic loaded cement and a mobile articulating antibiotic loaded spacer.

Management of infected arthroplasties requires an appropriate multi-disciplinary approach with close involvement of the infectious disease team to identify the pathogens involved and treat the patient appropriately.

 

References

1. Tsukayama DT, Estrada R, Ruperto RB. Infection after total hip arthroplasty. A study of the treatment of one hundred and six infections. J Bone Joint Surg Am. 1996; 78:512-523.

2. Ip D, Yam SK, Chen CK. Implications of the changing pattern of bacterial infections following total joint replacements. J Orthop Surg (Hong Kong). 2005; 13:125-130.

3. Zimmerli W, Widmer AF, Blatter M, Frei R, Ochsner PE. Role of rifampicin for treatment of orthopedic implant-related staphylococcal infections: a randomized controlled trial. Foreign-Body Infection (FBI) Study Group. JAMA. 1998; 279:1537-1541

4. Manfredi R, Sabbatani S, Chiodo F. Severe staphylococcal knee arthritis responding favourably to linezolid, after glycopeptide-rifampicin failure: a case report and literature review. Scand J Infect Dis. 2005; 37: 513-517.

5. Rana B, Butcher I, Grigoris P, Murnaghan C, Seaton RA, Tobin CM. Linezolid penetration into osteo-articular tissues. J Antimicrob Chemother. 2002; 50:747-750.

6. Bengtson S, Knutson K. The infected knee arthroplasty. A 6-year follow-up of 357 cases. Acta Orthop Scand. 1991; 62: 301-311.

7. Buechel FF, Femino FP, D�Alessio J. Primary exchange revision arthroplasty for infected total knee replacement: a long-term study. Am J Orthop. 2004; 33:190-198.

8. Haddad FS, Masri BA, Campbell D, McGraw RW, Beauchamp CP, Duncan CP. The PROSTALAC functional spacer in two-stage revision for infected knee replacements. Prosthesis of antibiotic-loaded acrylic cement. J Bone Joint Surg Br. 2000; 82:807-812.

9. Haleem AA, Berry DJ, Hanssen AD. Mid-term to long-term followup of two-stage reimplantation for infected total knee arthroplasty. Clin Orthop Relat Res. 2004; 428:35-39.

   Authors

   Drs Haddad and Adejuwon are from University College London & Princess Grace Hospitals, London, United Kingdom.

   Correspondence should be addressed to: Fares S. Haddad, BSc, MCh(Orth), FRCS(Orth), University College London & Princess Grace Hospitals, c/o 42-52 Nottingham Place, London W1U 5NY, United Kingdom.