The infected T.K.R

1. The infected T.K.R Khalil Allah. Nazem Feb 2013

2. In the face of an increasing prevalence of TKA, intensified efforts at infection prevention seem logical to reduce the overall burden of PJI.

3. As an over view, prevention of PJI relies upon • Augmentation of the host response • Optimization of the wound environment • Reduction of bacterial contamination in the pre-intra and post operation times

4. In addition to prevention, a thorough understanding of the principle of diagnosis and treatment is essential

5. Although the incidence rates of infection following TKR appear to have fallen over the past several decades, the reported incidence varies in many studies

6. Many inherent patient risk factors are known to predispose toward post operative deep infection. Host factors include a diagnosis of RA, skin ulcers, D.M ,history of malignancy, obesity, smoking, renal or liver transplantation, HIV positive, prior open knee surgery or periarticularFx, prior septic arthritis or osteomyelitis.

7. Risk factors related to surgeon: • Increased INR after operation hematoma require reoperation early wound healing complications • Recent intra articular injection of corticosteroide . • Prolonged operative time

8. Risk factors related to surgeon: • Proper use of AnB prophylaxis represents the single most effective method of reducing infection in TKR. • Optimization of surgical environment. • Use low dose ABLC in high risk patients and revision surgery. • Frequent irrigation. • Carful surgical technique. • Excellent wound closure is important variables under the surgeon control

9. Hematogenousinfection of TKR in early postoperative period or many years after operation is often influenced by the surgeon through education efforts made with arthroplasty patients. (Oral- genitourinary- gastrointestinal) In general invasive procedures that potentially cause bacteremia should simply avoided in the first 3-6 months.(Dental procedures greater than 75 minute in DM and RA are at higher risk). AAOS no longer has published guidelines for the use of prophylactic AnB for high risk patients (Antibiotic prophylaxis for bacteremia in patients with joint replacement.)

10. Diagnosis • No criteria for the definitive diagnosis of PJI have attained universal agreement • It is well recognized that some true PJI have negative culture (up to 19%) • Current definition of PJI includes a combination of clinical sign and symptom, histologic analysis of tissue and results of cultures • The diagnosis of definitive PJI is made if evaluation established at least one of the following criterion • Two or more positive culture • Histologic • Gross purulent is observed • Actively discharge sinus tract

11. It seems reasonable to identify offending organism and enacting directed treatment strategies

12. In most series gram positive ,may polymicrobial (9%), in current era many resistant organism • MRSA and MRSE have emerged as common nosocomial pathogens often requiring complex AnBs and potentially inferior treatment outcome • Resistant Infections definitely need two staged operations • Fungal PJI are rare and needs two staged treatment

13. Identification and diagnosis of biofilm organisms is difficult • Culture independent molecular method (detection of 16s ribosomal deoxy ribonucleic acid) • Culture samples obtain by sonication of prosthesis

14. Timing of the clinical presentation is a critical factor in diagnosis • These various clinical presentation is critical factor and classified as a useful guide to selecting the most appropriate treatment option

15. Classification System of Prosthetic Joint Infection: Time to Onset of Infection Dictates Treatment

16. Classification System of Prosthetic Joint Infection: Time to Onset of Infection Dictates Treatment

18. Treatment • Variables that must consider before treatment include: • Deep or superficial • Duration from T.K.A • Host factors • Soft tissues (extensor mechanism) • Implant is loose or fixed • Pathogens responsible • Ability of surgeon • Patient's expectations

19. Treatment goals • Eradication of infection, alleviation of pain, maintenance of function • When confronted with an infected T.K.A, the treating physician should start by considering the question prosthesis retain or removal

20. Treatment methods where the prosthesis is retained • Antibiotic suppression:Thismethod alone will not eliminate deep infection but can be used as suppression treatment when the following criteria are met • Prosthesis removal is not feasible • Microorganism has low virulence and susceptible to an oral antibiotic • The antibiotic can be tolerated without serious toxicity • The prosthesis is not loose • Other prosthesis or cardiac valvularprosthesis are not present • Success rates are 16-24% • Rifampin with a quinolone has been reported to be more successful

21. Treatment methods where the prosthesis is retained • Debridement with prosthesis retention This method indicated only in infections in early post operative period or acute hematogenous with fixed and functional prosthesis and patient has this criterion • Short duration of symptoms • Susceptible gram-positive organism • Absence of prolonged postoperative drainage or sinus tract • No prosthesis loosing • No other arthroplasty or cardio vascular prosthesis • Success rates are 19-32% • Factors that worsen the results are • Post operative drainage longer then 2weeks • Existence of sinus tract • Hinged prosthesis • Immune compromised hosts • Arthroscopy is not suitable surgical method for debridement and retentions

22. Treatment methods where by the prosthesis is removed • Resection arthroplasty: The ideal candidate is a patient with polyarticular RA with limited ambulatory demands, which allow the patient to sit more readily than is feasible with a knee arthrodesis. The primary disadvantage is mobility and pain during transfer or ambulation

23. Treatment methods where by the prosthesis is removed Arthrodesis: • Advantages: excellent potential for resolving infections alleviating pain, providing stable knee • Disadvantage: elimination of knee motion • Indications: • high functional demands • Single joint disease • Young patients • Extensor mechanism disruption • Poor soft tissue • Systemic immunocompromise • Bad micro organism • Relative contraindication: • Bilateral knee disease • Ipsilateral hip or ankle disease • Over segmental bone loss • Contralateral limb amputation

24. Method of Arthrodesis: • IM nailing • External fixation • Dual plate fixation • IM nailing appears to show a higher trend toward success union but has a higher risk of recurrent infection compare to ext fixation

25. Amputation • Is rarely indicated except in cases if life threatening systemic sepsis or persistent local infection associated with massive bone loss. • Factors must commonly leading to amputation include multiple revisions sever bone loss, intractable pain

26. Reimplantation • Is currently the primary accepted method of treatment for infected T.K.A • contraindications: • persisted or recalcitrant infection • medical conditions • extensor mechanism disruptions • Poor soft tissue envelope • Reimplantation can be performed as a direct exchange technique or two stages

27. Factors associated with successful direct exchange: • Infection by gram positive • Absence of sinus formation • Use of antibiotic cemented • A prolonged 12week course of AB therapy • This method indicated only in groups of patients highly selected by arthroplasty surgeons familiar with the treatment of prosthetic infection

28. Two stage reimplantation • This protocol consist of soft tissue debridement and removal of infected prosthesis and cement, followed by 6weeks IV antibiotics and subsequent reimplantation • The success rate is 85-95% • Use of adjunctive antibiotic delivery provided by the ABLC gradually lead to decrease AB duration and shorter time delays prior to reimplantation

29. Antibiotic cement spacers • Low dose ABLC (<2g per 40g) should be used for prophylaxis in reimplantation or primary T.K.As in high risk patients or for prosthetic fixation at reimplantation • The higher dose rations should be reserved for treatment of active infection with spacer • AB elution increase by prosityof cement and mixing with another AB 3.6 grof tobramycin + 1gr vancomycin in 40gr cement are good • The primary function of block spacer include delivery of local AnB and maintenance of collateral ligament length • Potential disadvantages include presence of a foreign body and bone loss incurred.

30. Different types of block spacers: • Simple tibiofemoral block • Molded arthrodesis block • Articulating mobile spacers • Medullary dowels

31. Molded arthrodesis block

32. Time period between resection and reimplantation • Usually 4-6 weeks • One of the most important issues is the determination of when it is safe and appropriate to proceed with reimplantation.

33. Guidelines: • C.R.P, ESR • Open biopsy or aspiration • It is preferable to utilize intraoprative decision making based on the appearance of the knee joint supplemented by analysis of frozen section

34. If concern arises about the presence of persistent infection, it is prudent to perform other debridement inserted new ABLC spacers, closed the wound, and await the results of culture and sensitivity testing.