Infection after primary total hip and knee replacement is a dreaded complication that can cause serious debilitating disease. Proven risk factors include.
1, Revision surgery
2. Rheumatoid arthritis
3. Diabetes mellitus
4. Obesity
5.Malnutrition
6.Use of immunosuppressants
7, the presence of psoriatic lesions on the skin
Infections are mainly typed based on the length of the clinical presentation disease course to guide treatment. Therefore, early diagnosis and timely management of infections is important, not only from a medical standpoint, but also of public health importance. This article reviews current strategies for the management of infections after initial total hip and knee replacement, particularly with regard to phase I and phase II prosthesis removal arthroplasty for chronic hip and knee infections.
The rate of deep infection in all initial total hip and knee replacements is approximately 1 to 2 percent. Given the increasing number of total U.S. arthroplasties, infection rates have actually been quite low in recent decades, but total hip and knee infections place a heavy burden on health systems. It is estimated that the net cost of treating a single patient is $15,000 to $30,000, and it costs approximately $200 million annually to treat total hip replacement infections alone. Patient factors such as diabetes, rheumatoid arthritis, and immune status should also be considered in detail. However, revision surgery is a high risk factor for infection. Although reports in the literature are mixed, the risk of revision surgery is two to three times greater than that of initial total hip and knee replacement.
Clearly, it is important to prevent infection. Before joint replacement surgery, a detailed history and careful physical examination to identify possible sources of infection such as infected diabetic foot ulcers is critical. The AAOS recently recommended routine prophylactic application of keflex, amoxicillin, or clindamycin (if penicillin allergic) for 2 years prior to other procedures (e.g., scaling) following total hip or knee replacement. Routine prophylaxis is also available 2 years after total hip and knee replacement in some patients who are immunosuppressed due to disease or use of immunosuppressive drugs. Finally, the addition of prophylactic antimicrobials to the bone cement of cemented arthroplasties is recommended, especially in revision surgery. However, there are no studies to confirm that this technique reduces infections in primary total hip and knee replacements.
Staphylococcus epidermidis and Staphylococcus aureus are the 2 most common groups of bacteria found in postoperative infections after total hip and knee replacement. Some common but uncommon microorganisms include streptococci, gram-negative bacteria such as Pseudomonas, Klebsiella, and Escherichia coli. Sometimes, anaerobic bacteria such as Enterococcus and Peptococcus are present in mixed infections. Finally, fungal infections such as Mycobacterium tuberculosis and Candida albicans, although rare, may be present, especially in immunocompromised patients. Another important aspect of etiology to consider is the virulence of the microorganism. Some authors have previously reported increasing difficulties in the eradication of certain bacteria. Some authors have suggested that treatment options be chosen according to the type of microorganism. In an earlier influential article by Buchholz reporting on stage I prosthesis removal for revision hip infections, Gram-negative bacteria such as Klebsiella, Aspergillus, and Pseudomonas were found to be associated with high failure rates. This party reported that approximately 50% of Gram-negative infections failed to be treated. However, the results of this study must be treated with caution as many patients were not given intravenous antimicrobials postoperatively. Some literature confirms the reduced efficacy of specific microorganisms such as plasma coagulase-positive staphylococci and certain gram-negative bacteria. However, due to the lack of solid evidence in evidence-based medicine, the decision to retain or remove the prosthesis should not be based primarily on the type of bacteria, but rather on the length of the clinical course.
In general, staging of postoperative infection after total hip and knee replacement is based on the spatial relationship between surgery and the appearance of symptoms and the route of entry of infectious microorganisms into the joint cavity. Acute or early infection is usually defined as approximately 1 month after surgery or within 1 month of symptom onset regardless of when the joint was replaced. Chronic or late infection is defined as a disease duration greater than 1 month. Determining when symptoms first appear is particularly important because treatment options depend on the course of the disease. In general, if the infection is acute, irrigation, debridement and retention of the prosthesis may be attempted. Chronic infections, on the other hand, have no chance of being cured without some form of excisional arthroplasty. The route of infection is another important aspect to consider. Sources of postoperative infection include intraoperative contamination and cluster F images of the wound due to excessive drainage from the incision or drainage site.
Hematogenous can occur early or late postoperatively several years after total hip or knee replacement), and systemic sources include.
1, urinary tract infections
2.Upper respiratory tract infection
3, cellulitis
4, chronic venous stasis ulcers
5, periodontal abscess
6.Bone and joint infections in other areas
7.Operations that destroy the local skin and mucosal barrier. Such as cystoscopy, colonoscopy, broncoscopy, prophylactic scaling and intra-articular injections. Identifying the source of infection helps to determine when the joint is infected and helps to prevent secondary infection by controlling the source of infection.
Diagnosing a total joint infection begins with a detailed history and careful physical examination. In particular, it is important to ask about the wound after a previous surgery. In addition, prolonged exudate or misuse of antimicrobial agents after the initial surgery may also indicate a postoperative infection. And, the presence of fever, night sweats, chills, swelling, stiffness, and active pain may help to identify acute or chronic infection. Finally, signs of infection such as redness, stiffness, pallor, swelling, local lymph node enlargement, wound exudation, sinus tracts, and active pain should be examined. Routine blood tests and x-rays should also be taken to diagnose total hip and knee infections. Reading the X-rays should allow observation of the progression of translucent lines around the former prosthesis or necrotic bone. The diagnostic value of a complete blood count alone is minimal, and the combination of ESR and CRP is of infinite diagnostic value. BritishColumbia in Vancouver prospectively analyzed 202 revision hips. the sensitivity of CRP and ESR to diagnose infection was 0.96 and 0.82, respectively. most importantly, when both CRP and ESR were negative, the likelihood of infection was 0. although false positives may occur, this study confirms that negative laboratory tests help to rule out infection.
Recently, it has been shown that Il-6 has good sensitivity and specificity for diagnosing infection. However, at present, routine screening for Il-6 is limited. If CRP or ESR is positive or if there is a high clinical suspicion of infection, arthrocentesis should be considered. While knee puncture is very simple, hip puncture often requires fluoroscopy and may result in delayed treatment unless managed properly. The sensitivity of punctures has been reported in the literature to be variable. For example, some have found hip punctures, cell counts, and cultures to be as sensitive and specific as 90%, while others have found their success rate to be modest. This may be partly related to the use of antimicrobials weeks or days prior to puncture. However, hip or knee puncture, cell count, and culture should be considered as adjuncts to a full clinical examination and routine blood work that may provide useful information. The value of nuclear scans in the literature is controversial, with mixed results. It appears that this is due, at least in part, to the different techniques used. In an early study in which technetium and indium were used in combination, the sensitivity for the diagnosis of joint infection was as low as 38%. In a subsequent serial scan of technetium and indium-labeled leukocytes, the sensitivity was 64%. in two other studies of indium-labeled leukocyte scans by Palestro et al, one reported a sensitivity of 86% and the other reported 100% for the diagnosis of joint infection. Therefore, it is important to determine the method used for radioisotope imaging. It is also important to recognize that isotope scans remain positive 1 year after routine total hip or total knee surgery, which limits their use. Although but certain conditions can be used as an adjunctive test, the results are generally not diagnostic. Finally, the accuracy of intraoperative examinations such as frozen sections and Gram staining is reported to vary widely in the literature.
And, the specificity and sensitivity of frozen sections may depend on the area and number of samples taken from the intraoperative tissue sample obtained, as well as the number of leukocytes observed per high-powered field of view. 10 leukocytes per high-powered field of view was suggested by Lonner et al. to diagnose periprosthetic infection to improve the specificity of frozen sections. Unless applied routinely, the operator should not rely solely on frozen sections or Gram staining to guide intraoperative management. In most cases, a complete preoperative workup such as history, physical examination, radiographs, and laboratory tests should help determine the preoperative plan. Intraoperative examination is most useful in guiding postoperative management. Several samples should be taken from the most obvious areas of inflammation within the joint and medullary cavity (if the prosthesis has been removed). The excised tissue should be sent for aerobic and anaerobic culture (or fungal culture if fungus is clinically suspected). This may be the only opportunity to identify the pathogenic microorganism and is essential for postoperative targeted antimicrobial therapy. If possible, the patient should be taken off antimicrobials at least several weeks prior to culture; otherwise, false-negative results can occur.
Treatment of acute postoperative total hip and knee replacement infections within 1 month of onset begins with frequent perfusion irrigation and debridement with retention of the prosthesis and replacement of the polyethylene liner of the combined prosthesis. The success rate of this approach has been reported in the literature to be 10% – 50%. Delayed treatment appears to be the most hazardous factor for successful outcomes. crockarell et al. performed open debridement and retention of the prosthesis followed by intravenous antimicrobial therapy in 42 cases of postoperative infection after total hip replacement. Treatment was successful in this group of patients with an average of 6 days of symptom onset. However, treatment failed in patients with an average of 3 weeks of symptom onset of infection. Although the success rate was high at 1 year postoperatively, the reinfection rate increased progressively with time. Furthermore, at a mean follow-up of 6 years, the success rate was approximately 33% in patients treated with irrigation and debridement within 2 weeks of the onset of infection and 0 in patients treated after 2 weeks of onset of infection. 35 cases of acute post-total hip replacement infection (4 weeks of symptom onset) were treated with irrigation and debridement and prosthesis retention by Tsukayama et al. with better results. The success rate for treating postoperative infections with this method was about 70% and for acute hematogenous infections about 50%. There is evidence that certain organisms are more difficult to remove and may require a more aggressive treatment approach. 31 cases of acute postoperative total knee replacement infections were treated by Deirmengian et al with irrigation debridement, prosthesis retention, and systemic antimicrobial application. In that small retrospective sample, the authors found that Staphylococcus aureus was more difficult to clear.
The cure rate for patients with Streptococcus and Staphylococcus epidermidis was greater than 50%, superior to the 10% cure rate for patients with positive Aureus cultures. The mean time to symptom onset for all patients before debridement was 9 days. The results confirm that rapid surgical debridement is the key to successful surgery. However, in the long term, despite early aggressive management, irrigation debridement and prosthesis retention often lead to persistent infection. It is generally accepted that chronic post-total joint arthroplasty infections are best treated with prosthetic revision and intravenous antimicrobial agents for at least 6 weeks. Whether revision I or revision II, deferred resection arthroplasty combined with antimicrobial interlocking blocks inter-articular placement remains controversial in the literature. For chronic postoperative infection after total hip and knee arthroplasty, US physicians prefer staged resection arthroplasty, which has been shown to have the highest success rate. However, some cases of I-stage revision to manage chronic infection can also be successful. A large study performed in the early 1980s confirmed that direct revision of an infected joint had an overall success rate of 77%, even when postoperative antimicrobials were not routinely applied intravenously (the current standard of care). The effect of this study may require further interpretation due to the varying doses of antimicrobial agents in the bone cement.
Amstutz et al. reported the results of 20 patients with postoperative infection after total hip surgery. At a mean follow-up of 10 years, the success rate of stage I revision was 100%. However, 5 of these patients were lost to follow-up, and the results may be biased. callaghan et al. reported the results of 24 patients treated with stage I revision for postoperative infection of the total hip. No patients were lost to follow-up. Only 8% of patients recurred, although the authors carefully selected the cases. Most of the organisms were Staphylococcus epidermidis. Moreover, patients with sinus tracts, immunosuppressed patients, and patients with insufficient bone mass were considered contraindications for prosthesis removal and arthroplasty. In a study of phase I revision for postoperative infection of the total hip, 1200 infected joints were collected from 12 units. At a mean follow-up of 5 years, 83% of patients were free of infection. Beneficial prognostic factors included good patient health and patients with Staphylococcus epidermidis, methicillin-susceptible Staphylococcus aureus, and streptococcal infections. The flaw in this literature is the inherent bias of nearly 50% of patients coming from the same unit. For example, many patients routinely do not have intravenous antimicrobials applied postoperatively, which may lead to a lower success rate. Recently, the literature has reported the results of 22 cases of stage I revision of total knee infection with an average follow-up of 10 years. The authors reported a 90% success rate for stage I revision with postoperative intravenous antimicrobial application. Although the mean follow-up time was sufficient to screen for infection, patient follow-up varied widely (1.4–19.6 years). Therefore, patients with short follow-up may develop infection later, thus overestimating the success rate of this study. A typical staged revision involves removal of the prosthesis and placement of beaded, block, or interarticular block antimicrobial bone cement (Figures 1, 2). Typically, specific antimicrobials are applied intravenously for 6-8 weeks followed by oral antimicrobials, if necessary. Complete blood counts, CRP, and ESR are routinely tested, and these laboratory tests and knee and hip punctures are often performed to guide the timing of prosthesis reimplantation. The advantages and disadvantages of different types of intercement blocks vary. Antimicrobial beads and blocks are relatively simple to implant, as there are many round spheres and a large surface area for antimicrobial release from the antimicrobial beads. However, the main drawback of antimicrobial beads and blocks is that joint movement is more limited after prosthesis removal and between reimplantations. And, stage II surgery may be more difficult due to scarring, improper soft tissue tension and possible bone loss. Recently, the articular-like interlock and PROSTALAC (antimicrobial-loaded bone cement prosthesis) have gained widespread popularity (Figures 3-5). While adding a degree of work effort and patient cost, the advantages are clear: easy stage II revision and better patient function during treatment.
A direct comparison of antimicrobial release systems for the staged treatment of postoperative infection after total hip and knee arthroplasty showed similar efficacy in terms of infection cure rates. The antimicrobial dose within the bone cement requires special attention. In stage II revisions (e.g., total knee or heterozygous hip revisions), antimicrobial agents are often added to the bone cement, limiting the dose to approximately 1 gram of antimicrobial powder per packet of bone cement (approximately 40 grams). Higher doses have been found to reduce the strength of the bone cement. However, antimicrobial doses within temporary interblocks are usually higher, which facilitates an increase in the amount and duration of action of antimicrobial agents within the local environment of the hip and knee. The total amount of antimicrobial within the bone cement interblocks is highly variable in the literature. Some authors have added as low as 2 grams, while others have added up to nearly 20 grams per interbody block without reported negative systemic effects. Although clinical application of interbody cement blocks often feels safe, the patient should be closely monitored postoperatively. Renal function should be evaluated when gentamicin and vancomycin are added to the bone cement and used intravenously.
Classification of the infection into acute and chronic helps in developing a treatment plan. For acute infections within 2-4 weeks of symptom onset, irrigation, debridement, and polyethylene pad replacement with retention of the prosthesis is possible. When attempting to retain the prosthesis, thorough debridement and rapid treatment of the infection before biofilm formation is essential for successful healing. Another important prognostic factor to consider includes the virulence of the microorganism and the immune status of the organism. Despite aggressive management, irrigation and debridement of acute infections of the total hip and knee often recur. Therefore, the patient should be informed accordingly. After the initial attempt to retain the prosthesis, further management may be required. This includes resectionplasty with or without prosthetic reimplantation, long-term antimicrobial application, joint fusion and, rarely, above-knee amputation. For chronic infections, factors for cure include patient health status, prosthesis removal, thorough debridement, followed by bacterial culture and targeted antimicrobial therapy. And, monitoring for persistent infection includes laboratory tests such as CRP, ESR, and arthrocentesis cultures. Direct revision or deferred revision of chronic hip and knee infections is controversial. Several publications report success with stage I revision in carefully selected cases. However, in the United States, where most chronic infections are revised in stages, this approach has a high cure rate, with many studies now confirming a 90% success rate.