Background: Two-stage septic revision is the prevailing method for addressing late periprosthetic infections. Using at least dual-antibiotic-impregnated bone cement leads to synergistic effects with a more efficient elution of individual antibiotics. Recent data on the success rates of multiantibiotic cement spacers in two-stage revisions are rare. Methods: We conducted a retrospective follow-up single-center study involving 250 patients with late periprosthetic hip infections and 95 patients with prosthetic knee infections who underwent septic two-stage prosthesis revision surgery between 2017 and 2021. In accordance with the antibiotic susceptibility profile of the microorganisms, a specific mixture of antibiotics within the cement spacer was used, complemented by systemic antibiotic treatment. All patients underwent preoperative assessments and subsequent evaluations at 3, 6, 9, 12, 18, and 24 months post operation and at the most recent follow-up. Results: During the observation period, the survival rate after two-step septic revision was 90.7%. Although survival rates tended to be slightly lower for difficult-to-treat (DTT) microorganism, there was no difference between the pathogen groups (easy-to-treat (ETT) pathogens, methicillin-resistant staphylococci (MRS), and difficult-to-treat (DTT) pathogens). Furthermore, there were no differences between monomicrobial and polymicrobial infections. No difference in the survival rate was observed between patients with dual-antibiotic-loaded bone cement without an additional admixture (Copal^® G+C and Copal^® G+V) and patients with an additional admixture of antibiotics to proprietary cement. Conclusion: Employing multiple antibiotics within spacer cement, tailored to pathogen susceptibility, appears to provide reproducibly favorable success rates, even in instances of infections with DTT pathogens and polymicrobial infections.

Background: Synovitis, like that associated with chronic bacterial arthritis, is a very rare finding during the implantation of knee endoprostheses. In such cases, we fix the knee prostheses with cement containing two antibiotics and carry out a course of systemic antibiotic administration. The aim was to analyze these cases for incidence, detection of bacteria, risk factors, and outcome. Methods: Out of 7534 knee replacements between January 2013 and December 2020, 25 cases were suspected during the surgical procedure to have suffered from bacterial arthritis and were treated accordingly. Total synovectomy was carried out, whereby five intraoperative synovial samples were examined bacteriologically, and the complete synovitis was analyzed histologically. The mean follow-up was 65.3 ± 27.1 (24–85) months. Results: In nine cases (0.12%), the diagnosis of bacterial arthritis was made histologically and by clinical chemistry (elevated CRP), and in two of these cases, pathogen verification was performed. Eight of these nine patients had previously had injections or surgery associated with the corresponding knee joint or had an underlying immunomodulatory disease. None of the patients developed a periprosthetic infection at a later stage. Conclusion: With an incidence of 0.12%, it is rare to unexpectedly detect bacterial synovitis during surgery. Total synovectomy, use of bone cement with two antibiotics, and immediate systemic antibiotic therapy seem to keep the risk of periprosthetic infection low.

Background/Objectives: This study was designed to verify the hypothesis that graphical cell differentiation of synovial cell count analysis is helpful for diagnosis of acute periprosthetic joint infection (PJI) and that the additional erythrocyte field has advantages to differentiate PJI from hematoma. Methods: A total of 77 total knee arthroplasties and 31 total hip arthroplasties underwent aspiration within six weeks of primary implantation. The aspirate was analyzed with the cell counter Yumizen H500 and examined by cultivation. Serum CRP was also determined. A total of 43 patients underwent revision and microbiological and histological analysis of the periprosthetic tissue, according to Morowitz and Krenn, was performed. The ICM criteria for diagnosing PJI were used. Results: Thirty-two cases (29.6%) were classified as acute infection. The graphical type differentiation LMNE (leukocyte–monocyte–neutrophil–eosinophil) showed 28 cases with type II (infection type), 63 cases with type IV (indifferent type), 13 cases with type V (hematoma type with a peak in the erythrocyte field) and 4 cases with type VI (mixed infection and hematoma). The LMNE matrix assessment had an accuracy of 98.7%, sensitivity of 96.9%, specificity of 98.7%, positive predictive value of 96.9%, negative predictive value of 98.7%, a positive likelihood ratio of 73.62, and a negative likelihood ratio of 0.03. Only one single non-infectious hematoma sample was misclassified as type VI (mixed infection/hematoma). Conclusions: The graphical type differentiation of the cell count analysis of synovial aspirates is a helpful method for diagnosis of acute periprosthetic joint infection and differentiating between hematoma and real early periprosthetic infections. This report shows that the new erythrocyte field of the Yumizen H500 is a useful additional diagnostic tool.

Background: The two-stage septic exchange is the most common therapy concept in the treatment of periprosthetic hip and knee infections. However, before the second-stage reimplantation can be carried out, the physician has to assess whether or not the eradication of the periprosthetic joint infection (PJI) has been successful. Therefore, the aim of this study was to evaluate possible predictive parameters for the successful treatment of PJI before and at the time of reimplantation. Methods: This study investigated a total of 145 patients with periprosthetic hip infection and 93 patients with periprosthetic knee infection, who all underwent a two-stage septic exchange between 2017 and 2021. In order to identify possible risk factors for reinfections, the patients underwent preoperative examination of serological inflammatory parameters, microbiological and histological examination of the periprosthetic membrane at the time of reimplantation, as well as postoperative evaluations at regular intervals for a period of at least 24 months. Results: During the follow-up period, reinfection occurred in 11.3% of cases after the two-stage septic revision. None of the serological, microbiological, or histological parameters were able to significantly predict the risk of reinfection. Risk factors associated with reinfection were BMI and previous revision surgery. Conclusions: Currently, there is no reliable predictive factor indicating the risk of reinfection at the time of reimplantation. New diagnostic methods need to be developed to evaluate the possibility and timing of endoprosthesis reimplantation.

The rising number of arthroplasties is combined with a rising number of periprosthetic joint infections, which leads to life-concerning consequences for the patients, including extended antibiotic treatment, further surgery and increased mortality. The heterogeneity of the symptoms and inflammatory response of the patients due to, e.g., age and comorbidities and the absence of a single diagnostic test with 100% accuracy make it very challenging to choose the right parameters to confirm or deny a periprosthetic joint infection and to establish a standardized definition. In recent years, additional diagnostic possibilities have emerged primarily through the increasing availability of new diagnostic methods, such as genetic techniques. The aim of the review is to provide an overview of the current state of knowledge about the various tests, including the latest developments. The combination of different tests increases the accuracy of the diagnosis. Each physician or clinical department must select the tests from the available methods that can be best implemented for them in organizational and technical terms. Serological parameters and the cultivation of the samples from aspiration or biopsy should be combined with additional synovial tests to create an accurate figure for the failure of the prosthesis, while imaging procedures are used to obtain additional information for the planned therapeutic procedure.

Background: Two-stage septic hip revision arthroplasty has higher mortality rates than aseptic hip revision arthroplasty, and patients over 75 years have higher fracture rates than younger patients after cementless total hip arthroplasty. Therefore, the aim of this study was to examine whether two-stage septic hip revision arthroplasty in older patients leads to higher complication and mortality rates, as well as whether changing to cementless hip prostheses in older patients could lead to higher fracture and subsidence rates of the stem prosthesis than in younger patients. Material and Methods: In total, 286 two-stage-revision procedures for periprosthetic infections of the hip in 186 patients younger and 118 patients older than 75 years were followed for a minimum of 24 (50.24 ± 20.77) months. A total of 71.3% of procedures were performed via a transfemoral approach using cementless cups and revision stems (93.7%). Complications and mortality were analyzed retrospectively. Results: There was a one-year mortality rate of 1.0% with no difference in the groups, and a general mortality rate of 2.8% with a significantly higher rate in older adults than in the younger group (5.9% vs. 0.6%; p = 0.01). The rate of fractures of the bony flap in transfemoral approaches (9.1%), fissure rate of the isthmus (2.8%), rate of subsidence of cementless stems (1.0%), and rate of reinfections (4.89%) did not differ between the two groups. The general complication rate (not associated with cementless two-stage septic revision) (22.0%) was significantly higher in the older patient group (33.9% vs. 13.7%; p < 0.001). Conclusions: Septic two-stage revision hip arthroplasty, mostly using a transfemoral approach and cementless reimplantation, does not result in a higher one-year mortality rate, reinfection rate, and rate of fissures and fractures of the bony flap, but demonstrates a generally higher mortality and complication rate in older adults. This should be taken into consideration when determining the indication and when offering advice to older adults.