Periprosthetic Knee Infection Research Articles

Knee Arthrodesis for Periprosthetic Knee Infection: Fusion Rate, Complications, and Limb Salvage-A Systematic Review.

The aim of this systematic review was to investigate the outcomes of knee arthrodesis (KA) after periprosthetic joint infection (PJI) of the knee. Differences in clinical outcomes and complication rates among the intramedullary nailing (IMN), external fixation (EF), and compression plating (CP) procedures were compared. A total of 23 studies were included. Demographics, microbiological data, types of implants, surgical techniques with complications, reoperations, fusion, and amputation rates were reported. A total of 787 patients were evaluated, of whom 601 (76.4%), 166 (21%), and 19 (2.4%) underwent IMN, EF, and CP, respectively. The most common causative pathogen was coagulase-negative Staphylococcus (CNS). Fusion occurred in 71.9%, 78.8%, and 92.3% of the patients after IMN, EF, and CP, respectively, and no statistically significant difference was found. Reinfection rates were 14.6%, 15.1%, and 10.5% after IMN, EF, and CP, respectively, and no statistically significant difference was found. Conversion to amputation occurred in 4.3%, 5%, and 15.8% of patients after IMN, EF, and CP, respectively; there was a higher rate after CP than after EF. The IMN technique is the most common option used for managing PJI with KA. No differences in terms of fusion, reinfection, or conversion-to-amputation rates were reported between IMN and EF. CP is rarely used, and the high amputation rate represents an important limitation of this technique.

Comparison of Delphi Consensus Criteria and Musculoskeletal Infection Society Outcome Reporting Tool Definitions of Successful Surgical Treatment of Periprosthetic Knee Infection

BackgroundAgreement on success following surgical treatment for periprosthetic joint infection (PJI) is important for comparing the efficacy of different surgical approaches with varying consequences and outcomes and setting patient expectations. We compared success rates following two-stage exchange arthroplasty for knee PJI using two expert-consensus definitions of success. MethodsProspectively documented data for 57 knees treated by a single surgeon at an academic tertiary care center were retrospectively reviewed. Treatment outcomes were quantified using the Delphi Consensus Criteria and the Musculoskeletal Infection Society Outcome Reporting Tool (MSIS ORT). ResultsSuccess rates were 81% using the Delphi Consensus Criteria and 56% using the MSIS ORT (P = .008). The MSIS ORT success rates increased to 76% when aseptic revisions and deaths unrelated to PJI were not penalized as failures of treatment. Predicted probabilities of successful treatment in a hypothetical case scenario were lowest based on the MSIS ORT and similarly higher using Delphi Consensus Criteria and MSIS ORT modified for both women (53.0, 90.8, and 88.7%) and men (29.1, 89.1, and 89.3%). ConclusionsStudy observations underscore the need for a uniformly accepted single definition of surgical treatment success.

Are silver-coated megaprostheses superior to uncoated megaprostheses in managing chronic end-stage periprosthetic hip and knee infection?

Outcomes for silver coated megaprostheses (SC-MP) used in cases of end-stage periprosthetic joint infection (PJI) have not been clearly defined. Although attractive, concerns over implant longevity and the risk of infection relapse exist among the scientific community. Therefore, we sought to investigate the effect of silver coating in lower-extremity MPs used in such difficult-to-treat scenarios. The study's primary hypothesis was that the periprosthetic infection control rate would be higher in patients with silver-coated implants. Non-interventional retrospective study with a historical comparison group. We identified all consecutive end-stage hip and knee PJI cases at our center managed with exchange arthroplasty using a silver-coated megaprosthesis from January 2016 to March 2021, these cases were compared with a historical cohort of end-stage PJI cases managed with uncoated megaprostheses. The main outcome studied was infection control rate. Secondarily, we analyzed the short-to-medium-term survivorship of this type of silver-coated implant. Fifty-nine megaprostheses used in cases of end-stage PJI were included in this study. We identified 30 cases of chronic hip or knee PJI in which a silver-coated modular megaprosthesis was implanted. Our non-coated megaprosthesis (NC-MP) historical group included 29 patients. Both groups had similar demographic characteristics. We found no statistically significant differences in infection control rate (80% vs. 82.8%, p = 0.47) or implant survivorship (90% vs. 89.65%, p = 1) after a mean follow-up for SC-MP of 46.43months, and 48months for the non-coated MP group. In relapsed cases, there were no differences in infection eradication after DAIR (66% SC-MP vs. 60% NC-MP success rate, p = 1). During the follow-up we observed one case of skin argyria without further repercussion. We were unable to confirm our initial hypothesis that use of silver-coated implants in end-stage PJI scenarios may be associated with better outcomes in terms of infection control or implant survivorship.

Ideal Timing of Reimplantation in Patients with Periprosthetic Knee Infection Undergoing 2-Stage Exchange: A Diagnostic Scoring System.

This study evaluated appropriate thresholds for serum biomarkers, synovial fluid white blood cell (SF-WBC) count, and synovial fluid neutrophil (polymorphonuclear leukocyte [PMN]) percentage to predict infection in a patient group who underwent definitive reimplantation after receiving a continuous course of antibiotic therapy for chronic knee periprosthetic joint infection (PJI). These thresholds were then used to generate a scoring system to predict recurrence (or persistence) of infection. The study included 153 patients with a median age of 73 years (range, 46 to 91 years) who underwent 2-stage revision for chronic knee PJI. Staphylococci were identified at baseline in 107 (70%) of the patients. After the 96-week follow-up period, 12% (19) of the 153 patients had recurrence of the PJI. A receiver operating characteristic (ROC) curve analysis was used to assess the predictive value of common serum biomarkers and SF aspiration before reimplantation, and the area under the curve (AUC) was evaluated. Variables that were significantly different between patients with and without infection recurrence were evaluated using a multivariable logistic regression model. A half-integer-point scoring system was created based on the final beta coefficients. Regarding the prediction of recurrent infection, a D-dimer level of >1110 ng/mL yielded a sensitivity of 74%, specificity of 61%, and AUC of 0.69; an SF-WBC count of >934 cells/µL showed a sensitivity of 68%, specificity of 90%, and AUC of 0.79; and an SF-PMN percentage of >52% showed a sensitivity of 73%, specificity of 90%, and AUC of 0.82. The beta coefficients were approximated to 1.5 for the D-dimer level and to 2 for the SF-WBC count and SF-PMN percentage. A total score of >2 was used to classify patients with a high risk of infection recurrence. The ability to discriminate infection recurrence was demonstrated by an AUC of 0.90 (95% confidence interval: 0.82 to 0.99). Patients with a score of >2 on our proposed scoring system based on serum biomarkers, SF-WBC count, and SF-PMN percentage should not undergo reimplantation, as they are at a high risk for recurrent PJI. Patients with a score of ≤2 can undergo definitive reimplantation with the lowest risk of recurrence. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Periprosthetic Hip and Knee Infection: Is an Ipsilateral Uninfected Total Joint Arthroplasty at Risk?

BackgroundPeriprosthetic joint infections (PJIs) of total hip arthroplasty (THA) or total knee arthroplasty (TKA) may occur in the setting of an uninfected ipsilateral prosthetic joint. However, the risk to that uninfected ipsilateral joint is unknown. We analyzed the survivorship free from PJI in at risk THAs and TKAs following treatment of an ipsilateral knee or hip PJI, respectively. MethodsUsing our institutional total joint registry, we identified 205 patients who underwent treatment for PJI (123 THAs and 83 TKAs) with an at-risk ipsilateral in situ knee or hip, respectively, between 2000 and 2019. In total, 54% of index PJIs were chronic and 46% were acute. The mean age was 70 years, 47% were female, and the mean body mass index was 32. Kaplan-Meier survivorship analyses were performed. Mean follow-up was 6 years. ResultsThe 5-year survivorship free of PJI in an at-risk THA after an ipsilateral TKA was treated for PJI was 97%. The 5-year survivorship free of PJI in an at-risk TKA when the ipsilateral THA was treated for PJI was 99%. Three PJIs occurred (2 THAs and 1 TKA), all over 1 year from the index ipsilateral PJI treatment. One hip PJI was an acute hematogenous infection that resulted from pneumonia. The other 2 new PJIs were caused by the same organism as the index PJI and were due to a failure of source control at the index joint. ConclusionsWhen diagnosed with PJI in a single joint, the risk of developing PJI in an ipsilateral prosthetic joint within 5 years was low (1 to 3% risk). In the rare event of an ipsilateral infection, all occurred greater than one year from the index PJI and 2 of 3 were with the same organism when source infection control failed. Level of EvidencePrognostic Level III.

Arthrodesis following persistent periprosthetic knee infection using femoral condyle allograft: a case report and review of literature

Periprosthetic joint infections (PJI) of the knee are difficult to treat and can require costly and prolonged hospital stays, weeks or months of antibiotic therapy, and multiple surgical procedures. Knee arthrodesis is considered a last resort for persistent knee joint infections and provides stability and pain relief by fusing the knee joint. The authors describe a case of a persistent and difficult to treat periprosthetic total knee arthroplasty (TKA) infection, subjected to multiple surgeries and revisions, where an arthrodesis was performed as a last resort. The arthrodesis was performed using a femoral-tibial endomedullary nail with interposed femoral condyle allograft. Complete graft integration and consolidation was achieved without complications. The patient performed well post-operatively and is currently ambulatory with walking aids and has no knee pain. The removal of well-fixed metaphyseal sleeves in TKA can be challenging and associated with complications such as damage to the surrounding bone and soft tissue during the removal process. Taking special care and not rushing this step can present an extremely meaningful difference in the final outcome. In cases with large bone defects, especially after sleeve removal, allograft usage can be extremely useful for managing dead space and limb-length discrepancies while promoting faster bone healing. When successful, as was the case described, arthrodesis using allografts can have beneficial outcomes with high patient satisfaction and deliver function to previously very unhealthy joints and limbs.

Periprosthetic Knee and Hip Infection — Is It Possible to Compare Treatment Outcomes?

Background. It is known that the outcomes of patients treatment with periprosthetic joint infection (PJI) are significantly influenced by the state of the patient’s body, the nature of the pathogen, the state of tissues in the area of the infectious focus and the treatment tactics. However, topographic and anatomical features of the blood supply to the knee and hip joints, as well as the volume of soft tissues, can affect the spectrum of pathogens, manifestations of the infectious process and, as a consequence, the effectiveness of treatment.
 The aim of the study was to conduct a comparative analysis of the somatic status of patients, the etiology of the infectious process and the effectiveness of treatment of PJI depending on its localization.
 Methods. A single-center retrospective study was conducted. The cases of 337 patients were studied — 119 patients with knee and 218 patients with hip PJI who underwent treatment with a two-stage technique during the period from 2007 to 2017. A comparative analysis of the PJI pathogens structure and concomitant pathology between patients with hip and knee PJI was carried out. The frequency of infection relief in the groups following the first stage was counted.
 Results. Recurrence was diagnosed four times more frequently in patients with hip PJI compared to knee PJI. Risk factors for recurrence were gram-negative pathogens, microbial associations, and fistulous forms of the infectious process. Localization of the infectious process in the hip area was associated with a statistically significant greater volume of blood loss during the prolonged debridement surgery.
 Conclusion. Recurrences of PJI occur more frequently in the hip area compared to the knee joint. Further analysis of critical factors in recurrence development is necessary for potential intervention.

Two-Stage Treatment of Chronic Periprosthetic Knee Infections With the Use of Gentamicin-Articulated Spacers: Success Rate and Predictors of Failure at the Minimum Seven-Year Follow-Up.

The purpose of this study was to assess the survivorship rates of 2-stage treatment with gentamicin-impregnated polymethylmethacrylate articulated knee spacer in patients with chronic periprosthetic joint infection and to identify risk factors associated with failure. We conducted a retrospective study among 73 patients with chronic periprosthetic joint infection after primary total knee replacement with articulated polymethylmethacrylate gentamicin-impregnated spacers (Subiton, Medical Labs, Ind Argentina), performed in a single institution with a minimum follow-up of 7years. Clinical and functional assessment was performed with Knee Society Score and Western and Ontario McMaster Universities Osteoarthritis Index. A univariate and multivariate analysis was performed to identify the variables that influenced the success and failure rates. We included 73 patients. There were 53 (71.3%) monomicrobial, 11 (15%) polymicrobial, and 10 (13.7%) negative cultures infections. The success and failure rates were 90.5% (n= 66) and 9.5% (n= 7), respectively. Multivariate analysis identified that age (odds ratio= 1.77; P= .039), greater erythrocyte sedimentation rate values prior to the first stage (odds ratio= 1.04; P= .006), and polymicrobial infections (odds ratio= 7.32; P= .0003) were independent variables associated with failure. Two-stage revision with polymethylmethacrylate gentamicin-impregnated knee spacers is an effective strategy for the treatment of chronic periprosthetic joint infection after total knee arthroplasty. Age, higher erythrocyte sedimentation rate values prior first stage, and polymicrobial infections were independent risk factors for treatment failure.

High Incidence of Acute Kidney Injury Following Antibiotic-Loaded Spacer Insertion for Periprosthetic Joint Infection: An Updated Review of the Literature

BackgroundThe use of antibiotic-impregnated cement during 2-stage revision arthroplasty for periprosthetic joint infection poses a risk of renal complications following spacer insertion. This systematic review aimed to investigate the rate of acute kidney injury (AKI) following antibiotic-loaded spacer insertion and to identify risk factors associated with this complication. MethodsA systematic review was performed using PubMed, Cochrane Central, and Scopus databases. All clinical studies that documented renal complications following antibiotic-loaded spacer insertion for periprosthetic knee (total knee arthroplasty [TKA]) or hip (total hip arthroplasty [THA]) infection were included. Articles that combined THA and TKA outcomes were also included and labeled “THA + TKA.” Descriptive statistics were analyzed when data were available. ResultsThere were 24 studies (9 THA, 7 TKA, 8 THA + TKA) included. The mean incidences of spacer-related AKI across THA, TKA, and THA + TKA cohorts were 4.2 (range, 0 to 10%), 14 (range, 0 to 19%), and 27% (range, 0 to 35%), respectively. The most common patient-related risk factors for AKI were underlying chronic kidney disease or high baseline creatinine, low preoperative hemoglobin, and blood transfusion requirement. Spacer-related risk factors included high antibiotic dosage (>3.6 g/cement batch) and antibiotic type. While most recovered without complication, select patients required hemodialysis for acute management (2 THA, 18 THA + TKA) and/or developed chronic kidney disease (8 TKA, 8 THA). ConclusionThe rate of AKI following spacer insertion was high and likely under-reported in the literature. Surgeons should be cognizant of this devastating complication and should closely monitor at-risk patients for AKI following antibiotic-loaded spacer insertion.

Gram staining of the preoperative joint aspiration for the diagnosis of infection after total knee arthroplasty

PurposeGram staining of joint fluid for the diagnosis of postoperative joint infection after total knee arthroplasty is considered to have limited efficacy because of the low sensitivity. However, the specificity of the gram staining is reported to be high in most reports. This study aimed to evaluate the sensitivity and specificity of the gram staining when used on the aspirated joint fluid in patients with suspected postoperative knee joint infection after total knee arthroplasty. MethodsWe retrospectively reviewed the reports of synovial fluid samples retrieved from suspected infected joints at eight hospitals between 2012 and 2019. A total of 179 samples of aspirated joint fluid from knee joints (80 culture-positive samples and 99 culture-negative samples) were evaluated in this study. ResultsOf the 80 gram stains performed on samples from infected patients, there were 60 true positives and 20 false negatives. In contrast, of the 99 stains performed on samples from aseptic knees, there were 99 true negatives and no false positives. The sensitivity and specificity for detecting periprosthetic knee infections were 75.0% and 100.0%, respectively. Further, we divided infected samples into the early aspiration group (within 14 days) and the late aspiration group (15 days or more) based on the duration between the onset of symptoms and aspiration. The sensitivity of the gram staining was 84.2% and 41.2% in the first and second groups, respectively. ConclusionsIn this study, gram staining of preoperatively aspirated joint fluid for the infected periprosthetic knee joint with short-lived symptoms showed high sensitivity.

Novel, static, permanent spacers to treat chronic knee periprosthetic joint infections

PurposeTo discuss a static and permanent spacer in the treatment of chronic periprosthetic knee infection. MethodsIn this study, patients who were diagonised with chronic periprosthetic knee infection and not appropriate to undergo revision operations were included and were treated with static and permanent spacers. Infection recurrence rate was recorded, Visual Analogue Scale (VAS) score and Knee Society Score (KSS) were used to record patients’ pain and knee function before the operation and at the final follow-up (minimum 24 months).ResultsFifteen patients were identified for this study. Pain and function were significantly improved at the latest follow-up evaluation. One patient had a recurrent infection and underwent amputation. No patients had signs of residual instability at the final follow-up evaluation, and no breakage or subsidence of the antibiotic spacer were identified at the final radiographic follow-up evaluation.ConclusionOur study provided evidence that the static and permanent spacer was a reliable salvage procedure to treat periprosthetic knee infection in compromised patients.

Treatment of periprosthetic knee infection and coexistent periprosthetic fracture: A case report and literature review

Periprosthetic joint infection (PJI) and periprosthetic fracture (PPF) are among the most serious complications following total knee arthroplasty. Herein, we present one patient with these two complications with details on the characteristics, treatment strategy, and outcome. A 69-year-old female patient who suffered from PJI and PPF following total knee arthroplasty was treated by a two-stage revision surgery. After thorough foreign material removal and debridement, we used a plate that was covered with antibiotic-loaded bone cement to link with a hand-made cement spacer to occupy the joint space and fix the fracture. Although the infection was cured, the fracture did not heal and caused bone defect due to the long interval between debridement and revision. In the revision surgery, a cemented stem and cortical allogenic splints were used to reconstruct the fracture and bone defect. At the final follow-up 27 mo after revision, the patient was satisfied with postoperative knee functions with satisfactory range of motion (104º) and Hospital for Special Surgery knee score (82 points). The radiographs showed no loosening of the prosthesis and that the bone grafts healed well with the femur. Our two-stage revision surgery has proved to be successful and may be considered in other patients with PJI and PPF.

Medial gastrocnemius rotational flap for the reconstruction of extensor mechanism disruption in periprosthetic knee infections: a retrospective series with minimum twoyear follow-up.

Extensor mechanism disruption following total knee arthroplasty has a prevalence ranging from 0.3 to 3%. Its management is challenging, especially in case of associated infection of the prosthetic implant. Surgical options are limited due to the septic process, and the use of allograft or synthetic mesh are not recommended. The aim of this study was to report clinical outcomes, complications, survival, and surgical technique of medial gastrocnemius flap for the treatment of extensor mechanism disruptions associated with periprosthetic knee infection. This is a retrospective study from a prospectively collected arthroplasty registry from 2012 to 2019. Patients who received the gastrocnemius flap in the setting of a two-stage knee replacement for periprosthetic infection were included. Results of physical examination, Knee Society Score, Oxford Knee Score, and measurement of the range of motion registered pre-operatively were compared to those obtained at last follow-up. Survival was analysed through Kaplan-Meier curve. A total of 15 patients were included, with a mean age of 63.4 years (range 36-77). The reconstruction of the extensor mechanism demonstrated a success rate of 73.3%. The mean extension lag at final follow-up was 7.5° (range, 0-30). The mean Knee Society Score and Oxford Knee Score improved from 29.0 (range, 21-36) and 17.5 (range, 13-22) respectively, to 82.9 (range, 74-89) and 36.0 (range, 33-39). Medial gastrocnemius rotational flap is a reliable option for joint and limb salvage in case of periprosthetic knee infection associated with wide soft tissue degeneration and extensor mechanism disruption. The technique and surgical protocol presented in this study are reproducible and guaranteed good clinical outcomes and infection control.

Periprosthetic knee infection in octogenarians: a single institution experience at midterm outcome

PurposePeriprosthetic joint infections (PJI) of total knee arthroplasties (TKAs) in the elderly is among the clinically most challenging scenarios given multimorbidity combined with poor bone and soft tissue quality. Despite increasing prevalence, limited is known on PJI among this unique group of patients. As such, this study analyzed PJI characteristics, implant survivorship and non-surgical complications of octogenarians revised PJI for the knee.MethodsWe identified 31 patients that were revised for PJIs of the knee between 2010 and 2019 using a single university-based registry. Mean age was 83 years (range 80–87), 48% were females, and mean BMI was 29 kg/m2. Mean age adjusted Charlson Comorbidity Index was 7, and mean ASA score was 3. Major causative pathogens included Coagulase-negative Staphylococci (26%), Staphylococcus aureus (13%), and Streptococci (13%). Two-stage exchange was performed in 30 patients, permanent resection arthroplasty in one joint. Kaplan–Meier survivorship analyses were performed. Mean follow-up was 4 years.ResultsThe 2-year survivorship free of any recurrent PJI was 96%, and there was one PJI relapse noted at 6 months. Moreover, there were three additional revisions for aseptic loosening, and one further revision for fracture. As such, the 2-year survivorship free of any revision was 87%. In addition to the aforementioned revisions, there was one additional plate osteosynthesis for a Vancouver C fracture, resulting in a 79% survivorship free of any reoperation at 2 years. Mean perioperative complication score according to the Clavien–Dindo classification was 2 out of 5. A total of three patients died: one patient 40 days after resection arthroplasty, two others 4 months and 8 months after reimplantation.ConclusionsOctogenarians revised for PJI of the knee are at low risk of recurrent infection and overall revision at 2 years. However, moderate rates of perioperative complications and mortality at short term must acknowledge before deciding upon procedure.Level of evidenceTherapeutic level IV.

Management of acute periprosthetic knee infection: a comparison of arthroscopic and open debridement

IntroductionIn acute periprosthetic knee infections, debridement and implant retention (DAIR) is the preferred treatment prior to one- and two-stage revisions. The aim of this study is to compare the outcomes of arthroscopic and open debridement of infected primary total knee arthroplasties (TKA).Material and methodsWe analyzed clinical, laboratory, and antibiotic treatment data, collected in patients with periprosthetic knee infection treated with DAIR at a Swiss Level 1 orthopedic and trauma center over a 10-year period between January 2005 and May 2015. Inclusion criteria were primary total knee arthroplasty and early postoperative or acute hematogenous periprosthetic joint infection (PJI). The primary endpoint was the need for further revision surgery due to persistent infection. The secondary endpoint was the prosthesis salvage in further infection surgeries.ResultsForty-two patients with 44 acute or hematogenous periprosthetic knee infections were included. We recorded 20 recurrent infections (45%) in our study population: 10 (77%) out of 13 in the arthroscopic DAIR group and 10 (32%) out of 31 in the open DAIR group. Two-stage revision, meaning complete removal of the TKA, insertion of a spacer and replantation at a second stage, had to be performed in three patients treated initially arthroscopically (23%) and in six patients treated initially with an open surgical procedure (21%).ConclusionsOpen debridement for acute periprosthetic knee infection shows clear benefits in terms of infection eradication and prosthesis salvage compared to arthroscopic DAIR.

One and a Half-Stage Revision With Prosthetic Articulating Spacer for Definitive Management of Knee Periprosthetic Joint Infection.

This paper is a comprehensive review that describes indications, contraindications, clinical outcomes, and pearls and pitfalls of 1.5-stage revision total knee arthroplasty (TKA) utilizing a primary TKA femoral component, all-polyethylene tibial component, and hand-crafted antibiotic cement for the management of chronic periprosthetic joint infection. The 1.5-stage exchange TKA details placement of an articulating spacer for an indefinite period, prolonging revision until reinfection, deterioration of functional status, or construct failure. A 1.5-stage revision TKA technique is a viable option for treatment of chronic periprosthetic knee infections. The inherent advantages of decreased health-care costs, decreased morbidity and mortality, and improved emotional ease from having a single procedure is attractive, especially if reinfection rates are determined to be equivocal to 2-stage revision.

High Rate of Intramedullary Canal Culture Positivity in Total Knee Arthroplasty Resection for Prosthetic Joint Infection

BackgroundPeriprosthetic infection is a devastating complication following total knee arthroplasty. A 2-stage protocol often includes an interim antibiotic spacer with intramedullary (IM) dowels. However, the necessity of IM dowels has recently been challenged. Specifically, the data supporting bacterial colonization of the IM canal are limited and controversial. The purpose of this study was to identify the rate of positive IM cultures during resection arthroplasty in periprosthetic knee infection. MethodsA total of 66 IM diaphyseal cultures were taken during resection arthroplasty from 34 patients diagnosed with periprosthetic knee infection. These IM cultures were taken from the femoral and tibial canals using separate sterile instruments. All patients had infected primary total knee arthroplasty implants at the time of resection. ResultsThirty one percent (n = 21) of IM canal cultures in this study were positive from either the tibial or the femoral diaphysis at the time of resection arthroplasty. There were 18 of 21 (86%) of the positive IM canal cultures with concordant intraoperative joint cultures where the IM cultures matched the intraarticular cultures. ConclusionWith a 31% positive IM canal culture rate, this study confirms the logic of using IM dowels with an antibiotic spacer to treat periprosthetic knee infection. Since the failure of a 2-stage reimplantation is catastrophic, any attempt to provide additional local antibiotic delivery seems warranted. Since nearly one-third of our patients had positive IM cultures, this simple addition to an antibiotic spacer has the potential to improve 2-stage results. Claims supporting the elimination of IM dowels during resection arthroplasty seem ill-advised.

Results of the Articular Spacer Application in Treatment of Knee Periprosthetic Infection

Background. Currently, on the general background the number of primary totak knee arthroplasties (TKA) increasing, so does the revisions. Among all the causes of revisions, periprosthetic joint infection occupies one of the leading positions. The generally accepted tactics of two-stage revisions, along with the infection suppression, implements other tasks: reducing pain, preserving and/or restoring joint function. Articular antibacterial spacers allow you to complete all the tasks and preserve/restore the quality of patients` life on staged treatment. However, studies demonstrating the results of periprosthetic joint infection treatment and the use of various articular spacers still do not clear it`s optimal design.
 The aim of the study was to improve the intermediate treatment results of periprosthetic knee joint infection using articular spacer implantation.
 Methods. A single-center retrospective cohort study was performed. At the first stage of the study, the results of surgical treatment of 420 patients with periprosthetic knee joint infection treated at the clinic in 20112019 were analyzed. At the second stage, after applying the inclusion and exclusion criteria, 182 patients were included in the analysis. Two representative groups are identified among them. In the comparison group, hand-made cement liner with articulating surface was used, in the main group conventional one.
 Results. The implantation of the endoprosthesis components with the restoration of anatomical relationships in the joint and the ligamentous balance, the replacement of the cement liner with conventional one made of ultra-high molecular weight polyethylene led to reduction in the surgery duration, intraoperative blood loss and period of hospitalization, an increase in the range of motions in the joint, greater stability of the components and suppression of infection in 94.6% of patients.
 Conclusion. The use of various spacers did not significantly affect the probability of infection suppression; however, the number of infection relapses was lower in the group where the liner made of ultra-high molecular weight polyethylene was used. Optimization of surgical treatment techniques and the use of articular spacer based on a three-component conventional endoprosthesis has significantly improved the treatment results of patients with periprosthetic infection of the knee joint.

The Diagnostic Accuracy of Neutrophils to Lymphocytes Ratio, Platelets to Lymphocytes Ratio, Monocytes to Lymphocytes Ratio, and Platelets to Mean Platelet Volume Ratio in Diagnosing Periprosthetic Knee Infections. Are Gender-Specific Cutoff Values Needed?

BackgroundThis study aimed to assess the most appropriate thresholds for neutrophils to lymphocytes ratio (NLR), platelets to lymphocytes ratio, monocytes to lymphocytes ratio (MLR), and platelets to mean platelet volume ratio in patients who had a suspected prosthetic knee infection. Furthermore, we evaluated the diagnostic accuracy of our proposed thresholds by men and women. MethodsA total of 261 consecutive patients affected by painful total knee arthroplasty were included. International Consensus Meeting diagnostic criteria were used to identify periprosthetic infections. Sensitivity, specificity, positive, and negative predictive values were calculated for each cutoff value obtained. The area under the receiver operating characteristic curve was evaluated. ResultsNLR reported the best diagnostic accuracy. MLR and NLR reported higher area under the curves in men and women. We obtained an MLR value ≥0.30 (optimal cutoff value for men) and ≥0.17 (optimal cutoff value for women). In men, the sensitivity and the specificity were 0.71 and 0.77, respectively, versus 0.82 and 0.29, in women. For NLR, we obtained a value ≥2.52 (best cutoff value for men) and ≥2.46 (best cutoff value for women). These cutoffs reported a sensitivity and specificity of 0.71 and 0.88 versus 0.54 and 0.76 in men and women, respectively. ConclusionThese biomarkers present a low diagnostic accuracy in periprosthetic joint infection detection. Men whose MLR and NLR were above cutoff values had a 77 and 88% probability of presenting a septic prosthetic failure. NLR of at least 2.46 was reasonably sensitive for women who have a periprosthetic knee infection. Level of EvidenceDiagnostic study, Level II.

Management of periprosthetic knee joint infections: focus on the role of Nuclear Medicine (v2)

When faced with a painful knee replacement, ruling out infection is mandatory to set the correct therapeutic approach. However, it is not always easy, especially in subclinical/chronic infections. A multidisciplinary approach is necessary to assess in the most correct way each case of suspected periprosthetic knee joint infection. This review explores the role of nuclear medicine investigations in the management of periprosthetic knee infections and their proper use within a multidisciplinary pathway. A PubMed search was conducted selecting studies from the past 10 years. Triphasic bone scintigraphy has high sensitivity (93%) but poor specificity (56%) for periprosthetic joint infections of the knee, with a high negative predictive value (NPV), ranging from 96% to 100%. Consequently, a negative bone scan is useful in ruling out infection. In contrast, radiolabeled leukocyte scintigraphy is characterized by a sensitivity of 85.7-93%, specificity of 93.6-100%, diagnostic accuracy of 92.6-98%, NPV of 93-97.8%, and positive predictive value (PPV) of 66.7-100%. By adding a tomographic acquisition with hybrid single-photon emission computed tomography combined with computed tomography technique (SPECT/CT), the diagnostic accuracy increases. Because 18F-fluorodeoxyglucose (FDG) accumulates at both sites of inflammation and infection, FDG positron emission tomography (PET/CT) shows low specificity. A common decision-making process in the diagnosis of periprosthetic joint infection is not yet validated and multidisciplinary integration is mandatory. In this context, nuclear medicine can contribute decisively.