Outcomes of rotating versus pure hinge knee arthroplasty in the setting of one-stage exchange for periprosthetic joint infection.

PURPOSE: Rotating or pure hinge knee prostheses are often used in case of periprosthetic joint infection (PJI). Five-year survival data of rotating hinge implants ranging from 52 to 90%, whereas pure hinge data are sparse. This study describes the results of both hinge knee prostheses after one-stage septic exchange. METHODS: One hundred sixty-seven one-stage septic exchanges of a primary unconstrained total knee arthroplasty (TKA) to a cemented hinge prosthesis (117 rotating and 50 pure hinge TKAs) performed between 2008 and 2017 were retrospectively reviewed. Exclusion criteria were stem extensions or augments used in primary TKA, history of extensor mechanism reconstruction, and a follow-up less than two years after surgery. Rates of reinfection, mechanical failures, and all-cause revision-free survival data were documented. RESULTS: At five years, the all-cause revision-free survival was 77% (95% CI 69 to 82). Thirty-one patients (19%) had further revision for aseptic reasons. In the rotating hinge group, the mechanical failure rate was more than twice as high as in the pure hinge group (13% vs 6%), significantly influenced by higher body weight. At a mean follow-up of 6.7 years, 21 (13%) patients had a reinfection and underwent a further surgery. Reinfection rates did not differ between the two groups. CONCLUSION: The use of hinge TKA in the revision of PJI shows favourable five year infection-free and all-cause revision-free survival rates of 91% and 77%, respectively. Our study showed poorer results of the rotating hinge design. These results may help surgeons to choose proper implants in case of septic knee revision.

Preoperative MRSA screening using a simple questionnaire prior elective total joint replacement.

INTRODUCTION: The purpose of this study was to evaluate the management and results of our standarized protocol for preoperative identification of MRSA colonisation in patients undergoing primary total hip and knee replacement procedures. METHODS: Following hospital protocol, between January 2016 and June 2019 37,745 patients awaiting elective joint replacement underwent a standardized questionnaire to assess the risk of MRSA infection, identifying patients requiring preoperative MRSA screening. An evaluation of the questionnaire identified effective questions for identifying infected patients. Furthermore, an analysis evaluated the impact of comorbidities or Charlson Comorbidity Index scores on positive MRSA colonization. Additionally, we evaluated the cost savings of targeted testing compared to testing all surgery patients. RESULTS: Of the 37,745 patients, 8.057 (21.3%) were swabbed, with a total of 65 (0.81%) positive tests. From this group 27 (36.48%) who were treated were negative before surgery. Some of the questionnaire results were consistently associated with a higher chance of colonization, including hospitalization during the past year (47,7%), previous history of MRSA (44,6%), and agriculture or cattle farming related work (15,4%). By selectively testing high-risk patients identified through the questionnaire, we achieved a 79% reduction in costs compared to universal MRSA screening. CONCLUSION: Our results suggest that the simple and standardized questionnaire is a valuable tool for preoperative screening, effectively identifying high-risk patients prone to MRSA colonisation. The risk of periprosthetic joint infection (PJI) and its associated sequelae may be reduced by this approach.

Diagnostic utility of open biopsy in patients with two culture-negative aspirations in the diagnostic work-up of periprosthetic joint infection.

INTRODUCTION: Different approaches have been proposed for bacterial identification in patients with a suspected periprosthetic joint infection (PJI). If a one-stage procedure is considered, a higher rate of preoperative bacterial identification can be achieved if biopsy is included in the diagnostic work-up. The performance of open biopsy (OB) in the context of PJI has not been clearly determined yet. The purpose of this study was to determine the value of an OB added to two consecutive culture-negative joint aspirations during PJI workup. MATERIALS AND METHODS: We retrospectively analyzed the OB data from a single institution. Patients under PJI work-up of the hip or knee with two culture-negative periprosthetic aspirations who underwent OB were included. Sensitivity and specificity were calculated using the musculoskeletal infection society (MSIS) criteria as gold standard. Patients undergoing urgent irrigation and debridement and patients with history of surgery to the affected joint in the prior 6 weeks were excluded. RESULTS: 126 patients were included in this study. 62 (49.2%) patients had prior revisions, 48 of them due to PJI. The sensitivity and specificity of OB was 69.4% and 89.1%, respectively. The OB procedure led to the identification of the causative germ in 50 out of 126 (40%) cases so they could undergo one-stage (septic) exchange. CONCLUSION: The OB is a valuable resource if preoperative synovial fluid cultures are negative, a high suspicion of infection persists and a one-stage procedure is preferred. It intends bacteria identification and allows surgeons to evaluate prosthetic complications for further surgical procedures.

Successful eradication rate following one-stage septic knee and hip exchange in selected pre-operative culture-negative periprosthetic joint infections.

PURPOSE: The main requirement for performing the one-stage septic exchange is the pre-operative identification of the pathogen and its susceptibility. The purpose of this study is to evaluate the success rate with special focus on reinfection in a cohort of patients who underwent one-stage septic knee or hip revision for pre-operative culture-negative PJI. METHODS: We retrospectively analyzed 640 patients treated by one-stage revision for chronic knee or hip PJI between January 1, 2016, and December 31, 2018. Only cases with pre-operative culture-negative PJI, with culture-negative synovial aspirations and one negative open biopsy, were analyzed. We evaluated the septic and aseptic complication and the rate of complication-free survival defined as the time from the date of first operation and the date of complication events. RESULTS: A total of 22 patients fulfilled the inclusion and were enrolled. The mean age of the group was 73.2 ± 9.8 years, with a median ASA score of 3 (range 3-4). After mean follow-up of 3.6 ± 2.6 years, 86.4% (19 out of 22) of patients reported no complications. Two patients (9.1%) after one-stage hip required revision arthroplasty due to septic failure, while one patient (4.5%) with one-stage knee had revision for femoral component aseptic loosening. CONCLUSION: Our analysis suggests that the absence of pre-operative pathogen detection may not be contraindication to the one-stage revision in selected patients. The one-stage exchange might be considered in patients with pre-operative negative cultures in presence of ASA > 3 and multiple comorbidities that are not able to tolerate multiple surgeries.

[Arthrofibrosis of the hip joint : Diagnostic and therapeutic challenge]. / Arthrofibrose des Hüftgelenks : Diagnostische und therapeutische Herausforderung.

Arthrofibrosis is a frequent complication after total knee arthroplasty (TKA). Recently, arthrofibrosis could be successfully verified histologically after primary total hip arthroplasty (THA) and the clinical presentation on the hip could be described for the first time. Possible diagnostic and therapeutic approaches have not yet been published. The diagnostic work-up differs only slightly from that for the knee joint. Other causes, such as aseptic loosening, malalignment or periprosthetic joint infection should be excluded. The gold standard is still invasive diagnostics with histological evidence of arthrofibrosis according to the synovia-like interface membrane (SLIM) criteria. Conservative treatment approaches include mobilization under anesthesia and medication according to Traut, analogous to the knee joint. Surgical treatment should be carried out under strict interpretation of the indications and after detailed clarification for the patient. In contrast to the knee joint, open arthrolysis should be preferred to arthroscopic arthrolysis of the hip joint. It must be taken into consideration that the evidence for conservative as well as surgical treatment, including possible revision arthroplasty, cannot be assessed due to the absence of clinical data. Studies under controlled conditions on the possible treatment approaches in the presence of arthrofibrosis are desirable and necessary in order to be able to assess the significance of the symptoms. In addition to treatment, great importance should also be attached to the diagnostics. Histological confirmation of the diagnosis of arthrofibrosis should only be considered to a limited extent in the case of an assumed, only moderately successful surgical intervention.

Which International Consensus Meeting Preoperative Minor Criteria is the Most Accurate Marker for the Diagnosis of Periprosthetic Joint Infection in Hip and Knee Arthroplasty?

BACKGROUND: The accurate preoperative diagnosis of periprosthetic joint infection (PJI) is critical. The aim of this study was to evaluate the diagnostic accuracy and performance of the 2018 International Consensus Meeting (ICM) preoperative minor criteria for the diagnosis of chronic PJI in total hip and knee arthroplasty. METHODS: We retrospectively reviewed 260 patients that underwent a revision knee or hip arthroplasty at our institution between 2015 and 2017. All major and minor 2018 ICM criteria (except erythrocyte sedimentation rate, D-dimer) were available for all patients included. Cases with at least 1 major criterion were considered as infected. Receiver operative characteristic curve analysis was performed for preoperative minor criteria. RESULTS: The diagnostic performance of the preoperative minor criteria ranked as per the area under the curve was PMN% (0.926), alpha defensin (0.922), white blood cell count (0.916), leukocyte esterase (0.861), and serum C-reactive protein (0.860). Increasing the PMN % cutoff from 70% to 77.8% improves the diagnostic accuracy (86.5% vs 90.8%). The highest diagnostic performance was achieved by combining all 5 preoperative parameters, and at current ICM thresholds, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive were 93.5%, 95.4%, 92.1%, 89.7%, and 96.5%, respectively. CONCLUSION: The diagnostic performance of preoperative minor criteria was outstanding (PMN%, alpha defensin, white blood cell count) or excellent (leukocyte esterase, serum C-reactive protein). PMN% showed the best diagnostic utility (area under the curve) and should have an increased weight-adjusted score in the ICM scoring system.

Distinct clonal lineages and within-host diversification shape invasive Staphylococcus epidermidis populations.

S. epidermidis is a substantial component of the human skin microbiota, but also one of the major causes of nosocomial infection in the context of implanted medical devices. We here aimed to advance the understanding of S. epidermidis genotypes and phenotypes conducive to infection establishment. Furthermore, we investigate the adaptation of individual clonal lines to the infection lifestyle based on the detailed analysis of individual S. epidermidis populations of 23 patients suffering from prosthetic joint infection. Analysis of invasive and colonizing S. epidermidis provided evidence that invasive S. epidermidis are characterized by infection-supporting phenotypes (e.g. increased biofilm formation, growth in nutrient poor media and antibiotic resistance), as well as specific genetic traits. The discriminating gene loci were almost exclusively assigned to the mobilome. Here, in addition to IS256 and SCCmec, chromosomally integrated phages was identified for the first time. These phenotypic and genotypic features were more likely present in isolates belonging to sequence type (ST) 2. By comparing seven patient-matched nasal and invasive S. epidermidis isolates belonging to identical genetic lineages, infection-associated phenotypic and genotypic changes were documented. Besides increased biofilm production, the invasive isolates were characterized by better growth in nutrient-poor media and reduced hemolysis. By examining several colonies grown in parallel from each infection, evidence for genetic within-host population heterogeneity was obtained. Importantly, subpopulations carrying IS insertions in agrC, mutations in the acetate kinase (AckA) and deletions in the SCCmec element emerged in several infections. In summary, these results shed light on the multifactorial processes of infection adaptation and demonstrate how S. epidermidis is able to flexibly repurpose and edit factors important for colonization to facilitate survival in hostile infection environments.

Results of the first 1,000 procedures after resumption of elective orthopedic services following COVID-19 pandemic: Experiences of a high-volume arthroplasty center.

OBJECTIVES: This study aims to investigate the effectiveness of a screening questionnaire to identify high-risk patients for novel coronavirus-2019 (COVID-19) among those undergoing elective orthopedic surgery. PATIENTS AND METHODS: Between May 4th, 2020 and June 11th, 2020, a total of 1,021 consecutive patients (492 males, 529 females; mean age: 62.3±15.1 years; range, 13 to 91 years) who were scheduled for elective orthopedic surgery were included. A screening questionnaire was applied to all patients. The patients admitted to hospital were also tested for COVID-19 infection through reverse transcription-polymerase chain reaction of the nasopharyngeal swab. RESULTS: Of the patients, 1,003 (98.2%) underwent elective surgery as planned. The screening questionnaire classified 30 patients as high-risk for COVID-19. A total of 18 procedures (n=18, 1.8%) were postponed due to the high risk of possible transmission of COVID-19. None of 991 low-risk patients were tested positive for COVID-19. CONCLUSION: The use of guiding principles for resuming elective orthopedic surgery is safe without a higher risk for complications in selected cases.

Revision Arthroplasty with Total Femur Replacement for the Management of Complex Post-traumatic Bone Defect in a Patient with Dwarfism. / Revisionsendoprothetik mit Totalfemurendoprothese zur Behandlung komplexer posttraumatischer Knochendefekte bei einem Patienten mit Zwergwuchs.

Dwarfism leads to an early onset of osteoarthritis of the joints of the lower limb. Due to bone deformities, arthroplasty is challenging. The incidence of implant-associated complications is higher compared to the normal population and often ends up with multiple revision arthroplasties. We report the first case in the literature of a 48-year-old patient with dwarfism who required implantation of a custom-made total femoral replacement due to aseptic stem loosening and a concomitant valgus gonarthrosis.

Preliminary clinical results of coated porous tibia cones in septic and aseptic revision knee arthroplasty.

PURPOSE: To analyze the first results of calcium-phosphate-coated porous tibia cones. METHODS: Patients treated with TrabecuLink®-CaP Cones were retrospectively recruited from January 2016 to December 2017. These custom-made cones were produced using titanium alloy Ti-6Al-4 V (Tilastan®) and using additive manufacturing with a special calcium-phosphate coating (HX®-coating). Clinical outcome was evaluated using Oxford Knee Score. For radiological evaluation of the implants, patients sent us outpatient taken radiographs. A minimum follow-up of one year was required. Lastly, we analyzed postoperative complications and revision rates. RESULTS: 52 patients with revision knee arthroplasty (RKA) were recruited for final analysis, of whom, we had 17 septic RKAs (33%) and 35 aseptic cases of RKA (67%). The bone defects were grouped into 17 AORI Type 2A (32.7%), 14 Type 2B (26.9%) and 21 Type 3 (40.4%). After a mean follow-up of 22 months (13.2-34.8; SD = ± 10), we had 4 surgical revisions (7.7%), 2 septic and 2 aseptic cases. The mean Oxford Knee Score was 28.6 points (8-47; SD = ± 10). 22 of 28 radiographs (78.6%) showed regular positioning of the cones and TKAs at a mean follow-up of 16.8 months (13.2-34.8; SD = ± 6). Three patients (10.7%) showed slight radiolucencies in the bone-cement interfaces and 3 patients (10.7%) had beginning heterotopic ossifications. CONCLUSIONS: This study shows the initial clinical results of calcium-phosphate-coated tibia cones showing a good functional outcome. Further research should focus on long-term clinical and radiological follow-up.

Results at 10-24 years after single-stage revision arthroplasty of infected total hip arthroplasty in patients under 45 years of age.

INTRODUCTION: The management of periprosthetic joint infection (PJI) of the hip is a challenging procedure. One-stage exchange is carried out in specialist centres with comparable infection free survival rates. However, there is a paucity of long-term results of this approach in young patients. METHODS: All patients undergoing one-stage exchange due to PJI with a known causative organism ⩽45 years of age with a minimum of 10-year follow-up (mean 15 years; range 10-24 years) were enrolled in this retrospective study. Patients older than 45 years of age or patients with a two-stage procedure were excluded from the study. The primary outcome measure was failure rate with special focus on reinfection at latest follow-up. Failure was defined as revision surgery for infection. Furthermore, functional outcome using the Harris Hip Score was determined initially and at latest follow-up. 26 patients fulfilled the inclusion criteria and were available for final follow-up. RESULTS: The study cohort consists of 16 male and 10 female patients with a mean age of 36.8 years (range 20-45 years) and a mean BMI of 29.8 kg/m2 (range 20.7-40.6 kg/m2). Prior to the single-stage procedure, the patients underwent an average of 3.1 previous surgical interventions (range 1-9). The mean hospital stay after septic revision was 19.7 days (11-33 days). Most infections were caused by Staphylococcus epidermidis (n = 8, 30.8%), followed by Staph. aureus (n = 7, 26.9%) and Propionibacterium acnes (n = 6, 23.1%). At latest follow-up, the overall survival rate was 76.9 %, while infection control could be achieved in 96.2%. At final examination, the mean Harris Hip Score improved from 46.2 to 78.9 (range 18.0-99; SD, 22.6). CONCLUSIONS: Single-stage revision surgery for the management of PJI in patients ⩽45 years is a successful treatment option with high infection control, even after long-term follow-up.

How reliable is the next generation of multiplex-PCR for diagnosing prosthetic joint infection compared to the MSIS criteria? Still missing the ideal test.

INTRODUCTION: Identification of the pathogen in case of a periprosthetic joint infection (PJI) remains 1 of the greatest challenges in septic surgery. Rapid germ identification enables timely, specific, antimicrobial therapy. The first multiplex PCR (polymerase chain reaction) generation (Unyvero-i60) enables germ detection within 5 hours with a sensitivity of 78.8% and a specificity of 100%. The aim of this study is to investigate the performance of the new generation of cartridges (Unyvero-ITI) of multiplex PCR in the case of a PJI. METHODS: In a prospective study, intraoperatively aspirated synovial fluid from 97 patients with aseptic or septic hip or knee revision surgery (49 aseptic, 48 septic) was examined with the multiplex PCR system (Unyvero-ITI) and the results were compared with the MSIS criteria. In addition, the time until the microbiological result was obtained in the event of a germ detection was documented. RESULTS: The multiplex PCR showed a germ detection with a sensitivity of 85.1% and a specificity of 98.0%. In 7 cases a false negative result was found and in one patient a false positive result was found. The general accuracy of this test procedure was 91.8%. The detection of germs was carried out within 5 hours with the multiplex PCR compared to 4.9 days in conventional microbiological diagnostics. CONCLUSIONS: The new generation of multiplex-PCR was able to improve germ detection. The possibility of prompt detection of germs offers the option of faster, targeted antimicrobial therapy. This diagnostic tool offers significant advantages, particularly in the context of an acute periprosthetic infection.

The 2018 International Consensus Meeting Minor Criteria for Chronic Hip and Knee Periprosthetic Joint Infection: Validation From a Single Center.

BACKGROUND: Recently, a revised definition of the minor criteria scoring system for diagnosing periprosthetic joint infection (PJI) was developed by the second International Consensus Meeting on musculoskeletal infection. The new system combines preoperative and intraoperative findings, reportedly achieving high sensitivity and specificity. We aimed to validate the modified scoring system at a high-volume center. METHODS: We retrospectively reviewed patients who underwent a revision total hip or knee arthroplasty at our institution from May 2015 to August 2018. Serum C-reactive protein, synovial white blood cell count and polymorphonuclear percentage, leukocyte esterase test, alpha-defensin, microbiological and histologic results, and documented existence of sinus tract and intraoperative purulence were available for all patients. Cases with at least 1 major criterion were considered as infected. Using the new minor criteria, a score of ≥6 reflects PJI, while a score <3 can be considered as noninfected. Sensitivity, specificity, mean accuracy (ACC), positive predictive value (PPV), and negative predictive value (NPV) were analyzed. RESULTS: A total of 345 cases were included. A cutoff score of ≥6 points had the following diagnostic performance: area under the curve (AUC) = 0.90; ACC = 0.88; sensitivity = 0.96; specificity = 0.84; PPV = 0.70; NPV = 0.98. Diagnostic performance was better for the hip (AUC = 0.92; ACC = 0.90; sensitivity = 0.96; specificity = 0.86; PPV = 0.81; NPV = 0.98) than the knee (AUC = 0.89; ACC = 0.85; sensitivity = 0.95; specificity = 0.83; PPV = 0.59; NPV = 0.98). CONCLUSION: The modified scoring system proposed by the 2018 International Consensus Meeting in diagnosing PJI showed high sensitivity and a good performance, especially as rule-out diagnostic criteria. The cutoff level seems to be different between the hip and knee. Further validation studies considering the acknowledged limitations are recommended.

An alternative treatment option for Paprosky Type IIIb acetabular defect using multiple tantalum wedges - A case report.

The treatment of severe acetabular defects in revision total hip arthroplasty (Paprosky type IIIa and IIIb) is demanding and choosing the appropriate surgical technique remains controversial. The introduction of trabecular metal augments has led to a variety of new treatment options. The authors present a case of a Paprosky Type IIIb acetabular defect due to eight subsequent revisions of the left hip. The patient was treated with an alternative treatment option using multiple tantalum wedges. Anatomical reconstruction was achieved and at 12 months follow-up, the patient was pain free and was able to walk without walking aids.

Serum C-reactive protein relationship in high- versus low-virulence pathogens in the diagnosis of periprosthetic joint infection.

Little is known about the relationship between the virulence of pathogens in periprosthetic joint infection (PJI) and C-reactive protein (CRP) levels. In this context, we assessed the performance of CRP for PJI. We collected the following data from 987 cases of total joint revision due to PJI and 386 cases of aseptic revision: age, gender, comorbidities, values for serum CRP, leukocytes, microbiology for preoperatively taken aspirations and at least 2 intraoperative biopsies, and presence or absence of a draining sinus. The mean CRP value in the PJI group was 50.2 mg l-1 (sd=62.2), while a lower CRP value of 11.6 mg l-1 (sd=25.3) was found in the control group. There were no significant differences for the CRP values between patients with and without draining sinus (P=0.4423). The difference in CRP between high-virulence and low-virulence micro-organisms was significant for both the hip and the knee (P<0.0001). For the hip, the area under the receiver operating characteristic curve (AUC) of CRP as a diagnostic marker for PJI was 0.830 and, for the knee, the AUC was 0.884. The optimal cutoff point for CRP as a diagnostic marker of PJI, calculated using Youden's index, was 8.90 mg l-1 for the hip and 9.99 mg l-1 for the knee. The study results add valuable new information regarding the organism profile that may help with the diagnostic workup and with the research and development of new strategies for diagnosing and treating PJI.

Ten-Year Results Following One-Stage Septic Hip Exchange in the Management of Periprosthetic Joint Infection.

BACKGROUND: Although 2-stage revision is still considered the gold standard for surgical management of periprosthetic joint infection (PJI), 1-stage revision has been reported to be as effective. Long-term reports for 1-stage revision in hip PJIs are lacking. METHODS: We reviewed our 10-11 years of results of 85 patients who underwent 1-stage exchange of the hip with an antibiotic-loaded bone cemented prosthesis due to PJI to determine the following: (1) What is the infection-free survival? (2) What is the overall survival? and (3) What are the long-term clinical outcomes? All 1-stage revision total hip arthroplasties (THAs) for infection between January 2006 and December 2007, with a minimum 10-year follow-up (range 10-11), were included in this retrospective cohort. Patients from another country or patients who were unable to participate were excluded. Eighty-five patients with a hip PJI were available at the last follow-up. Thirty-seven patients died during the 10-year study. Harris Hip Scores were recorded before the surgery and at last follow-up. Failures are reported as infection-related or aseptic. RESULTS: The 10-year infection-free survival was 94% and the surgery-free survival was 75.9%. The Harris Hip Scores improved from 43 (range 3-91) to 75 (range 10-91) (P < .001). The main indication for re-revision after 1-stage exchange was instability (10/20 patients). CONCLUSION: One-stage exchange of the hip for PJI is a reliable treatment option with high rate of infection control and long-lasting favorable outcomes.

Interprosthetic Femoral Sleeves in Revision Arthroplasty: A 20-Year Experience.

BACKGROUND: Interprosthetic femoral fractures in patients with ipsilateral stemmed total hip arthroplasty (THA) and total knee arthroplasty (TKA) can be technically demanding to treat surgically. Nonunion and implant failure are among the main complications following fixation of interprosthetic femoral (IF) fractures. Total femoral arthroplasty (TFA) is associated with a high incidence of infection and instability. IF sleeves have been designed to avoid the disadvantages of these techniques and to provide a stable construct. The aim of this study was to present the results with this device from a single center. METHODS: We reviewed 26 patients who underwent revision arthroplasty procedures, using custom-made cemented IF sleeves between 1997 and December 2017 in our institution. Two-part sleeves were used in 18 patients and one-part sleeves in 8 patients. The most common indication was an IF fracture (18 patients). Patients were monitored for postoperative complications, implant failure, and re-revision. The minimum follow-up of the survivors with nonrevised sleeves was 12 months. RESULTS: Twenty-three patients were included for the final analysis. The mean survivorship of the IF sleeve was 4.6 years at latest follow-up (mean 48.5 months; range 12 to 156). The overall rate of complications was 47.8%. The rate of mechanical failure was 21.7%. Late infections occurred in 3 patients (13%). At the latest follow-up, the mean Harris Hip Score was 69.9 points (range 39 to 94), and the mean functional Knee Society Score was 42.5 points (range 0 to 90), with average knee flexion of 95° (range 90° to 100°). CONCLUSION: The IF sleeve is a valid technique for the management of selected patients with IF fractures, particularly when a stable fracture fixation is not possible. Hip instability is not a concern, and functional improvement is achievable. Careful planning is required preoperatively to avoid mechanical failure.