Periprosthetic Joint Infection Research Articles

Combining Multiple Spectroscopic Techniques to Reveal the Effects of Staphylococcus aureus Infection on Human Bone Tissues.

Osteomyelitis (OM) and periprosthetic joint infections (PJIs) are major public health concerns in Western countries due to increased life expectancy. Infections usually occur due to bacterial spread through fractures, implants, or blood-borne transmission. The pathogens trigger an inflammatory response that hinders bone tissue regeneration. Treatment requires surgical intervention, which involves the precise removal of infected tissue, wound cleansing, and local and systemic antibiotic administration. Staphylococcus aureus (SA) is one of the most common pathogens causing infection-induced OM and PJIs. It forms antimicrobial-resistant biofilms and is frequently found in healthcare settings. In this proof-of-concept, we present an approach based on multiple spectroscopic techniques aimed at investigating the effects of SA infection on bone tissue, as well as identifying specific markers useful to detect early bacterial colonization on the tissue surface. A cross-section of a human femoral diaphysis, with negative-culture results, was divided into three parts, and the cortical and trabecular regions were separated from each other. Two portions of each bone tissue type were infected with SA for one and seven days, respectively. Multiple techniques were used to investigate the impact of the infection on bone tissue, Brillouin-Raman microspectroscopy and attenuated total reflection Fourier transform infrared spectroscopy were employed to assess and develop a new noninvasive diagnostic method to detect SA by targeting the bone of the host. The results indicate that exposure to SA infection significantly alters the bone structure, especially in the case of the trabecular type, even after just one day. Moreover, Raman spectral markers of the tissue damage were identified, indicating that this technique can detect the effect of the pathogens' presence in bone biopsies and pave the way for potential application during surgery, due to its nondestructive and contactless nature.

Assessing the predictive value of pre- and post-operative inflammatory markers in patients undergoing total knee arthroplasty

Background and objectiveTotal Knee Arthroplasty (TKA) has proven highly effective in improving quality of life for patients with severe knee conditions. Despite advancements, surgical complications such as periprosthetic joint infections (PJIs) pose risks. The potential predictive value of pre- and post-operative inflammatory markers like neutrophil-to-lymphocyte ratio (NLR), D-dimer, and albumin levels on surgical outcomes is garnering attention. There is a growing interest in leveraging these markers to enhance patient selection and outcome prediction in the context of TKA.Focusing on the natural course of these markers, and the incidence of PJIs and to refine perioperative care strategies, improve patient outcomes, and identify high-risk patients for targeted intervention.MethodsThe study included 94 patients who underwent total knee arthroplasty (TKA) between 2019 and 2023. Blood tests were conducted before surgery and at 1, 3, 7, and 15 days after surgery to assess various parameters including white blood cell count, neutrophils, lymphocytes, platelets, hemoglobin, C-reactive protein, D-dimers, total protein, albumin, and total cholesterol values and ratios.ResultsFollowing total knee arthroplasty (TKA), key observations in blood markers included a sharp rise in white blood cell (WBC) counts from 5.81 to 10.22 (*10^9/L) on the first day post-surgery, with levels returning close to preoperative values by day-15. Neutrophil counts similarly increased from 3.46 to 8.50 (*10^9/L) on day-1, decreasing to 4.01 by day-15. Hemoglobin levels significantly decreased from 115.70 g/L to 90.62 by day-3 before improving to 100.30 by day-15. C-reactive protein (CRP) levels also saw a significant rise from 6.15 mg/L to a peak of 47.07 on day-3, then reducing to 10.55 by day-15, indicating a response to inflammation.ConclusionFollowing total knee arthroplasty (TKA), a significant initial postoperative increase in white blood cell count, neutrophils, and C-reactive protein levels, indicative of an acute inflammatory response, before returning towards baseline values by day 15. Hemoglobin levels displayed a notable dip post-surgery, gradually improving by the study’s end. These patterns emphasize the dynamic nature of inflammatory and hematological responses after TKA, highlighting their potential role in predicting surgical outcomes and guiding postoperative care.

Topological optimization of hip spacer reinforcement

The use of an antibiotic-enriched hip spacer represents the optimal treatment for periprosthetic joint infections (PJI). The addition of reinforcement significantly enhances its mechanical properties. Employing the explicit method enables accurate prediction of the mechanical behavior of both the spacer and its reinforcement. Topological optimization of the reinforcement emerges as the most effective strategy to prevent bone demineralization, enhance antibiotic diffusion, and improve spacer resistance. The objective of this study is to conduct topological optimization of a validated numerical model of a reinforced hip spacer and to select, from the obtained topologies, the one that best improves mechanical properties and prevents stress shielding while minimizing volume. The results indicate that an 8 mm thick titanium reinforcement, optimized to 70% of its original volume, proves to be the most effective choice.

Simultaneous Periprosthetic Joint Infection and Infective Endocarditis: Prevalence, Risk Factors, and Clinical Presentation

BackgroundInfective endocarditis (IE) and periprosthetic joint infections (PJI) occur due to hematogenous bacterial spread, theoretically increasing the risk for concurrent infections. There is a scarcity of literature investigating this specific association. We aimed to assess the prevalence, comorbidities, and clinical presentation of patients who have simultaneous PJI and IE. MethodsWe retrospectively identified 655 patients (321 men, 334 women; 382 total hip arthroplasty, 273 total knee arthroplasty) who developed a PJI from July 1, 2015, to December 31, 2020, at one institution. There were two groups created: patients diagnosed with PJI with IE (PJI + IE) and PJI patients who did not have IE (PJI). We analyzed clinical outcomes and comorbidities. ResultsThere were nine patients who had PJI with IE (1.4% of PJI patients). The C-reactive protein (170.9 versus 78, P = 0.026), Elixhauser comorbidity score (P = 0.002), length of hospital stay (LOS) (10.9 versus 5.7 days, P = 0.043), and the two-year post-discharge mortality rate (55.6 versus 9.0%, P = 0.0007) were significantly greater in the PJI+IE group. Comorbidities such as iron deficiency anemia (P = 0.03), coagulopathy (P = 0.02), complicated diabetes mellitus (P = 0.02), electrolyte disorders (P = 0.01), neurological disease (P = 0.004), paralysis (P = 0.04), renal failure (P = 0.0001), and valvular disease (P = 0.0008) occurred more frequently in the PJI + IE group. Modified Duke’s criteria were met for possible or definite IE in 8 of the 9 patients (88.9%). ConclusionConcurrent PJIs and IE, although rare, are a potentially devastating disease state with increased LOS and two-year mortality rates. This emphasizes the need for appropriate IE workups in patients who have a PJI. The modified Duke’s criteria is effective in establishing a diagnosis for IE in this scenario.

High mortality rate and restricted mobility in above knee amputation following periprosthetic joint infection after total knee arthroplasty: A systematic review.

To systematically review the literature on the outcomes of above knee amputation as a salvage procedure after periprosthetic joint infection in total knee arthroplasty. This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Medline, Scopus, Web of Science, and Embase electronic databases were utilized to identify all studies evaluating clinical outcomes of patients with above knee amputation following PJI from inception to June 24, 2023. Studies were excluded for failure to report functional outcomes specifically related to AKA in PJI following TKA, utilizing surgical interventions other than amputation, AKA indicated for other reasons than PJI, technical studies, conference abstracts, case reports and non-English language. The quality of studies was assessed with the Methodological Index for Non-Randomized Studies (MINORS) criteria. Seven retrospective studies, categorized as Therapeutic Level III evidence, were analyzed, involving a total of 188 patients who underwent AKA following PJI after TKA. The findings consistently indicate that post-AKA, patients experienced a notable decline in their level of independence and reported worsening ambulatory status. Infection and wound complications were common post-AKA, leading to revision surgeries, while the mortality rate ranged from 9 to 50% in the included studies. Polymicrobial organisms were frequently found in pre-AKA PJI, with MRSA being a common causative organism. AKA due to PJI following TKA is associated with restricted mobility and high mortality rate. Polymicrobial infections and MRSA were identified as common infecting organisms, emphasizing the complexities and challenges associated with managing these infections. The reported functional outcomes, ambulatory status, complications, reoperations, and mortality rates highlight the importance of providing comprehensive, individualized care to these patients.

Predictors of outcome following two-stage revision total knee arthroplasty.

Two stage revision arthroplasty remains the gold standard for peri-prosthetic joint infections of the knee. However, the functional outcomes of revision surgeries and the factors governing them require further investigation. The purpose of this study was to (a) evaluate impact of early and late stage I surgery and interval between stage I and stage II; (b) understand the impact of infecting organism and resistance; (c) to estimate long term survivorship and causes of failure. A retrospective review of 86 patients, who underwent two stage revision for prosthetic joint infections of the knee, was performed. Time between onset of symptoms to stage I (T1), and T1 to re-implantation (T2), along with microbiological studies, were analysed for their impact on functional outcomes, failure modalities and survivorship. In this study, the mean KSS-Knee improved from 64.0 ± 10.0 pre-operatively to 76.9 ± 10.4, and 77.2 ± 10.1 at the 5 and 10 year follow up respectively. The KSS-Function improved from 44.4 ± 8.8 pre-operatively to 72.2 ± 9.5 and 79.8 ± 8.1 at 5 and 10 year follow-up respectively. This study also found that T1 and T2 remained critical factors in determining functional outcome and longevity of the implant and a delay in these intervals was a significant predictor of failure. Gram negative, poly-microbial infections and organisms with methicillin and vancomycin resistance demonstrated lower survivorship (p-value, 0.001 at 5, 10 and 12 years). Re-infections occurred in 4 cases while 9 cases failed due to aseptic causes. Two-stage revision arthroplasty produced good functional outcomes when the infection was caused by single sensitive organism that did not exhibit high resistance to antibiotics. Stage I performed within 4 weeks and the subsequent re-implantation procedure undertaken within 6 weeks demonstrated better outcomes.

Nontobacco Nicotine Dependence and Rates of Periprosthetic Joint Infection and Other Postoperative Complications in Shoulder Arthroplasty: A Retrospective Analysis.

Nontobacco nicotine products, including e-cigarettes and vaping, are marketed as healthier alternatives to tobacco. However, the literature on nontobacco nicotine dependence (NTND) is scarce. It is important to analyze the influence of these products as they pertain to medical and surgical postoperative complications. This study hypothesizes that patients with NTND will experience more postoperative complications. Using the TriNetX database, which aggregates deidentified medical records from 89 healthcare organizations in the Research Network, Current Procedural Terminology and 10th revision of the International Classification of Diseases codes were used to identify patients undergoing primary shoulder arthroplasty (SA) from January 2012 to February 2024. Patients were divided into cohorts based on their NTND status before surgery. 90-day major medical complications and 2-year implant-related complications were assessed. Statistical analyses involved calculating risk ratios for postoperative complications. This study analyzed a total of 89,910 SA patients, of which 6,756 were 1:1 propensity matched into NTND or control cohorts. Within the 90-day postoperative period, the NTND cohort exhibited significantly higher rates of sepsis (1.80 vs. 1.20, P = 0.012), surgical site infection (1.20 vs. 0.70%, P = 0.007), and wound disruptions (0.70 vs. 0.40%, P = 0.048), average opioids prescribed (4.46 vs. 3.338, P < 0.001), readmission (10.20% vs. 6.20%, P 0.001) compared with the non-NTND cohort. At the 2-year follow-up, mechanical loosening was notably higher in the NTND group (1.10 vs. 0.30%, P 0.001), as were rates of prosthetic joint infections (2.20 vs. 1.20%, P 0.001). No significant difference was observed for revision rates (3.20% vs. 2.90%, P = 0.269). NTND is associated with higher 90-day rates of wound distruptions, infections, sepsis, as well as increased rates of mechanical loosening and prosthetic joint infection at 2 years postoperatively after SA. These results highlight the need for comprehensive NTND preoperative screening and tailored patient counseling in this patient population.

Outcomes of Total Knee Arthroplasty Following a Sham Incision Procedure in Patients with Previous Knee Incisions.

Tenuous blood supply carries a risk of wound-healing problems and subsequent infection following total knee arthroplasty (TKA). This risk may be increased by the presence of previous incisions. Performing a sham incision procedure allows for detection of wound-healing problems prior to performing TKA. The purpose of this retrospective case series is to describe the indications for and technique of a sham incision procedure in patients with previous knee incisions who underwent TKA following this procedure and to report the clinical outcomes observed in these patients following further surgery. Patients who had prior knee incisions, had undergone a sham incision prior to TKA, and had a minimum follow-up of 2 years were identified, and their cases were retrospectively reviewed. The identified cases typically adhered to the surgeon's standard protocol, which consisted of making a midline incision adventitious to TKA, dissecting down to deep fascia, and closing the wound with suture. Incisions were then observed for at least 4 weeks to determine the viability of the skin flaps before TKA was performed via the same incision. A total of 47 knees in 47 patients were included in the study cohort. TKA was performed at an average of 21.1 weeks (range, 4 to 163 weeks) following the sham incision. There were no cases of skin necrosis or periprosthetic joint infection at an average follow-up of 4.6 years (range, 2 to 12 years) after sham incision. A total of 11 patients (23.4%) required manipulation under anesthesia for stiffness. In our series, no patients developed skin necrosis or periprosthetic joint infection following TKA subsequent to a sham incision procedure, suggesting that healed sham incisions are safe to use for TKA and may be considered prior to TKA in cases in which local previous incisions increase the risk of wound-healing problems. Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Role of Serum Biomarkers in Differentiating Periprosthetic Joint Infections from Aseptic Failures after Total Hip Arthroplasties.

Background/Objectives: Periprosthetic joint infection (PJI) is a disastrous complication after joint replacement procedures as the diagnosis remains a significant challenge. The objective of this study is to assess the accuracy and test the interdependency of the proposed compound serum biomarkers for the diagnosis of PJI after total hip arthroplasties (THA). Methods: From January 2019 to December 2023, 77 consecutive cases that underwent revision total hip arthroplasties (rTHA) were included in a single-retrospective, observational cohort study. A total of 32 arthroplasties were classified as having septic complications using the European Bone and Joint Infection Society (EBJIS) definition from 2021, while the other 45 cases were assigned as aseptic failures (AF). Results: In the univariate analysis between the two groups created, statistically significant differences (p < 0.005) were found for the following variables: time from primary arthroplasty to symptom onset (Time PA-SO), neutrophil count, Lymphocyte count, haematocrit level (HCT) and haemoglobin level (HGB), C-reactive protein (CRP), the neutrophil lymphocyte ratio (NLR), platelet lymphocyte ratio (PLR), monocyte lymphocyte ratio (MLR), systemic inflammation index (SII), systemic inflammation response index (SIRI), and aggregate inflammation systemic index (AISI). The ROC curve analysis showed that the SII (sensitivity 90.6% and specificity 62.2%) and the NLR (sensitivity 84.4% and specificity 64.4%) are the most accurate biomarkers. The multivariate analysis confirmed that NLR > 2.63 (p = 0.006), PLR > 147 (p = 0.021), MLR > 0.31 (p = 0.028), SII > 605.31 (p = 0.002), SIRI > 83.34 (p = 0.024), and AISI > 834.86 (p = 0.011) are all closely related to PJI diagnosis independently. Conclusions: The proposed serum biomarkers can be correlated with PJI diagnosis with the reserve of relatively low specificities.

Outcomes of Obese Patients Undergoing Primary Total Knee Arthroplasty: Trends Over 30 Years.

The rates of obesity among patients undergoing total knee arthroplasty (TKA) have substantially increased. In addition, obesity is a well-established risk factor for complications after TKA. The purpose of this study was to analyze trends in body mass index (BMI) and complication risk among obese patients undergoing primary TKA treated at a single institution over 3 decades. Utilizing an institutional total joint registry, 13,919 primary TKAs performed to treat osteoarthritis between 1990 and 2019 were identified. Patients were stratified by BMI according to the World Health Organization (WHO) classification into 3 groups: non-obese (BMI, <30 kg/m2), WHO Class-I and II obese (BMI, 30 to 39.9 kg/m2), and WHO Class-III obese (BMI, ≥40 kg/m2). Trends in BMI and survivorship free from reoperation, revision, and periprosthetic joint infection (PJI) were analyzed over time while controlling for age, sex, and the Charlson Comorbidity Index. Over the study period, there was a 90% increase in the prevalence of Class-II obesity (13% to 25%) and a 300% increase in Class-III obesity (3% to 12%). Analysis of the entire cohort demonstrated a decrease in the 2-year risk of any reoperation, any revision, and PJI (p < 0.05 for all) with time. The risk decreased significantly over time for non-obese patients for any reoperation (p = 0.029) and any revision (p = 0.004) and for Class-III obese patients for any reoperation (p = 0.038) and any revision (p = 0.012), but it remained stable for Class-I and II obese patients. The risk of PJI decreased from 1990 to 2019 for non-obese patients (p = 0.005), but there were no significant changes in PJI risk for any obesity group. Despite increasing rates of obesity among our patients who underwent TKA, we observed decreasing risks of reoperation, revision, and PJI over time. The risks of reoperation and revision declined among non-obese patients, remained stable for Class-I and II obese patients, and declined for Class-III obese patients. The PJI risk declined for non-obese patients over the study period, but no such decline occurred for any category of obesity. Despite the decreasing risks of reoperation and revision, further work is needed to improve PJI risk in obese patients. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Modular component exchange has no advantage in Debridement, Antibiotics and Implant Retention (DAIR) for early onset hip and knee prosthetic joint infection.

Debridement, Antibiotics and Implant Retention (DAIR) has been the mainstay of treatment for early onset periprosthetic joint infection in spite of variable results. Modular component exchange is a widely recommended strategy to improve success rates with DAIR though very strong evidence to support its practice is still lacking. Eighty six patients underwent DAIR for early onset PJI following primary hip and knee arthroplasty were divided into two groups for this retrospective review. 45 patients (group 1) underwent DAIR with modular component exchange and 41 patients without exchange (group 2). We compared success rates based on infection eradication (primary outcome variable) and need for revision surgical procedures between these two groups. We also assessed differences in primary outcome based on type of arthroplasty, timing of DAIR and addition of local antibiotics. The overall success rate after DAIR was 71%. The outcome was similar in both groups (69% vs 74%, P = 0.66). The need for revision surgical procedures was 27% which was similar in both groups (P = 0.98) with 23% needing revision of prosthetic components. Type of arthroplasty (hip or knee) and addition of local antibiotics had no bearing on infection eradication after DAIR with or without modular component exchange. DAIR with in 45days of primary arthroplasty had significantly higher success rate compared to DAIR after 45days in both groups. We observed that modular component exchange did not improve infection eradication after DAIR for early onset PJI following hip and knee arthroplasty. Reasonable success rates can be expected after DAIR especially if the patient develops early clinical signs and the procedure is carried out as early as possible.

Safety of Intraoperative Cell Salvage in Two-Stage Revision of Septic Hip Arthroplasties.

(1) Background: The aim of this study was to evaluate the safety of intraoperative cell salvage (ICS) during reimplantation in the two-stage revision of septic hip arthroplasties. (2) Methods: As part of an internal quality control study, blood cultures were taken from the processed ICS blood during reimplantation and examined for possible bacterial load (study group). Due to a high rate of bacterial detection with uncertain clinical significance, consecutive ICS samples were also examined from patients undergoing aseptic revision hip arthroplasty (control group). Microbiological samples, patient and surgical characteristics and the follow-up data were analyzed retrospectively. (3) Results: 9 out of 12 (75%) patients in the study group and 5 out of 8 (63%) patients in the control group had positive ICS blood cultures. There was no significant difference between the groups (p = 0.642). The initial pathogens causing the periprosthetic joint infection (PJI) were not detected, but the bacterial spectrum resembled skin flora, with a high proportion of coagulase-negative staphylococci. No complications due to possible bloodstream-associated infections were observed. In summary, the detected pathogens were interpreted as contamination without clinical significance. (4) Conclusions: ICS in the context of reimplantation was considered a safe and recommendable procedure to optimize patient blood management.

Antimicrobial susceptibility testing of bone and joint pathogens using isothermal microcalorimetry.

The rise in osteomyelitis and periprosthetic joint infections, in combination with increasing life expectancy and the prevalence of diabetes, underscores the urgent need for rapid and accurate diagnostic tools. Conventional culture-based methods are often time-consuming and prone to false-negatives, leading to prolonged and inappropriate antibiotic treatments. This study aims to improve osteomyelitis diagnostics by decreasing the time to detection and the time to an antibiotic susceptibility result to enable a targeted treatment using isothermal microcalorimetry (IMC). IMC measures heat flow in real-time, providing insights into bacterial metabolism without the need for labeling. Using clinical isolates from bone infections, assessing their response to antibiotics through IMC, we demonstrated that IMC could detect bacteria within 4 h and determine antimicrobial susceptibility profiles within 2-22 h (median 4.85, range 1.28-21.78). This is significantly faster than traditional methods. A decision tree, based on antibiotic susceptibility, accurately categorized pathogens, achieving high accuracy (74-100%), sensitivity (100%), and specificity (65-100%). These findings suggest that IMC could redefine diagnostics of bone and joint infections and potentially infections in general, offering timely and precise treatment guidance, thereby improving patient outcomes and reducing health care burdens. Further optimization and clinical validation are needed to fully integrate IMC into routine diagnostics.

Survivorship and Functional Outcomes After Complex Primary Total Knee Arthroplasty With Contemporary Rotating-Hinge Implants

Background: Initial fixed-bearing hinge designs for primary total knee arthroplasty (TKA) had high rates of aseptic loosening. There are limited data on contemporary rotating-hinge implants. Purpose: We sought to determine survivorship and functional outcomes of contemporary rotating-hinge implants used in primary TKA. Methods: Retrospective review identified 54 primary rotating-hinge TKAs implanted in 49 patients from 2014 to 2018 at a single institution. Patients identified were 76% women, the mean body mass index was 29 kg/m2, the mean age was 65 years, and the mean follow-up was 3 years. The primary diagnosis for TKA in all cases was severe instability and ligamentous compromise. Secondary diagnoses included post-traumatic osteoarthritis (11, 20%), neurologic disease (10, 19%), inflammatory arthritis (10, 19%), connective tissue disease (3, 6%), valgus deformity (16, 30%), varus deformity (2, 4%), and recurvatum (2, 4%). Preoperative, postoperative (within 6 weeks), and most recent radiographs were reviewed. In this study, we collected preoperative, 1-year, and 2-year patient-reported outcome measures (PROMs) for patients with primary rotating-hinge TKA. Patient-reported outcome measures were prospectively collected, including the Knee Injury and Osteoarthritis Outcome Survey for Joint Replacement (KOOS JR) scores and the Mental (MCS) and Physical Component Scores (PCS) of the Veterans RAND 12-Item Health Survey (VR-12). Kaplan-Meier analysis was used to determine implant survivorship. Results: Reoperation was required in 6% (3/54); indications included periprosthetic joint infection (1), peripatellar fibrosis (1), and periprosthetic femur fracture (1). At both 2 and 5 years, survivorship free from all-cause reoperation was 95% and from revision for aseptic loosening was 100%. Mean KOOS JR scores increased from 47 preoperatively to 65 at 2 years postoperatively. On radiographic review, there were no progressive radiolucent lines consistent with aseptic loosening at final follow-up. Conclusion: The findings of this single-center, multi-surgeon retrospective case series on the use of rotating-hinge implants for primary TKA suggest excellent 2-year survivorship free from reoperation and no revisions for aseptic loosening. We report modest improvement in a variety of PROMs at 1-year and 2-year follow-up. Despite improvement, clinical outcomes were poor for a primary implant. Longer-term follow-up is required to monitor the durability of primary hinges.

Immunohistochemistry Study of Antimicrobial Peptides as a Future Diagnostic and Prognostic Tool for Periprosthetic Joint Infections.

Periprosthetic joint infection (PJI) is a reputable complication of arthroplasty surgery. Septic loosening is an implant biofilm-related infection with different characteristics and treatment than aseptic loosening. Misdiagnosing PJI results in choosing an inappropriate treatment and, in most cases, failure to achieve asepsis. The worldwide increase ofarthroplasty surgeries forces us to research more accurate ways to detect PJIs earlier, cheaper, and faster. In the current study, we investigated 52 arthroplasty revision surgeries (septic and aseptic) and, using immunohistochemistry staining of periprosthetic tissue, successfully demonstrated an important increase in antimicrobial peptides human β defensin-3 (HBD-3) and cathelicidin (LL-37) in the PJI group. Furthermore, we observed that patients with a positive LL-37 stain were associated with a more reserved prognosis at one-year follow-up. Thesepromising results suggest thatantimicrobial peptides HBD-3 and LL-37 could be used as future biomarkers for PJI detection.

Outcomes of a cemented modular rotational-hinge design as the final implant in a two-stage replacement due to chronic knee periprosthetic joint infection.

Outcomes of a cemented modular rotational-hinge design as the final implant in a two-stage replacement due to chronic knee periprosthetic joint infection.

Low UKA implantation volume, comorbidities, male sex, and implantation of constrained TKA are risk factors for septic revision after knee arthroplasty implantation : A register-based study from the German Arthroplasty Register

Periprosthetic joint infection (PJI) is one of the main causes of revision surgeries after total knee arthroplasty (TKA) and unicondylar knee replacement. Patient- and hospital-related risk factors must be evaluated to prevent PJI. This study identifies influencing factors and differences in infection rates between various types of implant. The basis for the data is the German Arthroplasty Register (EPRD). Septic revisions were calculated with the aid of Kaplan-Meier estimates, with septic revision surgery defined as the primary endpoint. Patients with constrained and unconstrained TKA or UKA were analysed using the Holm multiple log-rank test and the Cox proportional hazard model. The 300,998 cases of knee arthroplasty analysed included 254,144 (84.4%) unconstrained TKA, 9993 (3.3%) constrained TKA and 36,861 (12.3%) UKA, with a maximum follow-up of 7 years. After 1 year, the PJI rate was 0.5% for UKA and 2.8% for TKA, whereas after 7 years it was 4.5% for UKA and 0.9% for TKA (p < 0.0001). In constrained TKA, the PJI rate was significantly increased compared with unconstrained TKA (p < 0.0001). After 1 year, the PJI rate was 2.0% for constrained TKA and 0.8% for unconstrained TKA, as well as 3.1% and 1.4% respectively after 7 years. Implantation of a constrained TKA (HR = 2.55), male sex (HR = 1.84), an increased Elixhauser Comorbidity Index score (HR = 1.18-1.56) and an implantation volume of less than 25 UKA per year (HR = 2.15) were identified as risk factors for revision surgeries; an Elixhauser Comorbidity Index score of0 (HR = 0.80) was identified as a preventive factor. A reduced implantation volume and constrained knee arthroplasty are linked to a higher risk of PJI. Comorbidities (increased Elixhauser Comorbidity Index score), male sex and a low UKA-implantation volume were identified as risk factors for PJI. Patients who fulfil these criteria need specific infection prevention measures. Further analyses are required to investigate the potential influence of prevention and risk factor modification. III.

Prevalence and Risk Factors of Vitamin D Deficiency in Patients Scheduled to Undergo Revision Arthroplasty of the Hip, Knee and Shoulder-Data from a Single-Centre Analysis.

Vitamin D is crucial for ideal bone health and good muscle function, both essential requirements for successful joint arthroplasty. Hence, vitamin D deficiency has recently been identified as a predictor of poorer outcomes in patients scheduled to undergo total joint arthroplasty (TJA). Moreover, there is ample evidence today that vitamin D deficiency is associated with periprosthetic joint infection. Yet, vitamin D deficiency seems to be frequent in patients who are scheduled to undergo TJA. However, the prevalence of hypovitaminosis D in patients who require revision arthroplasty (rTJA) is largely unknown. Further, risk factors of vitamin D deficiency in these patients remain to be elucidated. For this reason, the primary objective of this study was to assess the vitamin D status of patients scheduled to undergo rTJA of the hip, knee and shoulder. The secondary objective was to identify potential risk factors for hypovitaminosis D in these patients. Serum vitamin D [25(OH)D] levels of 249 patients who were scheduled for rTJA were assessed over a period of twelve months at a high-volume TJA centre. Collectively, 23% of patients reported a routine intake of vitamin D supplements (58/249). Notably, 81% of patients (155/191) who did not report a routine vitamin D intake presented with insufficient vitamin D levels (below 30 ng/mL), while only 19% of patients (36/191) had sufficient vitamin D levels. Of those who reported a routine vitamin D intake, 75% (43/58) had sufficient vitamin D levels, while 25% (15/58) showed insufficient vitamin D status. Patients who did not routinely take any vitamin D supplements had significantly lower vitamin D levels compared to patients who reported regular vitamin D intake (19.91 ng/mL vs. 40.66 ng/mL). Further, BMI and nicotine abuse were identified as potential risk factors for hypovitaminosis D in patients without vitamin D supplementation. Moreover, the season of spring seems to be a risk factor in patients with vitamin D supplementation, while age itself did not appear to be a significant risk factor for low vitamin D levels. In conclusion, we found an alarmingly high rate of vitamin D deficiency in patients scheduled to undergo rTJA. Notably, reported routine vitamin D supplementation showed significantly increased serum vitamin D levels compared to patients with no reported supplementation. Due to the high prevalence of vitamin D deficiency, we believe that vitamin D status should routinely be assessed in patients who are scheduled to undergo rTJA.

Diamond-like carbon (DLC) surface treatment decreases biofilm burden by S. aureus on titanium alloy in vitro- a pilot study.

Periprosthetic joint infection is a complication of total joint arthroplasty with treatment costs over $1.6billion dollars per year in the US with high failure rates. Therefore, generation of coatings that can prevent infection is paramount. Diamond-like carbon (DLC) is an ideal coating for implants as they are wear-resistant, corrosion-resistant, inert, and have a low friction coefficient. The purpose of this study was to test the efficacy of DLC surface treatment in prevention of biofilm on titanium discs infected with Staphylococcus aureus in vitro. Titanium alloy discs (n = 4 non-coated and n = 4 DLC-coated) were infected with 5 × 105 colony-forming units (CFU) of S. aureus for 2 weeks then analysed via crystal violet and scanning electron microscopy (SEM). Crystal violet analysis yielded differences in the appearance of biofilm on implant surface where DLC-coated had a clumpier appearance but no difference in biofilm quantification. Interestingly, this clumpy appearance did lead to differences in SEM biofilm coverage where significantly less biofilm coverage was found on DLC-coated discs (81.78% vs. 54.17%, p < 0.003). DLC-coated titanium alloy implants may have preventative properties in S. aureus infection. Observing differences in biofilm coverage does warrant additional testing including CFU titration and biofilm kinetics with eventual use in an animal model of periprosthetic joint infection.

Is 18F-fluoride PET/CT an Accurate Tool to Diagnose Loosening After Total Joint Arthroplasty?

Several studies using positron emission tomography (PET) show highly elevated periprosthetic bone uptake of fluorine-18 sodium fluoride (18F-fluoride), suggestive of implant loosening after arthroplasty. Focus so far has been on qualitative but not on quantitative assessment. There is also a lack of intraoperative confirmation of preoperative 18F-fluoride PET findings. Although the method seems to have acceptable accuracy and high sensitivity, an attempt to improve the specificity and an overall validation of the method appear warranted. (1) Is there a difference in 18F-fluoride uptake around loose versus well-fixed THA and TKA components? (2) Can 18F-fluoride uptake measures provide a threshold that differentiates loose from well-fixed implants undergoing revision for a variety of septic and aseptic indications? (3) In a population restricted to THA and TKA undergoing revision for aseptic indications, can measurement of 18F-fluoride uptake still distinguish loose from well-fixed components? (4) What is the interrater reliability of measuring 18F-fluoride uptake? This was a retrospective assessment of a diagnostic test, 18F-fluoride PET/CT, which was performed prior to revision surgery. We included 63 patients with 31 THAs and 32 TKAs. Sixty-five percent of patients were female, and the mean age at 18F-fluoride PET/CT was 66 years. The THA had different modes of fixation (cemented, cementless, and hybrid; 45%, 32%, and 23%, respectively), whereas all TKAs were cemented. Imaging was conducted using routine protocols 1 hour after tracer injection. The interobserver reproducibility was analyzed using Spearman rank correlations and Bland-Altman analyses. Two independent observers were trained separately by a nuclear physician to measure maximal periprosthetic standardized uptake values (SUVmax) for each arthroplasty component (n = 126). Findings at surgery (whether the components were well fixed or loose, as well as the presence or absence of infection) were used as a reference. Presence of periprosthetic joint infection was retrospectively determined based on the criteria suggested by the European Bone and Joint Infection Society (EBJIS): clinical features in combination with blood analysis, synovial fluid cytologic analysis, and microbiology test results. Receiver operating characteristic (ROC) curves were plotted to assess the area under the curve (AUC) for each investigated component separately, indicating suitable SUVmax thresholds that differentiate loose from well-fixed components. After excluding patients with confirmed or suspected PJI per the EBJIS criteria (n = 12), the above analysis was repeated for the remaining patients with aseptic loosening (n = 51). We found higher 18F-fluoride uptake around loose versus well-fixed components in all but femoral TKA components (median [range] SUVmax for well-fixed versus loose THA cups 10 [7 to 30] versus 22 [6 to 64], difference of medians 12; p = 0.003; well-fixed versus loose TKA femoral components 14 [4 to 41] versus 19 [9 to 42], difference of medians 5; p = 0.38). We identified favorable ROC curves for all investigated components except femoral TKA components (THA cups AUC 0.81 [best threshold 13.9]; THA femoral stems AUC 0.9 [best threshold 17.3]; femoral TKA components AUC 0.6 [best threshold 14.3]; tibial TKA components AUC 0.83 [best threshold 15.8]). 18F-fluoride was even more accurate at diagnosing loosening when we limited the population to those patients believed not to have prosthetic joint infection (THA cups AUC 0.87 [best threshold 14.2]; THA femoral stems AUC 0.93 [best threshold 15.0]; femoral TKA components AUC 0.65 [best threshold 15.8]; tibial TKA components AUC 0.86 [best threshold 14.7]). We found strong interrater correlation when assessing SUVmax values, with Spearman ρ values ranging from 0.96 to 0.99 and Bland-Altman plots indicating excellent agreement between the two independent observers. Measuring SUVmax after 18F-fluoride PET/CT is a useful adjunct in the diagnostic evaluation for suspected implant loosening after THA and TKA. The method appears to be both accurate and reliable in diagnosing implant loosening for all components except femoral TKA components. In a real-world mixed population with both low-grade infection and aseptic loosening, the method seems to be fairly easy to learn and helpful to subspecialized arthroplasty clinicians. When infection can be ruled out, the method probably performs even better. Further prospective studies are warranted to explore the reason why femoral TKA component loosening was more difficult to ascertain using this novel technique. Level III, diagnostic study.