Success Rates of Debridement, Antibiotics, and Implant Retention in 230 Infected Total Knee Arthroplasties: Implications for Classification of Periprosthetic Joint Infection

Perioperative Demographic and Laboratory Characteristics of Failed Debridement, Antibiotics, and Implant Retention: Can We Determine Which Patients Will Fail?

BACKGROUND

Debridement, antibiotics, and implant retention (DAIR) are the mainstays surgical treatment for acute periprosthetic joint infection (PJI). However, reoperation following DAIR is common and the risk factors for DAIR failure remain unclear. This study aimed to assess the perioperative characteristics of patients who failed initial DAIR treatment.

METHODS

A retrospective review was conducted on 83 patients who underwent DAIR for acute PJI within 3 months following index surgery from 2011 to 2022, with a minimum one-year follow-up. Surgical outcomes were categorized using the Musculoskeletal Infection Society outcome reporting tool (Tiers 1 to 4). Patient demographics, laboratory data, and perioperative outcomes were compared between patients who had failed (Tiers 3 and 4) (n = 32) and successful (Tiers 1 and 2) (n = 51) DAIR treatment. Logistic regression was also performed.

RESULTS

After logistic regression, Charlson Comorbidity Index (odds ratio [OR]: 1.57; P = .003), preoperative C-reactive protein (OR: 1.06; P = .014), synovial white blood cell (OR: 1.14; P = .008), and polymorphonuclear cell (PMN%) counts (OR: 1.05; P = .015) were independently associated with failed DAIR. Compared with total hip arthroplasty, total knee arthroplasty patients (OR: 6.08; P = .001) were at increased risk of DAIR failure. The type of organism and time from primary surgery were not correlated with DAIR failure.

CONCLUSIONS

Patients who had failed initial DAIR tended to have significantly higher Charlson Comorbidity Index, C-reactive protein, synovial white blood cell, and PMN%. The total knee arthroplasty DAIRs were more likely to fail than the total hip arthroplasty DAIRs. These characteristics should be considered when planning acute PJI management, as certain patients may be at higher risk for DAIR failure and may benefit from other surgical treatments.

LEVEL OF EVIDENCE

III.

Targeting Bacteria-Induced Ferroptosis of Bone Marrow Mesenchymal Stem Cells to Promote the Repair of Infected Bone Defects

The specific mechanisms underlying bacteria-triggered cell death and osteogenic dysfunction in host bone marrow mesenchymal stem cells (BMSCs) remain unclear, posing a significant challenge to the repair of infected bone defects. This study identifies ferroptosis as the predominant cause of BMSCs death in the infected bone microenvironment. Mechanistically, the bacteria-induced activation of the innate immune response in BMSCs leads to upregulation and phosphorylation of interferon regulatory factor 7 (IRF7), thus facilitating IRF7-dependent ferroptosis of BMSCs through the transcriptional upregulation of acyl-coenzyme A synthetase long-chain family member 4 (ACSL4). Moreover, it is found that intervening in ferroptosis can partially rescue cell injuries and osteogenic dysfunction. Based on these findings, a hydrogel composite 3D-printed scaffold is designed with reactive oxygen species (ROS)-responsive release of antibacterial quaternized chitosan and sustained delivery of the ferroptosis inhibitor Ferrostatin-1 (Fer-1), capable of eradicating pathogens and promoting bone regeneration in a rat model of infected bone defects. Together, this study suggests that ferroptosis of BMSCs is a promising therapeutic target for infected bone defect repair.

The Mark Coventry Award: PhotothermAA Gel Combined With Debridement, Antibiotics, and Implant Retention Significantly Decreases Implant Biofilm Burden and Soft-Tissue Infection in a Rabbit Model of Knee Periprosthetic Joint Infection

BACKGROUND

Chronic periprosthetic joint infection (PJI) is a major complication of total joint arthroplasty. The underlying pathogenesis often involves the formation of bacterial biofilm that protects the pathogen from both host immune responses and antibiotics. The gold standard treatment requires implant removal, a procedure that carries associated morbidity and mortality risks. Strategies to preserve the implant while treating PJI are desperately needed. Our group has developed an anti-biofilm treatment, PhotothermAA gel, which has shown complete eradication of 2-week-old mature biofilm in vitro. In this study, we tested the anti-biofilm efficacy and safety of PhotothermAA in vivo when combined with debridement, antibiotics and implant retention (DAIR) in a rabbit model of knee PJI.

METHODS

New Zealand white rabbits (n = 21) underwent knee joint arthrotomy, titanium tibial implant insertion, and inoculation with Xen36 (bioluminescent Staphylococcus aureus) after capsule closure. At 2 weeks, rabbits underwent sham surgery (n = 6), DAIR (n = 6), or PhotothermAA with DAIR (n = 9) and were sacrificed 2 weeks later to measure implant biofilm burden, soft-tissue infection, and tissue necrosis.

RESULTS

The combination of anti-biofilm PhotothermAA with DAIR significantly decreased implant biofilm coverage via scanning electron microscopy compared to DAIR alone (1.8 versus 81.0%; P < .0001). Periprosthetic soft-tissue cultures were significantly decreased in the PhotothermAA with DAIR treatment group (log reduction: Sham 1.6, DAIR 2.0, combination 5.6; P < .0001). Treatment-associated necrosis was absent via gross histology of tissue adjacent to the treatment area (P = .715).

CONCLUSIONS

The addition of an anti-biofilm solution like PhotothermAA as a supplement to current treatments that allow implant retention may prove useful in PJI treatment.

Debridement, Antibiotics, and Implant Retention in Unicompartmental Knee Arthroplasty Infection

BACKGROUND

This multicenter study sought to further investigate the method and outcome of debridement, antibiotics, and implant retention (DAIR) for the management of unicompartmental knee periprosthetic joint infection (PJI).

METHODS

This retrospective study was performed on 52 patients who underwent DAIR for PJI of a unicompartmental knee arthroplasty (UKA) across 4 academic medical centers, all performed by fellowship-trained arthroplasty surgeons. Patient demographics, American Society of Anesthesiologists score, infecting organism, operative data, antibiotic data, and success in infection control at 1 year were collected.

RESULTS

The average time from index surgery to diagnosis of PJI was 11.1 weeks (range, 1.4 to 48). There was no correlation between time of diagnosis and success at 1 year (R = 0.09, P = .46). There was an association between surgical synovectomy and the eradication of infection (R = 0.28, P = .04). Overall, there was an 80.8% (42 of 52) infection-controlled success rate at 1 year from the DAIR procedure. All DAIR failures went on to require another procedure, either 1-stage (2 of 10) or 2-stage (8 of 10) revision to total knee arthroplasty (TKA). Of the DAIR successes, 6 (14.3%) went on to require conversion to TKA for progression of arthritis within 5 years.

CONCLUSIONS

This study demonstrates that DAIR is a safe and moderately effective procedure in the setting of acute PJI of UKA across institutions, with a success rate consistent with DAIR for TKA. The data suggest that a wide exposure and thorough synovectomy be incorporated during the DAIR UKA to improve the likelihood of successful eradication of PJI at the 1-year mark.

LEVEL OF EVIDENCE

Level III.

Nanoparticle ultrasonication outperforms conventional irrigation solutions in eradicating Staphylococcus aureus biofilm from titanium surfaces: an in vitro study

PURPOSE

Bacterial biofilms create a challenge in the treatment of prosthetic joint infection (PJI), and failure to eradicate biofilms is often implicated in the high rates of recurrence. In this study, we aimed to compare the effectiveness of a novel nanoparticle ultrasonication technology on Staphylococcus aureus biofilm eradication compared to commonly used orthopedic irrigation solutions.

METHODS

Twenty-four sterile, titanium alloy discs were inoculated with a standardized concentration of methicillin-resistant S. aureus and cultured for seven days to allow for biofilm formation. Discs were then treated with either ultrasonicated nanoparticle therapy or irrigation with chlorhexidine gluconate, povidone-iodine or normal saline. The remaining bacteria on each surface was subsequently plated for colony-forming units of S. aureus. Bacterial eradication was reported as a decrease in CFUs relative to the control group. Mann-Whitney U tests were used to compare between groups.

RESULTS

Treatment with ultrasonicated nanoparticles resulted in a significant mean decrease in CFUs of 99.3% compared to controls (p < 0.0001). Irrigation with povidone-iodine also resulted in a significant 77.5% reduction in CFUs compared to controls (p < 0.0001). Comparisons between ultrasonicated nanoparticles and povidone-iodine demonstrated a significantly higher reduction in bacterial CFUs in the nanoparticle group (p < 0.0001).

CONCLUSION

Ultrasonicated nanoparticle were superior to commonly used bactericidal irrigation solutions in the eradication of S. aureus from a titanium surface. Future clinical studies are warranted to evaluate this ultrsonication technology in the treatment of PJI.

Investigating the translational value of Periprosthetic Joint Infection (PJI) models to determine the risk and severity of Staphylococcal biofilms

With the advent of antibiotic-eluting polymeric materials for targeting recalcitrant infections, using preclinical models to study biofilm is crucial for improving the treatment efficacy in periprosthetic joint infections. The stratification of risk and severity of infections is needed to develop an effective clinical dosing framework with better outcomes. Here, using in-vivo and in-vitro implant-associated infection models, we demonstrate that methicillin-sensitive and resistant Staphylococcus aureus (MSSA and MRSA) have model-dependent distinct implant and peri-implant tissue colonization patterns. The maturity of biofilms and the location (implant vs tissue) were found to influence the antibiotic susceptibility evolution profiles of MSSA and MRSA and the models could capture the differing host-microbe interactions in vivo. Gene expression studies revealed the molecular heterogeneity of colonizing bacterial populations. The comparison and stratification of the risk and severity of infection across different preclinical models provided in this study can guide clinical dosing to effectively prevent or treat PJI.

Fellowship Training in Arthroplasty Improves Treatment Success of Debridement, Antibiotics, and Implant Retention for Periprosthetic Knee Infections

Background

Debridement, antibiotics, and implant retention (DAIR) is a well-accepted surgical strategy for periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). DAIR in TKA may be incorrectly thought of as a "simple" procedure not requiring formal specialized training in arthroplasty. Currently, there are no studies comparing the risk of treatment failure based on surgeon fellowship training.

Methods

A retrospective review was performed of consecutive patients who underwent DAIR for TKA PJI at our institution. Two cohorts were created based on whether DAIR was performed by an arthroplasty fellowship-trained (FT) surgeon or nonarthroplasty fellowship-trained (NoFT) surgeon. Primary outcome was treatment failure following DAIR at a minimum of 1 year postoperatively. Treatment failure was based on the Tier 1 International Consensus Meeting definition of infection control. Secondary outcomes were also recorded including death during the totality of PJI treatment.

Results

A total of 112 patients were identified (FT = 68, NoFT = 44). At a mean follow-up of 7.3 years [standard deviation = 3.9], 73 patients (59.8%) failed treatment. Fellowship training in arthroplasty significantly improved treatment success rates (FT, 35/68 [51.5%]; NoFT, 10/44 [22.7%]; odds ratio 2.5 [95% confidence interval 1.1 to 5.9; P = .002]). Survivorship also differed significantly between the cohorts; at timepoints of 1.5 months, 5 months, 30 months, and 180 months, survivorship of the FT cohort was 79.4%, 67.6%, 54.4%, and 50.7%, respectively, compared with a survivorship of 65.9%, 52.3%, 25%, and 22.7% in the NoFT cohort (P = .002).

Conclusions

TKA PJI treated with DAIR should not be considered a simple procedure. Improved treatment success may be associated with subspecialty fellowship training in arthroplasty.

Level of Evidence

IV.

Risk Factors for Therapeutic Failure and One-Year Mortality in Patients with Intramedullary Nail-Associated Infection after Trochanteric and Subtrochanteric Hip Fracture Repair

Despite the implications of trochanteric and subtrochanteric intramedullary (IM) nail infection for patients with hip fracture, little is known about risk factors for therapeutic failure and mortality in this population. We performed a retrospective observational analysis including patients diagnosed with trochanteric and subtrochanteric IM nail infection at a Spanish academic hospital during a 10-year period, with a minimum follow-up of 22 months. Of 4044 trochanteric and subtrochanteric IM nail implants, we identified 35 cases of infection during the study period (0.87%), 17 of which were chronic infections. Patients with therapeutic failure (n = 10) presented a higher average Charlson Comorbidity Index (CCI) (5.40 vs. 4.21, p 0.015, CI 0.26-2.13) and higher rates of polymicrobial (OR 5.70, p 0.033, CI 1.14-28.33) and multidrug-resistant (OR 7.00, p 0.027, CI 1.24-39.57) infections. Upon multivariate analysis, polymicrobial infection and the presence of multidrug-resistant pathogens were identified as independent risk factors for therapeutic failure. Implant retention was associated with an increased risk of failure in chronic infection and was found to be an independent risk factor for overall one-year mortality in the multivariate analysis. Our study highlights the importance of broad-spectrum empirical antibiotics as initial treatment of trochanteric and subtrochanteric IM nail-associated infection while awaiting microbiological results. It also provides initial evidence for the importance of implant removal in chronic IM-nail infection.

Outcomes after débridement, antibiotics, and implant retention for prosthetic joint infection in shoulder arthroplasty

BACKGROUND

Patients who undergo total shoulder arthroplasty usually have excellent long-term outcomes. However, a subset of patients is diagnosed with a prosthetic joint infection (PJI) requiring revision procedures and prolonged recovery. The purpose of this study was to evaluate rates of recurrent shoulder PJI in patients undergoing débridement, antibiotics, and implant retention (DAIR), single-stage revision, and 2-stage revision. We also sought to compare outcomes and complications across procedures.

METHODS

Retrospective chart review was conducted for patients diagnosed with PJI after primary shoulder arthroplasty between January 2010 and August 2021. Patients were included if they underwent treatment with DAIR, single-stage revision, or 2-stage revision. Demographic information, surgical details, complications, laboratory data, postoperative antibiotic regimen, and infectious pathogen were collected. Postoperative patient-reported outcomes were collected: American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, Single Assessment Numeric Evaluation, Shoulder Activity Scale, and PROMIS Upper Extremity. Chi-square, t test, and 1-way analysis of variance were used as appropriate to evaluate each factor.

RESULTS

Sixty-five patients were included in the study, 26% treated with DAIR, 9% treated with single-stage revision, and 65% treated with 2-stage revision. There were no significant differences in patient comorbidities. Patients undergoing DAIR were diagnosed significantly earlier than those undergoing single- and 2-stage revision procedures (12.6 ± 22.9 months vs. 49.6 ± 48.4 vs. 25.0 ± 26.6, P = .010). Recurrent PJI was noted in 23.1% of patients: 29.4% of DAIR patients, no single-stage patients, and 23.8% of 2-stage patients (P = .330). Patients undergoing 2-stage revision with treatment failure had a significantly higher Elixhauser Comorbidity Index (0.2 ± 3.7 vs. 3.7 ± 3.9, P = .027). There was no significant difference in patient-reported outcomes across groups.

CONCLUSION

Patients undergoing treatment of shoulder PJI with DAIR did not have an increased rate of reinfection compared with single-stage and 2-stage revision procedures. Patients treated with DAIR were diagnosed with PJI significantly earlier than those undergoing single-stage and 2-stage revision procedures. There was no difference in complication rates between groups. This information adds to the body of work detailing outcomes after DAIR for shoulder PJI and provides encouraging data for use in this patient population. Future studies with a larger sample size may be conducted to further investigate specific pathogens, infection timelines, and antibiotic regimens that reduce the risk of treatment failure.

Outcomes After Successful Debridement, Antibiotic, and Implant Retention Therapy for Periprosthetic Joint Infection in Total Knee Arthroplasty

BACKGROUND

Controversy surrounds debridement, antibiotic and implant retention (DAIR) for treatment of acute periprosthetic joint infection (PJI). Data regarding DAIR's rate of infection resolution is variable with little investigation of functional outcomes.

METHODS

We identified 191 DAIR cases at a single institution from 2008 to 2020. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and Patient Reported Outcome Measurement Information System-10 (PROMIS) scores were collected. Patient Reported Outcome Scores were obtained from 60 cases. Median follow-up (IQR) was 4.5 (2.1 to 7.6) versus 3.0 (1.2 to 5.3) years for the control group. Mean scores were compared to a cohort of uncomplicated total knee arthroplasties matched by age, body mass index, and sex using generalized linear models adjusted for follow-up duration. Kaplan-Meier survivorship curves for PJI were constructed.

RESULTS

Mean Patient Reported Outcome Scores for the DAIR cohort were 57.2 ± 19.7 for KOOS-JR, 41.6 ± 7.1 for PROMIS physical health (PH), and 46.6 ± 8.7 for PROMIS mental health (MH). Mean control group values were 65.8 ± 21.0 for KOOS-JR, 44.6 ± 8.4 for PROMIS PH, and 49.2 ± 9.2 for PROMIS MH. No difference was observed in KOOS-JR (P = .83) or PROMIS MH (P = .11). PROMIS PH was lower in the DAIR cohort compared to the control group (P = .048). Median follow-up (years) for all 191 cases was 5.9 (range, 0.5 to 13.1). Survivorship (years) without subsequent operation for infection was 84% at 1, 82% at 2, and 79% at 5.

CONCLUSION

Knee and MH outcomes in successful DAIR procedures were similar to uncomplicated total knee arthroplasty. DAIR's success rate was 79% in treating acute PJI at 5 years.

LEVEL OF EVIDENCE

Level III.

How We Approach Suppressive Antibiotic Therapy Following Debridement, Antibiotics, and Implant Retention for Prosthetic Joint Infection

The optimal treatment of prosthetic joint infection (PJI) remains uncertain. Patients undergoing debridement, antibiotics, and implant retention (DAIR) receive extended antimicrobial treatment, and some experts leave patients at perceived highest risk of relapse on suppressive antibiotic therapy (SAT). In this narrative review, we synthesize the literature concerning the role of SAT to prevent treatment failure following DAIR, attempting to answer 3 key questions: (1) What factors identify patients at highest risk for treatment failure after DAIR (ie, patients with the greatest potential to benefit from SAT), (2) Does SAT reduce the rate of treatment failure after DAIR, and (3) What are the rates of treatment failure and adverse events necessitating treatment discontinuation in patients receiving SAT? We conclude by proposing risk-benefit stratification criteria to guide use of SAT after DAIR for PJI, informed by the limited available literature.

Validation of a Classification System for Optimal Application of Debridement, Antibiotics, and Implant Retention in Prosthetic Joint Infections following Total Knee Arthroplasty: A Retrospective Review

INTRODUCTION

Periprosthetic joint infection (PJI) remains a serious complication after total knee arthroplasty (TKA). While debridement, antibiotics, and implant retention (DAIR) are considered for acute PJI, success rates vary. This study aims to assess a new scoring system's accuracy in predicting DAIR success.

METHODS

119 TKA patients (2008-2019) diagnosed with PJI who underwent DAIR were included for analysis. Data were collected on demographics, laboratory values, and clinical outcomes. This was used for validation of the novel classification system consisting of PJI acuteness, microorganism classification, and host health for DAIR indication. Statistical analysis was carried out using SPSS programming.

RESULTS

Mean follow-up was 2.5 years with an average age of 65.5 ± 9.1 years, BMI of 31.9 ± 6.2 kg/m2, and CCI of 3.04 ± 1.8. Successful infection eradication occurred in 75.6% of patients. The classification system demonstrated 61.1% sensitivity, 72.4% specificity, and 87.3% positive predictive value (PPV) when the DAIR cutoff was a score less than 6. For a cutoff of less than 8, sensitivity was 100%, specificity was 37.9%, and PPV was 83.3%.

CONCLUSIONS

To date, no consensus exists on a classification system predicting DAIR success. This novel scoring system, with high PPV, shows promise. Further refinement is essential for enhanced predictive accuracy.

Piezoelectric ultrasonic debridement as new tool for biofilm removal from orthopedic implants: A study in vitro

Pulse lavage (PL) debridement is the standard treatment used in Debridement, Antibiotics and Implant Retention (DAIR) for bacterial biofilm removal during acute and early postoperative cases of periprosthetic joint infection (PJI). The failure rate of DAIR is still high due to the inadequacy of PL in removing the biofilm. Ultrasound-based techniques are a well-established tool for PJI diagnosis due to their ability to completely eradicate the biofilm from implant surfaces. Hence, this study investigates the efficiency of a piezoelectric ultrasonic scalpel (PUS) in removing bacterial biofilm from different orthopedic implant materials in vitro and compares the results with PL. Biofilms of methicillin-resistant Staphylococcus aureus strains were grown on titanium alloy (Ti6Al4V ELI), stainless steel (AISI 316L), and ultrahigh molecular weight polyethylene (UHMWPE) disks for 24 h. The disks of each material were divided into three groups: (i) a control group (no lavage/debridement), (ii) a group treated with PL, (iii) a group treated with PUS. The disks were then sonicated for viable cell count to measure the residual biofilm content. Compared to the initial cell count (105  CFU/mL for each material), PL showed a two-log reduction of CFU/mL (p < 0.001 for each material), while for PUS a four-log reduction was found (p < 0.001 for each material). The comparison between the two lavage/debridement displayed a two-log reduction of CFU/mL (p < 0.001 for each material) of PUS compared with PL. Its increased efficiency compared with PL promotes the use of PUS in removing bacterial biofilm from orthopedic implants, suggesting its implementation to improve the success rate of DAIR.

Rat model of recalcitrant prosthetic joint infection using biofilm inocula

Prosthetic joint infection (PJI) is a rare but devastating complication of joint arthroplasty. Biofilm formation around the prosthesis confers tolerance to antibiotics so that treatment is challenging. Most animal models of PJI use planktonic bacteria to establish the infection which fails to reproduce the pathology of chronic infection. We aimed to establish a rat model of Staphylococcus aureus PJI in male Sprague-Dawley rats using biofilm inocula and demonstrate its tolerance to frontline antibiotics. Pilot studies indicated that infection could be introduced to the knee joint by a biofilm-coated pin but that handling the prosthetic without disturbing the biofilm was difficult. We, therefore, developed a pin with a slotted end and used a miniature-biofilm reactor to develop mature biofilm in this niche. These biofilm-laden pins consistently produced infection of the bone and joint space. Treatment with high dose cefazolin, 250 mg/kg, starting the day of surgery reduced or cleared pin-adherent bioburden within 7 days, however when escalation from 25 to 250 mg/kg cefazolin treatment was delayed for 48 h, rats were unable to clear the infection. To track infections, we used bioluminescent bacteria, however, the bioluminescent signal did not accurately track the degree of infection in the bone and joint space as the signal did not penetrate the bone. In conclusion, we demonstrate that using a custom prosthetic pin, we can generate biofilm in a specific niche using a novel bioreactor setup and initiate a rat PJI that rapidly develops tolerance to supra-clinical doses of cefazolin.

Intraosseous regional prophylaxis in total knee arthroplasty

Prophylactic antibiotics are important in reducing the risk of periprosthetic joint infection (PJI) following total knee arthroplasty. Their effectiveness depends on the choice of antibiotic and the optimum timing of their administration, to ensure adequate tissue concentrations. Cephalosporins are typically used, but an increasing number of resistant organisms are causing PJI, leading to the additional use of vancomycin. There are difficulties, however, with the systemic administration of vancomycin including its optimal timing, due to the need for prolonged administration, and potential adverse reactions. Intraosseous regional administration distal to a tourniquet is an alternative and attractive mode of delivery due to the ease of obtaining intraosseous access. Many authors have reported the effectiveness of intraosseous prophylaxis in achieving higher concentrations of antibiotic in the tissues compared with intravenous administration, providing equal or enhanced prophylaxis while minimizing adverse effects. This annotation describes the technique of intraosseous administration of antibiotics and summarizes the relevant clinical literature to date.

Incidence, functional outcomes and cure rate of hematogenous infection in a 2,498 Total Knee Arthroplasties cohort

PURPOSE

The primary aim of the present study is to report the late acute hematogenous (LAH) prosthetic joint infection (PJI) cure rate following Total knee arthroplasty (TKA) treated by means of debridement, antibiotics, and implant retention (DAIR) in a long-term follow-up. The secondary purpose is to report the functional outcomes at that follow-up and to compare them with a non-infected group.

MATERIAL AND METHODS

This study cohort consists of 2,498 TKA performed from September 2005 to April 2010 that had a minimum follow-up of 10 years. The diagnosis of PJI and classification into LAH was done in accordance with the Zimmerli criteria. The primary outcome was the failure rate, defined as death before the end of antibiotic treatment, a further surgical intervention for treatment of infection, life-long antibiotic suppressive treatment or chronic infection. The Knee Society Score (KSS) was used to evaluate clinical outcomes.

RESULTS

Ten patients were diagnosed with acute hematogenous PJI during the study period (0.4%). All of them were managed with DAIR, which was performed by a knee surgeon and/or PJI surgeon. The failure rate was 0% at the 8.5-year (SD, 2.4) follow-up mark. The KSS score was 82.1 vs. 84.1 (p n.s.) at final follow-up.

CONCLUSION

Although the literature suggests that TKA DAIR for LAH periprosthetic joint infection is associated with high rates of failure, the results presented here suggest a high cure rate with good functional outcomes.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Success of Debridement, Antibiotics, and Implant Retention in Prosthetic Joint Infection Following Primary Total Knee Arthroplasty: Results from a Prospective Multicenter Study of 189 Cases

BACKGROUND

This study aimed to identify the success rate of debridement, antibiotics, and implant retention (DAIR) for prosthetic joint infection (PJI) in a large prospective cohort of patients undergoing total knee arthroplasty (TKA). The ability for different PJI classification systems to predict success was assessed.

METHODS

Prospective data recorded in the Prosthetic Joint Infection in Australia and New Zealand Observational (PIANO) study was analyzed. 189 newly diagnosed knee PJIs were managed with DAIR between July 2014 and December 2017. Patients were prospectively followed up for 2 years. A strict definition of success was used, requiring the patient being alive with documented absence of infection, no ongoing antibiotics and the index prosthesis in place. Success was compared against the Coventry (early PJI = ≤1 month), International Consensus Meeting (early = ≤90 days), Auckland (early = <1 year), and Tsukayama (early = ≤1 month, hematogenous = >1 month with <7 days symptoms, chronic = >1 month with >7 days symptoms) classifications.

RESULTS

DAIR success was 45% (85/189) and was highest in early PJIs defined according to the Coventry (adjusted odds ratio [aOdds Ratio (OR)] = 3.9, P=0.01), the ICM (aOR = 3.1, p=0.01), and the Auckland classifications (aOR = 2.6, P=0.01). Success was lower in both hematogenous (aOR = 0.4, P=0.03) and chronic infections (aOR = 0.1, P=0.003).

CONCLUSION

Time since primary TKA is an important predictor of DAIR success. Success was highest in infections occurring <1 month of the primary TKA and progressively decreased as time since the primary TKA increased.

Combination d-Amino Acid and Photothermal Hydrogel for the Treatment of Prosthetic Joint Infections

Prosthetic joint infection (PJI) is a devastating complication requiring surgical intervention and prolonged antimicrobial treatment. The prevalence of PJI is on the rise, with an average incidence of 60,000 cases per year and a projected annual cost of $1.85 billion in the US. The underlying pathogenesis of PJI involves the formation of bacterial biofilms that protect the pathogen from the host immune response and antibiotics, making it difficult to eradicate such infections. Biofilms on implants are also resistant to mechanical brushing/scrubbing methods of removal. Since the removal of biofilms is currently only achievable by the replacement of the prosthesis, therapies aimed at eradicating biofilms while enabling retention of implants will revolutionize the management of PJIs. To address severe complications associated with biofilm-related infections on implants, we have developed a combination treatment that is based on a hydrogel nanocomposite system, containing d-amino acids (d-AAs) and gold nanorods, which can be delivered and transforms from a solution to a gel state at physiological temperature for sustained release of d-AAs and light-activated thermal treatment of infected sites. Using this two-step approach to utilize a near-infrared light-activated hydrogel nanocomposite system for thermal treatment, following initial disruption with d-AAs, we were able to successfully demonstrate in vitro the total eradication of mature Staphylococcus aureus biofilms grown on three-dimensional printed Ti-6Al-4V alloy implants. Using a combination of cell assays, computer-aided scanning electron microscopy analyses, and confocal microscopy imaging of the biofilm matrix, we could show 100% eradication of the biofilms using our combination treatment. In contrast, we were only able to see 25% eradication of the biofilms using the debridement, antibiotics, and implant retention method. Moreover, our hydrogel nanocomposite-based treatment approach is adaptable in the clinical setting and capable of combating chronic infections brought about by biofilms on medical implants.

Host Immune Regulation in Implant-Associated Infection (IAI): What Does the Current Evidence Provide Us to Prevent or Treat IAI?

The number of orthopedic implants for bone fixation and joint arthroplasty has been steadily increasing over the past few years. However, implant-associated infection (IAI), a major complication in orthopedic surgery, impacts the quality of life and causes a substantial economic burden on patients and societies. While research and study on IAI have received increasing attention in recent years, the failure rate of IAI has still not decreased significantly. This is related to microbial biofilms and their inherent antibiotic resistance, as well as the various mechanisms by which bacteria evade host immunity, resulting in difficulties in diagnosing and treating IAIs. Hence, a better understanding of the complex interactions between biofilms, implants, and host immunity is necessary to develop new strategies for preventing and controlling these infections. This review first discusses the challenges in diagnosing and treating IAI, followed by an extensive review of the direct effects of orthopedic implants, host immune function, pathogenic bacteria, and biofilms. Finally, several promising preventive or therapeutic alternatives are presented, with the hope of mitigating or eliminating the threat of antibiotic resistance and refractory biofilms in IAI.

Assessment of antimicrobial mismatches in empirical treatment in early PJI after aseptic revision arthroplasty

Background

In early periprosthetic joint infection (PJI), 'debridement, antibiotics and implant retention' (DAIR) is a widely accepted form of treatment. Empirical antimicrobial treatment is started while culture results of tissue samples taken during debridement are pending.

Objectives

In this retrospective study we assessed the antimicrobial mismatch rate between empirical treatment and the susceptibility of the causative microorganisms of PJI after aseptic revision arthroplasty. We analysed risk factors for antimicrobial mismatches and the impact of mismatches on the outcome of PJI treatment.

Results

A total of 119 patients were included in the analysis. In 72% (86/119) of the cases there was an antimicrobial mismatch in empirical treatment. Most of the antimicrobial mismatches were caused by multidrug-resistant (MDR) Staphylococcus spp. (77%, 66/86). In multivariable analysis, polymicrobial PJI was significantly associated with antimicrobial mismatch (OR: 6.89; 95% CI: 2.38-19.53; P < 0.001), and antimicrobial mismatch was significantly associated with reduced success rate of PJI treatment (OR: 0.20; 95% CI: 0.05 ± 0.82; P = 0.026). There was no difference in successful outcome between PJI caused by Gram-negative bacilli (61%) and Gram-positive bacteria (69%, P = 0.516).

Conclusions

Mismatching empirical antimicrobial treatment after DAIR following aseptic revision arthroplasty was significantly associated with failure of PJI treatment. Polymicrobial PJI is a risk factor for antimicrobial mismatch of the empirical treatment of PJI. Antimicrobial mismatch and delay in targeted treatment should be integrated in the approach to optimize antibiotic treatment to improve clinical outcomes, while minimizing unintended side effects of antimicrobial use (antimicrobial stewardship).

Risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for the treatment of periprosthetic joint infection

BACKGROUND

Prosthesis removal and antibiotic bone cement spacer implantation is a very important link in two-stage revision of periprosthetic joint infection (PJI) after artificial joint replacement, which is key to the smooth progress of second-stage revision surgery. There are few reports on the risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for PJI. This study aimed to investigate the risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for the treatment of PJI.

METHODS

Clinical data of 40 patients who underwent prosthesis removal and antibiotic bone cement spacer implantation for PJI after arthroplasty in our hospital from January 2013 to July 2019 were retrospectively analyzed. During the follow-up period of at least 2 years, 21 patients underwent complete two-stage revision after the removal of the antibiotic bone cement spacer, and 19 patients did not receive a new prosthesis due to other factors, such as reinfection or the patient's wishes, record the infection control of patients during the treatment. Reinfection after prosthesis removal and antibiotic bone cement spacer implantation was defined as failure of effective control of infection, symptoms of reinfection, requires increased antibiotic therapy or reoperation. Multivariate Cox proportional hazards model was used to analyze the risk factors associated with reinfection after prosthesis removal and antibiotic bone cement spacer implantation.

RESULTS

Of the 40 patients, nine (22.5%) developed reinfection after prosthesis removal and antibiotic bone cement spacer implantation with a mean follow-up duration of 31 months, and multivariate analysis revealed that history of prior revision surgery (hazard ratio [HR] = 6.317, confidence interval [CI]: 1.495-26.700; p = 0.012) and presence of sinus tract before treatment (HR = 5.117, 95% CI: 1.199-21.828; p = 0.027) were independent risk factors for reinfection after prosthesis removal and antibiotic bone cement spacer implantation.

CONCLUSION

History of prior revision surgery and presence of sinus tract are two independent risk factors for reinfection in patients with PJI treated with prosthesis removal and antibiotic bone cement spacer implantation.

A Comparison of Outcomes of Culture positive and Culture negative Acute Knee Prosthetic Joint Infection following Debridement, Antibiotics and Implant Retention (DAIR)

PURPOSE

We aim to compare the outcome of culture-positive (CP PJI) and culture-negative (CN PJI) acute knee prosthetic joint infection (PJI) following debridement, antibiotics and implant retention (DAIR) with polyethylene insert exchange. We also aim to analyze the factors associated with the successful outcome of DAIR and the influence of failed DAIR on the outcome of subsequent two-stage revision arthroplasty.

METHODS

We performed a retrospective review of 36 consecutive patients who underwent DAIR for acute PJI between January 2013 and January 2018. The patient's demographic data, McPherson grade, surgical details, laboratory and microbiology data were retrieved from the medical records. All the patients have been followed up for a minimum of 3 years or until re-operation, revision or death and any complications, incidence of DAIR failure, revision and mortality were noted.

RESULTS

The mean follow-up was 4.9 ± 2.4 years. Among the 36 patients, 16 had CP PJI and 20 had CN PJI. Among the 16 patients with CP PJI, 8 patients had success with DAIR and 8 patients had a recurrence of infection (50%) at a mean of 21 months (range, 2 weeks to 55 months). Among the 20 patients with CN PJI, 14 patients had success with DAIR and 6 patients had a recurrence of infection [30% (6/20)] at a mean of 69 months (range, 13-221 months) (p < .05). The Kaplan-Meir survival analysis showed survivorship did not vary significantly between both groups (p > .05). Univariate regression analysis showed symptom duration of more than one month found to be significantly associated with the DAIR failure. There was no difference in failure rate after DAIR between age, Charlson comorbidity index, early postoperative versus acute hematogenous group and type of organism grown. Ten out of 14 DAIR failures were successfully managed with two-stage revision surgery with no recurrence of infection till the final follow-up. In the remaining 4 patients, one underwent re-debridement, two underwent arthrodesis and one was left with an antibiotic cement spacer.

CONCLUSION

DAIR with polyethylene exchange will give comparable results irrespective of the culture positivity. Symptom duration of more than 30 days for DAIR is significantly associated with DAIR failure. DAIR failures can be successfully managed with two-stage revision.

Treatment patterns and failure rates associated with prosthetic joint infection in unicompartmental knee arthroplasty: A systematic review

Background

Prosthetic joint infection (PJI) following unicompartmental knee arthroplasty (UKA) is a rare but challenging complication. A paucity of literature exists regarding the management of PJI in UKA. This systematic review aims to assess current treatment patterns in UKA PJI and analyze the failure rates associated with treatment.

Methods

PubMed, Scopus, and EMBASE were systematically searched for studies that presented cases of PJI following UKA. Data regarding study design, country of publication, index procedure type, diagnosis of PJI, number and incidence of PJI, timing of PJI (acute versus chronic), treatment, and outcomes were recorded. Failure rates in acute and chronic PJI as well as total failure rates were analyzed.

Results

Sixteen articles were identified that met inclusion criteria. These included 97 PJI cases (37 acute, 58 chronic, 2 unknown timing); incidence across all studies of 0.80%. The most common treatment for all PJI cases was debridement, antibiotics, and implant retention (DAIR) (40.2%), followed by two-stage conversion to total knee arthroplasty (TKA) (33.0%), one-stage conversion to TKA (23.7%), and one-stage exchange UKA (3.1%). There were no significant differences in failure rates across procedures for acute, chronic or overall PJI management (p > 0.05 for all).

Conclusion

This systematic review found relatively few studies reporting on PJI after UKA compared to the available TKA evidence. Further research is warranted to better elucidate the most appropriate treatment of PJI after UKA in both the acute and chronic setting along with risk factors for failure.

Risk Factors for Periprosthetic Joint Infection after Primary Total Knee Arthroplasty

Periprosthetic joint infection (PJI) is a major adverse event of primary total knee arthroplasty (TKA) from the patient's perspective, and it is also costly for health care systems. In 2010, the reported incidence of PJI in the first 2 years after TKA was 1.55%, with an incidence of 0.46% between the second and tenth year. In 2022, it has been published that 1.41% of individuals require revision TKA for PJI. The following risk factors have been related to an increased risk of PJI: male sex, younger age, type II diabetes, obesity class II, hypertension, hypoalbuminemia, preoperative nutritional status as indicated by prognostic nutritional index (PNI) and body mass index, rheumatoid arthritis, post-traumatic osteoarthritis, intra-articular injections prior to TKA, previous multi-ligament knee surgery, previous steroid therapy, current tobacco use, procedure type (bilateral), length of stay over 35 days, patellar resurfacing, prolonged operative time, use of blood transfusions, higher glucose variability in the postoperative phase, and discharge to convalescent care. Other reported independent risk factors for PJI (in diminishing order of importance) are congestive heart failure, chronic pulmonary illness, preoperative anemia, depression, renal illness, pulmonary circulation disorders, psychoses, metastatic tumor, peripheral vascular illness, and valvular illness. Preoperative intravenous tranexamic acid has been reported to diminish the risk of delayed PJI. Knowing the risk factors for PJI after TKA, especially those that are avoidable or controllable, is critical to minimizing (ideally preventing) this complication. These risk factors are outlined in this article.

Differing Microorganism Profile in Early and Late Prosthetic Joint Infections Following Primary Total Knee Arthroplasty - Implications for Empiric Antibiotic Treatment

BACKGROUND

Prosthetic joint infection (PJI) is the leading cause of revision following total knee arthroplasty (TKA). Prior to microorganism identification, the choice of the correct empiric antibiotics is critical to treatment success. This study aims to 1) compare the microorganism and resistance profile in early and late PJIs; 2) recommend appropriate empiric antibiotics.

METHODS

A multicentre retrospective review was performed over a 15-year period. First episode PJIs were classified by both the Tsukayama Classification and Auckland Classification. For each PJI case, the causative organism and antibiotic sensitivity were recorded.

RESULTS

Of eligible patients, 232 culture-positive PJI cases were included. Using either classification system, early PJIs (<4 weeks or <1 year since primary) were significantly more likely to be resistant and polymicrobial. The predominant organisms were coagulase-negative Staphylococci in early PJIs while Staphylococcus aureus was the most common in late PJIs. The distribution of gram-negative cases was higher in early Class-A than late Class-C PJIs (25% versus 6%, P = .004). Vancomycin provided significantly superior coverage when compared to Flucloxacillin for early infections, and addition of a gram-negative agent achieved coverage over 90% using both classification systems.

CONCLUSION

Based on the microbiological pattern in Tsukayama criteria, Vancomycin with the consideration of Gram-negative agent should be considered for Class-A infections given the high proportion of resistant and polymicrobial cases. For Class-C infections, Cephazolin or Flucloxacillin is likely sufficient. We recommend antibiotics to be withheld in Class-B infections until cultures and sensitivities are known.

Worse outcome of debridement, antibiotics, and implant retention in acute hematogenous infections than in postsurgical infections after total knee arthroplasty: a multicenter study

Background

We sought to determine (1) the success rate of debridement, antibiotics, and implant retention (DAIR) for acute periprosthetic joint infection (PJI) of the knee in patients with acute postsurgical infection and in those with acute hematogenous infection via a multicenter study, (2) the factors related to the failure of DAIR for overall acute PJI and acute hematogenous PJI via subgroup analysis, and (3) whether the PJI recurrence patterns differed between the two groups over time after DAIR.

Methods

This retrospective multicenter study included 101 acute knee PJI. Acute postsurgical PJI was defined as PJI diagnosed < 3 months following initial knee arthroplasty surgery. DAIR was performed for 34 cases of acute postsurgical PJIs (postsurgical group) and 67 cases of acute hematogenous PJIs (hematogenous group). The success rates between groups were compared, and factors related to DAIR failure were analyzed.

Results

The overall success rate of DAIR was 77%. The success rate tended to be higher in the postsurgical group than in the hematogenous group (p = 0.060). However, there was no significant factor related to DAIR failure in the subgroup analysis of acute hematogenous PJIs. In the postsurgical group, the recurrence of PJI occurred until 3 months, whereas in the hematogenous group, recurrence occurred for up to 2 years.

Conclusions

The failure rate tended to be higher in the acute hematogenous PJI group than in the acute postsurgical PJI group. Since acute hematogenous infections may recur for a longer period than postsurgical infections, careful follow-up is required after DAIR.

Retrospective analysis of the management strategies for surgical site infections post total hip and knee arthroplasty from tertiary care centres in Edmonton, Alberta

BACKGROUND

Surgical site infection (SSI) following hip and knee arthroplasty poses serious health and economic burden.

AIM

To evaluate SSI management strategies and outcomes to help address this problem.

METHODS

We performed a retrospective cohort study of adults undergoing primary total hip or knee arthroplasty who were identified to have a complex SSI by infection prevention and control surveillance audit. Audits identified SSI within 90 days of arthroplasty. Patients at two tertiary referral centres in Edmonton, Alberta, Canada from 2012 to 2019 were included and SSI cases were followed for two years.

FINDINGS

We identified 240 SSIs and found that 202 (84%) were managed with debridement with antibiotics and implant retention (DAIR), of which 71% achieved cure. The use of any topical intra-operative antibiotic in DAIR was not associated with improved outcome (OR = 1.68, 95% CI 0.91 - 3.10, p-value = 0.097). DAIR performed at 31-90 days from arthroplasty had lower chance of cure compared to DAIR performed within 30 days, however this was not statistically significant (60 vs 73%, p-value = 0.123). Initial treatment failures requiring additional surgery had 51% cure. The majority (78%) of treatment failures initially managed with DAIR ultimately required two-stage revision.

CONCLUSIONS

We provide insight from a population-based perspective on the surgical management of SSIs after primary total hip and knee arthroplasty in a large cohort. Additionally, we follow SSIs that had initial management failure. This data can inform future studies such as the economic burden associated with these infections, and plan interventions to optimize SSI management.

Does a 2-Stage Debridement Result in Higher Rates of Implant Retention Compared With Single Debridement Alone?

BACKGROUND/METHODS

We retrospectively reviewed 89 patients with acute prosthetic joint infection treated with debridement, antibiotics, and implant retention (DAIR) or 2-DAIR. Patients had <3 weeks of symptoms and met Musculoskeletal Infection Society criteria for infection. Sixty-three patients were treated with DAIR, whereas 26 patients were managed using a 2-DAIR protocol where patients underwent initial debridement, antibiotic bead placement, and subsequent return to the operating room at an average of 16.3 days for repeat debridement and modular component exchange. Patients received a 6-week course of intravenous antibiotics and 3 months of oral antibiotics for suppression. Demographics, comorbidities, implant retention rates, and complications were compared between the groups. The McPherson host type and infection type classification system were used to categorize patients in both the DAIR and 2-DAIR groups. Regression analysis was performed to control postoperative vs acute hematogenous infection, procedure, and comorbidities. The McPherson host types and infection types were not different between DAIR and 2-DAIR patients, P = .728 and P = .061, respectively.

RESULTS

There was no difference in the overall implant retention rate between DAIR and 2-DAIR (63.49% vs 69.23%, P = .605). The average days to reinfection was significantly longer for the 2-DAIR cohort compared with DAIR (271.3 vs 165.3, P = .024) in patients who failed treatment. However, when controlling for infection, microorganism, index procedure, and comorbidities, there was no difference in days to reinfection (P = .679). There were no differences in complications, 90-day readmission, or revision rates between the groups.

CONCLUSIONS

A staged debridement for acute prosthetic joint infection did not improve the rates of infection control. Randomized trials are needed to define indications and potential benefits of 2-DAIR.

Effective single-stage revision using intra-articular antibiotic infusion after multiple failed surgery for periprosthetic joint infection : a mean seven years' follow-up

AIMS

Periprosthetic joint infections (PJIs) with prior multiple failed surgery for reinfection represent a huge challenge for surgeons because of poor vascular supply and biofilm formation. This study aims to determine the results of single-stage revision using intra-articular antibiotic infusion in treating this condition.

METHODS

A retrospective analysis included 78 PJI patients (29 hips; 49 knees) who had undergone multiple prior surgical interventions. Our cohort was treated with single-stage revision using a supplementary intra-articular antibiotic infusion. Of these 78 patients, 59 had undergone more than two prior failed debridement and implant retentions, 12 patients had a failed arthroplasty resection, three hips had previously undergone failed two-stage revision, and four had a failed one-stage revision before their single-stage revision. Previous failure was defined as infection recurrence requiring surgical intervention. Besides intravenous pathogen-sensitive agents, an intra-articular infusion of vancomycin, imipenem, or voriconazole was performed postoperatively. The antibiotic solution was soaked into the joint for 24 hours for a mean of 16 days (12 to 21), then extracted before next injection. Recurrence of infection and clinical outcomes were evaluated.

RESULTS

A total of 68 patients (87.1%) were free of infection at a mean follow-up time of 85 months (24 to 133). The seven-year infection-free survival was 87.6% (95% confidence interval (CI) 79.4 to 95.8). No significant difference in infection-free survival was observed between hip and knee PJIs (91.5% (95% CI 79.9 to 100) vs 84.7% (95% CI 73.1 to 96.3); p = 0.648). The mean postoperative Harris Hip Score was 76.1 points (63.2 to 92.4) and Hospital for Special Surgery score was 78. 2 (63.2 to 92.4) at the most recent assessment. Polymicrobial and fungal infections accounted for 14.1% (11/78) and 9.0% (7/78) of all cases, respectively.

CONCLUSION

Single-stage revision with intra-articular antibiotic infusion can provide high antibiotic concentration in synovial fluid, thereby overcoming reduced vascular supply and biofilm formation. This supplementary route of administration may be a viable option in treating PJI after multiple failed prior surgeries for reinfection. Cite this article: Bone Joint J 2022;104-B(7):867-874.

Skeletal infections: microbial pathogenesis, immunity and clinical management

Osteomyelitis remains one of the greatest risks in orthopaedic surgery. Although many organisms are linked to skeletal infections, Staphylococcus aureus remains the most prevalent and devastating causative pathogen. Important discoveries have uncovered novel mechanisms of S. aureus pathogenesis and persistence within bone tissue, including implant-associated biofilms, abscesses and invasion of the osteocyte lacuno-canalicular network. However, little clinical progress has been made in the prevention and eradication of skeletal infection as treatment algorithms and outcomes have only incrementally changed over the past half century. In this Review, we discuss the mechanisms of persistence and immune evasion in S. aureus infection of the skeletal system as well as features of other osteomyelitis-causing pathogens in implant-associated and native bone infections. We also describe how the host fails to eradicate bacterial bone infections, and how this new information may lead to the development of novel interventions. Finally, we discuss the clinical management of skeletal infection, including osteomyelitis classification and strategies to treat skeletal infections with emerging technologies that could translate to the clinic in the future.

Current treatments for biofilm-associated periprosthetic joint infection and new potential strategies

Periprosthetic joint infection (PJI) remains a devastating complication after total joint arthroplasty. Bacteria involved in these infections are notorious for adhering to foreign implanted surfaces and generating a biofilm matrix. These biofilms protect the bacteria from antibiotic treatment and the immune system making eradication difficult. Current treatment strategies including debridement, antibiotics, and implant retention, and one- and two-stage revisions still present a relatively high overall failure rate. One of the main shortcomings that has been associated with this high failure rate is the lack of a robust approach to treating bacterial biofilm. Therefore, in this review, we will highlight new strategies that have the potential to combat PJI by targeting biofilm integrity, therefore giving antibiotics and the immune system access to the internal network of the biofilm structure. This combination antibiofilm/antibiotic therapy may be a new strategy for PJI treatment while promoting implant retention.

The lifetime revision risk of unicompartmental knee arthroplasty

AIMS

Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calculate the 'lifetime risk' of revision for UKA as a more meaningful estimate of risk projection over a patient's remaining lifetime, and to compare this to TKA.

METHODS

Incidence of revision and mortality for all primary UKAs performed from 1999 to 2019 (n = 13,481) was obtained from the New Zealand Joint Registry (NZJR). Lifetime risk of revision was calculated for patients and stratified by age, sex, and American Society of Anesthesiologists (ASA) grade.

RESULTS

The lifetime risk of revision was highest in the youngest age group (46 to 50 years; 40.4%) and decreased sequentially to the oldest (86 to 90 years; 3.7%). Across all age groups, lifetime risk of revision was higher for females (ranging from 4.3% to 43.4% vs males 2.9% to 37.4%) and patients with a higher ASA grade (ASA 3 to 4, ranging from 8.8% to 41.2% vs ASA 1 1.8% to 29.8%). The lifetime risk of revision for UKA was double that of TKA across all age groups (ranging from 3.7% to 40.4% for UKA, and 1.6% to 22.4% for TKA). The higher risk of revision in younger patients was associated with aseptic loosening in both sexes and pain in females. Periprosthetic joint infection (PJI) accounted for 4% of all UKA revisions, in contrast with 27% for TKA; the risk of PJI was higher for males than females for both procedures.

CONCLUSION

Lifetime risk of revision may be a more meaningful measure of arthroplasty outcomes than implant survival at defined time periods. This study highlights the higher lifetime risk of UKA revision for younger patients, females, and those with a higher ASA grade, which can aid with patient counselling prior to UKA. Cite this article: Bone Joint J 2022;104-B(6):672-679.

Antibiotic-free antimicrobial poly (methyl methacrylate) bone cements: A state-of-the-art review

Prosthetic joint infection (PJI) is the most serious complication following total joint arthroplasty, this being because it is associated with, among other things, high morbidity and low quality of life, is difficult to prevent, and is very challenging to treat/manage. The many shortcomings of antibiotic-loaded poly (methyl methacrylate) (PMMA) bone cement (ALBC) as an agent for preventing and treating/managing PJI are well-known. One is that microorganisms responsible for most PJI cases, such as methicillin-resistant S. aureus, have developed or are developing resistance to gentamicin sulfate, which is the antibiotic in the vast majority of approved ALBC brands. This has led to many research efforts to develop cements that do not contain gentamicin (or, for that matter, any antibiotic) but demonstrate excellent antimicrobial efficacy. There is a sizeable body of literature on these so-called "antibiotic-free antimicrobial" PMMA bone cements (AFAMBCs). The present work is a comprehensive and critical review of this body. In addition to summaries of key trends in results of characterization studies of AFAMBCs, the attractive features and shortcomings of the literature are highlighted. Shortcomings provide motivation for future work, with some ideas being formulation of a new generation of AFAMBCs by, example, adding a nanostructured material and/or an extract from a natural product to the powder and/or liquid of the basis cement, respectively.

Do Antibiotic-Loaded Calcium Sulfate Beads Improve Outcomes After Debridement, Antibiotics, and Implant Retention? A Matched Cohort Study

BACKGROUND

Dissolvable antibiotic-loaded calcium sulfate beads are used as an intraoperative adjunct during debridement with antibiotics and implant retention (DAIR) for periprosthetic joint infections (PJI) to reduce the historically higher failure rates than one- or two-stage exchange. This study evaluated clinical outcomes after DAIRs performed with and without these antibiotic beads. The primary outcome was post-DAIR failure secondary to recurrent PJI at 2 years. The secondary outcome was early failure secondary to recurrent PJI within 90 days.

MATERIAL AND METHODS

DAIRs performed for acute or acute hematogenous PJI at a single institution were retrospectively identified between 2013 and 2018. All DAIRs with adjunctive antibiotic beads (cases) were then exactly matched to a cohort of DAIRs without beads (controls) based on Charlson Comorbidity Index. The McNemar's test and Wilcoxon signed-rank test were used to evaluate differences in outcomes and patient characteristics.

RESULTS

Twenty DAIR cases (with antibiotic beads) were matched with 20 DAIR controls. There was no difference in age, sex, body mass index, joint, erythrocyte sedimentation rate, C-reactive protein, microbiology profile, antibiotic-resistance profile, or intraoperative lavage adjuncts between groups. There were no statistically significant differences between cases and controls for either overall infection-related failure at 2 years (P = .21) or early infection-related failure at 90 days (P = 1.00).

CONCLUSION

Adjunctive dissolvable antibiotic-loaded calcium sulfate beads did not reduce the incidence of recurrent PJIs at 2 years or 90 days postoperatively after DAIR. Given the added cost of these antibiotic dissolvable beads without clinical benefits, we cannot recommend their use as an adjunct treatment during DAIRs.

Debridement, antibiotics, and implant retention after revision arthroplasty : antibiotic mismatch, timing, and repeated DAIR associated with poor outcome

AIMS

Debridement, antibiotics, and implant retention (DAIR) is a widely accepted form of surgical treatment for patients with an early periprosthetic joint infection (PJI) after primary arthroplasty. The outcome of DAIR after revision arthroplasty, however, has not been reported. The aim of this study was to report the success rate of DAIR after revision arthroplasty with a follow-up of two years.

METHODS

This retrospective study, conducted at the Sint Maartenskliniek, Nijmegen, the Netherlands, included 88 patients who underwent DAIR within 90 days of revision total hip or total knee arthroplasty between 2012 and 2019. Details of the surgical procedures and PJI were collected. Univariate analysis and a subgroup analysis of the culture-positive group were performed. Kaplan-Meier survivorship curves were constructed.

RESULTS

The overall success rate of DAIR, with respect to the retention of components and the cure of infection, was 68% after two years. DAIR performed with an interval of > 30 days after the index revision procedure (odds ratio (OR) 0.24 (95% confidence interval (CI) 0.08 to 0.72); p = 0.008), a repeated DAIR within 90 days (OR 0.37 (95% CI 0.14 to 0.97); p = 0.040), and the use of an immunosuppressive agent (OR 0.13 (95% CI 0.02 to 0.67); p = 0.012) were associated with a significantly reduced success rate. In the culture-positive group, a mismatch between the antibiotic treatment and the susceptibility of the organism was associated with a significantly lower success rate (OR 0.13 (95% CI 0.03 to 0.62); p = 0.007).

CONCLUSION

DAIR is an acceptable form of surgical treatment for patients with a suspected early PJI after revision arthroplasty of the hip or knee. DAIRs performed after a prolonged interval, multiple DAIRs, and antibiotic mismatches were significantly associated with an increased risk of failure. Optimization of the host immune response and the prevention of antibiotic mismatch are modifiable factors that may improve the outcome. The high rate of mismatches was an important finding, underlining the need for a review of the local microbiological data, which might improve the outcome. Cite this article: Bone Joint J 2022;104-B(4):464-471.

Predictors of treatment success following peri-prosthetic joint infection: 24-month follow up from a multi-center prospective observational cohort study of 653 patients

Background

Periprosthetic joint infection (PJI) is a devastating condition and there is a lack of evidence to guide its management. We hypothesized that treatment success is independently associated with modifiable variables in surgical and antibiotic management.

Methods

The is a prospective, observational study at 27 hospitals across Australia and New Zealand. Newly diagnosed large joint PJIs were eligible. Data were collected at baseline and at 3, 12, and 24 months. The main outcome measures at 24 months were clinical cure (defined as all of the following: alive, absence of clinical or microbiological evidence of infection, and not requiring ongoing antibiotic therapy) and treatment success (clinical cure plus index prosthesis still in place).

Results

Twenty-four-month outcome data were available for 653 patients. Overall, 449 patients (69%) experienced clinical cure and 350 (54%) had treatment success. The most common treatment strategy was debridement and implant retention (DAIR), with success rates highest in early postimplant infections (119 of 160, 74%) and lower in late acute (132 of 267, 49%) and chronic (63 of 142, 44%) infections. Selected comorbidities, knee joint, and Staphylococcus aureus infections were independently associated with treatment failure, but antibiotic choice and duration (including rifampicin use) and extent of debridement were not.

Conclusions

Treatment success in PJI is associated with (1) selecting the appropriate treatment strategy and (2) nonmodifiable patient and infection factors. Interdisciplinary decision making that matches an individual patient to an appropriate management strategy is a critical step for PJI management. Randomized controlled trials are needed to determine the role of rifampicin in patients managed with DAIR and the optimal surgical strategy for late-acute PJI.

Current Insights in the Evaluation and Treatment of Infected Total Knee Arthroplasty

Total knee arthroplasty is a widely successful procedure, but a small percentage of patients have a postoperative course complicated by periprosthetic joint infection (PJI). PJI is a difficult problem to diagnose and to treat, and the management of PJI differs, depending on the acuity of the infection. This paper discusses the established and newer technologies developed for the diagnosis of PJI as well as different treatment considerations and surgical solutions currently available.

Cost-effectiveness of Single vs Double Debridement and Implant Retention for Acute Periprosthetic Joint Infections in Total Knee Arthroplasty: A Markov Model

Background

Periprosthetic joint infection (PJI) is a common cause of revision total knee surgery. Although debridement and implant retention (DAIR) has lower success rates in the chronic setting, it is an accepted treatment of acute PJI, whether postoperatively or with late hematogenous seeding. There are two broad DAIR strategies: single debridement and planned double debridement. The purpose of this study is to evaluate the cost-effectiveness of single vs double DAIR for acute PJI in total knee arthroplasty.

Methods

A decision tree using single or double DAIR as the treatment strategy for acute PJI was constructed. Quality-adjusted life years and costs associated with the two treatment arms were calculated. Treatment success rates, failure rates, and mortality rates were derived from the literature. Medical costs were derived from both the literature and Medicare data. A cost-effectiveness plane was constructed from multiple Monte Carlo trials. A sensitivity analysis identified parameters most influencing the optimal strategy decision.

Results

Double DAIR was the optimal treatment strategy both in terms of the health utility state (82% of trials) and medical cost (97% of trials). Strategy tables demonstrated that as long as the success rate of double debridement is 10% or greater than the success rate of a single debridement, the two-stage protocol is cost-effective.

Conclusions

A double DAIR protocol is more cost-effective than single DAIR from a societal perspective.