STUDY DESIGN:Modified Delphi consensus process. OBJECTIVE:To establish a standardized, consensus-driven definition for postoperative spine infection (PSI) for research, diagnosis, and management. SUMMARY OF BACKGROUND DATA:Postoperative infection is a devastating and common complication following spine surgery. Rates of PSI in the literature range from 0% to over 20% depending on surgical indication and invasiveness. Despite the implications of PSI, there is no universally accepted diagnostic standard or consensus definition for infection following spine surgery, hindering research and treatment of this challenging clinical condition. METHODS:A multispecialty workgroup convened by the Musculoskeletal Infection Society (MSIS) conducted a systematic literature review. Using data from the systematic review, an expert panel completed a modified Delphi process to achieve consensus. The panel included nine fellowship-trained, board-certified physicians with expertise in infectious diseases, orthopaedic and neurologic spine surgery, and musculoskeletal radiology. Iterative rounds focused on criterion selection, importance ranking, categorical grouping, and final constellation development for PSI diagnosis. Consensus was defined as a 2/3 majority, with a target of 100%. RESULTS:The workgroup achieved 100% consensus on a new PSI definition, which incorporates six clinical domains: wound features, microbiology, imaging, inflammatory biomarkers, intraoperative findings, and histology. A single microbiological stand-alone criterion-identification of a phenotypically indistinguishable organism from two or more deep operative site specimens-was established as pathognomonic for postoperative spine infection. Additional primary and secondary supporting criteria were defined, with specific combinations required to classify cases as definite or probable PSI. Final definitions were ratified by the boards of MSIS and the European Bone & Joint Infection Society (EBJIS). CONCLUSION:This consensus-based definition provides a standardized framework for diagnosing postoperative spine infection, facilitating research and clinical management. The criteria balance sensitivity and specificity across diverse clinical scenarios and represent the first multispecialty, society-endorsed definition for PSI.

Vertebral osteomyelitis is a general term for a heterogenous group of spine infections involving the vertebral bone, intervertebral discs, and facet joints. These infections can often spread contiguously to adjacent paraspinal structures, including paravertebral muscles and the epidural space and frequently presents with nonspecific and indolent symptoms, which can delay diagnosis. Treatment can be arduous, requiring prolonged courses of antibiotics often combined with surgical debridement. This review focuses primarily on pyogenic vertebral osteomyelitis in adults, reviewing the pathophysiology, epidemiology, microbiology, diagnosis, and treatment of this infection.

Modified Delphi consensus process To establish a standardized, consensus-driven definition for postoperative spine infection (PSI) for research, diagnosis, and management. Postoperative infection is a devastating and common complication following spine surgery. Rates of PSI in the literature range from 0% to over 20% depending on surgical indication and invasiveness. Despite the implications of PSI, there is no universally accepted diagnostic standard or consensus definition for infection following spine surgery, hindering research and treatment of this challenging clinical condition. A multispecialty workgroup convened by the Musculoskeletal Infection Society (MSIS) conducted a systematic literature review. Using data from the systematic review, an expert panel completed a modified Delphi process to achieve consensus. The panel included nine fellowship-trained, board-certified physicians with expertise in infectious diseases, orthopaedic and neurologic spine surgery, and musculoskeletal radiology. Iterative rounds focused on criterion selection, importance ranking, categorical grouping, and final constellation development for PSI diagnosis. Consensus was defined as a 2/3 majority, with a target of 100%. The workgroup achieved 100% consensus on a new PSI definition, which incorporates six clinical domains: wound features, microbiology, imaging, inflammatory biomarkers, intraoperative findings, and histology. A single microbiological stand-alone criterion—identification of a phenotypically indistinguishable organism from two or more deep operative site specimens—was established as pathognomonic for postoperative spine infection. Additional primary and secondary supporting criteria were defined, with specific combinations required to classify cases as definite or probable PSI. Final definitions were ratified by the boards of MSIS and the European Bone & Joint Infection Society (EBJIS) This consensus-based definition provides a standardized framework for diagnosing postoperative spine infection, facilitating research and clinical management. The criteria balance sensitivity and specificity across diverse clinical scenarios and represent the first multispecialty, society-endorsed definition for PSI.

PurposeOsseointegration (OI) is a novel alternative to traditional socket-suspended prostheses for lower-limb amputees, eliminating the socket-skin interface and allowing for weight bearing directly on the skeletal system. However, the stoma through which the implant attaches to the external prosthesis creates an ingress route for bacteria, and infection rates as high as 66% have been reported. The aims of this study are to classify infection management and long-term outcomes in this patient population to maximize implant salvage. MethodsAn institutional review board-approved retrospective analysis was performed on all patients who underwent lower-limb OI at our institution between 2017 and 2022. Demographic, operative, and outcome data were collected for all patients. Patients were stratified by the presence and severity of infection. Chi-square and t tests were performed on categorical and continuous data, respectively, using an alpha of 0.05. ResultsOne hundred two patients met our study criteria; 62 had transfemoral OI and 40 had transtibial OI. Patients were followed for 23.8 months on average (range, 3.5-63.7). Osteomyelitis was more likely than soft tissue infection to be polymicrobial in nature (71% vs 23%, P < 0.05). Infections at the stoma were mostly (96%) managed with oral antibiotics alone, whereas deeper soft tissue infections also required intravenous antibiotics (75%) or operative washout (19%). Osteomyelitis was managed with intravenous antibiotics and required operative attention; 5 (71%) underwent washout and 2 (29%) underwent explantation. Both implants were replaced an average of 3.5 months after explantation. There was no correlation between history of soft tissue infection and development of osteomyelitis (P > 0.05). The overall implant salvage rate after infection was 96%. ConclusionsThis study describes our institution's experience managing infection after OI and soft tissue reconstruction. Although infections do occur, they are easily treatable and rarely require operative intervention. Explantation due to infection is rare and can be followed up with reimplantation, reaffirming that OI is a safe and effective treatment modality.

Background: Variability in the definition of treatment success poses difficulty when assessing the reported efficacy of treatments for hip and knee periprosthetic joint infection (PJI). To address this problem, we determined how definitions of PJI treatment success have changed over time and how this has affected published rates of success after one-stage and two-stage treatments for hip and knee PJI. Methods: A systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted to identify one-stage and two-stage revision hip and knee PJI publications in major databases (2006-2021). Definition of treatment success, based on Musculoskeletal Infection Society tier criteria, was identified for each study. Publication year, number of patients, minimum follow-up, and study quality were also recorded. The association of success definitions and treatment success rate was measured using multi-variable meta-regression. Results: Study quality remained unchanged in the 245 publications included. Over time, no antibiotics (tier 1) and no further surgery (tier 3) (40.7 % and 54.5 %, respectively) became the two dominant criteria. After controlling for type of surgery, study quality, study design, follow-up, and year of publication, studies with less strict success definitions (tier 3) reported slightly higher odds ratios of 1.05 [1.01, 1.10] ( p = 0.009 ) in terms of treatment success rates compared to tier 1. Conclusions: PJI researchers have gravitated towards tier-1 and tier-3 definitions of treatment success. While studies with stricter definitions had lower PJI treatment success, the clinical significance of this is unclear. Study quality, reflected in the methodological index for non-randomized studies (MINORS) score, did not improve. We advocate for improving PJI study quality, including clarification of the definition of treatment success.

This review summarizes our current understanding of the medical and surgical management of fungal osteoarticular infections (FOAI). These infections are uncommon, heterogenous, and often severe; management is often highly dependent on expert opinion with a dearth of high-quality evidence. FOAI can be broadly categorized into three groups: native infections with endemic fungi, hematogenous infections among patients with underlying immunodeficiency, and complications of orthopedic surgery. Management of this diverse set of infections relies on careful coordination with orthopedic surgery, and attention to the patient’s overall medical and orthopedic prognosis. Extended courses of antifungal therapy are generally used, although shorter courses may be reasonable when surgical extirpation of infection is complete, and finite antifungal therapy is usually unsuccessful when infected hardware is not resected. Future advances in management of FOAI may emerge as more is learned about eradicating biofilm-embedded persister cells, as the roles of depot and topical antifungal agents are further elucidated, and as effective therapeutic drug monitoring is developed for these uncommon, but devastating, conditions.

Commentary The human microbiome—the ecosystem of bacteria living and interacting on (and in) human tissues—is enormously complex. Our understanding of its impact is evolving. Next-generation sequencing (NGS) techniques allow for the identification of microbial species and can be used to elaborately interrogate the composition of the bacterial community in specific anatomic sites. This has been extensively described in relation to the gut microbiome, the largest concentration of bacteria in the human body, where complex ecological interactions alter immunology1, pathogenesis2 and metabolic functions3. Far less is known about the microbiomes of anatomic sites previously considered sterile, such as the placenta, the central nervous system, and now the synovium. No one disputes that bacteria and bacterial DNA may transiently penetrate these protected spaces, but whether bacteria truly live there remains to be demonstrated. This preliminary study by Goswami et al. represents a relevant attempt to identify the microbiome of the human osteoarthritic hip and knee. The investigators obtained synovial fluid, tissue, and swabs from patients undergoing primary total hip or knee arthroplasty for osteoarthritis—patients with no overt signs of infection. Concordance in bacterial community composition among samples from the same patient was observed. Variations in diversity were seen depending on the hospital of enrollment and on whether patients had received a corticosteroid injection; these differences may be proxies for broader differences in patient-specific microbial composition. Surprisingly, comorbidities and demographic variables had no significant impact on the microbes found within a joint in this study. The detected microbes ranged from common to obscure—including some that are traditionally considered pathogenic and many others that are not. Some of the common sequences obtained included those of Staphylococcus, Streptococcus, and Pseudomonas. However, even though these are recognized orthopaedic pathogens, it would be surprising to confirm that they persist in clinically uninfected joints. Other bacteria found with frequency included some that are typically found in the environment but only occasionally cause opportunistic infections, such as Paenarthrobacter and Brevundimonas. The limitations of NGS techniques are important to consider. The presence of nucleic acids does not mean the presence of living microbes: remnants of dead bacteria, contamination introduced during sample collection and processing, and even miscategorized mammalian DNA in the vast NGS sequence libraries can all lead to positive findings even when no living bacteria are present. NGS findings are also difficult to confirm by alternate means (such as microscopy or culture), as the microbial burden is so low. A healthy degree of skepticism is warranted, given recent studies of low-biomass microbiomes in other tissues not known to harbor bacteria, such as the human fetus4,5. To their credit, the authors acknowledge these important limitations of their study. So, what can we learn from this study? First, the study serves as a reminder that the presence of microbial DNA in joints, in the absence of other findings of infection, is not diagnostic of infection. This is an important point particularly as it pertains to the molecular diagnosis of periprosthetic joint infection, which is gaining faster in popularity than in evidence. Optimizing molecular tests to diagnose infections is complicated by the implication that all joints may have subclinical quantities of bacterial DNA. Second, it is plausible that microbial nucleic acids are present in osteoarthritic joints. If the findings of this study are confirmed, further work should be done to establish whether these products are being produced intra-articularly by living bacteria, whether they are unique to diseased joints, and whether they represent a disease state that might benefit from treatment. The burden of proof should be high. Further confirmation of these findings with optimal controls, using alternate methodologies, and with replication across other populations (for instance, comparing osteoarthritic and healthy joints) will be needed to convince us that a stable microbiome exists within the joint capsule. Lastly, the techniques used in this study are less broadly available and much more complex than other existing diagnostic tools. The expertise to critically evaluate this type of methodology is beyond the scope of many clinicians. Further education and elaboration on clinically relevant findings are critical to realize the full clinical benefit of NGS in orthopaedics. In summary, this provocative paper offers evidence that microbial DNA is present in the osteoarthritic joint. The next steps that are needed will be to confirm these findings with appropriate controls at every juncture, and to evaluate whether these nucleic acids derive from living intra-articular bacterial communities or from transient circulation of dead microbes.

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Introduction: The most common complication following transcutaneous osseointegration for amputees is infection. Although an obvious source of contamination is the permanent stoma, operative site contamination at the time of implantation may be an additional source. This study investigates the impact of unexpected positive intraoperative cultures (UPIC) on postoperative infection. Methods: Charts were reviewed for 8 patients with UPIC and 22 patients with negative intraoperative cultures (NIC) who had at least 1 year of post-osseointegration follow-up. All patients had 24 h of routine postoperative antibiotic prophylaxis, with UPIC receiving additional antibiotics guided by culture results. The main outcome measure was postoperative infection intervention, which was graded as (0) none, (1) antibiotics unrelated to the initial surgery, (2) operative debridement with implant retention, or (3) implant removal. Results: The UPIC vs. NIC rate of infection management was as follows: Grade 0, 6/8 = 75 % vs. 14/22 = 64 %, p= 0.682; Grade 1, 2/8 = 25 % vs. 8/22 = 36.4 % (Fisher's p= 0.682); Grade 2, 1/8 = 12.5 % vs. 0/22 = 0 % (Fisher's p= 0.267); Grade 3, 0/8 = 0 % vs. 1/22 = 4.5 % (Fisher's p= 1.000). No differences were statistically significant. Conclusions: UPIC at index osseointegration, managed with directed postoperative antibiotics, does not appear to increase the risk of additional infection management. The therapeutic benefit of providing additional directed antibiotics versus no additional antibiotics following UPIC is unknown and did not appear to increase the risk of other adverse outcomes in our cohort.

Background: An intra-articular infection after anterior cruciate ligament (ACL) reconstruction (ACLR) is a rare complication but one with potentially devastating consequences. The rare nature of this complication raises difficulties in detecting risk factors associated with it and with worse outcomes after one has occurred. Purpose: To (1) evaluate the association between an infection after ACLR and potential risk factors in a large single-center cohort of patients who had undergone ACLR and (2) assess the factors associated with ACL graft retention versus removal. Study Design: Case-control study; Level of evidence, 3. Methods: All ACLR procedures performed at our institution between January 2010 and December 2018 were reviewed; a total of 11,451 procedures were identified. A retrospective medical record review was performed to determine the incidence of infections, patient and procedure characteristics associated with an infection, infection characteristics, incidence of ACL graft retention, and factors associated with the retention versus removal of an ACL graft. Multivariable logistic regression analysis was used to identify potential risk factors for an infection after ACLR. Results: Of the 11,451 ACLR procedures, 48 infections were identified (0.42%). Multivariable logistic regression analysis revealed revision ACLR (odds ratio [OR], 3.13 [95% CI, 1.55-6.32]; P = .001) and younger age (OR, 1.06 [95% CI, 1.02-1.10]; P = .001) as risk factors for an infection. Compared with bone–patellar tendon–bone autografts, both hamstring tendon autografts (OR, 4.39 [95% CI, 2.15-8.96]; P < .001) and allografts (OR, 5.27 [95% CI, 1.81-15.35]; P = .002) were independently associated with an increased risk of infections. Overall, 15 ACL grafts were removed (31.3%). No statistically significant differences besides the number of irrigation and debridement procedures were found for retained versus removed grafts, although some trends were identified ( P = .054). Conclusion: In a large single-center cohort of patients who had undergone ACLR and those with an infection after ACLR, patients with revision cases and younger patients were found to have a higher incidence of infection. The use of bone–patellar tendon–bone autografts was found to be associated with the lowest risk of infection after ACLR compared with both hamstring tendon autografts and allografts. Larger cohorts with a larger number of infection cases are needed to determine the factors associated with graft retention versus removal.

Background Debridement, antibiotics, and implant retention (DAIR) failure remains high for total hip and knee arthroplasty periprosthetic joint infection (PJI). We sought to determine the predictive value of the CRIME80 and KLIC for failure of DAIR in acute hematogenous (AH) and acute postoperative (AP) PJIs, respectively. Methods We identified 134 patients who underwent DAIR for AH PJI with <4 weeks of symptoms after index arthroplasty and 122 patients who underwent DAIR for AP PJI <90 days from index. In the AH group, 15 patients (11%) failed at 90 days and overall, 33 (25%) had failed by 2 years. In the AP group, 39 (32%) failed at 90 days and overall, 52 (43%) failed by 2 years. Logistic regression models were used to determine the area under the curve (AUC) to establish thresholds using the Youden index. Results For the AP cohort, AUCs were below 0.66 for KLIC, Charlson comorbidity index, Elixhauser comorbidity index, and McPherson host grade. For the AH cohort, 90-day AUCs were 0.70 for CRIME80 and below 0.66 for Charlson comorbidity index, Elixhauser comorbidity index, and McPherson host grade. In multivariate analysis controlling for age, sex, and body mass index, the CRIME80 AUC improved to 0.77 at 90 days. Conclusion To the authors' knowledge, this study represents the first external validation of the KLIC and CRIME80 for predicting DAIR failure in a North American population. The results indicate that alternative methods for predicting DAIR failure at 90 days and 2 years for acute PJI are needed. Level of Evidence Prognostic III.

Background: The concordance between preoperative synovial fluid culture and multiple intraoperative tissue cultures for identifying pathogenic microorganisms in periprosthetic joint infection (PJI) remains unknown. Our aim is to determine the diagnostic performance of synovial fluid culture for early organism identification. Methods: A total of 363 patients who met Musculoskeletal Infection Society criteria for PJI following primary total joint arthroplasty were identified from a retrospective joint infection database. Inclusion criteria required a positive preoperative intra-articular synovial fluid sample within 90 days of intraoperative tissue culture(s) at revision surgery. Concordance was defined as matching organism(s) in aspirate and intraoperative specimens. Results: Concordance was identified in 279 (76.8%) patients with similar rates among total hip arthroplasties (77.2%) and total knee arthroplasties (76.4%, P = .86). Culture discordance occurred in 84 (23.1%) patients; 37 (10.2%) had no intraoperative culture growth and 33 (90.1%) were polymicrobial. Monomicrobial Staphylococcal PJI cases had high sensitivity (0.96, 95% confidence interval [CI] 0.92-0.98) and specificity (0.85, 95% CI 0.80-0.90). Polymicrobial infections had the lowest sensitivity (0.06, 95% CI 0.01-0.19). Conclusion: Aspiration culture has favorable sensitivity and specificity when compared to tissue culture for identifying the majority of PJI organisms. Clinicians can guide surgical treatment and postoperative antibiotics based on monomicrobial aspiration results, but they should strongly consider collecting multiple tissue cultures to maximize the chance of identifying an underlying polymicrobial PJI. (C) 2021 Elsevier Inc. All rights reserved.

BACKGROUND:Reported clinical outcomes have varied for debridement, antibiotics, and implant retention (DAIR) and little is known regarding trends in utilization. We sought to evaluate the rate of DAIR utilization for total knee arthroplasty (TKA) and total hip arthroplasty (THA) periprosthetic joint infection (PJI) over a decade and clinical factors associated with these trends. METHODS:A retrospective study of primary TKAs and THAs was performed using Medicare data from 2005 to 2014 using the PearlDiver database platform. Current Procedural Technology and International Classification of Diseases Ninth Edition codes identified patients who underwent a surgical revision for PJI, whether revision was a DAIR, as well as associated clinical factors including timing from index arthroplasty. RESULTS:The proportion of revision TKAs and THAs performed using DAIR was 27% and 12% across all years, respectively. This proportion varied by year for TKAs and THAs with a linear trend toward increasing relative use of DAIR estimated at 1.4% and 0.9% per year (P < .001; P < .001). DAIR for TKA and THA performed within 90 days increased at a faster rate, 3.4% and 2.1% per year (P < .001; P < .001). Trends over time in TKA DAIRs showed an association with Elixhauser Comorbidity Index (ECI), 0-5 group increasing at 2.0% per year (P = .03) and patients >85 years (P = .04). CONCLUSION:The proportion of revision arthroplasty cases for PJI managed with DAIR has been increasing over time in the United States, with the most substantial increase seen <90 days from index arthroplasty. Age, gender, and ECI had a minimal association with this trend, except in the TKA population >85 years and in those with a very low ECI score.

Background: The role of daptomycin, a potent, safe, convenient anti-staphylococcal antibiotic, in treatment of prosthetic joint infection (PJI) is unclear. We evaluated our experience with the largest cohort of patients with staphylococcal PJI managed with daptomycin.Methods: A cohort of staphylococcal hip and knee PJI treated with daptomycin was identified by hospital records from 2009 to 2016. All cases met Musculoskeletal Infection Society International Consensus criteria for PJI. The primary endpoint was 2 year prosthesis retention. Univariate analyses and regression statistics were calculated.Results: 341 patients with staphylococcal PJI were analyzed. 154 two-stages (77%) and 74 DAIR procedures (52%) met criteria for treatment success at 2 years. 77 patients were treated with daptomycin, of which 34 two-stages (68%) and 15 DAIRs (56%) achieved treatment success. Pairwise and regression analysis found no association between treatment success and daptomycin use. Organism (DAIR only) and Charlson Comorbidity Index scores (DAIR and two-stage) were significantly associated with treatment outcome. Six daptomycin patients (7.8%) had adverse side effects.Discussion: Daptomycin fared no better or worse than comparable antibiotics in a retrospective cohort of staphylococcal hip and knee PJI patients, regardless of surgical strategy.Conclusion: The convenient dosing, safety, and potency of daptomycin make it an attractive antibiotic for staphylococcal PJI. However, these advantages must be weighed against higher costs and rare, but serious side effects.

Background COVID-19, the illness caused by the novel coronavirus, SARS-CoV-2, has sickened millions and killed hundreds of thousands as of June 2020. New York City was affected gravely. Our hospital, a specialty orthopedic hospital unaccustomed to large volumes of patients with life-threatening respiratory infections, underwent rapid adaptation to care for COVID-19 patients in response to emergency surge conditions at neighboring hospitals. Purposes We sought to determine the attributes, pharmacologic and other treatments, and clinical course in the cohort of patients with COVID-19 who were admitted to our hospital at the height of the pandemic in April 2020 in New York City. Methods We conducted a retrospective observational cohort study of all patients admitted between April 1 and April 21, 2020, who had a diagnosis of COVID-19. Data were gathered from the electronic health record and by manual chart abstraction. Results Of the 148 patients admitted with COVID-19 (mean age, 62 years), ten patients died. There were no deaths among non-critically ill patients transferred from other hospitals, while 26% of those with critical illness died. A subset of COVID-19 patients was admitted for orthopedic and medical conditions other than COVID-19, and some of these patients required intensive care and ventilatory support. Conclusion Professional and organizational flexibility during pandemic conditions allowed a specialty orthopedic hospital to provide excellent care in a global public health emergency.

Abstract Background Unicompartmental knee arthroplasty (UKA) is an increasingly popular alternative to total knee replacement due to easier recovery and greater satisfaction. However, limited evidence guides the management of periprosthetic joint infection (PJI) in UKA specifically. We retrospectively reviewed the largest cohort of UKA PJI to date, providing our experience in a high volume tertiary institution. Methods An institutional PJI database was queried from 2008 to 2016 to identify all PJI cases with an index procedure of UKA. Treatment, diagnostic criteria, Charlson Comorbidity Index (CCI) and microbiology data were collected. Success was defined as no further surgical treatment for infection at 2 years. A chi-square test or Fisher’s exact test was used for comparisons between treatment success and failure groups. Survival probability was calculated using the Kaplan–Meier method. Results A total of 24 UKA PJIs were identified with 22 meeting MSIS criteria. Median age at infection was 65.9 years (range, 50.8–87.4), median BMI was 26.7 kg/m2 (range, 21.2–49.5), 75% male (18/24).The average follow-up time was 2.83 years. 9 patients presented with early (4 weeks of symptoms). 63% (15/24) of PJI cases were staphylococcal and 8.3% (2/24) were culture negative. Patients were either treated with 1 stage exchange (n = 3, 100% success), two-stage exchange (n = 5, 80% success) or implant retention (n = 16, 75% success). Overall survivorship was 79% at 2 years (95% confidence interval [CI], 63%–95%). Overall there was no significant association between success and CCI (P = 0.46), infection type (P = 0.29), surgical therapy (P = 0.62), and microorganism (P = 0.05). Conclusion In this series, UKA PJIs tended to present more often as early post-operative or hematogenous infections. We observed no significant benefit with revision surgery and therefore conclude that implant retention should be considered as first-line surgical treatment. Outcomes of UKA PJI appear comparable to those in TKA PJIs. Disclosures All authors: No reported disclosures.

Objective: To evaluate the outcomes of a single-stage surgical protocol to treat a presumed aseptic long-bone nonunion with positive intraoperative cultures obtained at the time of surgery. Design: Retrospective comparative series. Setting: Orthopaedic specialty hospital. Patients and Methods: We retrospectively identified 77 patients with long-bone nonunions thought to be aseptic preoperatively, which grew bacteria from cultures obtained at the time of index nonunion surgery. Intervention: Fifty (65%) patients underwent open debridement of the nonunion site followed by surgical stabilization through plates and screws. Twenty-seven (35%) patients underwent exchange nailing with canal reamings used for cultures. Main Outcome Measurement: Rate of radiographic union, time to clinical and radiographic union, nonunion rate after index nonunion surgery, and final union rate after revision procedures. Results: Osseous union after the index nonunion surgery was achieved in 84% of the patients (65 of 77). Time to clinical union was 6.3 months (range, 1–24 months), and time to radiographic union was 7.4 months (range, 2–24 months). Eighteen percent (14 of 77 patients) did not heal after the index nonunion surgery and required additional surgeries. The final union rate after revision surgery was 99% (76 of 77 patients). Conclusions: Eighty-four percent of presumed aseptic nonunions of long-bone fractures with positive intraoperative cultures fully healed after a single-stage surgical protocol and long-term antibiotic when appropriate. When patients are diagnosed with a subclinical infected nonunion, they should be counseled about the higher likelihood of reoperation, but in most cases can expect excellent union rates after 1 additional surgery. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Question: In patients undergoing removal of orthopaedic implants that were used to treat below-the-knee fractures, does a single preoperative dose of cefazolin reduce risk for surgical site infection (SSI)? Design: Randomized (allocation concealed), blinded (patients, surgeons, data collectors), controlled trial (Wound Infections Following Implant Removal [WIFI] trial) with follow-up at 30 days after implant removal. Setting: 17 teaching hospitals and 2 academic hospitals in the Netherlands. Patients: 477 patients 18 to 75 years of age (mean age, 44 years; 43% men) who were undergoing removal of orthopaedic implants that were used to treat fractures of the foot, ankle, tibia, and fibula. Exclusion criteria were active SSI or fistula, current antibiotic therapy for concomitant disease or infection, reimplantation during the same surgery, allergy to cephalosporins, kidney disease, immunosuppressant therapy, or pregnancy. 99% of patients were included in the primary intention-to-treat analysis. Intervention: Patients were allocated to preoperative intravenous cefazolin, 1,000 mg, in a bolus of 0.9% sodium chloride (n = 232), or to a bolus of 0.9% sodium chloride (saline solution) (n = 245). Main outcome measures: The primary outcome was SSI (superficial and deep) at 30 days after implant removal. Secondary outcomes included health-related quality of life (EuroQol 5-Dimension 3-Level [EQ-5D-3L] questionnaire) and functional outcome (Lower Extremity Functional Scale [LEFS]) at 6 months. An estimated 216 patients per group were needed to detect a 6.7% between group difference in SSIs with 80% power (2-sided a = 0.05). Main results: 66 patients (14%) developed an SSIwithin 30 days (58 superficial and 8 deep). The cefazolin and saline solution groups did not differ for SSIs at 30 days (Table I) or for health-related quality of life (EQ-5D-3L, 0.78 vs. 0.79; absolute difference, -0.002 [95% confidence interval (CI), -0.07 to 0.04]) or function (LEFS, 62.3 vs. 62.2; absolute difference, 0.1 [95% CI, -3.6 to 3.8]) at 6 months. Conclusion: In patients undergoing removal of orthopaedic implants that were used to treat below-the-knee fractures, a single preoperative dose of cefazolin, 1,000mg, did not reduce SSIs more than saline solution at 30 days.