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Background: Patients with inflammatory arthritis are at increased risk of prosthetic joint infections (PJIs), but diagnosis in these patients can be challenging because active inflammatory arthritis produces elevated inflammatory markers that may mimic those seen in PJI. Purpose : In this pilot study, we sought to identify the clinical, microbiologic, and histopathologic features of culture-positive and culture-negative PJI in patients with inflammatory arthritis who underwent total hip arthroplasty (THA) or total knee arthroplasty (TKA). We also sought to obtain preliminary data to support a definitive study of optimal methods for PJI diagnosis in patients with inflammatory arthritis. Methods : We performed a retrospective analysis of TKA and THA patients treated for PJI from 2009 to 2018 at a single tertiary care orthopedic institution. Data were extracted from a longitudinally maintained hospital infection database. We reviewed hematoxylin and eosin slides of osteoarthritis and inflammatory arthritis PJI cases matched 3:1, respectively, by age, sex, and culture status. Clinical characteristics were evaluated using the Fisher exact test, χ 2 test, Student t test, and Mann-Whitney U test where appropriate. Results : A total of 807 PJI cases were identified (36 inflammatory arthritis and 771 osteoarthritis cases). Patients with inflammatory arthritis presented younger, had a higher Charlson Comorbidity Index, more frequently used glucocorticoids, were more likely women, and had a higher proportion of culture-negative PJI compared with osteoarthritis patients. Of the 88 inflammatory arthritis cases reviewed for histopathology, a higher proportion of culture-positive than culture-negative PJI cases had >10 polymorphonuclear leucocytes per high-power field and met Musculoskeletal Infection Society criteria but presented with less chronic inflammation. Conclusions : This retrospective prognostic study suggests that culture-negative PJI may be more frequent in patients with inflammatory arthritis than in those with osteoarthritis. Chronic infections, antibiotic use, or misdiagnosis may be contributing factors to unclear PJI diagnoses among culture-negative cases. This preliminary work supports the need for further studies to assess the differences in clinical features between culture-negative and culture-positive PJI in patients with inflammatory arthritis and the ability of biological diagnostic markers to discriminate between them in this population., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Peter Sculco, MD, reports relationships with EOS Imaging, Intellijoint Surgical, and Lima Corporate. Laura Donlin, PhD, reports relationships with Karius, Inc, and Stryker. Linda Russell, MD, reports a relationship with the Arthritis Foundation. Mark Figgie, MD, reports relationships with HS2, Insight, Lima, Mekanika, and Wishbone. Susan M Goodman, MD, reports relationships with Novartis and UCB. The other authors declare no potential conflicts of interest., (© The Author(s) 2023.)

Competing Interests: Conflict of InterestMeghan A. Kirksey, MD, PhD; Elaine I. Yang, MD; Mausam Kuvadia, MD; and Andy O. Miller, MD, declare that they have no conflicts of interest.

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., Competing Interests: Conflict of InterestAndy O. Miller, MD, Milan Kapadia, BS, Meghan A. Kirksey, MD, PhD, Milan Sandhu, MS, Deanna Jannat-Khah, DrPH, Trang Bui, MD, MPH, K. Keely Boyle, MD, Alexandra Krez, BA, Linda Russell, MD, Jennifer O’Neill, DNP, APN, NEA-BC, Emily M. Stein, MD, MS, Michael W. Henry, MD, and Vinicius C. Antao, MD, PhD, declare that they have no conflicts of interest. Emily M. Stein, MD, MS, reports grants from Novartis and Radius, outside the submitted work. Douglas E. Padgett, MD, reports personal fees from DJO Global, PSI LLC, and Tangen, outside the submitted work., (© Hospital for Special Surgery 2020.)

In 2018, Inabathula et al. published the results of a historical control study examining 90-day peri-prosthetic joint infection (PJI) rates at a single center before and after the institution of an extended post-operative oral antibiotic protocol for high-risk total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients. In the study, "Extended Oral Antibiotic Prophylaxis in High-Risk Patients Substantially Reduces Primary Total Hip and Knee Arthroplasty 90-Day Infection Rate" ( J Bone Joint Surg Am . 2018;100[24]:2103-2109), the authors considered any one of several patient-related criteria-including diabetes, a body mass index of 35 kg/m 2 or higher, or active smoking-as sufficient to designate a patient "high risk" for PJI. Before the extended antibiotic therapy protocol was instituted, PJI rates for primary THA and TKA in the high-risk subgroup were 4.3% and 2.1%, respectively. After it was instituted, the respective rates dropped to 1.1% and 0.4%, comparable to those seen in the non-high-risk patients treated using standard peri-operative prophylaxis. After adjusting for patient factors, regression analysis showed that high-risk patients receiving only peri-operative antibiotics were more likely to develop PJI than high-risk patients receiving the extended antibiotic protocol. Although these results suggest possible benefits of extended antibiotic prophylaxis in arthroplasty, methodologic limitations and inadequate discussion of potential drawbacks of widespread adoption of such protocols limit the impact of the findings. Future research is warranted to more narrowly define risk factors for PJI and to demonstrate the safety and efficacy of extended antibiotics in reducing the long-term burden of PJI., Competing Interests: Conflict of InterestChristopher J. DeFrancesco, MD; Michael C. Fu, MD, MHS; Cynthia A. Kahlenberg, MD; and Andy O. Miller, MD, declare that they have no conflicts of interest. Mathias P. Bostrom, MD, reports personal fees from Smith & Nephew, outside the submitted work., (© Hospital for Special Surgery 2019.)

Background: Propionibacterium acnes ( P. acnes ) has become increasingly recognized as a cause of periprosthetic joint infection (PJI)., Questions/purposes: It is not currently known if the clinical presentation of P. acnes varies depending on the joint being infected., Methods: We retrospectively reviewed patients infected with P. acnes after total hip, knee, and shoulder arthroplasty from two institutions. Patients were classified as having a PJI based on the Musculoskeletal Infection Society criteria and were excluded if they had a polymicrobial culture. Patient demographics, preoperative laboratory values, and microbiology data were analyzed., Results: Eighteen knees, 12 hips, and 35 shoulders with a P. acnes PJI were identified. Median ESR was significantly higher in the knee (38.0 mm/h, IQR 18.0-58.0) and hip (33.5 mm/h, IQR 15.3-60.0) groups compared to the shoulder group (11.0 mm/h, IQR 4.5-30.5). C-reactive protein levels were higher in the knee (2.0 mg/dl, IQR 1.3-8.9) and hip (2.4 mg/dl, IQR 0.8-4.9) groups compared to the shoulder group (0.7 mg/dl, IQR 0.6-1.5). Median synovial fluid WBC was significantly higher in the knee group than shoulder group (19,950 cells/mm 3 , IQR 482-60,063 vs 750 cells/mm 3 , IQR 0-2825, respectively). Peripheral blood WBC levels were similar between groups, as was mean time of P. acnes growth in culture. Clindamycin resistance was present in all groups., Conclusion: The manner in which a patient with P. acnes PJI presents is joint specific. Inflammatory markers were significantly higher in the knee and hip groups compared to the hip and shoulder groups, and long hold anaerobic cultures up to 14 days are necessary to accurately identify this organism.

Background: Pin infection continues to be a nuisance when using definitive external fixation. Prophylactic antibiotic treatment has been proposed in an effort to decrease pin complications., Questions/purposes: We performed a prospective, randomized, single-blinded study to answer the following questions: (1) what was the effect of a 10-day course of oral prophylactic antibiotics administered immediately after external fixation surgery on the incidence of a subsequent pin infection, (2) what was the effect on the severity of a subsequent pin infection, and (3) what was the effect on the timing of a subsequent pin infection?, Methods: Patients were randomized into antibiotic treatment and control groups, and incidence, severity, and time of onset of pin infection were recorded., Results: The incidence of pin infection for the entire cohort during the 90-day observation period was 46/58 (79%) without a statistically significant difference ( p  = 0.106). There was no statistical difference found ( p  = 0.512) in pin infection severity. There was no significant difference in the time of onset of infection between the two groups from the date of surgery ( p  = 0.553)., Conclusions: Our randomized data do not suggest that oral antibiotics alter the incidence, timing, or severity of pin infection. This study does not support the use of prophylactic oral antibiotics in healthy patients.

Background: Early detection of surgical site infection (SSI) following spinal surgery would allow for prompt treatment and would improve overall outcome, yet early diagnosis is a challenge. Computed tomography (CT) guided aspiration of fluid collections may aid in diagnosis, as its diagnostic utility has previously been demonstrated in the setting of hip SSI, knee SSI, and spontaneous diskitis. There is no literature on its use in post-operative spinal SSIs., Questions/purposes: The current study aims to (1) determine the diagnostic value of CT-guided aspiration in evaluating suspected SSI; (2) identify the characteristics of the clinical presentation that are predictive of SSI; and (3) identify characteristics of the hematologic workup that are predictive of SSI., Methods: Thirty patients who underwent CT-guided aspiration of paraspinal post-operative fluid collections and culture of aspirate fluid over the 6-year period from 2006 to 2011 were retrospectively reviewed. Aspirate fluid culture results were compared to intraoperative cultures, which were used as the "gold standard" for diagnosing SSI. The diagnostic value was evaluated by determining the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of aspirate fluid cultures. Clinical presentation, patient demographics, comorbidities, and laboratory values were reviewed for association with infection risk., Results: Eleven of thirty patients undergoing CT-guided aspiration were subsequently confirmed to have SSI through positive cultures. Wound drainage, wound erythema, elevated ESR, and cloudiness of aspirate fluid were associated with SSI. The sensitivity and specificity of aspirate cultures were 36.4 and 89.5%, respectively, and the respective positive predictive value (PPV) and negative predictive value (NPV) were 66.7 and 70.8%., Conclusions: Cloudy aspirate fluid was highly suggestive of infection, while wound erythema, drainage, and elevated ESR were also suggestive of SSI. CT-guided aspirations are a useful adjunct tool in evaluating for SSI but further studies are necessary before it can be considered a stand-alone diagnostic procedure.

Background: Prevention, early identification, and effective management of periprosthetic joint infection (PJI) in patients with inflammatory joint disease (IJD) present unique challenges for physicians. Discontinuing disease-modifying anti-rheumatoid drugs (DMARDs) perioperatively may reduce immunosuppression and infection risk at the expense of increasing disease flares. Interpreting traditional diagnostic markers of PJI can be difficult due to disease-related inflammation., Purposes: This review is designed to answer how to (1) manage immunosuppressive/DMARD therapy perioperatively, (2) diagnose PJI in patients with IJD, and (3) treat PJI in this population., Methods: The PubMed database was searched for relevant articles with subsequent review by independent authors., Results: While there is evidence to support the use of methotrexate perioperatively in RA patients, it remains unclear whether using anti-tumor necrosis factor medications perioperatively increases the risk of surgical site infections. Serum erythrocyte sedimentation rate and C-reactive protein can be useful for diagnosis of PJI in this population, but only as part of comprehensive workup that ultimately relies upon sampling of joint fluid. Management of PJI depends on several clinical factors including duration of infection and the likelihood of biofilm presence, the infecting organism, sensitivity to antibiotic therapy, and host immune status. The evidence suggests that two-stage revision or resection arthroplasty is more likely to eradicate infection, particularly when MRSA is the pathogen., Conclusion: Immunosuppression and baseline inflammatory changes in the IJD population can complicate the prevention, diagnosis, and treatment of PJI. Understanding the increase in risk associated with IJD and its treatment is essential for proper management when patients undergo lower extremity arthroplasty.