The purpose of this study was to explore the role of mNGS in the diagnosis of PJI by detecting the presence of bacteria in periprosthetic tissues. Patients who were suspected of PJI and underwent surgery in our center were enrolled. Microbial culture and mNGS were performed on periprosthetic tissues collected intraoperatively. Patient age, body mass index (BMI), laboratory tests, microbial culture and mNGS results were recorded. The diagnostic performance of microbial culture and mNGS in the diagnosis of PJI was compared. A total of 44 patients were included. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of periprosthetic tissue microbial culture in the diagnosis of PJI were 72.72%, 77.27%, 76.19%, 73.91% and 75%, respectively. The sensitivity, specificity, PPV, NPV and accuracy of periprosthetic tissue mNGS in the diagnosis of PJI were 95.45%, 90.91%, 91.3%, 95.24% and 93.18%, respectively. The sensitivity and specificity of mNGS in the diagnosis of PJI were superior to those of microbial culture. Periprosthetic tissue can be used as an alternative to synovial fluid and sonication fluid, as mNGS can improve the diagnosis of PJI. mNGS of the periprosthetic tissues showed higher sensitivity than microbial culture.

Preoperative diagnosis is important for patients who need revision surgery due to PJI. Microbial culture plays an important role in PJI diagnosis, but the sensitivity of cultures is low when the sample amount is limited or when a patient is treated with antibiotics before sample collection. In this study, metagenomic next-generation sequencing (mNGS) was used to detect bacteria in preoperative puncture synovial fluid samples from patients with suspected PJI, and the preoperative and intraoperative culture results were compared to estimate the diagnostic efficiency. From July 2016 to December 2018, patients with suspected PJI who underwent prosthetic joint revision surgery were included, and the results of those who had been tested by preoperative synovial fluid culture and mNGS were obtained. The demographic characteristics, medical history, laboratory test results, culture results, and mNGS results of each patient were recorded. Then, the efficiency of preoperative synovial fluid mNGS was compared to that of synovial fluid culture for diagnosing PJI. A total of 37 patients were included, and 24 patients (25 joints) were diagnosed with PJI. The sensitivity, specificity and accuracy of preoperative synovial fluid mNGS were 92%, 91.7%, and 83.7%, respectively. The sensitivity, specificity and accuracy of preoperative synovial fluid culture were 52%, 91.7% and 43.7%, respectively. With a low volume of synovia (1 ml) mNGS can be performed with a higher sensitivity and specificity as compared to synovial culture. Thus, mNGS can be used as an effective supplemental method to improve diagnostic efficiency during the preoperative period.

Objective: To report on our clinical outcomes and on the experience of managing acute periprosthetic joint infection (PJI) with debridement, antibiotics, and implant retention (DAIR).Methods: We performed a retrospective review of all patients who were diagnosed with acute PJI after primary hip or knee replacement surgeries and who were managed with DAIR in our prospective joint replacement registry from 2008 to 2019. The diagnosis of PJI was made according to the 2011 Musculoskeletal Infection Society (MSIS) criteria. The symptom onset duration, inflammatory marker levels (i.e. C‐reactive protein [CRP], erythrocyte sedimentation rate [ESR], white cell count [WBC], and synovial WBC count), functional scores including the Knee Society Score (KSS), the KSS functional score and the Harris Hip Score (HHS), bacteriology, and surgical outcomes of the patients were tracked and recorded. A paired sample of joint fluid and tissues was also sent for a metagenomic next‐generation sequencing (mNGS) test. A paired‐samples t‐test was used to compare the differences in the inflammatory markers and functional scores before and after surgery.Results: A total of 24 patients with 7 infections after hip replacements and 17 infections after knee replacements were included. A total of 21 patients exhibited early postoperative infections, and 3 exhibited late acute hematogenous infections. During a mean follow‐up time of 29.2 ± 15.1 months, 22 patients were successfully treated, whereas 2 patients were unsuccessfully treated and required repeated DAIR. The overall success rate of DAIR was 91.7%. For staphylococcal infections, DAIR had a 100% success rate. Five patients who presented with symptoms between 4 and 8 weeks also achieved a 100% success rate. At the last follow‐up, the mean CRP level decreased from 52.6 ± 34.0 to 5.4 ± 3.5 (P < 0.001), and the mean ESR level decreased from 72.3 ± 34.3 to 20.2 ± 12.1 (P < 0.001). The mean KSS score increased from 44.8 ± 12.2 to 81.4 ± 9.2 (P < 0.001), and the mean KSS functional score increased from 38.1 ± 3.5 to 73.9 ± 23.0 (P < 0.001), and the mean HHS score increased from 34.4 ± 6.9 to 84.1 ± 15.1 (P < 0.001). The overall pathogen identification rate was 91.7% (22/24 cases). The success rates for Staphylococcus, Streptococcus, and the other pathogens were 100% (9/9 cases), 71.4% (5/7 cases), and 100% (6/6 cases), respectively.Conclusion: Debridement, antibiotics, and implant retention has a high success rate for the treatment of acute PJI and may be performed in selected patients whose symptoms have been sustained for over 4 weeks. A high rate of success for staphylococcal infections was reported with the use of DAIR.

Aim: To explore the role of an adipokine-termed fatty acid-binding protein 4 (FABP4) in osteoarthritis (OA). Methods: Patients with primary knee OA and non-OA controls were included. Paired tissues including plasma, synovial fluid (SF), subcutaneous fat and infrapatellar fat pad (IPFP) were harvested during surgery. FABP4 concentration was determined by ELISA. Results: Plasma FABP4 increased significantly with OA stage (n = 263). OA patients (n = 38) had significantly higher plasma and SF FABP4 than non-OA patients (n = 29). FABP4 level of IPFP was positively correlated with SF FABP4. Conclusion: OA patients had significantly high systemic and local FABP4, and IPFP may be the main source of FABP4 in synovial cavity. FABP4 may be a promising biomarker for OA.

The best fixation method (i.e., cemented or cementless) in primary total hip arthroplasty (THA) remains controversial. We reviewed the most updated annual reports from 5 international joint replacement registries with more than 5-year follow up (Sweden, Norway, England-Wales, Australia and New Zealand). We aimed at discovering the fixation method that leads to better long-term survival and less implant-related complications. In addition, we systemically reviewed several randomized controlled trials (RCTs) that were currently available in literature. We concluded that cemented fixation had better overall long-term survivorship than cementless fixation in primary THA. After age stratification, cemented fixation had better survival in older patients while cementless fixation had better survival in younger patients. Periprosthetic fractures were more common in cementless fixation and thus such risk should be informed to patients before surgery.