ObjectiveMany observational studies have found an association between Alzheimer’s disease (AD) and osteoporosis. However, it is unclear whether there is causal genetic between osteoporosis and AD.MethodsA two-sample Mendelian randomization (MR) study was used to investigate whether there is a causal relationship between osteoporosis and AD. Genes for osteoporosis and AD were obtained from published the genome-wide association studies (GWAS). Single nucleotide polymorphisms (SNPs) with significant genome-wide differences (p < 5 × 10−8) and independent (r2 < 0.001) were selected, and SNPs with F ≥ 10 were further analyzed. Inverse variance weighted (IVW) was used to assess causality, and the results were reported as odds ratios (ORs). Subsequently, heterogeneity was tested using Cochran’s Q test, pleiotropy was tested using the MR–Egger intercept, and leave-one-out sensitivity analysis was performed to assess the robustness of the results.ResultsUsing the IVW method, MR Egger method, and median-weighted method, we found that the results showed no significant causal effect of osteoporosis at different sites and at different ages on AD, regardless of the removal of potentially pleiotropic SNPs. The results were similar for the opposite direction of causality. These results were confirmed to be reliable and stable by sensitivity analysis.ConclusionThis study found that there is no bidirectional causal relationship between osteoporosis and AD. However, they share similar pathogenesis and pathways.

Objectives: The purpose of this study was to explore the clinical value of metagenomic next-generation sequencing (mNGS) in the diagnosis of polymicrobial periprosthetic joint infection (PJI). Methods: Patients with complete data who underwent surgery at our hospital between July 2017 and January 2021 for suspected periprosthetic joint infection (PJI), according to the 2018 ICE diagnostic criteria, were enrolled, and all patients underwent microbial culture and mNGS detection, which were performed on the BGISEQ-500 platform. Microbial cultures were performed on two samples of synovial fluid, six samples of tissue, and two samples of prosthetic sonicate fluid for each patient. The mNGS was performed on 10 tissues, 64 synovial fluid samples, and 17 prosthetic sonicate fluid samples. The results of mNGS testing were based on the interpretation of mNGS results in the previous literature and the assertions of microbiologists and orthopedic surgeons. The diagnostic efficacy of mNGS in polymicrobial PJI was assessed by comparing the results of conventional microbial cultures and mNGS. Results: A total of 91 patients were finally enrolled in this study. The sensitivity, specificity, and accuracy of conventional culture for the diagnosis of PJI were 71.0%, 95.4%, and 76.9%, respectively. The sensitivity, specificity, and accuracy of mNGS for the diagnosis of PJI were 91.3%, 86.3%, and 90.1%, respectively. The sensitivity, specificity, and accuracy of conventional culture for the diagnosis of polymicrobial PJI were 57.1%, 100%, and 91.3%, respectively. mNGS had a sensitivity, specificity, and accuracy of 85.7%, 60.0%, and 65.2%, respectively, for the diagnosis of polymicrobial PJI. Conclusions: mNGS can improve the diagnosis efficiency of polymicrobial PJI, and the combination of culture and mNGS is a promising method to diagnose polymicrobial PJI.

Background Osteopetrosis is a genetic disease characterized by defects in osteoclast formation and function. There were a few cases of subtrochanteric femur fractures treated with dynamic hip screw (DHS) in patients with osteopetrosis, but unfortunately the healing outcome was rather poor. Case presentation We present our experience for treating a patient with intermediate autosomal recessive osteopetrosis (IRO) suffering from subtrochanteric femur fracture. In this case, we successfully used dynamic hip screw (DHS) internal fixation through meticulous preoperative planning and postoperative care, as well as application of surgical techniques. The patient displayed stable internal fixation with no limitation of activities during follow-up for 15 months. In addition to this case, a review of previous case reports showed an increasing number of case reports demonstrating that surgical treatment-related complications could be avoided preoperatively, intraoperatively, and postoperatively. Conclusion DHS for this patient, who suffered from subtrochanteric fractures with osteopetrosis, was successfully implemented. In the light of a comprehensive literature review, preoperative planning, surgical techniques, and postoperative rehabilitation care can significantly reduce the complications.

Background: Coxiella burnetii (C. burnetii) is the causative agent of Q fever and is found worldwide; however, prosthetic joint infections caused by C. burnetii are rarely seen. Because of advances in molecular diagnostic techniques, prosthetic joint infection (PJI) caused by C. burnetii can now be diagnosed.Case Presentation: A 77-year-old male who had undergone total knee arthroplasty had a displaced prosthesis and periprosthetic osteolysis; he had no obvious signs of infection, and microbiological culture was negative. However, C. burnetii was detected by metagenomic next-generation sequencing (mNGS) and pathogen-targeted next-generation sequencing (ptNGS). Finally, polymerase chain reaction (PCR) confirmed the diagnosis of C. burnetii prosthetic joint infection (PJI). After revision surgery (one-stage revision) and oral antibiotics (doxycycline and moxifloxacin hydrochloride), the patient's symptoms disappeared, and he regained the ability to walk. During the 6-month follow-up, the patient's knee showed no signs of swelling, pain or the recurrence of infection, and he experienced no significant complications. We also present a review of the literature for other cases of C. burnetii PJI. Conclusions:The symptoms of C. burnetii PJI may be different from those of Q fever, which may lead to misdiagnosis. mNGS and ptNGS may be helpful for the identification of C. burnetii. Once the diagnosis of C. burnetii PJI is confirmed, doxycycline in combination with a fluoroquinolone can be effectively administered after revision surgery.

The diagnosis and treatment of periprosthetic joint infection (PJI) is complex and the use of MRI in PJI is gaining attention from orthopedic surgeons as MR technology continues to advance. This study aimed to investigate whether metal artefact reduction sequence (MARS) MRI could be used as an adjunct in the preoperative diagnosis of PJI and to explore its role in PJI debridement planning. From January 2020 to November 2021, participants with metal joint prostheses that needed to be judged for infection were prospectively enrolled. According to Musculoskeletal Infection Society standards, 31 cases were classified as infection, and 20 as non-infection. The sensitivity and specificity of MARS MRI for the diagnosis of PJI were 80.65% and 75%, respectively. In MARS MRI, the incidence of bone destruction, lamellar synovitis, and extracapsular soft tissue oedema were significantly higher in PJI than in non-PJI. Fourteen suspicious occult lesions were found in the preoperative MARS MRI in 9 cases, and the location of 9 infection lesions was confirmed intraoperatively. In conclusion, MARS MRI is an effective diagnostic tool for PJIand can provide a visual reference for preoperative surgical planning.