Evaluation of myeloperoxidase in synovial fluid as a biomarker for chronic periprosthetic joint infection.

PURPOSE: There is no single biomarker that can perfectly diagnose periprosthetic joint infection (PJI). As diagnosing PJI remains a major challenge, accurate and rapid development of a biomarker is required. Myeloperoxidase (MPO) is a bactericidal enzyme that acts against pathogenic microorganisms, such as those found in PJI. We aimed to determine whether elevated MPO levels could be detected in infected synovial fluid and to evaluate its utility as a biomarker for diagnosing chronic PJI. METHODS: Patients who underwent revision total joint arthroplasty were categorised into two groups according to the criteria of the second International Consensus Meeting on Musculoskeletal Infection: chronic PJI or aseptic failure. MPO was measured in synovial fluid collected during surgery. Receiver operating characteristic curves were drawn, and the area under the curve, 95% confidence intervals, and sensitivity/specificity were calculated. RESULTS: Synovial fluid was obtained from 37 patients. Nineteen patients were categorised into the chronic PJI group and 18 in the aseptic failure group. MPO levels in the synovial fluid were significantly higher in the chronic PJI group than in the aseptic failure group (p < 0.001). This measurement demonstrated the diagnostic accuracy of MPO for diagnosing chronic PJI with high sensitivity and specificity. CONCLUSION: Although the results are debatable owing to the small sample size, measurement of MPO demonstrates high accuracy as a biomarker for diagnosing chronic PJI, and it may detect culture-negative chronic PJI. Furthermore, MPO can measure host response to chronic PJI without the potential of contamination.

Clinical usefulness of multiplex PCR-lateral flow for the diagnosis of orthopedic-related infections.

Objectives: Polymerase chain reaction (PCR)-based assays are being increasingly used for the diagnosis of orthopedic-related infections. Unfortunately, classical PCR requires imaging devices that are expensive and complex. We previously developed the PCR-lateral flow (PCR-LF) method, which does not require any additional imaging device. In the present study, the objective was to determine whether PCR-LF tests could be used to effectively diagnose orthopedic-related infections. Methods: In this study, we used PCR-LF to diagnose common causes of orthopedic-related infections and compared the results to those from conventional bacterial cultures of the same samples. Results: Notably, for 228 synovial fluid or pus specimens, the sensitivity and specificity of bacterial cultures were 53.5% and 97.7%, respectively, compared to 61.6% and 89.9% for PCR-LF. Although the difference in sensitivity between bacterial cultures and PCR-LF was not significant, when our analysis was limited to cases with suspected periprosthetic joint infection, the sensitivity of PCR-LF (66.1%) was superior to that of bacterial cultures (42.9%). Conclusion: This study indicates that PCR-LF is a useful method for diagnosing orthopedic-related infections.

Two-stage revision total hip arthroplasty for periprosthetic infections using antibiotic-impregnated cement spacers of various types and materials.

Antibiotic-impregnated hip cement spacers of various types and materials have been used in the treatment of periprosthetic hip infections. We developed a handmade spacer by using polymethylmethacrylate (PMMA) and/or α -tricalcium phosphate ( α -TCP). In this study, we retrospectively reviewed the surgical outcomes in 36 consecutive patients treated with 2-stage revision total hip arthroplasty by using our antibiotic-impregnated hip cement spacers. We aimed to analyze the infection control and reinfection rates after revision surgery. Moreover, we analyzed the possible predictors of postoperative reinfection. After exclusion of 1 patient who died immediately after the first-stage surgery, infection was controlled in 33 of the 36 hips (success rate, 91.7%). Two of these 33 hips underwent resection arthroplasty. Of the 36 hips that had been treated with the antibiotic-cement spacer, 31 hips (86.1%) were eligible for the second-stage prosthesis re-implantation. The 31 protocol hip joints of patients followed up for >6 months (mean, 48.6 months). Ten of these 31 hips (32.3%) became reinfected. No possible predictor examined differed significantly between the reinfection-positive and reinfection-negative groups. However, spacers consisting of PMMA cement alone were associated with the highest risk of reinfection. Therefore, α -TCP-containing antibiotic-impregnated hip cement spacers might decrease the reinfection rate in patients undergoing re-implantation.

Lower SMI is a risk factor for dysphagia in Japanese hospitalized patients with osteoporotic vertebral and hip fracture: A retrospective study.

Objectives: Many patients with osteoporotic fragile fracture often suffer from dysphagia that results in malnutrition, further deterioration of physical strength, and rehabilitation difficulties. This study aims to investigate the risk factors for dysphagia in hospitalized patients with osteoporotic vertebral and/or hip fractures. Methods: Between January 2020 and December 2021, 569 inpatients were managed for osteoporotic vertebral or hip fractures. Of these, 503 patients were analyzed and 66 were excluded as the required data could not be obtained or dysphagia with causative diseases such as cerebrovascular disease. The patients were divided into 2 groups: patients with dysphagia (P-group) and patients without dysphagia (N-group). We investigated gender, fracture site, age, systemic skeletal muscle mass index (SMI), bone mineral density (BMD), and body mass index (BMI) in early stage of hospitalization and studied their relationship with dysphagia. Results: There were no significant differences in gender and fracture site between the 2 groups. A significant difference was observed in age, SMI, BMD, and BMI (P < 0.01). We performed a logistic regression analysis with the P-group as the objective variable and age, SMI, BMD, and BMI as explanatory variables. We divided objective groups into all patients, patients with vertebral fracture, patients with hip fracture, men, and women. SMI was an independent risk factor in all groups. Conclusions: Lower SMI was a risk factor for dysphagia in hospitalized patients with osteoporotic vertebral and hip fractures. We carefully observed swallowing function of patients with decreased SMI to maintain the nutritional status and prevent rehabilitation difficulties.

Double-layered antibiotic-loaded cement spacer as a novel alternative for managing periprosthetic joint infection: an in vitro study.

BACKGROUND: Previous studies comparing antibiotic-loaded calcium phosphate cement to polymethylmethacrylate cement reported that although the former has higher elution volumes over a longer period, it is mechanically weak when used alone. To counter this problem, a double-layered antibiotic-loaded cement spacer in which calcium phosphate cement is coated with polymethylmethacrylate cement was created. METHODS: In this study, we compared the double-layered spacer to the polymethylmethacrylate cement spacer in terms of eluent antibiotic concentration, bioactivity against methicillin-resistant Staphylococcus aureus, and mechanical strength. Double-layered and polymethylmethacrylate cement spacers that were loaded with vancomycin (VCM) were prepared and immersed in phosphate buffer for 84 days. To facilitate VCM elution from calcium phosphate cores in double-layered spacers, we also drilled multiple holes into the calcium phosphate layer from the spacer surface. RESULTS: We found that VCM concentrations in double-layered spacer eluents were higher than those in polymethylmethacrylate cement spacer eluents. The double-layered spacer also had higher bioactivity than the polymethylmethacrylate cement spacer. Although the polymethylmethacrylate cement spacer eluent lost the ability to inhibit bacterial growth on day 56, the double-layered spacer eluent maintained this ability for the duration of our study. Finally, the double-layered spacer retained high mechanical strength throughout the study period. CONCLUSIONS: The beneficial biomechanical and drug-eluting properties of the double-layered spacer might qualify it to serve as a promising biomaterial that could be used for managing periprosthetic joint infections.

Clinical results of arthroscopic surgery in patients over 50 years of age-what viability does it have as a joint preservative surgery?

BACKGROUND: To identify whether hip arthroscopy is a suitable option for treating hip pain in elderly patients and investigate the clinical outcomes of hip arthroscopic surgery for labrum tear and/or osteoarthritis in patients over 50 years of age. METHODS: Between August 2009 and May 2014, a series of 23 patients (6 men and 17 women) with a mean age of 59 years underwent arthroscopy. We retrospectively examined the clinical records, radiographs, and outcome questionnaires from all patients. The mean follow-up period was 28 months. RESULTS: The mean Japan Orthopedic Association hip score after surgery improved by a statistically significant amount. Eight patients (34.8%) were noted to have a progression of osteoarthritis (OA) diagnosed by radiograph, and one underwent THA after 13 months following arthroscopic surgery. The patients in which OA progression was noted were identified as having radiographical OA preoperatively and acetabular cartilage damage in the arthroscopic findings. CONCLUSIONS: Arthroscopic surgery performed in selected patients over 50 years of age might be beneficial if classified as Tönnis grade 0 preoperatively and/or classified as Outerbridge grade II in the arthroscopic findings.

Early fracture of the modular neck of a MODULUS femoral stem.

We present the case of a 46-year-old woman who underwent revision surgery approximately 4 years after total hip arthroplasty because of a fracture of the modular neck of a MODULUS femoral stem. The fractured surfaces of the retrieved implant were inspected using optical and scanning electron microscopy. Three-dimensional finite element analysis was also performed to identify the stresses that might have caused the failure. We concluded that active, obese patients who are implanted with a high-offset, small-sized modular component could experience stress-induced fractures of the modular neck, with proper fixation and osseointegration of the distal stem, especially if residual bone or tissue is present on the inner surface of the neck that could contribute to micromovement and decreased proximal fixation.