Intraoperative Direct Sonication of Implants and Soft Tissue for the Diagnosis of Periprosthetic Joint Infection.

BACKGROUND: Sonication is very efficacious for the microbiological diagnosis of periprosthetic joint infection (PJI), but it involves many steps and multiple workplaces and personnel and therefore carries a potential contamination risk. We present an innovative version of the sonication culture method that involves direct sonication of the retrieved implant and soft tissue, without a sonication tube, intraoperatively and incubation using a BACT/ALERT 3D blood culture system to enhance the efficacy of microbiological diagnosis of PJI. METHODS: We performed a prospective study of consecutive patients requiring implant removal and classified them as having PJI or aseptic failure according to standard criteria. The removed prosthetic components and adjacent soft tissue were directly sonicated in a small metal container, without a sonication tube, during the operation. The sonication fluid was immediately incubated in blood culture bottles in the operating room and cultured in the BACT/ALERT 3D blood culture system. The synovial fluid was also cultured in the BACT/ALERT 3D system to serve as a comparison. RESULTS: Of the 64 included patients, 36 had PJI and 28 had aseptic failure. Fluid from direct sonication and conventional synovial fluid showed sensitivities of 91.7% and 55.6% (p < 0.001) and specificities of 82.1% and 92.9%, respectively. Fourteen cases of PJI were detected by culture of fluid from direct sonication but not by culture of synovial fluid. Higher sensitivity was obtained by direct sonication of only tissue than by direct sonication of only the implant (88.9% versus 75.0%). No significant difference in detection time was found between Staphylococcus aureus and coagulase-negative Staphylococcus. CONCLUSIONS: When combined with incubation in BACT/ALERT bottles, direct intraoperative sonication of implants and soft tissues without a sonication tube was more sensitive than conventional synovial fluid culture and could reliably and rapidly detect the bacteria commonly found in PJI. LEVEL OF EVIDENCE: Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Factors contributing to 1-year dissatisfaction after total knee arthroplasty: a nomogram prediction model.

BACKGROUND: Identifying risk factors and early intervention are critical for improving the satisfaction rate of total knee arthroplasty (TKA). Our study aimed to identify patient-specific variables and establish a nomogram model to predict dissatisfaction at 1 year after TKA. METHODS: This prospective cohort study involved 208 consecutive primary TKA patients with end-stage arthritis who completed self-reported measures preoperatively and at 1 year postoperatively. All participants were randomized into a training cohort (n = 154) and validation cohort (n = 54). Multiple regression models with preoperative and postoperative factors were used to establish the nomogram model for dissatisfaction at 1 year postoperatively. The least absolute shrinkage and selection operator method was used to screen the suitable and effective risk factors (demographic variables, preoperative variables, surgical variable, and postoperative variables) collected. These variables were compared between the satisfied and dissatisfied groups in the training cohort. The receiver operating characteristic (ROC) curve, calibration plot, and decision curve analysis were used to validate the discrimination, calibration, and clinical usefulness of the model. Results were evaluated by internal validation of the validation cohort. RESULTS: The overall satisfaction rate 1 year after TKA was 77.8%. The nomogram prediction model included the following risk factors: gender; primary diagnosis; postoperative residual pain; poor postoperative range of motion; wound healing; and the rate of change in the degree of coronal lower limb alignment (hip-knee-ankle angle, HKA).The ROC curves of the training and validation cohorts were 0.9206 (95% confidence interval [CI], 0.8785-0.9627) and 0.9662 (0.9231, 1.0000) (95% CI, 0.9231, 1.0000), respectively. The Hosmer-Lemeshow test showed good calibration of the nomogram (training cohort, p = 0.218; validation cohort, p = 0.103). CONCLUSION: This study developed a prediction nomogram model based on partially modifiable risk factors for predicting dissatisfaction 1 year after TKA. This model demonstrated good discriminative capacity for identifying those at greatest risk for dissatisfaction and may help surgeons and patients identify and evaluate the risk factors for dissatisfaction and optimize TKA outcomes.

Clinical characteristics and risk factors in the patients with chronic periprosthetic joint infection / 中华骨科杂志

Objective:To investigate the clinical characteristics and risk factors for patients with chronic periprosthetic joint infection (PJI) combined with sinus tract.Methods:The patients with PJI following hip and knee arthroplasty from July 2014 to January 2020 in our institution were retrospectively reviewed. There were 96 males and 101 females, aged from 26 to 86 years with mean age of 62.02±13.54 years. There were 95 hip PJI patients (48.2%, 95/197), 102 knee PJI patients (51.8%, 102/197), 68 patients (34.5%, 68/197) with sinus tract, 129 patients (65.5%, 129/197) without sinus tract, 162 patients (82.2%, 162/197) with positive culture results and 35 patients (17.8%, 35/197) with negative culture results. The patients were divided into two groups according to the sinus tract formation. The diagnosis of PJI was based on the 2011 Musculoskeletal Infection Society (MSIS) criteria. All of the included patients underwent serological laboratory tests (white blood cell count, neutrophil percentage, lymphocyte percentage, hemoglobin, platelet count, mean platelet volume, urea, creatinine, albumin, erythrocyte sedimentation rate, C-reactive protein) and pathogen isolation. The influence of sinus tract on the above test and the effects of complications on sinus tract formation were analyzed. We further investigated the relationship between sinus tract formation and the features of pathogen. In addition, the risk factors for sinus tract formation were analyzed.Results:The mean values of all serological tests were without statistical difference between the groups with and without sinus tract ( P>0.05). The presence of complications had no effect on the occurrence of sinus tract ( P>0.05). The incidence of sinus tract with highly virulent pathogen infection group (52.1%, 25/48) was significantly higher than that in low virulence pathogen group (27.5%, 19/69), in culture negative patients (40.0%, 14/35) and in other cases (22.2%, 10/45; χ 2=11.519, P=0.009). There was no statistical difference between groups based on the Gram staining, antibiotic resistance and polymicrobial infection. Multivariate logistic regression analysis revealed positive associations of extra joint infections ( OR=4.426, 95% CI: 1.095, 17.884) and high virulent pathogen infections ( OR=2.633, 95% CI: 1.171, 5.918) and negative association of age ≥70 ( OR=0.436, 95% CI: 0.205, 0.927) with the risk of sinus tract formation. Conclusion:The presence of sinus tract has no effect on the routine serum tests in patients with chronic PJI. There is only virulence factor which might affect sinus tract formation. For patients with the extra joint infections and high virulence pathogen infections, the formation of sinus tract should be vigilant during treatment.

Relevant factors of serum tests did not meet the diagnostic threshold in patients with periprosthetic joint infection / 中华骨科杂志

Objective:To investigate the relevant factors on serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) which did not meet the 2011 Musculoskeletal Infection Society (MSIS) diagnostic criteria in patients with periprosthetic joint infection (PJI).Methods:During December 2011 to December 2019, a total of 328 patients with PJI were hospitalized for surgery or antibiotic administration, including 152 males and 166 females, aged 62.10±13.74 (range 24-87) years. All patients underwent CRP and ESR before the antibiotic administration or the revision surgery. PJI was diagnosed based on the 2011 MSIS diagnostic criteria. There were 172 knee PJIs (52.4%), 151 hip PJIs (46.0%), 4 elbow PJIs (1.2%) and 1 shoulder PJI (0.3%). Patients were classified according to Tsukayama type, pathogen and immune status. We, further, analyzed relevant factors on CRP and ESR levels in PJI patients.Results:There were 119 patients with CRP and ESR did not meet the MSIS diagnostic criteria, accounting for 36.3% (119/328). Furthermore, there was no significant difference in Tsukayama types among them (χ 2=7.224, P=0.065). In addition, the ratio was 46.4% in patients with negative culture results, which was higher than that in positive culture results (27.4%, χ 2=12.276, P<0.001). The ratio was 42.9% in patients with normal immune status (grade A), which was higher than that of immune grade B (30.6%) and of immune grade C (23.8%) (χ 2=6.586, P=0.037). Multivariate logistic regression analysis showed the negative association between positive culture results and immune grade B with nonconformity ( OR=0.420, P=0.001; OR=0.578, P=0.04). Conclusion:The serum tests level unmet the threshold in MSIS criteria usually present in PJI patients with normal immune status and negative culture results. Thus, we should utilize other methods for diagnosing PJI.

Strontium Ameliorates Glucocorticoid Inhibition of Osteogenesis Via the ERK Signaling Pathway.

Glucocorticoid (GC) has been widely used in clinical work due to its anti-inflammatory and immune-inhibitory properties. However, long-term or high-dose administration is associated with side effects, such as GC-induced osteoporosis (GIOP), which causes great pain for and poses a heavy financial burden on patients. We sought to investigate the potential effects of strontium on GIOP and further explore its underlying mechanisms, including its reversal of the inhibitory effect of GC on osteogenesis of bone marrow-derived mesenchymal stem cells (BMSCs). We incubated BMSCs with Dexamethasone (DEX) in combination with or without strontium and then measured osteogenic and adipogenic gene expression levels by RT-qPCR and Western blot. We added a specific ERK signaling pathway inhibitor, U0126, to evaluate the involvement of that pathway. Strontium promoted osteogenic differentiation and matrix mineralization in DEX-treated BMSCs, accompanied by upregulation of RUNX2, Osx, ALP, BSP, COL1A1, and OCN. DEX blocked the expression of several osteogenesis-related marker genes by activating the ERK signaling pathway. U0126 attenuated the suppression of osteogenesis in DEX-treated BMSCs. These results suggested that strontium could enhance osteogenic differentiation and matrix mineralization by counteracting DEX's inhibitory effect on osteogenesis via the ERK signaling pathway. Therefore, strontium might be a promising therapeutic agent for GIOP.

Low-dose strontium stimulates osteogenesis but high-dose doses cause apoptosis in human adipose-derived stem cells via regulation of the ERK1/2 signaling pathway.

BACKGROUND: Strontium is a widely used anti-osteoporotic agent due to its dual effects on inhibiting bone resorption and stimulating bone formation. Thus, we studied the dose response of strontium on osteo-inductive efficiency in human adipose-derived stem cells (hASCs). METHOD: Qualitative alkaline phosphatase (ALP) staining, quantitative ALP activity, Alizarin Red staining, real-time polymerase chain reaction and Western blot were used to investigate the in vitro effects of a range of strontium concentrations on hASC osteogenesis and associated signaling pathways. RESULTS: In vitro work revealed that strontium (25-500 µM) promoted osteogenic differentiation of hASCs according to ALP activity, extracellular calcium deposition, and expression of osteogenic genes such as runt-related transcription factor 2, ALP, collagen-1, and osteocalcin. However, osteogenic differentiation of hASCs was significantly inhibited with higher doses of strontium (1000-3000 µM). These latter doses of strontium promoted apoptosis, and phosphorylation of ERK1/2 signaling was increased and accompanied by the downregulation of Bcl-2 and increased phosphorylation of BAX. The inhibition of ERK1/2 decreased apoptosis in hASCs. CONCLUSION: Lower concentrations of strontium facilitate osteogenic differentiation of hASCs up to a point; higher doses cause apoptosis of hASCs, with activation of the ERK1/2 signaling pathway contributing to this process.