BackgroundStrontium 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).MethodQualitative 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.ResultsIn 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.ConclusionLower 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.

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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.

Background: The purpose of this study was to determine the association between preoperative idiopathic serum CRP and ESR elevation in KOA patients with 90-day PJI after primary TKA.Methods: We reviewed our center’s database over a 60-month study period from November 2016 to October 2021. After excluding those with known diseases that elevate CRP and ESR, 882 KOA patients who met the initial screening criteria, namely, 293 males and 589 females aged 67.00±7.91 (range, 43-91) years, were divided into four groups based on the preoperative CRP level and ESR: 44 patients, CRP+ESR+; 27 patients, CRP+ESR-; 176 patients, CRP-ESR+; and 635 patients, CRP-ESR-. All patients underwent primary TKA, and the prevalence of PJI was evaluated based on the 2014 MSIS acute diagnostic criteria. The risk factors for CRP and ESR elevation were analyzed by binary logistic regression.Results: The total infection rate was 1.59% (14/882); infection rates in the CRP+ESR+, CRP+ESR-, CRP-ESR+ and CRP-ESR- groups were 6.82% (3/44), 0 (0/27), 2.27% (3/176), and 1.10% (7/635), respectively. There was a significant relationship between preoperative idiopathic ESR or CRP elevation and the prevalence of 90-day PJI (P=0.022). Diabetes mellitus (P=0.0004) and an elevated body mass index (BMI) (P<0.0001) were risk factors for CRP elevation; being female (P<0.0001) and having an elevated BMI (P<0.0001) or diabetes mellitus (P=0.0036) were risk factors for ESR elevation.Conclusion: Preoperative idiopathic CRP and/or ESR elevation increase the risk of 90-day PJI after primary TKA. Demographic characteristics and complications should be considered before deciding whether surgery can be performed, or additional perioperative treatment is needed to reduce the occurrence of PJI.