A multifunctional composite hydrogel that sequentially modulates the process of bone healing and guides the repair of bone defects.

Calcium carbonate (CaCO3), which exhibits excellent biocompatibility and bioactivity, is a well-established bone filling material for bone defects. Here, we synthesized CaCO3microspheres (CMs) to use as an intelligent carrier to load bone morphogenetic protein-2 (BMP-2). Subsequently, drug-loaded CMs and catalase (CAT) were added to methacrylated gelatin (GelMA) hydrogels to prepare a composite hydrogel for differential release of the drugs. CAT inside hydrogels was released with a fast rate to eliminate H2O2and generate oxygen. Constant BMP-2 release from CMs induced rapid osteogenesis. Resultsin vitroindicated that the composite hydrogels efficiently reduced the level of intracellular reactive oxygen species, preventing cells from being injured by oxidative stress, promoting cell survival and proliferation, and enhancing osteogenesis. Furthermore, animal experiments demonstrated that the composite hydrogels were able to inhibit the inflammatory response, regulate macrophage polarization, and facilitate the healing of bone defects. These findings indicate that a multi-pronged strategy is greatly expected to promote the bone healing by modulating pathological microenvironments.

Tourniquet use benefits to reduce intraoperative blood loss in patients receiving total knee arthroplasty for osteoarthritis: An updated meta-analysis with trial sequential analysis.

PURPOSE: The efficacy and safety of tourniquets use during total knee arthroplasty (TKA) in patients with osteoarthritis remain debated. This updated systematic review and meta-analysis aimed to further evaluate the role of tourniquets use in patients undergoing TKA for knee osteoarthritis by introducing trial sequential analysis. METHODS: PubMed, Embase, and the Cochrane Library were searched. We used the Cochrane risk of bias tool for quality assessment. Statistical heterogeneity across studies was evaluated using Cochran's Q and I2 statistic. Meta-analysis was performed using Stata/SE 14.0, and trail sequential analysis was performed using TSA software version 0.9.5.10 Beta. In addition, qualitative summary was also used to describe results. RESULTS: 15 randomized controlled trials (RCTs) involving 1202 patients were included in the meta-analysis. The pooled results showed that tourniquet use during TKA significantly reduced intraoperative blood loss (mean difference (MD)= -123.84, 95% confidence interval (CI): -163.37 to -84.32, p < .001)and shortened operation time (MD = -4.71, 95% CI: -7.6 to -1.82, p = .001), but there were no significant differences in postoperative blood loss, calculated blood loss, total blood loss, transfusion rate (p = .939), and deep venous thrombosis (DVT) rate between the tourniquet and no-tourniquet groups. TSA confirmed that the result of operation time was false positive, but the results of other outcomes were conclusive. The results of qualitative summary showed conflicting findings in terms of pain, range of motion (RoM) and swelling ratio between the two groups. CONCLUSIONS: Tourniquet use in patients receiving TKA for osteoarthritis benefits to reduce intraoperative blood loss but has no effect on postoperative blood loss, calculated blood loss, total blood loss, operation time, transfusion rate, and DVT rate. In addition, it remains unclear the difference between the tourniquet and non-tourniquet groups in terms of pain, RoM and swelling ratio.