Osteonecrosis of the femoral head (ONFH) is a disabling disease characterized by the disruption of the blood supply to the femoral head, leading to the apoptosis and necrosis of bone cells and subsequent joint collapse. Total hip arthroplasty is not optimal since most patients are young. Multiple risk factors contribute to osteonecrosis, including glucocorticoid (GC) usage, excessive alcohol intake, hypercholesterolemia, and smoking. Continuous stimulation by many variables causes a chronic inflammatory milieu, with clinical repercussions including endothelial dysfunction, leading to thrombosis, coagulopathy, and poor angiogenesis. Immune cells are the primary regulators of inflammation. Innate and adaptive immune cells interact with endothelial cells to hinder the regeneration and repair of bone lesions. An in-depth examination of the pathological drivers of ONFH reveals that endothelial dysfunction may be a major cause of osteonecrosis. Understanding the involvement of endothelial dysfunction in the chronic inflammation of osteonecrosis could aid in the development of possible therapies. This review summarizes the role of endothelial cells in osteonecrosis and further explains the pathophysiological mechanism of endothelial dysfunction in this disease from the perspective of inflammation to provide new ideas for the treatment of osteonecrosis.

Background: The purpose of this study was to compare total complications, complications stratified by type, readmissions, and reoperations at 30 and 90 days after outpatient and standard inpatient total knee and total hip arthroplasty (TKA, THA).Methods: A literature search was conducted from the PubMed, Cochrane Library, and Embase databases for articles published before 20 August 2021. The types of studies included prospective randomized controlled trials, prospective cohort studies, retrospective comparative studies, retrospective reviews of THA and TKA registration databases, and observational case-control studies. Comparisons of interest included total complications, complications stratified by type, readmissions, and reoperations at 30 and 90 days. The statistical analysis was performed using Review Manager 5.3.Results: Twenty studies with 582,790 cases compared relevant postoperative indicators of outpatient and inpatient total joint arthroplasty (TJA) (TKA and THA). There was a significant difference in the total complications at 30 days between outpatient and inpatient THA (p = 0.001), readmissions following TJA (p = 0.03), readmissions following THA (p = 0.001), stroke/cerebrovascular incidents following TJA (p = 0.01), cardiac arrest following TJA (p = 0.007), and blood transfusions following TJA (p = 0.003). The outcomes showed an obvious difference in 90-day total complications between outpatient and inpatient TJA (p = 0.01), readmissions following THA (p = 0.002), and surgical-related pain following TJA (p < 0.001). We did not find significant differences in the remaining parameters.Conclusion: Outpatient procedures showed comparable and even better outcomes in total complications, complications stratified by type, readmissions, and reoperations at 30 and 90 days compared with inpatient TJA for selected patients.

Avascular necrosis of the femoral head (ANFH) is a type of osteonecrosis due to the cessation of blood supply, characterized by persistent local pain and collapse of the joint. The etiology of ANFH is multifaceted, and while its precise pathogenesis remains elusive, it is currently widely believed that the femoral head is highly dependent on the vascular system. A large number of studies have shown that vascular injury is the initial factor in the onset of ANFH. In this review, we briefly introduced the process of angiogenesis and the blood supply to the femoral head, with a focus on summarizing the existing research on promoting angiogenesis for the treatment of ANFH. We conclude that providing alternative pathways through angiogenesis to resolve the problem of the obstructed free flow of the blood is an important means of treating ANFH. Moreover, we also looked forward to the mechanism of endothelial metabolism, which has not yet been studied in femoral head necrosis models, providing potential strategies for more effective use of angiogenesis for the treatment of femoral head necrosis.

Endothelial impairment and dysfunction are closely related to the pathogenesis of steroid-associated osteonecrosis of the femoral head (SONFH). Recent studies have showed that hypoxia inducible factor-1α (HIF-1α) plays a crucial role in endothelial homeostasis maintenance. Dimethyloxalylglycine (DMOG) could suppress HIF-1 degradation and result in nucleus stabilization by repressing prolyl hydroxylase domain (PHD) enzymatic activity. Our results showed that methylprednisolone (MPS) remarkably undermined biological function of endothelial progenitor cells (EPC) by inhibiting colony formation, migration, angiogenesis, and stimulating senescence of EPCs, while DMOG treatment alleviated these effects by promoting HIF-1α signaling pathway, as evidenced by senescence-associated β-galactosidase (SA-β-Gal) staining, colony-forming unit, matrigel tube formation, and transwell assays. The levels of proteins related to angiogenesis were determined by ELISA and Western blotting. In addition, active HIF-1α bolstered the targeting and homing of endogenous EPCs to the injured endothelium in the femoral head. Histopathologically, our in vivo study showed that DMOG not only alleviated glucocorticoid-induced osteonecrosis but also promoted angiogenesis and osteogenesis in the femoral head as detected by microcomputed tomography (Micro-CT) analysis and histological staining of OCN, TRAP, and Factor Ⅷ. However, all of these effects were impaired by an HIF-1α inhibitor. These findings demonstrate that targeting HIF-1α in EPCs may constitute a novel therapeutic approach for the treatment of SONFH.