Etiology and Pathogenesis of Corticosteroid-Associated Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is an intractable disease occurring at a relatively young age. The characteristic finding of ONFH – the femoral head collapse with severe hip pain – is observed in many cases, which frequently leads to further joint destruction, requiring surgical treatment. Among the associated factors of ONFH, majority of patients who require high-dose corticosteroid are still challenging due to inevitable therapeutic option regardless of poor prognosis. As a pathological mechanism, ONFH is defined as tissue necrosis in the femoral head region due to occlusion of the nutrient vessels; but the detailed micro-level processes leading to blood flow failure remains unclear. The elucidation of ONFH and the establishment of preventive therapy is desirable for these patients. Here, we discuss the etiology and pathogenesis of corticosteroid-associated ONFH by reviewing current literature.

Research on the Reasonable Grouting Strength of Rock-Like Samples in Different Strengths

One of the key points to make grouting reinforcement technology efficient and economical in engineering is to find out the optimal match relationship between different strengthsofrock mass and strength ofgrouting material. It can be called areasonable grouting strength. To explore that, 5 kinds of N (compressive strength of cement mortar) were used to make samples to simulate the different rock strengths. Five kinds of M (compressive strength of inorganic double-fluid material) were used to grout the structural plane of samples. Then the shearing experiment was carried out under the same normal stress conditions. Finally, based on the analyses of experimental results, the C (the reasonable range of grouting parameters) was proposed. The result shows that when M is the same, the smaller N is, the higher the τ(shearing strength of samples) growth rate is. When N is the same, with the increase of M, the growth rate of τ tends to zero. According to the shearing failure process and morphology of the samples, when N is the same, with the increase of M, the failure typeofsamples change from plastic flow failure to brittle sliding failure which is the same as the samples without the structural plane. C is equal to the ratio of M to N, and then the evaluation criteria of C is established by judging that if it is in the range from 1.19 to CMAX(CMAX = 0.0095N2 − 0.43N + 5.83). It will provide a certain basis to select the M in engineering in which N is known.