Effect of different surgical methods on traumatic response degree and osteoblast-osteoclast balance in patients with distal tibial fracture

Objective:To study the effect of different surgical methods on trauma response degree and osteoblast-osteoclast balance in patients with distal tibial fracture.Methods:58 cases of patients with distal tibial fracture who received open reduction and internal fixation in Orthopedics Department of our hospital from May 2013 to October 2015 were selected as research subjects and divided into delayed group (n = 29) and routine group (n = 29) according to different timing of surgery. Delayed group received open reduction and internal fixation 7–15 d after trauma and routine group received open reduction and internal fixation within 24 h after trauma. Levels of serum stress response indicators and osteoblast-osteoclast markers were compared between two groups.Results:On the day after operation, serum adrenocorticotropic hormone, cortisol, renin, angiotensin II, epinephrine and norepinephrine levels of delayed group were significantly lower than those of control group (P<0.05);on the 7th day after operation, serum osteocalcin, procollagen type I carboxyl-terminal peptide and bone alkaline phosphatase of delayed group were significantly higher than those of control group (P<0.05) while cross-linked carboxyl-terminal telopeptide of type I collagen and tartrate-resistant acid phosphatase isoform 5b levels were significantly lower than those of control group (P<0.05). Conclusions: Delayed open reduction and internal fixation treatment of distal tibial fracture can reduce the trauma caused by surgical procedures, increase osteoblast viability and inhibit osteoclast viability, which are conducive to fracture healing.

Microstructure of as-extruded 7136 aluminum alloy and its evolution during solution treatment

With the aid of scanning electron microscopy （SEM）, energy-dispersive spectroscopy （EDS）, X-ray diffraction （XRD）, differential scanning calorimetry （DSC） analysis and electron backscatter diffraction （EBSD）, the microstructure of the alloy in as-extruded state and various solution-treated states was investigated. The results indi- cate that second phase of the as-extruded 7136 aluminum alloy mainly consists of Mg（Zn, Cu, Al）2 and Fe-rich phases. The Mg（Zn, Cu, Al）2 phase directly dissolves into the matrix during solution treatment with various solution temperatures. After solution treated at 475℃ for 1 h, Mg（Zn, Cu, Al）2 phases are dissolved into the matrix, while Fe-rich phases still exist. Fe-rich phases could not dissolve into the matrix by prolonging solution time. The mechanical property test and EBSD observation show that two-stage solution treatment makes no significant improvement in mechanical properties and recrystallization of the alloy. The optimized solution treatment parameter is chosen as 475 ℃/1 h.

Transformation and dissolution of second phases during solution treatment of an Al-Zn-Mg-Cu alloy containing high zinc

The transformation and dissolution of Mg（Zn, Cu, Al）2 phase during solution treatment of an Al-Zn-Mg-Cu alloy containing high zinc were investigated by means of optical microscopy （OM）, scanning electron microscopy （SEM）, energy-dispersive X-ray spectrometry （EDX） and X-ray diffraction （XRD）. The results show that solution temperature is the main factor influencing phase dissolution. With solution temperature increasing, the content of residual phases decreases. Phase transformation from Mg（Zn, Cu, Al）2 to S（Al2CuMg） occurs under solution temperature of 450, 460 and 465 ℃. Mg（Zn, Cu, Al）2 phase is directly dissolved into the matrix under solution temperature of 470 and 475 ℃, and no S（Al2CuMg） phase transformed from Mg（Zn, Cu, Al）2 phase is observed. The formation of S（Al2CuMg） phase is mainly controlled by Zn elemental diffusion. The mechanism of transformation and dissolution of second phases was investigated. At low temperature, the dissolution of Zn is faster than that of Mg and Cu, resulting in an appropriate condition to form S（Al2CuMg） phase. At high temperature, the dissolution of main alloying elements has no significant barrier among them to form S（Al2CuMg） phase.