ABSTRACT
The initiation and operation of the tissue repair program between the broken ends after fracture is very important for fracture healing, which goes through three intertwined and gradual evolution stages: hematoma inflammatory organization stage, primitive callus formation stage and callus remodeling stage. It is completed by a variety of tissues, cells and cytokines in the bone marrow cavity. In the study of the mechanism of fracture healing, it is found that there are many signal pathways and molecules regulating bone repair, including bone formation, bone remodeling and neovascularization. At the cellular level, it regulates osteoblasts, chondrocytes, osteoclasts and endothelial cells. Hippo signaling pathway is a signal pathway that maintains the size of organs and the balance between cell proliferation and apoptosis, and also plays an important role in maintaining bone homeostasis and bone metabolism. In the process of regulating bone development and repair, it regulates the physiological activities of cells in microenvironment through protein kinase cascade reaction and transcriptional coactivator. The upstream and downstream effectors of Hippo signal pathway directly or indirectly regulate the proliferation, differentiation and apoptosis of bone metabolic cells, and the interaction with Wnt signal pathway, Notch signal pathway and other important pathways related to bone repair show that Hippo signal pathway plays an important role in the regulation of fracture healing and may become a new target to promote fracture healing. This article reviews the regulatory mechanism of Hippo signaling pathway and its regulatory role in the process of fracture healing, and looks forward to the research prospect of promoting bone healing by using it as a target.
ABSTRACT
Objective To explore the demographic factors and the risk of the pedicle screw insertion of the narrow pedi?cles. Methods Thoracolumbar spine thin?section CT image data of 312 adults from September 2014 to September 2015 were ana?lyzed. The pedicle width,medial and lateral cortical thickness, spongy bone thickness, spongy bone thickness/cortical thickness, e angle and screw path length of each pedicle were measured. The incidence and the distribution characteristics of the narrow pedi?cle were analyzed. Anatomic parameters and age, gender and stature were compared between the narrow pedicle group and non?narrow pedicle. The risk of the pedicle screw insertion of the narrow pedicle was assessed. Results Among the 3 081 pedicles, 74 narrow pedicles were determined as their pedicles width were less than 5 mm, and the proportion of narrow pedicle was 2.40%. Among the 312 subjects, 26 subjects were found having narrow pedicles, and the proportion of individuals with narrow pedicles in the population was 8.33% (26/312). The incidences of narrow pedicle in thoracolumbar spine were T10 0.32%, T11 0.32%, T12 0.98%, L1 7.54%, L2 2.92%. The spongy bone thickness, spongy bone thickness/cortical thickness of narrow pedicle were lower than non?narrow pedicle. However, there were no significant differences of medial and lateral cortical thickness, e angle and screw path length between the narrow pedicle and non?narrow pedicle. Difference of the mean age between the two subjects groups had no statistical significance. The percentage of female in narrow pedicle subjects group was 84.6%(22/26), which was higher than that in non?narrow pedicle subjects group (49.7%, 142/286). The mean stature of the male and female of stenosis pedicle group subjects were 163.8±1.3 cm and 152.5±4.3 cm, which were shorter than those of non?narrow subjects pedicle group (169.5±5.6 cm, 160.1±6.6 cm). The percentage of the cortical bone breakthrough by the pedicle screws of narrow pedicle group was (84.6%, 27/32), which was higher than that of non?narrow pedicle group (14.7%, 33/224). Conclusion L1 is the most common segment of thoracolumbar spine that narrow pedicle exist, which is the result of reduction of the spongy bone thickness. Narrow pedicle mostly appears in short stature female. There is high risk of cortical bone breakthrough by insertion of the posterior pedicle screws in the narrow pedicle.