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OBJECTIVE To explore a classification method which can provide the clinical guidance for internal fixation of tibial fracture. METHODS The different fractures were fixed according to their mechanical classification. Totally, 71 cases of tibial plateau fracture, tibial proximal fracture, tibial distal fracture and Pilon fracture were analyzed to test this selective principle. RESULTS All 71 patients were followed up for 6-32 months. The displacement was seldomly observed in cases treated acccording to the classification principle, while some cases against the principle had postoperative displacement. The difference was statistically significant (P less than 0.05). It was proved that there was remarkable correlation between tibial fracture classification, internal fixator and fixation methods. CONCLUSION Types IIIa3, IIIb1 and IIIb2 fractures without eccentric moment should be fixed with double plates or angle-stable materials combined with locking structure, otherwise displacement may occur.

SummaryCoordinating growth and communication between adjacent cells is a critical yet poorly understood aspect of tissue development and organ morphogenesis. We report a Rho GTPase signaling network underlying the jigsaw puzzle appearance of Arabidopsis leaf pavement cells, in which localized outgrowth in one cell is coordinated with localized inhibition of outgrowth of the adjacent cell to form interdigitating lobes and indentations. Locally activated ROP2, a Rho-related GTPase from plants, activates RIC4 to promote the assembly of cortical actin microfilaments required for localized outgrowth. Meanwhile, ROP2 inactivates another target RIC1, whose activity promotes well-ordered cortical microtubules. RIC1-dependent microtubule organization not only locally inhibits outgrowth but in turn suppresses ROP2 activation in the indentation zones. Thus, outgrowth-promoting ROP2 and outgrowth-inhibiting RIC1 pathways antagonize each other. We propose that the counteractivity of these two pathways demarcates outgrowing and indenting cortical domains, coordinating a process that gives rise to interdigitations between adjacent pavement cells.

Pollen-tube growth not only represents an essential stage of plant reproduction but also provides an attractive model for studying cell polarity and morphogenesis. For many years, pollen-tube growth has been known to require a tip-focused Ca2+ gradient and dynamic F actin, but the way that these are controlled remained a mystery until recently. Rop appears to be activated at growth sites by a tip-localized growth cue, acting as a central switch that controls the polar growth of pollen tubes, probably having its effect through phosphoinositides and Ca2+. These findings have begun to shed light on the molecular basis of pollen-tube growth and cell morphogenesis in plants.