[Clinical analysis for fixation failure of 13 patients with intertrochanteric fractures].

OBJECTIVE: To analysis the reasons of fixation failure for intertrochanteric fractures, so as to select correct operation indications and fixation methods. METHODS: Retrospective analysis the clinical data of 13 patients with failed internal fixation of intertrochanteric fractures from September 1997 to September 2008, and the failure reasons were summarized. There were 7 males and 6 females,ranging in age from 58 to 93 years,averaged 71 years. Two patients were treated with intramedullary fixation, 4 patients with anatomical proximal femoral plate, 3 patients with DHS fixation, 2 patients with hollow compression screws, and 2 patients with external fixation. According to Evans types: 1 patient was type II, 7 patients were type III, and 5 patients were type IV. RESULTS: Eight patients with unstable fractures and malreduction had no grafted bone. Six patients had bad position of neck screws in the femur neck. Postoperative collodiaphyseal angle: 3 patients were under 90 degree, 7 patients 90 to 110 degree, and 3 patients 110 to 130 degree. Five patients had internal fixed screw exited, 6 patients had neck screws cutting to superior lateral, 3 patients had early weight bearing, and 10 patients were osteoporosis occurred after operation from 6 weeks to 11 months, averaged 4.5 months. CONCLUSION: The fixation failure of intertrochanteric fractures was concerned with fractures types, reduction, fixation methods, osteoporosis and the time of weight bearing.

Complexation of a pentiptycene-based tweezer-like receptor with paraquat derivatives: ion-controlled binding and release of the guests.

A new tweezer-like receptor containing a pentiptycene unit and a benzene ring linked by two crown ether chains has been synthesized. It could form stable complexes with paraquat derivatives with different functional groups in solution and in the solid state. It was found that the complexes dissociated upon two one-electron reduction of the bipyridinium ring. Moreover, binding and release of the guest molecules could also be easily controlled by the addition and removal of potassium ion.