The aim of this study was designed to assess the risk factors of lag-screw cutout in the treatment of intertrochanteric fracture with a dynamic hip screw (DHS). From 2003 to 2007, 1,150 patients who had acute unilateral intertrochanteric fractures of the femur were enrolled to the study. All fractures were managed by closed reduction and internal fixation with 135°DHS devices. Patient demographics, fracture patterns, reduction and fixation and perioperative course parameters were all recorded. The follow-up period was 38 months on average (range 16-60 months). Finally, 937 patients were available for evaluation of final results in which we focused on lagscrew cutout. Excluding complications not related to screw position, 64 patients (6.8%) with screw cutout were encountered, and the remaining 873 patients had uneventful union, with the average union time of 17.5 weeks (range15-24 weeks). Upon analysis with logistic regression, the tip−apex distance (TAD) was shown to be the most important predictive factor for cutout, followed by screw position, fracture pattern, reduction and patient age. In order to decrease the risk of lag-screw cutout, it is important to ensure good fracture reduction and to place the lag screw in either the middle/middle or inferior/middle position with appropriate TAD.

SummaryMammalian aging of many tissues is associated with a decline in the replicative and functional capacity of somatic stem cells. Understanding the basis of this decline is a major goal of aging research. Human bone marrow-derived multipotent stromal cells (MSCs) have been applied in the treatment of fracture nonunion. Clinical application of MSCs requires abundant cells that can be overcome by ex vivo expansion of cells, but often at the expense of stemness and differentiation potentiality. We first demonstrated that late-passage MSCs exhibited decreased proliferation capacity, reduced expression of stemness markers such as Oct-4 and Nanog, and deterioration of osteogenic potential. Further, late-passage MSCs showed increased expression of p21 Cip1 ⁄ Waf1 (p21), an inhibitor of the cyclin-dependent kinase. Knockdown of p21 by lentivirus-mediated shRNAs against p21 in late-passage MSCs increased the proliferation capacity, the expression of Oct-4 and Nanog, and osteogenic potential compared with cells transduced with control shRNA. More importantly, reduction in p21 expression in MSCs enhanced the bone repair capacity of MSCs in a rodent calvarial defect model. Knockdown of p21 in MSCs also increased the telomerase activity and telomere length, and did not show chromosomal abnormalities or acquire transformation ability. Therefore, these data successfully demonstrate the involvement of senescence gene in the expression of stemness markers and osteogenic potential of MSCs.

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Open reduction and internal fixation with appropriate surgical technique is effective in the treatment of displaced fractures of the distal humerus in elderly patients.