The purpose of this study was to evaluate whether AGEs induce annulus fibrosus (AF) cell apoptosis and to further explore the mechanism by which this process occurs.

AF cells were treated with various concentrations of AGEs for 3 days. Cell proliferation was measured by the Cell Counting Kit-8 (CCK-8) and EdU incorporation assays. Cell apoptosis was examined by the Annexin V/PI apoptosis detection kit and Hoechst 33342. The expression of apoptosis-related proteins, including Bax, Bcl-2, cytochrome c, caspase-3 and caspase-9, was detected by western blotting. In addition, Bax and Bcl-2 mRNA expression levels were detected by RT-PCR. Mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) production of AF cell were examined by JC-1 staining and DCFH-DA fluorescent probes, respectively.

Our results indicated that AGEs had inhibitory effects on AF cell proliferation and induced AF cell apoptosis. The molecular data showed that AGEs significantly up-regulated Bax expression and inhibited Bcl-2 expression. In addition, AGEs increased the release of cytochrome c into the cytosol and enhanced caspase-9 and caspase-3 activation. Moreover, treatment with AGEs resulted in a decrease in MMP and the accumulation of intracellular ROS in AF cells. The antioxidant N-acetyl-L-cysteine significantly reversed AGE-induced MMP decrease and AF cell apoptosis.

These results suggest that AGEs induce rabbit AF cell apoptosis and mitochondrial pathways may be involved in AGE-mediated cell apoptosis, which may provide a theoretical basis for diabetic IVD degeneration.

Most patients with a nightstick fracture of the ulna are treated conservatively. Various techniques of immobilisation or early mobilisation have been studied. We performed a systematic review of all published randomised controlled trials and observational studies that have assessed the outcome of these fractures following above- or below-elbow immobilisation, bracing and early mobilisation. We searched multiple electronic databases, related bibliographies and other studies. We included 27 studies comprising 1629 fractures in the final analysis. The data relating to the time to radiological union and the rates of delayed union and nonunion could be pooled and analysed statistically.

We found that early mobilisation produced the shortest radiological time to union (mean 8.0 weeks) and the lowest mean rate of nonunion (0.6%). Fractures treated with above- or below-elbow immobilisation and braces had longer mean radiological times to union (9.2 weeks, 9.2 weeks and 8.7 weeks, respectively) and higher mean rates of nonunion (3.8%, 2.1% and 0.8%, respectively). There was no statistically significant difference in the rate of non- or delayed union between those treated by early mobilisation and the three forms of immobilisation (p = 0.142 to p = 1.000, respectively). All the studies had significant biases, but until a robust randomised controlled trial is undertaken the best advice for the treatment of undisplaced or partially displaced nightstick fractures appears to be early mobilisation, with a removable forearm support for comfort as required.

Cite this article: Bone Joint J 2013;95-B:952–9.

In a rabbit model we investigated the efficacy of a silk fibroin/hydroxyapatite (SF/HA) composite on the repair of a segmental bone defect. Four types of porous SF/HA composites (SF/HA-1, SF/HA-2, SF/HA-3, SF/HA-4) with different material ratios, pore sizes, porosity and additives were implanted subcutaneously into Sprague-Dawley rats to observe biodegradation. SF/HA-3, which had characteristics more suitable for a bone substitite based on strength and resorption was selected as a scaffold and co-cultured with rabbit bone-marrow stromal cells (BMSCs). A segmental bone defect was created in the rabbit radius. The animals were randomised into group 1 (SF/HA-3 combined with BMSCs implanted into the bone defect), group 2 (SF/HA implanted alone) and group 3 (nothing implanted). They were killed at four, eight and 12 weeks for visual, radiological and histological study.

The bone defects had complete union for group 1 and partial union in group 2, 12 weeks after operation. There was no formation of new bone in group 3. We conclude that SF/HA-3 combined with BMSCs supports bone healing and offers potential as a bone-graft substitute.