OBJECTIVE To study the improvement effects and mechanism of proanthocyanidins （PACs） on steroid-induced osteonecrosis of the femoral head （SONFH） in rabbits based on the receptor-interacting protein kinase 1 （RIPK1）/RIPK3/mixed lineage kinase domain-like protein （MLKL） signaling pathway. METHODS SONFH model in rabbits was induced by injecting Escherichia coli endotoxin+methylprednisolone. The successfully modeled rabbits were randomly divided into Model group （normal saline）， low-dose PACs group （PACs-L group， 11 mg/kg）， high-dose PACs group （PACs-H group， 22 mg/kg）， high-dose PACs+ RIPK1 activator （rRIPK1） group （PACs-H+rRIPK1 group， 22 mg/kg PACs+4 μg/kg rRIPK1）， along with a control group （normal saline）， with 6 rabbits in each group. Each administration group was given relevant medicine once a day intragastrically/via injection， for 4 consecutive weeks. After the last administration， the levels of tumor necrosis factor-α （TNF-α） and interleukin-6 （IL-6） in rabbit serum were measured. The changes in the microstructure of rabbit femurs， including bone mineral density （BMD）， trabecular thickness （Tb.Th）， trabecular number （Tb.N）， and trabecular separation （Tb. Sp） were examined. The histopathological features of rabbit femoral tissues were observed， and the apoptotic status of cells within the rabbit femoral tissues was detected. The mRNA expressions of vascular endothelial growth factor （VEGF） and bone morphogenetic protein 2 （BMP2） in rabbit femoral tissues were determined. The expressions of RIPK1/RIPK3/MLKL signaling pathway-related proteins in femoral tissues were detected. RESULTS Compared with the Control group， serum contents of TNF-α and IL-6， Tb.Sp， empty bone cavity rate， cell apoptosis rate， phosphorylation levels of RIPK1， RIPK3 and MLKL in femoral tissue were significantly increased in the Model group （P＜0.05）. BMD， Tb.Th， Tb.N， as well as the mRNA expression of VEGF and BMP2， along with protein expression of caspase-8， in the femoral tissues were all decreased （P＜0.05）. The bone cells in the femoral tissue were unevenly distributed， and the trabeculae were arranged sparsely. Compared with the Model group， the aforementioned quantitative indicators （P＜0.05） and pathological changes in all dosage groups of PACs showed significant improvements. Compared with the PACs-H group， the aforementioned quantitative indicators （P＜0.05） and pathological changes in the PACs-H+rRIPK1 group showed significant reversal. CONCLUSIONS PACs can ameliorate SONFH in rabbits， and its mechanism of action may be related to the inhibition of the activation of the RIPK1/RIPK3/MLKL signaling pathway， suppression of apoptosis in femoral tissue cells， and promotion of angiogenesis.

Objective: To analyze the clinical characteristics and treatment of pseudohypoparathyroidism(PHP) in children and to increase clinicians′understanding of this disorder. Methods: From January 2008 to November 2018, a total of 14 PHP patients at our hospital were retrospectively analyzed, as regarding the clinical manifestation, laboratory examination and imaging data.The patients were further divided into two groups according to onset age: group A(under 1 year) and group B(over or equal to 1 year). The laboratory findings were compared between the two groups. Results: Of the 14 patients(10 boys and 4 girls), the median age of onset was 12 years(range: 1 day to 16 years). Epilepsy is one of the most common manifestations of PHP.Laboratory findings include hypocalcemia(1.06-2.18mmol/L), hyperphosphatemia(2.1-3.5 mmol/L), and elevated concentrations of PTH(105.6-733.0 pg/ml). PTH levels were significantly lower in the group A than in group B(Z=2.07, P=0.042). Five patients were found to have calcifications in bilateral basal ganglia and cerebral parenchyma by head CT.All the patients were improved after treatment, which included calcium gluconate injection to control tetany, calcium supplement combined with vitamin D and/or calcitriol orally. Conclusion For children who presented frequent hypocalcemia tetany and calcifications in head CT, serum calcium, phosphorus, PTH levels should be further investigated to make a correct diagnosis.Calcium supplement combined with vitamin D or its metabolites is an effective therapy for PHP children.

Objective To provide accurate bone tunnel positioning reference for clinical individual anterior cruciate ligament (ACL) reconstruction by three-dimensional (3D) reconstruction of femoral and tibial original footprint of ACL.Methods Forty volunteers were selected for this study,including 20 males and 20 females,and aged 18 to 35 years old.3D CT scanning images of knee data were obtained.3D bone models of knee and footprint of ACL were reconstructed.On the 3D reconstruction models,the shape and position of original footprint of ACL were displayed.Statistical significance was compared for their difference.Results Femoral original footprint of ACL,long axis of footprint,distances to the distal margin of the articular cartilage (DDCM),distances to the posterior margin of the articular cartilage (DPCM),double bundle center distance,and tibial original footprint short axis of ACL were significantly different between genders (P ＜ 0.05).However,no significant difference was found between genders for tibial original footprint long axis of ACL (P ＞ 0.05).Conclusions The insertion mark shape and nature position of footprint of ACL could be observed by 3D reconstruction using CT scan images.