Tissue-engineered calcium phosphate cement in rabbit femoral condylar bone defects / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Calcium phosphate cement (CPC) is a favorable bone-graft substitute, with excellent biocompatibility and osteoconductivity. However, its reduced osteoinductive ability may limit the utility of CPC. To increase its osteoinductive potential, this study aimed to prepare tissue-engineered CPC and evaluate its use in the repair of bone defects. The fate of transplanted seed cells in vivo was observed at the same time.</p><p><b>METHODS</b>Tissue-engineered CPC was prepared by seeding CPC with encapsulated bone mesenchymal stem cells (BMSCs) expressing recombinant human bone morphogenetic protein-2 (rhBMP-2) and green fluorescent protein (GFP). Tissue-engineered CPC and pure CPC were implanted into rabbit femoral condyle bone defects respectively. Twelve weeks later, radiographs, morphological observations, histomorphometrical evaluations, and in vivo tracing were performed.</p><p><b>RESULTS</b>The radiographs revealed better absorption and faster new bone formation for tissue-engineered CPC than pure CPC. Morphological and histomorphometrical evaluations indicated that tissue-engineered CPC separated into numerous small blocks, with active absorption and reconstruction noted, whereas the residual CPC area was larger in the group treated with pure CPC. In the tissue-engineered CPC group, in vivo tracing revealed numerous cells expressing both GFP and rhBMP-2 that were distributed in the medullar cavity and on the surface of bony trabeculae.</p><p><b>CONCLUSION</b>Tissue-engineered CPC can effectively repair bone defects, with allogenic seeded cells able to grow and differentiate in vivo after transplantation.</p>

Diagnostic features of pathological fractures located in extremities caused by bone tumor or tumor like lesion / 中华骨科杂志

ObjectiveTo explore the clinical characteristics of pathological fracture in extremities caused by bone tumors or tumor-like lesions. MethodsFrom August 2002 to December 2010, 139 patients with pathological fractures were entered in the study, including 79 males and 60 females with an average age of 31.1 years. Fractures included tumor-like lesion in 55 cases, benign tumor in 13, giant cell tumor (GCT)in 7, primary malignant tumors in 28, and metastatic tumors in 36. Forces induced to fractures were classified into four grades: spontaneous fracture, functional activity, minor injury, severe injury. Age, fracture location, histological results, fractures forces, prodromes, and misdiagnosis were all observed. Chi-square test were use to compare forces and prodromes within different tumors. ResultsThe highest morbidity rate is 32.4％(45/139) which lies in 11-20 years old. The cites of fractures including femurs in 71 cases, humerus in 36, tibia in 15, fingers in 7, radiuses in 4, fibula in 3, ulnas in 2, and metatarsus in 1. Fracture forces include spontaneous fractures in 29 cases, functional activity in 42, minor injuries in 65, and traumatic injuries in 3. Sixty-seven patients(48.2％) had local prodromes. The prodromes of both malignant tumors and metastatic tumors were more than benign tumors. Twenty cases experienced misdiagnosis with average delay time of 12 weeks. ConclusionMinor injury forces and local prodromes are clinical key features of pathological fractures. Both of them are key points of avoiding misdiagnosis.