Objective To discuss the related factors of early pathological fracture after curettage of benign bone tumors in femoral shaft.Methods The clinical data of 47 patients with benign bone tumors in femoral shaft,treated by curettage with bone graft via the vastus lateralis approach from March 2004 to March 2011,were retrospectively analyzed.Thirteen patients of them presented with early pathological fracture after the curettage.In fracture group,there were 13 cases,11 males and 2 females,and the time from finishing curettage to fracture occurring ranged from 21 to 36 days.In non-fracture group,there were 34 cases,23 males and 11 females.The following data of fracture group and non-fracture group were compared and analyzed,such as specific value of absolute width of tumor and transverse diameter of bone shaft,specific value of defect width of bone window and sagittal diameter of bone shaft,defect length-width ratio of bone window,defect morphology of bone window,classification of bone tumor,violence of causing injury and compliance to medical advice.Results The average defect length-width ratio of bone window in fracture group was 3.72±3.58,in non-fracture group was 2.67±6.35.For classification of tumor,in fracture group 1 case was in incubation period,6 in active period,6 in invasion period; in non fracture group 21 cases were in incubation period,10 in active period,and 3 in invasion period.Four cases in fracture group had poor compliance to medical advice,and 9 in non-fracture group had good compliance.Between two groups,there were no statistical differences in specific value of absolute width of tumor and transverse diameter of bone shaft,specific value of defect width of bone window and sagittal diameter of bone shaft,and defect morphology of bone window.Conclusion When defect length-width ratio of bone window is larger than 4,the classification of tumor causes expanded incisal edge,and the cortical bone was damaged extensively,there are more possibilities for pathological fracture.

Objective:This study aims to reveal the special immune infiltrating environment and possible immune escape mechanism of giant cell tumor of bone through single-cell sequencing data.Methods:The fresh samples obtained from 4 patients with primary giant cell tumor of bone from January 2018 to December 2021 were collected, and single-cell transcriptome sequencing was performed on the 10X platform to explore the characteristics and immune environment of giant cell tumor of bone by using t-distributed stochastic neighbor embedding ( t-SNE). The main cell types and signal pathways of immune cell regulation and function in giant cell tumor of bone were observed by cell communication analysis. Results:Cell clustering, the definition of basic cell types, the classification of immune cells, and the mutual regulatory relationship between cell types were analyzed for 35 643 single-cell data from 4 giant cell tumor samples of bone. It was found that giant cell tumor of bone was composed of 9 basic cell types, in which the immune cells were mainly CD8 + T cells (51%) and the non-immune cells were mainly fibroblast like spindle stromal cells (74%). The immune infiltration of giant cell tumor of bone is dominated by cytotoxic CD8 + T cells and lacks exhausted CD8 + T cells. CD4 + T cells are characterized by high expression of immune checkpoint genes CTLA4 and TIGIT. In giant cell tumor of bone, immune cells mainly act on multinucleated osteoclast like giant cells through PARs and CCL signaling pathways, but not stromal cells. Conclusion:This study defined the main cell types of giant cell tumor of bone through single cell sequencing data, and further revealed the composition characteristics of its immune infiltration, and found that the target of its immune cells was mainly multinuclear osteoclast like giant cells, which provided effective information for further understanding the occurrence and development of giant cell tumor of bone.