A Study On Radiological Features About Pathological Fracture Of Giant Cell Tumor Around The Knee Joint

Objective Based on the consensus of the clinical experts, imaging experts, informatics experts, the purpose of the current study is to observe and measure the imaging features about the giant cell tumor (GCT) around knee with or without pathological fractures and to compare the radiological differences, explore the radiological features of pathological fractures and classify them in order to assess their severity and guide the development of surgical program effectively. Methods A GTOC (Giant Cell Tumor Of China) group was set up by Tian Jin Hospital, Xi Jing Hospital affiliated Fourth Military Medical University, Ji Nan Military General Hospital, to study the GCT. All experts reviewed the factors of imaging features influencing surgery about GCT accompanied with pathological fractures, then summarized, selected and analysised the relevant factors, determined the research indexs based on treatment experiences of230GCT patients around knee from five hospitals, and researching technology was discussed. From March2000to December2013, we collected230patients with GCT around knee, of which91patients with GCT from the domestic five bone tumor centers were involved in accord with the observation and measurement standard, including40males and51females with an average age of36.81years (range,17-78). The91patients were divided into no pathological fracture group (53cases) or pathological fracture group (38cases). We arranged their clinical materials, imaging datas, operation and follow-up records. Imaging datas of two groups such as X-ray, CT, MRI were observed, measured through the Image-J software. The radiological differences such as tumor volume, the distance between tumor and subchondral bone, Campanacci classification, soft tissue invasion and bone displacement were analyzed respectively. According to the statistical results in combination with other morphological characteristics, the severity of pathological fracture was preliminarily classified. Finally, a group meeting of GTOC held once again to discuss and amend the preliminary classification to develop a standard, comprehensive, accurate and practical clinical classification. Results The GTOC, which consist of tumor clinical experts, image experts, information specialist and a plurality of postgraduates from six provinces or cities determined the related indexs such as gender, age, location, tumor volume, distance of tumor to the subchondral bone, Campanacci grade, soft tissue invasion, internal and external articular fracture, fracture displacement and so on. GCT most frequently tended to occure in young adults between20and40years of age (58.2%,53/91), especially in pathological fracture group with78.9%.The proportion of tumors located at the distal femur of pathological fracture group was higher than that of no pathological fracture group, which had statistical significance (χ2=10.40, P=0.001). The tumor volume of pathological fracture group [(98.46±53.35) cm3] was greater than that of no pathological fracture group [(63.19±34.92) cm3], there was statistical difference between the two groups (t=-3.57, P=0.001). The distance between tumor and subchondral bone of pathological fracture group[(M=0.145, R=0.46)cm] was smaller than that of no pathological fracture group[(M=0.170,R=1.90) cm], the difference was statistically signifycant (u=-2.853, P=0.004). There were also significant differences in the incidence of pathologic fracture based on different degrees of soft tissue invasion (χ2=11.08,P=0.004).And①tumor located articular fractures;②fracture located in the joint, but the articular surface is intact;③undisplaced or a slight displacement;④tumor volume<200cm3;⑤distance to the subchondral bone tumors>3mm;⑥no soft tissue invasion and mass, if corresponded of①or②and③,④,⑤,⑥, pathologic fracture should be considered as "simple fracture". Whiled①intra-articular fracture and when the articular surface damage;②significant displacement fracture;③tumor volume>200cm3;④distance to the subchondral bone tumor<3mm;⑤soft tissue invasion and mass, if corresponded of any one or more of above,it should be considered as "complex fracture". Conclusion The tumor volume, distance between tumor and subchondral bone and the degrees of soft tissue invasion are closely related to pathological fracture of GCT around knee. Pathologic fracture based on imaging characteristics can be divided into "simple fracture" and "complex fractures" in order to distinguish its severity and guide the choice of surgical option in the future.