BACKGROUND:During total hip arthroplasty, it is difficult to accurately determine the exact orientation of the pelvis. Pelvic position is prone to change during treatment. After prosthesis implantation, angle deviation easily occurs. The surgeon is difficult to accurately determine the position and orientation of the prosthesis. OBJECTIVE:To investigate the effects of prosthesis position during total hip arthroplasty by using three-dimensional computer-aided technique, and to analyze the biomechanical properties of the prosthesis in total hip arthroplasty. METHODS:Data of ten patients undergoing total hip arthroplasty in theAffiliated Hospital of Binzhou Medical University from January to November 2015 were analyzed. SIEMENS/DEFINITION dual source CT was used to scan the skeleton of patients. CT data were colected as a basis for data in modeling. Slice thickness was 0.732 mm; resolution of the inner surface was 512 × 512. CT data were imported in three-dimensional reconstruction software of a computer. The models of femur and pelvis were established. According to the type of fracture, false models of total hip arthroplasty were established. Simultaneously, biomechanical prosthesis models were established. We determined research methods of prosthesis position by computer-aided techniques and analyzed biomechanical properties in total hip arthroplasty. RESULTS AND CONCLUSION:(1) The use of computer-aided technology couldclearly show the defect site. After determining the defect position using computer-aided techniques, prosthesis implantation and repair effect could be simulated in the software. (2) The computer-aided through technologycould accurately determine the vertical weight of the human. The acetabular center of rotation was used as the origin. A vertical paralel line was generated. The sagittal and coronal planes of the prosthesis could be set in new coordinates. (3) With the aid of computer, total hip prosthesis models were constrained and loaded, which lay the foundation for the operation through the model development. (4) The 10 patients achieved successful surgery. The position of prosthesis was correct in ninepatients, with a success rate of 90%. Patients were folowed up for 3 months. The patients did not have other complications. (5) These results suggest that computer-aided technology can do three-dimensional construction and analysis of the prosthesis, andcan construct the position of the prosthesis during total hip arthroplasty according to three-dimensional reconstruction of the digitized pelvis model so as to achieve precise positioning of surface hip prostheses, which can prevent excessive wear of the joint, make pelvis closer to the physiological state of the mechanical distribution, and achieve the desired effect.

Objective To evaluate the expression profile of succinate dehydrogenase (SDH)B and SDHC in pheochromocytoma (PCC) and paraganglioma(PGL) (collectively abbreviated as PPGL), and their value in the early diagnosis of malignancy. Methods SDHB and SDHC immunohistochemistry were performed on 140 tumor specimens from 126 PPGL patients (PCC n＝62, PGL n＝61, PCC+PGL n＝3). Results (1) Germline mutation status of 67 patients were determined, of which, identifying 37(55.2%) patients with germline mutation: 2 (3.0%) SDHA, 18 ( 26. 9%) SDHB, 2 ( 3. 0%) SDHC, 5 ( 7. 5%) SDHD, 2 ( 3. 0%) VHL, 7 ( 10. 4%) RET, and 1(1.5%) NF1; and 30 (44.8%) individuals without known mutation. (2) Among 30 PPGLs from 27 patients with SDH-related (SDHx) mutations, 96.7%(29/30) stained negative for SDHB, 76.7%(23/30) stained negative for SDHC, while only 28.6%(14/49) and 18.4%(9/49) stained negative for SDHB and SDHC respectively in the 49 PPGLs without SDHx mutation (P<0.05). (3) The sensitivity of the SDH immunostaining in detecting the presence of germline SDHx mutation was 96.7%for SDHB and 76.7%for SDHC, while the specificity was 71.4%for SDHB and 81.6% for SDHC. ( 4 ) Among PPGLs without SDHB expression, 22. 9% were malignant. This percentage is significantly higher than that in PPGLs with preserved SDHB expression (3.8%, P<0.05). Conclusion SDHB and SDHC immunohistochemistry may serve as post-surgical screening tools to predict the presence of germline SDHx mutation in PPGLs. Negative SDHB expression calls for intense follow-up to rule out malignancy.