BACKGROUND: Most of studies focus on the biomechanical characteristics of thoracic spine neoplasm, but there is little report on the fracture risk in the patients with vertebral hemangioma through finite element analysis.OBJECTIVE: To establish a finite element model of vertebral hemangioma, and to analyze its biomechanical characteristics, and assess the risk of vertebral fracture.METHODS: Three-dimensional finite element models of T12-L2 vertebrae from normal individuals, the patients with vertebral hemangioma (hemangioma accounting for 20%, 40%, 60%, 80% of the vertebral cancellous bone) and bone cement filling were established, respectively, and then the mechanical characteristics were analyzed. The stress distribution and characters of each model were determined under a vertical static pressure of 600 N.RESULTS AND CONCLUSION: (1) Three-dimensional finite element models of T12-L2 vertebrae were established successfully. Under static pressure, the stress distribution of L1 cortical bone showed no significant difference among models, and the maximum stress all occurred at the base of pedicle, zygapophysial joint and isthmus. (2) The stress distribution did not differ significantly between vertebral hemangioma accounting for 20%-40% of vertebral cancellous bone with complete cortical bone and normal ones, but which differed significantly in hemangioma accounting for 60%-80%. (3) To conclude, the established thoracolumbar three-dimensional model is available. Additionally,biomechanical tests manifest that the completeness of cortical bone and destruction ratio of cancellous bone destruction are key factors for the fracture risk of vertebral hemangioma.

Objective To compare the difference between a vertical line (AA) drawn to the line connecting the inner edge of the patellar tendon with the mid-point of the ending point in the posterior cruciate ligament, tibial posterior condylar line (PC), tibial plateau anterior line (AC), the maximal mediolateral distance (MMLD) and a vertical line (BB) drawn to aligning the mid-point of ending point in the posterior cruciate ligament with the medial 1 / 3 of the patellar tendon relative to the surigical transepicondylar axis (STEA) by MRI, and to explore a reliable reference to determine tibial component rotation in total knee arthroplasty , and whether it will change in knees with varus deformity. Methods Thirty healthy volunteers (Group1) and thirty osteoarthritis patients (Group2) were enrolled in this study. The angles were measured among the five tibial rotation axes and STEA after MRI. Results The angles were (-1.48 ± 2.38)°, (6.16 ± 4.53)°, (6.45 ± 5.24)° ,(5.08 ± 4.99)° and (3.24 ± 2.68)° respectively in group 1 and (-1.88 ± 2.21)°, (-3.13 ± 4.66)°, (11.13 ± 5.72)°, (4.11 ± 4.15)° and (5.12 ± 4.87)° respectively in group 2. The angle between AA and STEA was not affected by varus deformity (P > 0.05), but the others were (P < 0.05). Conclusion The angle between AA and STEA is the smallest which is used to determine tibial component rotation in knees with varus deformity is the most reliable one.

Objective:To explore the application feasibility of modified sentinel lymph node biopsy (SLNB) for acral malignant melanoma.Methods:The data of 60 patients with acral malignant melanoma in the Affiliated Tumor Hospital of Xinjiang Medical University from January 2017 to January 2020 were retrospectively analyzed. According to the sentinel lymph node (SLN) detection method, they were divided into observation group (30 cases) and control group (30 cases). The observation group used contrast-enhanced ultrasound combined with subcutaneous injection of methylene blue around the wrist or ankle joint to detect SLN; the control group used peritumoral injection of methylene blue to detect SLN. The patients were regularly followed up to evaluate the postoperative effect. The detection number, detection rate, sensitivity, false negative rate and the size of SLN were compared between the two groups.Results:In the observation group, the detection rate of SLN was 100.0% (30/30), the sensitivity was 87.5% (7/8), and the false negative rate was 3.3% (1/30); in the control group, the detection rate of SLN was 83.3% (25/30), the sensitivity was 62.5% (5/8), and the false negative rate was 12.0% (3/25); the differences were statistically significant (all P < 0.05). The number of SLN detected in the observation group (3.5±1.2) was significantly more than that in the control group (2.0±1.1), and the difference was statistically significant ( t = 7.121, P < 0.05). The minimum long-axis diameter of SLN detected in the observation group was (5.4±2.2) mm (range, 1.5-12.3 mm), and that in the control group was (11.8±5.4) mm (range, 10.0-16.8 mm), the difference between the two groups was statistically significant ( t = 6.353, P < 0.05). Conclusion:The modified SLNB for acral malignant melanoma has a higher application value in the detection of acral SLN than the peritumoral injection method, and a higher accuracy rate can be obtained.