BACKGROUND:Clinical fol ow-up studies have shown that alendronate is effective to prevent femoral head col apse fol owing traumatic osteonecrosis of the femoral head, but its mechanism remains poorly understood. OBJECTIVE:To analyze the effects and mechanisms of alendronate on prevention of col apse in traumatic osteonecrosis of the femoral head. METHODS:Total y 45 Sprague-Dawley rats were randomly divided into three groups, with 15 rats in each group. Placebo group received physiological saline after establishing models of avascular necrosis of the femoral head. Alendronate group received treatment of alendronate after model induction. Sham surgery group received an equal volume of physiological saline. At 5 weeks after model establishment, the rats were sacrificed. Femoral samples at the modeling side were col ected for general observation, X-ray irradiation, Micro-CT and histological detection. RESULTS AND CONCLUSION:General observation revealed that the femoral head was obviously deformed in the placebo group, but mild deformity was visible in the alendronate group. The ratio of height to width of the femoral head ranked as fol ows:sham surgery group>alendronate group>placebo group, showing significant differences. Micro-CT scanning results demonstrated that the mean number of bone trabecula was more in the alendronate group than in the placebo group, but less than sham surgery group, showing significant differences. The mean thickness of bone trabecula was less in the alendronate group than in the placebo group, but no significant difference was detectable as compared with the sham surgery group. The mean spacing of bone trabecula was less in the alendronate group than in the placebo group, but larger than in the sham surgery group, showing significant differences. Bone volume, bone surface area and bone mineral density were larger in the alendronate group than in the placebo group, but less than sham surgery group, showing significant differences. Histological detection results demonstrated that apparent sequestrum existed and osteoclasts were obviously inhibited in the alendronate group. The number of osteoclasts was noticeably less in the alendronate group than in the placebo group. Osteoblasts and new vessels were suppressed to some degrees. Results suggested that alendronate can inhibit curing reaction through inhibiting osteoclast and osteoblast activity and vessel formation, which can final y slow down the absorption of necrotic bone and preserve femoral head mass and shape. Thus, alendronate can be used as a preventive against femoral head col apse in rats with traumatic osteonecrosis of the femoral head.

Objective To evaluate effect of en bloc resection of malignant sacral tumor involving partial sacrum and ipsilateral sacroiliac joint with reservation of contralateral sacral foramina.Methods Between February 2005 and July 2010,16 patients with malignant sacral tumor involving partial sacrum and ipsilateral sacroiliac joint underwent hemi-sacrectomy and functional reconstruction.The operation achieved en bloc resection of tumor with reservation of contralateral sacral foramina.There were 10 males and 6 females,aged from 17 to 70 years (average,37.9 years).There were 5 cases of chondrosarcoma,3 cases of Ewing's sarcoma,2 cases of malignant schwannoma,2 cases of osteosarcoma,1 case of malignant giant cell tumor of bone,1 case of lymphoma and 2 cases of metastatic tumor.Results The surgical time ranged from 4 to 11.5 hours (average,6.5 hours).The average blood loss was 3600 ml (range,1500 to 5500 ml).Five patients underwent type Ⅰ resection,while 11 patients underwent type Ⅱ resection.All patients were followed up for 21 to 59 months (average,34.4 months).Three months after operation,13 patients had difficulty with ankle plantar flexion,while sphincter function was more or less reserved in 16 patients.Four patients (25％)had wound healing complications,which was cured after debridement and drainage.Local recurrence occurred in 7 patients.There were 5 cases of local recurrence among 6 patients who had intralesional margin;4 recurrence lesions located in the sacrum and 1 in soft tissue.Eight patients (50.0％) survived without tumor,2 patients (12.5％)survived with tumor,and 6 patients (37.5％) died of tumor.Conclusion The en bloc resection of tumor involving partial sacrum and ipsilateral sacroiliac joint with reservation of contralateral sacral foramina was feasible and had better outcome compared with total sacrectomy.

Objective:To explore the independent prognostic factors of primary osteosarcoma patients under 20 years old after radical surgery, so as to predict the prognosis and survival of patients.Methods:The clinicopathological data of 1 339 patients with primary osteosarcoma diagnosed and registered in the National Cancer Institute Surveillance, epidemiology and outcome database (SEER) from 1984 to 2014 were retrospectively analyzed. Kaplan Meier method was used to calculate the survival rate of patients. Log rank test was used to evaluate the survival difference. Cox multivariate analysis was used to determine the independent prognostic factors of osteosarcoma after radical surgery factor.Results:The results of primary osteosarcoma patients undergoing radical surgery found that 34 cases (2.54%) aged 0-5 years old, 236 cases (17.63%) aged 6-10 years old, and 600 cases (44.81%) aged 11-15 years old and 469 cases (35.02%) aged 16-20 years old. The median survival time was 68 months. Among them, 757(56.53%) were male and 582(43.47%) were female. Among the 1 339 cases, 986 were white (73.64%), followed by black 230(17.18%), and 123 other races (9.18%). Multivariate analysis revealed that males ( HR=1.242; 95% CI:1.024-1.505), axial osteosarcoma ( HR=1.589; 95% CI:1.179-2.166), and regional invasion of osteosarcoma ( HR=1.470; 95% CI:1.156-1.870), distant metastasis ( HR=3.536; 95% CI:2.725-4.589) were independent risk factors for overall survival. Other types of osteosarcoma ( HR=0.471; 95% CI:0.285-0.779) were independent protective factors for overall survival. Conclusions:Based on the SEER database, this study identified independent prognostic factors for patients with primary osteosarcoma under the age of 20 who underwent radical surgery, which will help clinicians formulate individualized medical strategies and predict patients′ prognosis.