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Abstract Background Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis. Methods This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation. Results BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months). Conclusion To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.

Abstract Background The use of nomograms for prognostication of individual cancer patients has been recommended in order to facilitate precision medicine. However, models for patients with soft tissue sarcomas (STSs) are limited because of the rarity and heterogeneity of such cancers. In addition, no model has been developed on the basis of an Asian cohort. Here, we attempted to develop and internally validate nomograms for patients with localized STSs of the trunk and extremity. Methods This study retrospectively extracted 2827 patients with primary trunk and extremity STSs after definitive surgery using the Bone and Soft Tissue Tumor Registry, which is a nationwide sarcoma database in Japan. We developed three nomograms predicting the probability of local recurrence-free survival (LRFS), distant metastasis-free survival (DMFS) and disease-specific survival (DSS) at 2 years after surgery, using the Cox multivariate model. The nomograms were internally validated for discrimination and calibration using bootstrap resampling and assessed for their clinical applicability by decision curve analysis (DCA). Results Local recurrence, distant metastasis and disease-specific death occurred in 241 patients (8.5%), 554 patients (19.6%) and 230 patients (8.1%), respectively. Histological diagnosis, grade and tumor size strongly influenced all three endpoints. The nomograms predicted accurately the probability of LRFS, DMFS and DSS (concordance index: 0.73, 0.70 and 0.75, respectively). DCA demonstrated that our nomograms had clinical applicability. Conclusion We have developed the first nomograms for STSs based on an Asian cohort. These nomograms allowed accurate prediction of LRFS, DMFS and DSS at 2 years after definitive surgery, and can be used as a guide by clinicians for appropriate follow-up and counseling of patients.