Note that with respect to the parameters with positive correlations (a and c), the relative distribution of open circles (for placebo) in the third quadrant is shifted to the first quadrant by weekly teriparatide (closed circles). Similarly, in the case of the parameters

with negative correlations (b and d), relative distribution of open circles (for placebo) in the second Rabusertib cost quadrant is shifted to the fourth quadrant by weekly teriparatide (closed circles), suggesting that weekly teriparatide reversed age-related changes in proximal femur geometry and biomechanical properties Discussion This longitudinal assessment by CT demonstrates the changes in bone geometry, vBMD, and mechanical properties at the Selleck BAY 11-7082 proximal femur by once-weekly injection of 56.5 μg

teriparatide for 72 weeks. This is the first longitudinal CT study to include comparison with a double-blinded placebo group. Previous studies have evaluated the effects of teriparatide on proximal femur geometry and its biomechanical properties using CT [8], but they did not include a placebo group. Generally, the effects of once-weekly teriparatide injection on proximal femur geometry in this study are similar to results with daily teriparatide injections reported in a subgroup of the EUROFORS study (EU-CT study) [8]. The same analysis software program was employed and the main effects included increases in cortical thickness/CSA as well as total vBMD. Cortical thickness/CSA increasing while bone perimeter remained unchanged over 72 weeks of once-weekly teriparatide, suggests that cortical bone formation took place at the endosteal surface resulting in an increase in cortical thickness with a significant decrease in BR. One difference observed between the weekly and daily treatment regimens is the effect on PTK6 cortical vBMD. Although only eight patients were included in the treatment-naïve group in the EU-CT study, daily teriparatide decreased cortical vBMD at the femoral neck after 6 months of treatment (∼3.0 % from baseline), which was consistent with the results of a previous large clinical

trial [11]. Moreover, a decrease in cortical BMD at the femoral neck with 12 months of daily teriparatide treatment [12] and a decrease in cortical BMD at the distal radius and tibia were reported [13]. In contrast, our results showed that once-weekly teriparatide maintained cortical vBMD at the femoral neck (−0.6 %, 48 weeks and −1.2 %, 72 weeks). This difference may be due to distinct patterns of bone remodeling between daily and weekly teriparatide treatment given that weekly teriparatide caused an increase in serum osteocalcin (bone formation marker) and a decrease in urinary NTX (bone resorption marker) [5]. Other factors such as cohort effects, differences in CT acquisition or the software may also have had an effect and help to explain the differences. The question of whether or not teriparatide stimulates periosteal apposition has been raised.