Daily subcutaneous Teriparatide injection increased bone mineral density of newly formed bone after tibia distraction osteogenesis, a randomized study.

ABSTRACT

Long bone defects are often treated by bone segment transport with the Ilizarov method requiring months spent with fixator mounted until bony consolidation of the newly formed bone. Shortening of consolidation would allow earlier fixator removal and earlier return to work. In pre-clinical studies parathyroid hormone, increased bone mineral density and mechanical properties of regenerate bone formed during distraction osteogenesis. Clinical studies showed that Teriparatide accelerated fracture healing in patients with osteoporotic fracture of the pelvis, hip, wrist and shoulder. We hypothesized that rhPTH(1-34) (Teriparatide) administered to patients who had undergone distraction osteogenesis, would increase mineralization of the regenerate formed during the consolidation phase. Sixteen patients with tibial defects after infection, underwent bone segment transport and at the time of docking the transport segment, were randomized to 8 weeks treatment with daily subcutaneous 0.20-µg Teriparatide injection followed by 8 weeks with no treatment, or to 8 weeks with no treatment followed by 8 weeks with daily subcutaneous 0.20 µg Teriparatide injection. Bone mineral density (BMD) of the regenerate was measured at the time of docking, 8 weeks after docking and 16 weeks after docking with DEXA. Functional evaluation was performed after one year. The design was a cross-over study. Overall BMD increased 0.14 g/cm2 in 8 weeks without treatment and 0.33 g/cm2 under Teriparatide treatment. After adjustment for a potential phase difference, 8 weeks of Teriparatide treatment led to an additional 0.19 g/cm2 BMD increase (95%-CI[0.11,0.28], p < 0.001). The ratio of the BMD increase between the two treatments was 0.33/0.14 = 2.43 (CI [1.21,3.65]). Teriparatide treatment during the consolidation phase of distraction osteogenesis doubled the mineralization rate of the regenerate when compared to no treatment.