Recent advances toward the clinical application of PTH (1-34) in fracture healing

Abstract

PTH 1-34, an active form of parathyroid hormone, has been shown to enhance osteoblastic bone formation when administered as a daily subcutaneous injection. The effect of the intermittent administration of PTH (1-34) is an uncoupling of bone turnover with an increase in bone mass and density and decrease in risk of vertebral and nonvertebral fractures. While PTH (1-34) has been used clinically to increase bone mass and reduce fracture risk in postmenopausal women with osteoporosis, there is increasing evidence that PTH (1-34) may promote fracture healing. Animal studies have demonstrated accelerated callus formation with enhanced remodeling and biomechanical properties of the healing fracture. Given these effects, PTH (1-34) will likely be used clinically to enhance fracture union in poor healing situations such as osteoporosis and recalcitrant nonunions.

Fig. 1

Radiographs of rat femur fracture calluses from three groups: control (normal saline), 5 µg/kg of PTH and 30 µg/kg of PTH at 21, 35, and 84 days after the generation of closed femur fractures and stabilization with a retrograde intramedullary pin. Bony bridging is seen at 21 days in the group treated with 30 µg/kg of PTH. Osseous bridging is seen in all three groups at day 35 but more abundant callus is seen in the groups treated with PTH. Increased callus remodeling is noted at day 35 in the group treated with 30 µg/kg of PTH. (Reprinted with permission from The Journal of Bone and Joint Surgery, Inc)