The effects of teriparatide on acceleration of bone healing following atypical femoral fracture: comparison between daily and weekly administration.

We compared the effectiveness of promoting bone healing between two teriparatide preparations for atypical femoral fracture (AFF). A total of 45 AFFs were included in this study, and we compared the duration of bone union. Teriparatide administered by daily injection enhanced bone union more than weekly administration in complete AFFs. INTRODUCTION: The efficacy of teriparatide for atypical femoral fracture (AFF) has been recently reported. Although two different teriparatide preparations can be used to treat osteoporosis in Japan, daily or weekly injection, all previous reports on the effectiveness of teriparatide for AFF only examined daily injection formulations. Therefore, we compared the promotion of bone healing between the two teriparatide preparations for AFF. METHODS: A total of 45 consecutive AFFs in 43 Japanese patients were included in this study. They received either a daily 20-µg teriparatide injection (daily group; n = 32) or a once-a-week 56.5-µg teriparatide injection (weekly group; n = 13). We compared the clinical background and duration of bone union between these two groups. RESULTS: When all patents were included, the fracture healing time was not significantly different between the two groups. Only patients with complete AFFs had significantly fewer daily bisphosphonate or denosumab injections than the weekly group (P < 0.05). The fracture healing time in the daily group (6.1 ± 4.1 months) was significantly shorter than that in the weekly group (10.1 ± 4.2 months) (P < 0.05). Even if the influence of bisphosphonate or denosumab usage was excluded, a similar significant difference was observed in the fracture healing time (P < 0.05). There was no significant difference between the two groups among patients with incomplete AFFs. CONCLUSIONS: Daily teriparatide injections enhance bone union more than weekly injections in complete AFF patients.

TRPV1, ASICs and P2X2/3 expressed in bone cells simultaneously regulate bone metabolic markers in ovariectomized mice.

OBJECTIVES: Nociceptors are expressed at peripheral terminals of neurons. Recent studies have shown that TRPV1, a nociceptor, is expressed in bone tissue and regulates bone metabolism. We have demonstrated that a TRPV1 antagonist improved pain-like behavior in ovariectomized (OVX) mice. The aim of this study was to determine whether nociceptors, including TRPV1, acid-sensing ion channel (ASIC) and P2X2/3 are expressed in bone cells, and to examine the effects of nociceptor antagonists on bone metabolism. METHODS: The expression of nociceptors in femoral bone tissue and cultured bone marrow cells in OVX and sham-operated mice were examined. The effects of nociceptor antagonists on the up-regulated expression of bone metabolic markers, Runx2, Osterix, osteocalcin and RANKL, were also examined. RESULTS: TRPV1, ASIC 2 and 3, and P2X2 and 3, were expressed in bone tissue and bone marrow cells, and the expression levels of ASIC1 and 2, and P2X2 were significantly increased in OVX mice in comparison with those in sham mice. Treatment with nociceptor antagonists significantly inhibited the expression of bone metabolic markers in OVX mice. CONCLUSION: An array of nociceptors, TRPV1, ASICs and P2X2/3, could simultaneously regulate not only increases in skeletal pain but also bone turnover in OVX mice.