Effect of bisphosphonates or teriparatide on mechanical complications after posterior instrumented fusion for osteoporotic vertebral fracture: a multi-center retrospective study
Authors: Kawabata Atsuyuki , Yoshii Toshitaka , Hirai Takashi , Ushio Shuta , Kaito Takashi , Yamashita Tomoya , Fujiwara Hiroyasu , Nagamoto Yukitaka , Matsuoka Yuji , Suzuki Hidekazu , Nishimura Hirosuke , Terai Hidetomi , Tamai Koji , Tagami Atsushi , Yamada Syuta , Adachi Shinji , Watanabe Kei , Katsumi Keiichi , Ohashi Masayuki , Shibuya Yohei , Harimaya Katsumi , Kawaguchi Kenichi , Yokoyama Nobuhiko , Oishi Hidekazu , Doi Toshiro , Kimura Atsushi , Inoue Hirokazu , Inoue Gen , Miyagi Masayuki , Saito Wataru , Nakano Atsushi , Sakai Daisuke , Nukaga Tadashi , Ikegami Shota , Shimizu Masayuki , Futatsugi Toshimasa , Ohtori Seiji , Furuya Takeo , Orita Sumihisa , Imagama Shiro , Ando Kei , Kobayashi Kazuyoshi , Kiyasu Katsuhito , Murakami Hideki , Yoshioka Katsuhito , Seki Shoji , Hongo Michio , Kakutani Kenichiro , Yurube Takashi , Aoki Yasuchika , Oshima Masashi , Takahata Masahiko , Iwata Akira , Endo Hirooki , Abe Tetsuya , Tsukanishi Toshinori , Nakanishi Kazuyoshi , Watanabe Kota , Hikata Tomohiro , Suzuki Satoshi , Isogai Norihiro , Okada Eijiro , Funao Haruki , Ueda Seiji , Shiono Yuta , Nojiri Kenya , Hosogane Naobumi , Ishii Ken 
Published: July 2020

Abstract
Background
The optimal treatment of osteoporosis after reconstruction surgery for osteoporotic vertebral fractures (OVF) remains unclear. In this multicentre retrospective study, we investigated the effects of typically used agents for osteoporosis, namely, bisphosphonates (BP) and teriparatide (TP), on surgical results in patients with osteoporotic vertebral fractures.

Methods
Retrospectively registered data were collected from 27 universities and affiliated hospitals in Japan. We compared the effects of BP vs TP on postoperative mechanical complication rates, implant-related reoperation rates, and clinical outcomes in patients who underwent posterior instrumented fusion for OVF. Data were analysed according to whether the osteoporosis was primary or glucocorticoid-induced.

Results
A total of 159 patients who underwent posterior instrumented fusion for OVF were included. The overall mechanical complication rate was significantly lower in the TP group than in the BP group (BP vs TP: 73.1% vs 58.2%, p = 0.045). The screw backout rate was significantly lower and the rates of new vertebral fractures and pseudoarthrosis tended to be lower in the TP group than in the BP group. However, there were no significant differences in lumbar functional scores and visual analogue scale pain scores or in implant-related reoperation rates between the two groups. The incidence of pseudoarthrosis was significantly higher in patients with glucocorticoid-induced osteoporosis (GIOP) than in those with primary osteoporosis; however, the pseudoarthrosis rate was reduced by using TP. The use of TP also tended to reduce the overall mechanical complication rate in both primary osteoporosis and GIOP.

Conclusions
The overall mechanical complication rate was lower in patients who received TP than in those who received a BP postoperatively, regardless of type of osteoporosis. The incidence of pseudoarthrosis was significantly higher in patients with GIOP, but the use of TP reduced the rate of pseudoarthrosis in GIOP patients. The use of TP was effective to reduce postoperative complications for OVF patients treated with posterior fusion.