Soji Tani1, Koji Ishikawa2, Yoshifumi Kudo1, Koki Tsuchiya1,3, Akira Matsuoka1, Hiroshi Maruyama1, Haruka Emori1,4, Ryo Yamamura1, Chikara Hayakawa1, Masaya Sekimizu1, Yusuke Oshita4, Tomoyuki Ozawa5, Toshiyuki Shirahata6, Takashi Nagai1, Tomoaki Toyone1, Katsunori Inagaki1. 1. Department of Orthopaedic Surgery, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8666, Japan. 2. Department of Orthopaedic Surgery, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa, Tokyo, 142-8666, Japan. koji.ishikawa@med.showa-u.ac.jp. 3. Department of Orthopaedic Surgery, Yamanashi Red Cross Hospital, 6663-1 Funatsu Fujikawaguchiko-machi, Minamitsuru-gun, Yamanashi, 401-0301, Japan. 4. Department of Orthopaedic Surgery, Showa University Northern Yokohama Hospital, 35-1, Chigasaki-Chuo Tsuzuki-ku, Yokohama, Kanagawa, Japan. 5. Department of Orthopaedic Surgery, Tokyo Kyosai Hospital, 2-3-8, Nakameguro, Meguro, Tokyo, 153-0061, Japan. 6. Department of Orthopaedic Surgery, Showa University Koto Toyosu Hospital, 5-1-38 Toyosu, Koto-ku, Tokyo, 135-8577, Japan.
Abstract
BACKGROUND: Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis. METHODS: This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation. RESULTS: BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months). CONCLUSION: To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.
BACKGROUND: Pedicle screw loosening is a major complication following spinal fixation associated with osteoporosis in elderly. However, denosumab is a promising treatment in patients with osteoporosis. The effect of denosumab on pedicle screw fixation is unknown. Therefore, we investigated whether denosumab treatment improves pedicle screw fixation in elderly patients with osteoporosis. METHODS: This was a 2-year prospective open-label study. From February 2015 to January 2016, we included 21 patients with postmenopausal osteoporosis who received initial denosumab treatment. At baseline, 12 months, and 24 months, we measured volumetric bone mineral density (BMD) using quantitative computed tomography (QCT) and performed CT-based finite element analysis (FEA). Finite element models of L4 vertebrae were created to analyze the bone strength and screw fixation. RESULTS: BMD increased with denosumab treatment. FEA revealed that both pullout strength of pedicle screws and compression force of the vertebra increased significantly at 12 and 24 months following denosumab treatment. Notably, pullout strength showed a stronger correlation with three-dimensional volumetric BMD around pedicle screw placement assessed by QCT (r = 0.83, at 24 months) than with two-dimensional areal BMD assessed by dual energy X-ray absorptiometry (r = 0.35, at 24 months). CONCLUSION: To our knowledge, this is the first study to reveal that denosumab treatment achieved strong pedicle screw fixation with an increase in BMD around the screw assessed by QCT and FEA; therefore, denosumab could be useful for osteoporosis treatment during spinal surgery in elderly patients with osteoporosis.
Entities:
Keywords:
Denosumab; Finite element analysis; Loosening; Osteoporosis; Pedicle screw
Authors: Harry K Genant; Cesar Libanati; Klaus Engelke; Jose R Zanchetta; Arne Høiseth; Chui Kin Yuen; Sigtas Stonkus; Michael A Bolognese; Edward Franek; Thomas Fuerst; Hoi-Shen Radcliffe; Michael R McClung Journal: Bone Date: 2013-07-17 Impact factor: 4.398