• Seiji Ohtori, Gen Inoue, Sumihisa Orita, Kazuyo Yamauchi, Yawara Eguchi, Nobuyasu Ochiai, Shunji Kishida, Kazuki Kuniyoshi, Yasuchika Aoki, Junichi Nakamura, Tetsuhiro Ishikawa, Masayuki Miyagi, Hiroto Kamoda, Miyako Suzuki, Gou Kubota, Yoshihiro Sakuma, Yasuhiro Oikawa, Kazuhide Inage, Takeshi Sainoh, Masashi Takaso, Tomoaki Toyone, and Kazuhisa Takahashi.
• Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. sohtori@faculty.chiba-u.jp
• Spine. 2013 Apr 15; 38 (8): E487-92.

Study DesignProspective study.ObjectiveTo examine the efficacy of teriparatide or bisphosphonate treatment to reduce pedicle screw (PS) loosening after instrumented lumbar posterolateral fusion in postmenopausal women with osteoporosis.Summary Of Background DataFailure of fixation caused by loosening of PSs in osteoporosis is a problem in spinal surgery. Oral administration of bisphosphonate or intermittent injection of parathyroid hormone treatment increases bone mass and reduces the risk of osteoporotic vertebral fractures. Although these treatments may be factor in improving bone quality, a clinical study of the efficacy of bisphosphonate or parathyroid hormone for reducing PS loosening that addresses the quality of the bone marrow and pedicle cortex has not yet been reported.MethodsSixty-two women with osteoporosis diagnosed with degenerative spondylolisthesis were divided into 3 groups: a teriparatide group (daily subcutaneous injection of 20 μg of teriparatide, n = 20), a bisphosphonate group (daily oral administration 2.5 mg of risedronate, n = 20), and a control group (without medication for osteoporosis, n = 22). All patients underwent decompression and 1- or 2-level instrumented posterolateral fusion with a local bone graft. Loosening of PSs and surgical outcome were evaluated radiographically, clinically, and by computed tomography 12 months after surgery.ResultsAt 12-month follow-up, the incidence of PS loosening was 7% to 13% in the teriparatide group, 13% to 26% in the risedronate group, and 15% to 25% in the control group. The incidence of PS loosening in the teriparatide group was significantly lower than that in the risedronate or the control group (P < 0.05). In contrast, the extent of PS loosening in the risedronate group was not significantly different from that in the control group (P > 0.05).ConclusionOur findings suggest that administration of teriparatide increased the quality of the lumbar spine bone marrow and pedicle cortex.

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