Effect of a selective estrogen receptor modulator on bone formation in osteoporotic spine fusion using an ovariectomized rat model

• Published in: The spine journal Vol. 16; no. 1; pp. 72 - 81
• Main Authors: Park, Sung Bae, MD, PhD, Kim, Chi Heon, MD, PhD, Hong, Minyoung, MS, Yang, Hee-Jin, MD, PhD, Chung, Chun Kee, MD, PhD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2016
• Subjects: Animals; Bone Density; Female; Fusion; Orthopedics; Osteogenesis - drug effects; Osteoporosis; Osteoporosis - drug therapy; Osteoporosis - surgery; Ovariectomy; Rat; Rats; Rats, Sprague-Dawley; Selective estrogen receptor modulator; Selective Estrogen Receptor Modulators - pharmacology; Selective Estrogen Receptor Modulators - therapeutic use; Spinal Fusion - methods; Spine; Trabecular; X-Ray Microtomography; Osteoporosis; Selective estrogen receptor modulator; Rat; Spine; Fusion; Trabecular
• ISSN: 1529-9430; 1878-1632
• DOI: 10.1016/j.spinee.2015.08.061

Abstract Background Context Selective estrogen receptor modulators (SERMs) are drugs used to treat osteoporosis. Selective estrogen receptor modulators improve bone mineral density and bone mechanical strength. However, there is a lack of data on the effect of SERMs on osteoporotic spinal fusion. Purpose This study aimed to investigate whether treatment with a SERM enhances spinal fusion in an ovariectomized (OVX) rat model. Study Design An in vivo animal study was carried out. Methods Female Sprague Dawley rats (n=90) were OVX or sham-operated, and randomized into three groups: control (sham-operated+fusion procedure+saline administration), OVX (OVX+fusion procedure+saline administration), and SERM (OVX+fusion procedure+administration of SERM). Eight weeks after OVX, a bilateral lumbar spinal fusion procedure was performed using autologous iliac bone. In each group, gene expression was evaluated at 2, 4, and 8 weeks after the fusion procedure, histologic analysis was performed at 4 and 8 weeks after the procedure, and bone parameters were measured by micro-computed tomography at 2 days, 4 weeks, and 8 weeks after the procedure. Results Bone mineral density and trabecular quality of the vertebral body were significantly higher in the SERM group compared with the OVX group 16 weeks after OVX. The fusion rate and bone volume ratio were higher in the fusion bed of the SERM group compared with the OVX group 8 weeks after the fusion procedure. Real-time reverse transcription polymerase chain reaction at 4 and 8 weeks after the fusion procedure showed increased expression of the genes for osteoblast-related markers (alkaline phosphatase, osteocalcin, runt-related transcription factor 2, and transforming growth factor) in the SERM group compared with the OVX group. The OVX group showed sparse bone mass between transverse processes. By contrast, the SERM group exhibited a compact bridging fusion mass within the fusion bed at 8 weeks after the fusion procedure. Conclusions Selective estrogen receptor modulator treatment improved the trabecular quality of the vertebral body, enhanced spinal fusion, and increased the amount of compact bone mass within the fusion bed in rats that had received an ovariectomy. Therapeutic SERM treatment may be recommended to improve the fusion rate in osteoporotic patients who undergo spinal fusion.