Yun Kyung Jeon1, Myung Jun Shin2, Yong Beom Shin3, Choong Rak Kim4, Seong-Jang Kim5, Hyun Yoon Ko6, In Joo Kim1. 1. Department of Internal Medicine, Pusan National University School of Medicine, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea; Medical Research Institute, Pusan National University, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea. 2. Medical Research Institute, Pusan National University, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea; Department of Rehabilitation Medicine, Pusan National University Hospital, Pusan National University School of Medicine, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea. 3. Medical Research Institute, Pusan National University, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea; Department of Rehabilitation Medicine, Pusan National University Hospital, Pusan National University School of Medicine, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea. Electronic address: yi0314@gmail.com. 4. Department of Statistics, Pusan National University, Busandaehak-ro, 63beon-gil, Geumjeong-gu, Busan 609-735, Korea. 5. Medical Research Institute, Pusan National University, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea; Department of Nuclear Medicine, Pusan National University School of Medicine, Gudeok-ro 179, Seo-gu, Busan 602-739, Korea. 6. Department of Rehabilitation Medicine, Pusan National University School of Medicine and Pusan National University Yangsan Hospital, Beomeo, Mulgeum, Yangsan, Gyeongnam, Korea; Research Institute for Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Beomeo, Mulgeum, Yangsan, Gyeongnam, Korea.
Abstract
BACKGROUND CONTEXT: Osteoporosis frequently occurs in elderly people and is commonly associated with neuromuscular diseases or severe cerebral palsy. Osteoporosis can cause pain via compression fractures or secondary neurologic deficits; thus, accurate evaluation of bone mineral density (BMD) is essential for the prevention and treatment of osteoporosis. However, spinal axial rotation caused by scoliosis may affect the outcome of BMD tests, such that BMD measurements may be significantly greater than actual BMD in patients with severe scoliosis of the spine. PURPOSE: We investigated the effect of axial rotation angle on BMD measurements of the phantom spine. STUDY DESIGN/ SETTING: Investigation for the effect of axial rotation with aluminum phantom spine. METHODS: A GE-Lunar Aluminum Spine Phantom was used to assess BMD. Bone mineral content (BMC), BMD, and cross-sectional area were measured 100 times at L1-L4 using a GE Lunar Prodigy Vision system. Dual-energy X-ray absorptiometry was performed at axial rotation angles of 0° to 25° (5° intervals). RESULTS: Cross-sectional area decreased and BMD values increased as the axial rotation angle increased, whereas BMC did not change significantly. A fitting function was obtained to evaluate the relationships among axial rotation angle, cross-sectional area, and BMD. We obtained an equation to estimate BMD at L1-L4: 1.000-0.001674x+0.0001043x(2)-0.000005333x(3), where x denotes the axial rotation angle. We found that the observed BMD needed adjustment when the angle was more than 5°. CONCLUSIONS: Bone mineral density values may be overestimated in patients with even slight (>5°) axial rotation. When osteoporosis is suspected in a clinical setting, the degree of axial rotation should be measured on a lumbar spine X-ray.
BACKGROUND CONTEXT: Osteoporosis frequently occurs in elderly people and is commonly associated with neuromuscular diseases or severe cerebral palsy. Osteoporosis can cause pain via compression fractures or secondary neurologic deficits; thus, accurate evaluation of bone mineral density (BMD) is essential for the prevention and treatment of osteoporosis. However, spinal axial rotation caused by scoliosis may affect the outcome of BMD tests, such that BMD measurements may be significantly greater than actual BMD in patients with severe scoliosis of the spine. PURPOSE: We investigated the effect of axial rotation angle on BMD measurements of the phantom spine. STUDY DESIGN/ SETTING: Investigation for the effect of axial rotation with aluminum phantom spine. METHODS: A GE-Lunar Aluminum Spine Phantom was used to assess BMD. Bone mineral content (BMC), BMD, and cross-sectional area were measured 100 times at L1-L4 using a GE Lunar Prodigy Vision system. Dual-energy X-ray absorptiometry was performed at axial rotation angles of 0° to 25° (5° intervals). RESULTS: Cross-sectional area decreased and BMD values increased as the axial rotation angle increased, whereas BMC did not change significantly. A fitting function was obtained to evaluate the relationships among axial rotation angle, cross-sectional area, and BMD. We obtained an equation to estimate BMD at L1-L4: 1.000-0.001674x+0.0001043x(2)-0.000005333x(3), where x denotes the axial rotation angle. We found that the observed BMD needed adjustment when the angle was more than 5°. CONCLUSIONS: Bone mineral density values may be overestimated in patients with even slight (>5°) axial rotation. When osteoporosis is suspected in a clinical setting, the degree of axial rotation should be measured on a lumbar spine X-ray.