Yoshiyuki Okamoto1, Hideki Murakami2, Satoru Demura2, Satoshi Kato2, Katsuhito Yoshioka2, Hiroyuki Hayashi2, Jiro Sakamoto3, Norio Kawahara4, Hiroyuki Tsuchiya2. 1. Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan. Electronic address: okamoto19780731@yahoo.co.jp. 2. Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kanazawa University, 13-1 Takaramachi, Kanazawa 920-8641, Japan. 3. Department of Human and Mechanical System Engineering, Faculty of Engineering, Kanazawa University, Kakumamachi, Kanazawa 920-1192, Japan. 4. Department of Orthopedic Surgery, Kanazawa Medical University Hospital, 1-1 Uchinadamachi, Kahoku 920-0293, Japan.
Abstract
BACKGROUND CONTEXT: Kyphotic deformity associated with vertebral fracture is believed to be a significant risk factor for additional vertebral fractures. However, previously published research is limited. PURPOSE: The purpose of this study was to estimate the biomechanical stresses that kyphotic deformity, with an initial vertebral fracture, place on adjacent vertebrae using three-dimensional finite element (FE) of the spine, head, and ribs. STUDY DESIGN: This study is based on the basic science. METHODS: Total Human Model for Safety, a three-dimensional FE model of the human body, was used and adjusted to represent an elderly osteoporotic woman. The 12th thoracic vertebra (T12), which is a frequent site of osteoporotic vertebral fractures, was transformed to a wedge shape at 0°, 10°, and 20° to create a normal model, a 10° kyphosis model, and a 20° kyphosis model. Additionally, compensated postures were created for the 10° and 20° kyphosis models. Thus, five models were created: (A) a normal model, (B) a 10° kyphosis model, (C) a 20° kyphosis model, (D) a 10° kyphosis model with compensated posture, and (E) a 20° kyphosis model with compensated posture. Compressive principal stresses (CPSs) on T1-L5 in each model were calculated. RESULTS: The highest CPS value was 7.78 MPa placed on the anterior part of the T10 vertebra in the 20° kyphosis model. In the 20° kyphosis model, the higher CPS values showed bimodal peaks at T6 and T7 in the midthoracic spine and at T10 and T11 in the two superior adjacent vertebrae. The maximum CPS values in the A, B, C, D, and E models at T10 were 3.12, 6.74, 7.78, 6.61, and 5.78 MPa. At T11, they were 1.70, 4.41, 6.45, 4.07, and 4.79 MPa. CONCLUSIONS: The existence of an initial vertebral fracture at T12 caused an increase in stress on adjacent vertebrae. Higher CPS values showed bimodal peaks in midthoracic vertebrae and in two superior adjacent vertebrae when T12 was transformed to a wedge shape in the 20° kyphosis model.
BACKGROUND CONTEXT: Kyphotic deformity associated with vertebral fracture is believed to be a significant risk factor for additional vertebral fractures. However, previously published research is limited. PURPOSE: The purpose of this study was to estimate the biomechanical stresses that kyphotic deformity, with an initial vertebral fracture, place on adjacent vertebrae using three-dimensional finite element (FE) of the spine, head, and ribs. STUDY DESIGN: This study is based on the basic science. METHODS: Total Human Model for Safety, a three-dimensional FE model of the human body, was used and adjusted to represent an elderly osteoporoticwoman. The 12th thoracic vertebra (T12), which is a frequent site of osteoporotic vertebral fractures, was transformed to a wedge shape at 0°, 10°, and 20° to create a normal model, a 10° kyphosis model, and a 20° kyphosis model. Additionally, compensated postures were created for the 10° and 20° kyphosis models. Thus, five models were created: (A) a normal model, (B) a 10° kyphosis model, (C) a 20° kyphosis model, (D) a 10° kyphosis model with compensated posture, and (E) a 20° kyphosis model with compensated posture. Compressive principal stresses (CPSs) on T1-L5 in each model were calculated. RESULTS: The highest CPS value was 7.78 MPa placed on the anterior part of the T10 vertebra in the 20° kyphosis model. In the 20° kyphosis model, the higher CPS values showed bimodal peaks at T6 and T7 in the midthoracic spine and at T10 and T11 in the two superior adjacent vertebrae. The maximum CPS values in the A, B, C, D, and E models at T10 were 3.12, 6.74, 7.78, 6.61, and 5.78 MPa. At T11, they were 1.70, 4.41, 6.45, 4.07, and 4.79 MPa. CONCLUSIONS: The existence of an initial vertebral fracture at T12 caused an increase in stress on adjacent vertebrae. Higher CPS values showed bimodal peaks in midthoracic vertebrae and in two superior adjacent vertebrae when T12 was transformed to a wedge shape in the 20° kyphosis model.
Authors: Ulrich Josef Spiegl; Max Joseph Scheyerer; Georg Osterhoff; Sebastian Grüninger; Klaus John Schnake Journal: Eur J Trauma Emerg Surg Date: 2021-09-29 Impact factor: 2.374
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