Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws
Background: There are a few biomechanical studies that describe posterior fixation methods with pedicle screws (PS) and lateral mass screws (LMS); the combination of both screw types and their effect on an allograft spacer in a surgically treated cervical segment is unknown. Methods: Finite element...
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MDPI AG
2020-10-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/10/20/7291 |
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| author | Soo-Bin Lee Hwan-Mo Lee Tae-Hyun Park Sung Jae Lee Young-Woo Kwon Seong-Hwan Moon Byung Ho Lee |
| author_facet | Soo-Bin Lee Hwan-Mo Lee Tae-Hyun Park Sung Jae Lee Young-Woo Kwon Seong-Hwan Moon Byung Ho Lee |
| author_sort | Soo-Bin Lee |
| collection | DOAJ |
| description | Background: There are a few biomechanical studies that describe posterior fixation methods with pedicle screws (PS) and lateral mass screws (LMS); the combination of both screw types and their effect on an allograft spacer in a surgically treated cervical segment is unknown. Methods: Finite element model (FEM) analyses were used to investigate the effects of a hybrid technique using posterior PS and LMS. Stress distribution and subsidence risk from a combination of screws under hybrid motion control conditions, including flexion, extension, axial rotation, and lateral bending, were investigated to evaluate the biomechanical characteristics of different six-screw combinations. Findings: The load sharing on the allograft spacer in flexion mode was highest in the LMS model (74.6%) and lowest in the PS model (35.1%). The likelihood of subsidence of allograft spacer on C6 was highest in the screws from the distal LMS (type 5) model during flexion and extension (4.902 MPa, 30.1% and 2.189 MPa, 13.4%). In lateral bending, the left unilateral LMS (type 4) model screws on C5 (3.726 MPa, 22.9%) and C6 (2.994 MPa, 18.4%) yielded the greatest subsidence risks, because the lateral bending forces were supported by the LMS. In counterclockwise axial rotation, the left unilateral LMS (type 4) model screws on C5 (3.092 MPa, 19.0%) and C6 (3.076 MPa, 18.9%) demonstrated the highest subsidence risks. Conclusion: The asymmetrical ipsilateral use of LMS and posterior PS in lateral bending and axial rotation demonstrated the lowest stability and greatest subsidence risk. We recommend bilateral symmetrical insertion of LMS or posterior PS and posterior PS on distal vertebrae for increased stability and reduced risk of allograft spacer subsidence. |
| first_indexed | 2024-03-10T15:31:58Z |
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| language | English |
| last_indexed | 2024-03-10T15:31:58Z |
| publishDate | 2020-10-01 |
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| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-e4e4ffc2621c492389cdca5faa606cf72023-11-20T17:36:18ZengMDPI AGApplied Sciences2076-34172020-10-011020729110.3390/app10207291Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle ScrewsSoo-Bin Lee0Hwan-Mo Lee1Tae-Hyun Park2Sung Jae Lee3Young-Woo Kwon4Seong-Hwan Moon5Byung Ho Lee6Department of Orthopedic Surgery, Bundang Jesaeng General Hospital, Daejin Medical Center, Seongnam 13590, KoreaDepartment of Orthopedic Surgery, Yonsei University College of Medicine, Seoul 03722, KoreaDepartment of Biomedical Engineering, College of Biomedical Science & Engineering, Inje University, Gyeongnam 621749, KoreaDepartment of Biomedical Engineering, College of Biomedical Science & Engineering, Inje University, Gyeongnam 621749, KoreaDepartment of Biomedical Engineering, College of Biomedical Science & Engineering, Inje University, Gyeongnam 621749, KoreaDepartment of Orthopedic Surgery, Yonsei University College of Medicine, Seoul 03722, KoreaDepartment of Orthopedic Surgery, Yonsei University College of Medicine, Seoul 03722, KoreaBackground: There are a few biomechanical studies that describe posterior fixation methods with pedicle screws (PS) and lateral mass screws (LMS); the combination of both screw types and their effect on an allograft spacer in a surgically treated cervical segment is unknown. Methods: Finite element model (FEM) analyses were used to investigate the effects of a hybrid technique using posterior PS and LMS. Stress distribution and subsidence risk from a combination of screws under hybrid motion control conditions, including flexion, extension, axial rotation, and lateral bending, were investigated to evaluate the biomechanical characteristics of different six-screw combinations. Findings: The load sharing on the allograft spacer in flexion mode was highest in the LMS model (74.6%) and lowest in the PS model (35.1%). The likelihood of subsidence of allograft spacer on C6 was highest in the screws from the distal LMS (type 5) model during flexion and extension (4.902 MPa, 30.1% and 2.189 MPa, 13.4%). In lateral bending, the left unilateral LMS (type 4) model screws on C5 (3.726 MPa, 22.9%) and C6 (2.994 MPa, 18.4%) yielded the greatest subsidence risks, because the lateral bending forces were supported by the LMS. In counterclockwise axial rotation, the left unilateral LMS (type 4) model screws on C5 (3.092 MPa, 19.0%) and C6 (3.076 MPa, 18.9%) demonstrated the highest subsidence risks. Conclusion: The asymmetrical ipsilateral use of LMS and posterior PS in lateral bending and axial rotation demonstrated the lowest stability and greatest subsidence risk. We recommend bilateral symmetrical insertion of LMS or posterior PS and posterior PS on distal vertebrae for increased stability and reduced risk of allograft spacer subsidence.https://www.mdpi.com/2076-3417/10/20/7291cervical spine surgeryallograft spacerlateral masspedicle screwsfinite element model |
| spellingShingle | Soo-Bin Lee Hwan-Mo Lee Tae-Hyun Park Sung Jae Lee Young-Woo Kwon Seong-Hwan Moon Byung Ho Lee Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws Applied Sciences cervical spine surgery allograft spacer lateral mass pedicle screws finite element model |
| title | Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws |
| title_full | Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws |
| title_fullStr | Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws |
| title_full_unstemmed | Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws |
| title_short | Biomechanical Comparison of Posterior Fixation Combinations with an Allograft Spacer between the Lateral Mass and Pedicle Screws |
| title_sort | biomechanical comparison of posterior fixation combinations with an allograft spacer between the lateral mass and pedicle screws |
| topic | cervical spine surgery allograft spacer lateral mass pedicle screws finite element model |
| url | https://www.mdpi.com/2076-3417/10/20/7291 |
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