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Germaneau A, Vendeuvre T, Delmotte A, D'Houtaud S, Brèque C, Petureau L, Doumalin P, Dupré JC, Brémand F, Maxy P, Richer JP, Rigoard P. Should we recommend occipital plate fixation using bicortical screws or inverted occipital hooks to optimize occipito-cervical junction fusion? A biomechanical study combining an experimental and analytical approach. Clin Biomech (Bristol, Avon) 2020; 80:105173. [PMID: 33010700 DOI: 10.1016/j.clinbiomech.2020.105173] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 08/31/2020] [Accepted: 09/03/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Occipito-cervical fusion can be necessary in case of cranio-cervical junction instability. Proximal stabilisation is usually ensured by bi-cortical occipital screws implanted through one median or two lateral occipital plate(s). Bone thickness variability as well as the proximity of vasculo-nervous elements can induce substantial morbidity. The choice of site and implant type remains difficult for surgeons and is often empirically based. Given this challenge, implants with smaller pitch to increase bone interfacing are being developed, as is a surgical technique consisting in inverted occipital hook clamps, a potential alternative to plate/screws association. We present here a biomechanical comparison of the different occipito-cervical fusion devices. METHODS We have developed a 3D mark tracking technique to measure experimental mechanical data on implants and occipital bone. Biomechanical tests were performed to study the mechanical stiffness of the occipito-cervical instrumentation on human skulls. Four occipital implant systems were analysed: lateral plates+large pitch screws, lateral plates+hooks, lateral plates+small pitch screws and median plate+small pitch screws. Mechanical responses were analysed using 3D displacement field measurements from optical methods and compared with an analytical model. FINDINGS Paradoxical mechanical responses were observed among the four types of fixations. Lateral plates+small pitch screws appear to show the best accordance of displacement field between bone/implant/system interface providing higher stiffness and an average maximum moment around 50 N.m before fracture. INTERPRETATION Stability of occipito-cervical fixation depends not only on the site of screws implantation and occipital bone thickness but is also directly influenced by the type of occipital implant.
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Affiliation(s)
- Arnaud Germaneau
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France; Spine & Neuromodulation Functional Unit, Department of Neurosurgery, CHU Poitiers, PRISMATICS Lab, Poitiers, France.
| | - Tanguy Vendeuvre
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France; Spine & Neuromodulation Functional Unit, Department of Neurosurgery, CHU Poitiers, PRISMATICS Lab, Poitiers, France
| | - Alexandre Delmotte
- Spine & Neuromodulation Functional Unit, Department of Neurosurgery, CHU Poitiers, PRISMATICS Lab, Poitiers, France; Centre du Rachis de la Sauvergarde, 69009 Lyon, France
| | - Samuel D'Houtaud
- Spine & Neuromodulation Functional Unit, Department of Neurosurgery, CHU Poitiers, PRISMATICS Lab, Poitiers, France; Service de Neurochirurgie Clinique, La Rochelle, France
| | - Cyril Brèque
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France; ABS Lab, Université de Poitiers, France
| | - Louis Petureau
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France
| | - Pascal Doumalin
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France
| | | | - Fabrice Brémand
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France
| | - Philippe Maxy
- Medtronic, Medtronic International Trading Sarl, Tolochenaz, Switzerland
| | | | - Philippe Rigoard
- Institut Pprime UPR 3346, CNRS - Université de Poitiers - ISAE-ENSMA, France; Spine & Neuromodulation Functional Unit, Department of Neurosurgery, CHU Poitiers, PRISMATICS Lab, Poitiers, France
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