TY - JOUR
T1 - C1-2 hypermobility and its impact on the spinal cord
T2 - a finite element analysis
AU - Patel, Arpan A.
AU - Greenberg, Jacob K.
AU - Steinmetz, Michael P.
AU - Vorster, Sarel
AU - Nevzati, Edin
AU - Spiessberger, Alexander
N1 - Publisher Copyright:
© AANS 2024.
PY - 2024/8
Y1 - 2024/8
N2 - OBJECTIVE The authors present a finite element analysis (FEA) evaluating the mechanical impact of C1-2 hypermobility on the spinal cord. METHODS The Code_Aster program was used to perform an FEA to determine the mechanical impact of C1-2 hypermobility on the spinal cord. Normative values of Young's modulus were applied to the various components of the model, including bone, ligaments, and gray and white matter. Two models were created: 25° and 50° of C1-on-C2 rotation, and 2.5 and 5 mm of C1-on-C2 lateral translation. Maximum von Mises stress (VMS) throughout the cervicomedullary junction was calculated and analyzed. RESULTS The FEA model of 2.5 mm lateral translation of C1 on C2 revealed maximum VMS for gray and white matter of 0.041 and 0.097 MPa, respectively. In the 5-mm translation model, the maximum VMS for gray and white matter was 0.069 and 0.162 MPa. The FEA model of 25° of C1-on-C2 rotation revealed maximum VMS for gray and white matter of 0.052 and 0.123 MPa. In the 50° rotation model, the maximum VMS for gray and white matter was 0.113 and 0.264 MPa. CONCLUSIONS This FEA revealed significant spinal cord stress during pathological rotation (50°) and lateral translation (5 mm) consistent with values found during severe spinal cord compression and in patients with myelopathy. While this finite element model requires oversimplification of the atlantoaxial joint, the study provides biomechanical evidence that hypermobility within the C1-2 joint leads to pathological spinal cord stress.
AB - OBJECTIVE The authors present a finite element analysis (FEA) evaluating the mechanical impact of C1-2 hypermobility on the spinal cord. METHODS The Code_Aster program was used to perform an FEA to determine the mechanical impact of C1-2 hypermobility on the spinal cord. Normative values of Young's modulus were applied to the various components of the model, including bone, ligaments, and gray and white matter. Two models were created: 25° and 50° of C1-on-C2 rotation, and 2.5 and 5 mm of C1-on-C2 lateral translation. Maximum von Mises stress (VMS) throughout the cervicomedullary junction was calculated and analyzed. RESULTS The FEA model of 2.5 mm lateral translation of C1 on C2 revealed maximum VMS for gray and white matter of 0.041 and 0.097 MPa, respectively. In the 5-mm translation model, the maximum VMS for gray and white matter was 0.069 and 0.162 MPa. The FEA model of 25° of C1-on-C2 rotation revealed maximum VMS for gray and white matter of 0.052 and 0.123 MPa. In the 50° rotation model, the maximum VMS for gray and white matter was 0.113 and 0.264 MPa. CONCLUSIONS This FEA revealed significant spinal cord stress during pathological rotation (50°) and lateral translation (5 mm) consistent with values found during severe spinal cord compression and in patients with myelopathy. While this finite element model requires oversimplification of the atlantoaxial joint, the study provides biomechanical evidence that hypermobility within the C1-2 joint leads to pathological spinal cord stress.
KW - atlantoaxial instability
KW - cervical
KW - Ehlers-Danlos syndrome
KW - finite element analysis
KW - hypermobility
UR - http://www.scopus.com/inward/record.url?scp=85200522252&partnerID=8YFLogxK
U2 - 10.3171/2024.2.SPINE231327
DO - 10.3171/2024.2.SPINE231327
M3 - Article
C2 - 38701531
AN - SCOPUS:85200522252
SN - 1547-5654
VL - 41
SP - 159
EP - 166
JO - Journal of Neurosurgery: Spine
JF - Journal of Neurosurgery: Spine
IS - 2
ER -