ABSTRACT
OBJECTIVE: To determine the area of a safety window that excludes the vertebral artery for the safe access of the occipital condyle screws during occipitocervical fixation. METHODS: This study included 138 cervical computed tomography angiograms. Six measurements per side were made in each imaging study. These measurements are from the vertebral artery to (A) the mastoid process, (B) the mastoid incisura, (C) the posterior condylar fossa, (D) the occipital condyle in its midline, and (E) the medial border of the condyle. We also measured from the tip of the mastoid process to the lower border of the occipital condyle on its lateral side (F). RESULTS: A total of 276 areas from 138 individuals were included, of which 51.4 % were men. The mean age was 54.2⯱â¯18.63 years. The mean variable measurements (mm) for all the population were 21⯱â¯4, 16⯱â¯3, 6⯱â¯2, 3⯱â¯2, 2⯱â¯1 and 35⯱â¯4 for variables A-F, respectively. We found significant differences between sex when we compared measurements A (pâ¯=â¯0.003), C (pâ¯=â¯0.001), D (pâ¯=â¯0.000) and F (pâ¯=â¯0.000). The incidence rate of dominance for the vertebral artery was 18.8 % and 30.4 % for right and left respectively. CONCLUSION: Women had significantly smaller measures than men. This could indicate a higher risk of iatrogenic injury secondary to a smaller vertebral artery-free area. Results may guide surgeons in the pre-surgical planning aiming to reduce the risk of iatrogenic injuries to the vertebral artery.
Subject(s)
Atlanto-Occipital Joint/surgery , Intraoperative Complications/prevention & control , Joint Instability/surgery , Spinal Fusion/adverse effects , Vertebral Artery/injuries , Adult , Aged , Female , Humans , Male , Middle Aged , Spinal Fusion/methodsABSTRACT
Knowing the dimensions of the vertebral elements is very important for the development of instrumentation related to the cervical spine. Ethnic variations have been reported in these dimensions and, to date, there have been no morphometric studies of this area performed on the Mexican population. We conducted a morphometric study of 150 cervical vertebrae (C3-C7) obtained from a northeastern Mexican population to determine the dimensions of the bodies, pedicles, laminae, spinous processes, and superior and inferior articular processes. We did not find significant differences (p<0.05) in measurements taken of the left and right sides. The dimensions of the vertebral bodies were larger at lower levels. The pedicles of the C3 vertebra were larger in all dimensions compared to the other vertebrae. The largest height of the laminae was observed at C7 and the largest transverse length was observed at C5. The dimensions of the bodies, spinous processes, and laminae increased from C3-C7, whereas the dimensions of the pedicles and superior and inferior articular process height decreased toward the lower cervical levels.
Las mediciones de los elementos vertebrales son importantes para la instrumentación de columna cervical. Se han reportado variaciones étnicas en estas medidas y en la actualidad no existen estudios morfométricos en la población mexicana. Se realizó un estudio morfométrico en 150 vértebras cervicales (C3-C7) para determinar las medidas de los cuerpos, pedículos, láminas, procesos espinosos y articulares superiores e inferiores. No se encontraron diferencias significativas (p<0.05) en las medidas tomadas entre ambos lados. Las dimensiones de los cuerpos vertebrales se incrementan en niveles más bajos. Los pedículos de la vértebra C3 son mayores en todas sus dimensiones. La mayor altura de las láminas se observó en C7 y la mayor longitud transversal en C5. Las dimensiones del cuerpo, procesos espinosos y láminas se incrementan de C3-C7, mientras las dimensiones de los pedículos, altura de procesos articulares superiores e inferiores disminuyen en los niveles cervicales más bajos.
