Computed Tomographic Measurement of Cervical Pedicle Morphology in Filipino Patients

Introduction: Studies have shown that Asian cervical pedicles are significantly smaller, thus increasing the technical difficulty of screw insertion when using standard 3.5 mm pedicle screws. Cervical pedicle morphology of a sample of Filipino patients was assessed using computed tomographic measurements. Objective: The study was carried out to measure the cervical pedicles and assess the feasibility of transpedicular screw fixation in the local setting. Methods: CT scans of bilateral C2 to C7 pedicles of 94 Filipinos with a mean age 52.9 years old (range: 18 to 82) composed of 37 females and 57 males were evaluated for inner diameter, lateral wall, and medial wall thickness. Results: The inner diameter of male pedicles was significantly wider compared to females. The medial wall and lateral wall thickness of males was also significantly greater except for C2-C5 and C2 & C6 respectively. C3 to C5 of male pedicles had a mean inner diameter of < 3.1 mm compared to C2 to C6 in females. For mean lateral wall thickness, only the right C4 and C5 lateral wall thickness in females was< 1.0 mm. All cervical spine levels in both males and females had a mean medial wall thickness of > 1.0 mm (range 1.47 to 1.89mm). Conclusion: The cervical pedicles of Filipinos are smaller than those reported in Euro-American populations and may be too small to adequately accommodate transpedicular screw fixation using 3.5 mm screws. It is recommended that pre-operative imaging for all levels should be performed when transpedicular screw insertion is indicated. Key words: cervical spine, morphometry, transpedicular fixation, computed tomography