Pamela M. Idenya

Background: Intraoral vertical ramus osteotomy (IVRO) requires placement of the osteotomy posterior to the mandibular lingula (ML) to avoid injuring the inferior alveolar neurovascular bundle (IANB), yet limited visualization of the ML makes it a “blind” procedure. Common lateral landmarks, including the antilingula (AL), midwaist point (MWP), and midpoint of the coronoid-gonion line (MCG), are used to guide osteotomy placement, but their reliability remains uncertain. This study evaluated their application in a Kenyan population. Methods: A retrospective cross-sectional analysis of cone-beam computed tomography (CBCT) scans of 304 rami was conducted. The ML and the lateral landmarks were identified using 3-dimensional reconstruction. Spatial relationships were assessed using polar plots to evaluate their correspondence with the ML. Results: The AL was present in 90.1% of cases but showed wide variability, with minimal overlap with the ML. The ML was posterior to the AL in 92.0% of cases, with an observed safe zone extending up to 15 mm posterior to the AL. The MWP and MCG demonstrated greater consistency but retained variability, with the ML located posterior to these landmarks in 92.1% and 96.4% of cases, and the observed safe zone extending up to 14 and 11 mm posterior to the MWP and MCG, respectively. Conclusion: Lateral mandibular landmarks are unreliable as sole guides for IVRO, and conventional safety margins of 2 to 5 mm may underestimate posterior ML variability in this population. The safe zone appears to lie further posterior, supporting the use of customized cutting guides to improve surgical safety.

Background: Transverse foramina are canals in cervical transverse processes transmitting the vertebral vessels and the accompanying sympathetic plexus. These foramina exhibit side, sex and population specific variations such as those of size, shape and number. Knowledge of these variations is important for cervical surgical procedures and prediction of vertebral artery variations. Objective: To describe the morphology and morphometry of cervical transverse foramina in an adult Kenyan population. Methods: Ninety-four neck CT scan images of 2 mm slice thickness in axial view were used to assess presence, number, completeness and shape of transverse foramina. Antero-posterior and transverse lengths were measured using NeusoftTM software. Paired and independent t-tests were used to compare morphometric parameters for side and sex respectively. One-way ANOVA was used to determine differences in foramina down the cervical spine. A p-value of ≤ 0.05 was considered significant. Results: Transverse foramina had a prevalence of 98.78% with 3.64% being duplicated. They were identified as type 1 (circular), type 2 (elongated antero-posteriorly), type 3 (elongated transversely), type 4 (oblique left-right elongation) and type 5 (oblique right-left elongation) in 69.62%, 3.62%, 13.38%, 7.23% and 6.15% respectively. 0.46% foramina were incomplete and 3.19% constricted. Diameters on the right were larger than left. C1 foramina were the largest and C7 smallest. The diameters decreased from C2 to C3 then increased to C6. Conclusion: Transverse foramina display side and level dependent variations. This is of clinical importance to spine surgeons to prevent intraoperative damage of vertebral vessels when operating in the cervical region. Keywords: Morphology and morphometry; transverse foramina; cervical vertebrae; in Kenyan Population; a radiological study.