Mapping occipital bone thickness using computed tomography for safe screw placement

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>Safe and effective insertion of occipital bone screws requires morphological analysis of the occipital bone, which is poorly documented in the literature. The authors of this study present morphological data for determining the area of screw placement for optimal internal fixation.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>The subjects of this institutional review board-approved retrospective study were 105 individuals without head and neck disease who underwent CT imaging at the authors’ hospital. There were 55 males and 50 females, with a mean age of 57.1 years (range 20–91 years). Measurements using CT were taken according to a matrix of 55 points following a grid with 1-cm spacing based on the external occipital protuberance (EOP).</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>The maximum thickness of the occipital bone was at the level of the EOP at 16.4 mm. Areas with thicknesses &gt; 8 mm were more frequent at the EOP and up to 2 cm in all directions, as well as up to 1 cm in all directions at a height of 1 cm inferiorly, and up to 3 cm from the EOP inferiorly. The male group tended to have a thicker occipital bone than the female group, and the differences were significant around the EOP. The ratio of the trabecular bone to the occipital bone thickness was &gt; 30% in the central region. At positions more than 2 cm laterally, the ratio was &lt; 15%, and the ratio gradually decreased further laterally.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>Screws that are 8 mm long can be placed in the area extending 2 cm laterally from the EOP at the level of the superior nuchal line and approximately 3 cm inferior to the center. These results suggest that it may be possible to effectively insert a screw over a wider area than the conventional reference range.</jats:p></jats:sec>

A computed tomography-based analysis of the structure of the mandible according to age and sex

“…Therefore, cortical thickness and the space between the cortex and the canal should be carefully evaluated prior to surgery because sufficient cortical thickness contributes to bony stability and prevention of IAN damage following fixation [ 4 , 24 – 26 ]. As mentioned earlier, the vital role of cortical thickness in bone surgery has been previously demonstrated, and it can thus be considered that cortical thickness affects the surgical procedure and postoperative stability [ 11 , 14 , 15 , 19 , 20 , 27 , 28 ]. Studies have indicated the importance of assessing cortical thickness to determine the optimum anatomical location for fixation [ 15 , 27 – 32 ].…”

“…As mentioned earlier, the vital role of cortical thickness in bone surgery has been previously demonstrated, and it can thus be considered that cortical thickness affects the surgical procedure and postoperative stability [ 11 , 14 , 15 , 19 , 20 , 27 , 28 ]. Studies have indicated the importance of assessing cortical thickness to determine the optimum anatomical location for fixation [ 15 , 27 – 32 ]. Placement of the plate and screw over the mandibular body should be performed with caution in order to avoid injury to the IAN canal that runs through the structure.…”

Mapping of Venous Sinus Anatomy and Occipital Bone Thickness for Safe Screw Placement in 100 Patients with 46,200 Standardized Measurements Using Computed Tomography Angiography

“…Since the thickest bone area highly overlapped with the areas where the VS was present, we agree with the recommendation from other studies to obtain a preoperative CTA to evaluate both the occipital thickness and morphology of the planned fixation area to identify abnormal VS anatomy to avoid iatrogenic injuries. 14,15 Also, the evaluation of systemic bone quality is warranted to determine the necessity of bicortical screw fixation.…”

Computed Tomographic Morphometric Study of the Occipital Bone Thickness in 100 Adult, Moroccan Patients

“…Various techniques were described and used widely; involve the screw placement to the occipital diploic bone [5][6][7][8]. The unique anatomy and function of the region, the perceived high risk of vascular and neurological complications, and the anatomical variations make OCF a challenging procedure.…”