Computed Tomography-Based Occipital Condyle Morphometry in an Indian Population to Assess the Feasibility of Condylar Screws for Occipitocervical Fusion

STUDY DESIGN: A retrospective computed tomography (CT)-based morphometric study of 82 occipital condyles in the Indian population, focusing on critical morphometric dimensions with relation to placing condylar screws. PURPOSE: This study focused on determining the feasibility of placing occipital condylar screws in an Indian population using CT anatomical morphometric data. OVERVIEW OF LITERATURE: The occipital condylar screw is a novel technique being explored as one of the options in occipitocervical stabilization. Sex and ethnic variations in anatomical structures may restrict the feasibility of this technique in some populations. To the best of our knowledge, there are no CT-based data on an Indian population that assess the feasibility of occipital condylar screws. METHODS: We measured the dimensions of 82 occipital condyles in 41 adults on coronal, sagittal, and axial reconstructed CT images. The differences were noted between the right and left sides and also between males and females. Statistical analysis was performed using the t-test, with a p-value of <0.05 considered significant. RESULTS: Mean sagittal length and height were 17.2±1.7 mm and 9.1±1.5 mm, respectively. Mean condylar angle/screw angle was 38.0°±5.5° from midline, with mean condylar length and width of 19.6±2.6 mm and 9.5±1.0 mm, respectively. Average coronal height on the anterior and posterior hypoglossal canal was 10.8±1.4 mm and 9.0±1.4 mm, respectively. The values in females were significantly lower than those in males, except for screw angle and condylar width. Based on Lin et al.'s proposed criteria, eight of 82 condyles were not suitable for condylar screws. CONCLUSIONS: Preliminary CT morphometry data of the occipital condyle shows that condylar screws are anatomically feasible in a large portion of the Indian population. However, because a small number of population may not be suitable for this technique, meticulous study of preoperative anatomy using detailed CT data is advised.