Morphological analysis and morphometry of the occipital condyle and its relation to surrounding structures: implication in craniovertebral junction surgery

Abstract

Anatomical knowledge of the occipital condyle (OC) and its relationships to surrounding structures is important for avoiding injury during craniovertebral junction (CVJ) surgeries such as the far lateral approach (FLA). Therefore, this study was conducted to evaluate the morphology and morphometry of OC and its relationship to digastric point (DP), foramen magnum (FM), jugular foramen (JF), and hypoglossal canal (HC). The study was performed on 100 dry skulls. Oval-like condyle was the most common OC shape, representing for 33.0% of all samples. The OC protruded into FM in 31.5 %. The average length, width and height of the OC were 21.32 ± 2.44, 10.51 ± 1.41, and 7.39 ± 1.14 mm, respectively. Extracranial orifice of HC (eHC) and intracranial orifice of HC (iHC) were commonly found 74.0% in anterior 1/3 of OC, and 45.0% in middle 1/3 of OC, respectively. The mean distance from posterior edge of the OC (OCPE) to eHC, iHC and JF were 13.70 ± 2.23 mm, 9.00 ± 1.59 mm, and 16.15 ± 2.35 mm, respectively. The most common shape of FM was hexagonal in 27.0%. The mean of anteroposterior diameter (APD) was 34.19 ± 2.46 mm, transverse diameter (TD) was 29.17 ± 2.14 mm and foramen magnum index (FMI) was 1.18. The mean distance between DP and bony landmarks, including Op-DP, OCPT-DP, and JF-DP values, were 54.54 ± 3.50, 36.72 ± 4.07, and 34.18 ± 4.15 mm, respectively. The prevalence of bilateral and unilateral posterior condylar canal (PCC) was 57.0% and 34.0%, respectively. The morphological analysis and morphometry data of OC and its relation to surrounding structures can help surgeons be aware of neurovascular injury and CVJ instability by surgery.