Feasibility of Screw Placement in the Occipital Condyle of Chinese Patients for Occipitocervical Arthrodesis: A Cadaveric Study.

Abstract

The feasibility of computed tomography (CT) and two-dimensional (2D) reconstruction-guided screw placement in the occipital condyle (OC) of Chinese patients was investigated. Twenty (40 OCs) fresh cadaveric specimens with intact superior cervical spine and occipital bones were placed in the prone position. Simulated screw placement was achieved by placing 4.0 mm diameter virtual screws with the help of the 2D reconstruction CT scan image technology. Maximal screw length, angulation in the sagittal and transverse planes, and medial and cranial base OC entry points were determined and recorded. Actual screw placement was achieved by similar placement; actual position and angulation were determined by postoperative CT scanning. Screws were successfully inserted in 36 of 40 (90%) OCs. Four ruptures of the medial OC wall were on the left side. Actual screw placement did not damage the hypoglossal canal, and no screws pierced the medial or lateral OC walls. Females displayed significantly smaller left and right maximum screw lengths than males (p < 0.05); no other significant gender differences were noted. The results can feasibly accommodate 4-mm OC screws for OA treatment. As in other populations, OC shape and size is smaller in females and varies in Chinese individuals, necessitating individualized imaging for good outcomes.