Background: To evaluate the clinical efficacy and safety of the modified technique utilizing the occipital bicortical screws and plate system in occipitocervical revision surgery.
Methods: Between October 2010 and May 2018, 12 consecutive patients were retrospectively evaluated. All patients had posterior occipitocervical resurgery utilizing modified technique of bicortical screws and occipital plate. The measurements of extracranial occiput on midline were conducted on computed tomography (CT) scans. The thickness of the occipital bone at the location of external occipital protuberance and below 15 mm were evaluated, respectively. For the procedure, the trajectory was drilled perpendicular to the external occipital protuberance for the specified depth with a depth-limited drilling, 2 mm away from the internal bone plate, then the trajectory was deepened at intervals of 1 mm each time until reaching the internal bone plate. Meanwhile, a probe was used to explore all the walls of the trajectory. Bicortical screws were inserted to the occipital plate and the depth of penetration was less than 2 mm from the internal bone plate. Clinical efficacy and radiographic evaluation were followed up.
Results: The thickest point was the external occipital protuberance, which was 15.49 ± 1.47 mm and decreased gradually on the midline to 13.41 ± 1.60 mm at below 15 mm. Twelve cases (mean age 41.17 years; range, 24-62 years), including five males and seven females, were followed up for 24.08 months (14-32 months). The interval time was 40.42 months (3-156 months) after the initial operation. At the final follow-up, JOA score increased from 8.58 ± 2.53 before surgery to 12.67 ± 1.84 (P < 0.05) and VAS score improved from 6.17 ± 1.21 to 2.08 ± 1.32 (P < 0.05). Besides, clinical symptoms were relieved in all patients after revision surgery. All patients had rigid internal fixations with bone fusion and no major complications occurred.
Conclusions: Posterior occipitocervical plate-screw system with bicortical screws had the advantages of safety, simple and promising efficacy without excessive tissue release or intraspinal manipulation, proving that it's valuable as a modified technique for occipitocervical revision surgery.
Keywords: Bicortical screw; Modified technique; Occipital plate; Occipitocervical instability; Revision surgery.
© 2021 The Authors. Orthopaedic Surgery published by Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.