How Does Screw Migration or Fracture After Anterior Cervical Plate Fixation Affect the Radiographic and Clinical Outcomes?

Abstract

A retrospective cohort study. The objective of this article is to assess the effect of screw migration and fracture associated with anterior cervical plating on long-term radiographic and clinical outcomes. Screw migration and breakage detected after anterior cervical discectomy/corpectomy and fusion with plating may cause various implant-related complications and reduce solid fusion rate. However, little is known about their long-term prognosis. Medical records and radiographic data of 248 consecutive patients who underwent anterior cervical discectomy and fusion or anterior cervical corpectomy and fusion with a dynamic plating system and were followed up for ≥2 years were retrospectively reviewed. Patients who experienced screw migration or breakage were classified as screw failure group (SF group, n=25). Patients without screw loosening or fracture until the last follow-up were defined as the nonfailure group (NF group, n=223). Visual analogue scales for neck pain, arm pain, and neck disability index were assessed. Radiologic measurements were performed to analyze solid fusion. The solid union was defined as interspinous motion ≤1 mm on flexion/extension lateral x-rays. A number of levels fused was significantly associated with increased risk of screw failure (P<0.01). A total of 13 patients in the SF group achieved solid fusion at final follow-up, although fusion rates at all postoperative time points were significantly lower in the SF group than in the NF group, including at final follow-up (P<0.01). Failures in 23 (92%) screw failure patients developed at the lowermost instrumented vertebra. The SF and NF groups experienced similar degrees of neck pain, arm pain, and neck disturbance index scores. There were no cases of complete screw extrusion or related complications requiring revision surgery. Although screw failure increased the incidence of pseudarthrosis, it did not aggravate postoperative arm pain, neck pain, or neck disability. As failed implants rarely migrate to an extent that endangers tracheoesophageal structures, immediate removal is rarely necessary.