Indication for anterior spinal cord decompression via a posterolateral approach for the treatment of ossification of the posterior longitudinal ligament in the thoracic spine: a prospective cohort study.

PURPOSE: For ossification of the posterior longitudinal ligament (OPLL) in the thoracic spine, anterior decompression is the most effective method for relieving spinal cord compression. The purpose of this study was to prospectively analyze the surgical outcomes based on our strategy in the treatment of thoracic OPLL. METHODS: This study included 23 patients who underwent surgery for thoracic OPLL based on the following strategy between 2011 and 2017. For patients with a beak-type OPLL in the kyphotic curve with a ≥ 50% canal occupying ratio, circumferential decompression via a posterolateral approach and fusion (CDF) was indicated. For other types of OPLL, posterior decompression and fusion (PDF) was commonly indicated. Posterior fusion without decompression (PF) was applied when the spinal cord was separated from the posterior spinal elements. Clinical and radiological outcomes were compared among the CDF, PDF, and PF groups with a minimum of 20-month follow-up. RESULTS: Ten, eleven, and two patients underwent CDF, PDF, and PF, respectively. The preoperative Japanese Orthopedic Association (JOA) score in the CDF group was significantly lower than that in the PDF group. The average recovery rate, according to JOA score, was 63%, 56%, and 25% in the CDF, PDF, and PF groups, respectively. The result in the CDF group was better than that in the PF group. CONCLUSIONS: Anterior decompression was appropriate for patients with localized spinal cord compression by a large OPLL in the kyphotic curve, and CDF via a posterolateral approach appears to be safe and effective. These slides can be retrieved under Electronic Supplementary Material.