Comparisons of Minimum 2-Year Outcomes Between Posterior Decompressive Fusion Surgeries With and Without Anterior Decompression Through a Posterior Approach for Thoracic Ossification of the Posterior Longitudinal Ligaments: A Retrospective Multicente

Study Design: Multicenter retrospective cohort study. Objective: To compare the clinical outcomes and surgical efficacies of circumferential decompression and instrumented fusion through the posterior approach (CDF) and posterior decompression with instrumented fusion (PDF) in patients with thoracic ossification of the posterior longitudinal ligament (OPLL). Summary of Background Data: Thoracic OPLL is a rare condition often requiring surgery. PDF has been widely performed because of its safety and acceptable neurological outcomes; however, it offers limited direct decompression. Compared with PDF, CDF, which is generally more invasive, allows for direct spinal cord decompression and may lead to improved neurological recovery; however, no previous studies with a large sample size have been conducted. Methods: This retrospective multicenter study included 64 patients (CDF: 21, PDF: 43) who underwent surgery for thoracic OPLL between 2005 and 2020 with ≥2-year follow-up. Clinical outcomes were assessed using the modified Japanese Orthopaedic Association (JOA) score. The operative parameters, intraoperative spinal cord decompression (through ultrasonography), and complications were also analyzed. Results: Patients with CDF had a longer operative time (median 538 vs. 400 min, P < 0.001), greater blood loss (1023 vs. 730 mL, P < 0.05), and longer fusion (9 vs. 7 segments, P < 0.01). Spinal cord floating on intraoperative ultrasonography was observed in 93.8% of patients with CDF versus 31.3% of patients with PDF ( P < 0.001). The JOA recovery rate at final follow-up was significantly higher in CDF (80% vs. 47.2%, P < 0.01). Dural injury occurred more frequently in CDF (42.9% vs. 16.3%, P < 0.05), whereas motor deterioration and reoperation rates were not significantly different. In patients with severe preoperative myelopathy (JOA ≤4), recovery rate at the final follow-up was also superior in CDF (77.5% vs. 44.4%, P < 0.05). Conclusion: CDF provides superior spinal cord decompression and neurological recovery compared with PDF. Despite its greater invasiveness, CDF should be considered for patients with severe preoperative myelopathy.