Removal of Posterior Longitudinal Ligament in Anterior Decompression for Cervical Spondylotic Myelopathy

Study Design: The clinical and radiologic results of the patients with removed posterior longitudinal ligament (PLL) were compared with those of the patients with preserved PLL in the treatment of cervical spondylotic myelopathy (CSM). Objective: To investigate effect of resection of the PLL in anterior decompression for CSM. Summary of Background Data: Anterior decompression has been proved to be effective in the treatment of CSM, and the pathogenic matters including herniated disc, proliferative osteophyte, and ossification of posterior longitudinal ligament should be definitely removed. However, it still remains controversial to remove degenerative or hypertrophic PLL, considering the potential risks of dura tears and neurologic injury. Methods: Between March 1997 and December 2002, 58 patients who underwent anterior decompression for CSM were included in this study. Among them, the PLL was removed in 31 patients (PLL removed group) and that was preserved in the other 27 patients (PLL preserved group). The clinical [ Japanese Orthopedic Association (JOA) score] and radiologic (diameter of the spinal cord on magnetic resonance image) results were compared between 2 groups. The risk of complications and reoperation was also evaluated. Results: With a 12-month follow-up, the mean JOA score increased from 10.4 +/- 1.8 to 15.2 +/- 1.2 in PLL removed group and that increased from 10.7 +/- 1.6 to 14.6 +/- 1.1 in PLL preserved group. The improvement rate between 2 groups was significantly different (74% +/- 23% vs. 63% +/- 21%, P<0.01). Radiologic study showed that the increase of diameter of the spinal cord in PLL removed group was significantly greater than that in PLL preserved group (3.78 +/- 1.25 mm vs. 2.02 +/- 1.03 mm P<0.01). Only 1 patient with PLL removed developed cerebrospinal fluid leakage after operation, and 8 patients (5 with PLL preserved and 3 with PLL removed) need posterior revision surgery. Conclusions: Removal of PLL was generally safe and helpful to get more decompression in anterior approach for CSM, although more technically demanding.