Abstract
Introduction
Degenerative cervical myelopathy (DCM) is an umbrella term that includes cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament (OPLL) and other forms of degenerative changes to the spinal axis. The surgical management of OPLL can be technically challenging for spine surgeons and may result in a higher incidence of perioperative complications than surgery for other forms of DCM. It is unclear whether surgery is equally effective and safe in patients with OPLL as it is in other forms of DCM. This study aims to compare the impact of cervical decompressive surgery on functional status and Quality of Life (QOL) outcomes in patients with OPLL and those with other forms of DCM.
Material and Methods
479 surgical patients with symptomatic DCM were prospectively enrolled in the CSM-International study at global 16 sites. Patients’ functional and neurological status were evaluated using the modified Japanese Orthopedic Assessment scale (mJOA) and the Nurick score. QOL was assessed using patient-reported outcome measures, including the Neck Disability Index (NDI) and the Short- Form 36 (SF-36) Health Survey. Improvements in functional status and QOL were assessed between baseline and 1- and 2-year follow-ups, and relative gains were compared between patients with and without OPLL. A sub-analysis was conducted in patients with “severe” myelopathy (a preoperative mJOA < 12) to determine whether surgical outcomes differed between patients with severe OPLL and those with other forms of severe DCM. Improvements in preoperative functional status and QOL at 2-years follow-up were compared between the two diagnosis groups, while controlling for relevant confounding variables.
Results
Of 479 patients, 135 (28.2%) exhibited evidence of OPLL and 344 (71.8%) displayed other forms of degenerative changes. There were no significant differences in demographics, surgical approach, or baseline severity scores between patients with OPLL and those with other forms of DCM. Patients with OPLL achieved similar functional outcomes at 1- and 2-years following surgery when compared with patients with other forms of DCM. With respect to QOL, the NDI and most subscales of the SF-36, there were no differences between the two diagnosis groups. However, the SF-36 Role Limitation Physical subscale (p = 0.0091) at 1-year and the SF-36 Social Functioning subscale at 1- and 2-years (p = 0.014, p = 0.018) were significantly lower in OPLL patients. In patients with severe myelopathy (preoperative mJOA < 12), 49 (28.65%) presented with OPLL and 122 (71.35%) with other forms of DCM. There were comparable improvements between preoperative and 2-year postoperative scores across all outcome measures (mJOA, Nurick, NDI, and SF-36) in patients with severe myelopathy due to OPLL and other forms of DCM. Finally, there was a significantly higher rate of perioperative complications in the OPLL group (p = 0.054). This significant difference was mainly due to a higher incidence of superficial infection (p = 0.0067), new neck pain (p = 0.079) and dural tear (p = 0.076) in the OPLL group. However, rates of neurological complication did not significantly differ (p = 0.73).
Conclusion
Surgical decompression for the treatment of OPLL results in significant improvements in functional status and QOL, comparable to gains seen in other forms of DCM.