脊椎ジャーナル

Evaluation of Progression of Ossification of Ligamentum Flavum in the Thoracic Spine Using Computed Tomography

Abstract

Yan Wang, Chuiguo Sun, Zhongqiang Chen and Fabo Feng

Objective: To evaluate the progression of Ossification of Ligamentum Flavum (OLF) in the thoracic spine based on cross-sectional Computed Tomography (CT) comparisons.

Method: OLF in spinal segments that did not require surgery because there were no cord compression of 17 patients who underwent laminectomies for treating symptomatic OLF were retrospectively reviewed (mean follow-up 6.3 years). Initial (preoperative or postoperative but before discharge) and final follow-up canal area unoccupied ratio (CAUR) of no-operated OLF were compared to evaluate the progression of OLF. Factors influencing OLF progression were also analyzed. Two-year follow-up and final follow-up results were assessed to evaluate the influence of OLF progression on long-term outcomes.

Result: Sixty OLF levels were compared between initial and final follow-up CT. The final follow up CAUR was significant lower than the initial in all OLF levels. Repeated measurement was used to reduce the effect of measurement error, and progression of OLF affected approximately 60% of patients and 33% of OLF segments, with annual growth rate in OLF area of 1.61%. CT mature/immature classification was an independent risk factor for the development of OLF. No patient exhibited neurological deterioration due to OLF progression.

Conclusion: Thoracic OLF that are not operated on still progress, and OLF classified as immature ossification on CT develop more significantly. Additionally, progression of OLF is not associated with neurologic regression in 5- 9 years follow-up, thus preventive laminectomy is unnecessary for OLF segments that do not compress the spinal cord.