Thoracic Myelopathy in Ossified Ligamentum Flavum: Surgical Management and Long-Term Outcome Following 2 Different Techniques of Surgical Decompression.

Abstract

Retrospective cohort study. Thoracic ossified ligamentum flavum (TOLF) has been reported to present with varying degrees of neuro-deficit and multiple factors have been purported to affect its outcome. Purpose of study was to analyze factors affecting outcome and impact of ultrasonic osteotome (UO). We retrospectively reviewed patients treated for thoracic myelopathy secondary to OLF between 2010 and 2017. 77 patients with complete clinico-radiological records and 2 years follow-up were included. Initial 45 patients, conventional high-speed burr (HSB-group A) was used for decompression. In others, UO was used in combination with HSB (group B). Myelopathy was graded using modified Japanese orthopaedic association grading pre-operatively and each postoperative visit. At final follow-up, recovery rate was calculated. Radiological details including location, morphology, dural ossification, signal change and spinal ossifications were recorded. Mean mJOA at presentation and final follow-up were 4.3±1.8 and 7.6±1.9 respectively (p = 0.001). HRR was 49.9±23 at final follow-up. A significant reduction in dural tear (12.5%; 29%) and surgical time (125.8±49.5; 189.4±52.5) were observed in group B (p = 0.00). However, there was no statistically significant difference (p = 0.18) in recovery rates between groups A (44.8±26.1) and B (52.8±24.3). Symptom duration (p = 0.00), severity of myelopathy (p = 0.04) and cord signal changes on MRI (p = 0.02) were important predictors of outcome. Use of UO significantly reduced operative time and dural tears, although resulted in similar recovery rate as compared with HSB. Pre-operative severity of myelopathy, symptom duration and presence of cord signal change were the most significant predictors of outcome.