Value of Additional Instrumented Fusion in the Treatment of Thoracic Ossification of the Ligamentum Flavum

Abstract

Objective :The ossification of the ligamentum flavum (OLF) is one of the major causes of thoracic myelopathy. Surgical decompression with or without instrumented fusion is the mainstay of treatment. However, few studies have reported on the added effect of instrumented fusion. The objective of this study was to compare clinical and radiological outcomes between surgical decompression without instrumented fusion (D-group) and that with instrumented fusion (F-group). Methods : A retrospective review was performed on 28 patients (D-group, n=17; F-group, n=11) with thoracic myelopathy due to OLF. The clinical parameters compared included scores of the Japanese Orthopedic Association (JOA), the Visual analogue scale of the back and leg (VAS-B and VAS-L), and the Korean version of the Oswestry disability index (K-ODI). Radiological parameters included the sagittal vertical axis (SVA), the pelvic tilt (PT), the sacral slope (SS), the thoracic kyphosis angle (TKA), the segmental kyphosis angle (SKA) at the operated level, and the lumbar lordosis angle (LLA; a negative value implying lordosis). These parameters were measured preoperatively, 1 year postoperatively, and 2 years postoperatively, and were compared with a linear mixed model. Results : After surgery, all clinical parameters were significantly improved in both groups, while VAS-L was more improved in the Fgroup than in the D-group (-3.4±2.5 vs. -1.3±2.2, p=0.008). Radiological outcomes were significantly different in terms of changes in TKA, SKA, and LLA. Changes in TKA, SKA, and LLA were 2.3°±4.7°, -0.1°±1.4°, and -1.3°±5.6° in the F-group, which were significantly lower than 6.8°±6.1°, 3.0°±2.8°, and 2.2°±5.3° in the D-group, respectively (p=0.013, p<0.0001, and p=0.037). Symptomatic recurrence of OLF occurred in one patient of the D-group at postoperative 24 months. Conclusion : Clinical improvement was achieved after decompression surgery for OLF regardless of whether instrumented fusion was added. However, adding instrumented fusion resulted in better outcomes in terms of lessening the progression of local and regional kyphosis and improving leg pain. Decompression with instrumented fusion may be a better surgical option for thoracic OLF.

Outcome of Decompressive Laminectomy with or without Posterior Screw Fixation for Thoracic Ossification of the Ligamentum Flavum with Disc Degeneration

“…Surgical decompression is required when myelopathy progresses, and the effectiveness of decompression surgery for OLF has been demonstrated in previous studies 8) . Various studies have reported sufficient treatment effects with only decompression surgery, and recurrence is uncommon 6,8,15) .…”

“…In some cases, a combined fixation technique has been used; however, given the pathophysiology potentially triggered by micro-movements or macro-movements, especially associated with partial facet removal during decompression, it may be reasonable to stabilize the motion via screw fixation after decompression 1,5,6,13,18,20) . Hwang et al 6) reported that screw fixation is beneficial for the progression of kyphosis in OLF. However, the need for fixation for specific patients is still controversial.…”

Early Recurrence of Thoracic Ossification of the Ligamentum Flavum After Posterior Decompression Surgery: A Case Report

“…It may be worth considering whether decompression surgery alone, without instrumented fusion, is sufficient for OLF in the thoracolumbar junction, while there have been some positive reports regarding the effectiveness of decompressive instrumented fusion for thoracic OLF [7,8]. The available evidence is insufficient for making clear judgments.…”