Surgical treatment of 40 patients with thoracic ossification of the ligamentum flavum

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>The authors evaluated different surgical methods used to treat thoracic ossification of the ligamentum flavum (OLF).</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>Data obtained in 40 patients who underwent posterior decompression for thoracic myelopathy caused by thoracic OLF were studied retrospectively. There were 32 men and eight women. All patients underwent posterior decompression in which laminoplasty was performed or laminectomy combined with lateral fusion. Every surgical specimen was stained with H &amp; E, and scanning electron microscopy was performed in 20 cases. The mean follow-up period was 28 months. Postoperative outcomes were evaluated using a recovery scale based on the Japanese Orthopaedic Association classification. There were a total of 168 ossified segments in this series, 77.4% of which were located in the lower thoracic spine. Marginal osteophyte formation was found in 36 patients; in 32 of the 36 patients, these marginal osteophytes were located at the intervertebral space either higher or lower than the ossified segment. Scanning electron microscopy showed elastic fiber breakdown, proliferation of collagenous fibers, calcification, and OLF in the same microscopy region. Laminoplasty was performed in four patients. In three cases surgery resulted in unchanged or worse outcome (increased kyphotic deformity in two), and in one it resulted in good outcome. Laminectomy combined with lateral fusion was performed in 36 patients, in 30 cases of which it resulted in a good or fair outcome, and increased kyphotic deformity in only one. Of these 36 laminectomy-treated patients, an en bloc laminectomy-treated procedure was performed in 16 patients; in 11 of the 12 patients with lateral or diffuse-type lesions the surgery resulted in a good or fair outcome. En bloc laminectomy, however, seems ineffective in the treatment of patients with thickened, nodular-type thoracic OLF, as the procedure resulted in worse outcome in two of the four patients. The authors have thus developed a new modality of laminectomy that they have termed “separating laminectomy,” which they performed in 16 patients with thickened, nodular-type OLF; in 13 cases it resulted in a good or fair outcome, and in only one case did it result in a worse outcome.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The pathogenesis of thoracic OLF is mainly due to the localized mechanical stress on the ligament. Laminectomy combined with lateral fusion is the treatment of choice for thoracic OLF; furthermore, in terms of the configuration of the ossified lesion, en bloc laminectomy is suitable for the treatment of lateral-type and diffuse-type OLF, and the separating laminectomy is suitable for the thickened, nodular-type OLF.</jats:p></jats:sec>

Epidemiological survey of ossification of the ligamentum flavum in thoracic spine: CT imaging observation of 993 cases

“…CT has a high-density resolution and no overlapping factors. It has a high sensitivity to ossification and can find the early formation of OLF when there is no obvious change in the thickness [7,8]. Therefore, MDCT was used in this study to identify the prevalence of OLF in a large study population, with greater sensitivity compared to previous studies.…”

“…OLF occurs mainly in the Asian population [2][3][4][5][6][7][8] and there are only a few reports in the Caucasian, African, and Arabic racial groups [9][10][11][12][13][14]. OLF is one of the commonest causes of thoracic spinal stenosis and spinal cord compression, which can cause serious neurological symptoms or even paraplegia.…”

Removal of ossified ligamentum flavum via a minimally invasive surgical approach

“…1,3,5,7 This leads to excellent visualization and complete resection of the pathological lesion. However, most cases of OLF involve multiple levels, thus necessitating an extended surgical decompression.…”

“…Patients often have long-standing symptoms, usually in excess of 1 year, prior to the establishment of the diagnosis. 1,[3][4][5]7 Controversy exists as to whether symptom duration is a reliable predictor of outcome. 4 In this particular case, the patient presented after only 4 months of symptomatic myelopathy, which may be a contributing factor to her expeditious full recovery.…”

“…Several studies have revealed that multilevel laminectomies with removal of the ligaments and facets for the treatment of OLF have resulted in the delayed development of a kyphotic deformity. 5,6,8 Preservation of the facets and/or ligaments is necessary to avoid a fusion. Therefore, some authors advocate the use of laminoplasty as a treatment option.…”