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Open Access Highly Accessed Research article

Thoracic myelopathy caused by ossification of ligamentum flavum of which fluorosis as an etiology factor

Wenbao Wang12*, Linghua Kong3, Heyuan Zhao1, Ronghua Dong1, Jing Zhou1 and Yun Lu3

Author Affiliations

1 Spine surgery department, Tianjin hospital, No. 406 Jiefangnan Road, Hexi District, Tianjin City, 300211, People's Republic of China

2 106 Fort Washington Avenue, Room 3H, New York City, NY, 10032, USA

3 Hand surgery department, Tianjin hospital, No. 406 Jiefangnan Road, Hexi District, Tianjin City, 300211, People's Republic of China

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Journal of Orthopaedic Surgery and Research 2006, 1:10  doi:10.1186/1749-799X-1-10

Published: 2 November 2006

Abstract

Purpose

To evaluate the clinical feature, operative method and prognosis of thoracic ossification of ligamentum flavum caused by skeletal fluorosis.

Methods

All the patients with thoracic OLF, who underwent surgical management in the authors' hospital from 1993–2003, were retrospectively studied. The diagnosis of skeletal fluorosis was made by the epidemic history, clinical symptoms, radiographic findings, and urinalysis. En bloc laminectomy decompression of the involved thoracic levels was performed in all cases. Cervical open door decompression or lumbar laminectomy decompression was performed if relevant stenosis existed. The neurological statuses were evaluated with the Japanese Orthopaedic Association (JOA) scoring system preoperatively and at the end point of follow up. Also, the recovery rate was calculated.

Results

23 cases have been enrolled in this study. Imaging study findings showed all the cases have ossification of ligamentum flavum together with ossification of many other ligaments and interosseous membranes, i.e. interosseous membranes of the forearm in 18 of 23 (78.3%), of the leg in 14 of 23 (60.1%) and of the ribs in 11 of 23 (47.8%). Urinalysis showed markedly increased urinary fluoride in 14 of 23 patients (60.9%). All the patients were followed up from 12 months to 9 years and 3 months, with an average of 4 years and 5 months. The JOA score increased significantly at the end of follow up (P = 0.0001). The recovery rate was 51.83 ± 32.36%. Multiple regression analysis revealed that the preoperative JOA score was an important predictor of surgical outcome (p = 0.0022, r = 0.60628). ANOVA analysis showed that patients with acute onset or too long duration had worse surgical result (P = 0.0003).

Conclusion

Fluorosis can cause ossification of thoracic ligamentum flavum, as well as other ligaments. En bloc laminectomy decompression was an effective method. Preoperative JOA score was the most important predictor of surgical outcome. Patients with acute onset or too long duration had worse surgical outcome.