Clinical features and surgical outcomes of patients with thoracic myelopathy caused by multilevel ossification of the ligamentum flavum

摘要

Background context: Thoracic myelopathy caused by multilevel (three or more levels) ossification of the ligamentum flavum (OLF) is rare. Little is known about its clinical features, and the surgical outcomes along with its related factors are also unclear. Purpose: To describe the clinical features, assess the safety and effectiveness of surgical decompression, and determine the prognostic factors relevant for patients with thoracic myelopathy caused by multilevel OLF. Study design/setting: A retrospective clinical study. Patient sample: Seventy-five consecutive multilevel OLF patients who underwent surgical decompression were analyzed. Outcome measures: Modified Japanese Orthopedic Association (JOA) scale and the recovery rate. Methods: Patients who underwent surgical decompression for symptomatic multilevel OLF during January 1996 to June 2010 were all included. Clinical data were collected from medical and operative records; patients were evaluated by using the JOA scale preoperatively and during the follow-up. Correlations between the surgical outcome and various factors were also analyzed. Results: Forty-three men and 32 women with a mean age of 54.7 years (range 36-78 years) were included. The mean number of involved levels is 4.6 and contiguous OLF presented in 73.3% of these patients. The most common involved levels were T10/T11 (15.4%), T9/T10 (13.3%), and T11/T12 (12.5%). Coexisting spinal disorders were found in 41 patients (54.7%). Preoperative evaluation showed the mean JOA score was 5.8±1.7; 37.3% of these patients had mild myelopathy, 53.3% had moderate myelopathy, and 9.3% had severe myelopathy. All patients received posterior laminectomy. The JOA score (mean 8.2±2.1) significantly increased postoperatively (p<.05), and multiple regression analysis showed that preoperative duration of symptoms and preoperative JOA score were important predictors of surgical outcome. Conclusions: Laminectomy with partially internal fixation is safe and effective in treatment of patients with symptomatic multilevel OLF. The results of our study show that preoperative JOA score and preoperative duration of symptoms were important predictors for the clinical outcome.