Surgical experience with symptomatic thoracic ossification of the ligamentum flavum

Object. Symptomatic thoracic ossification of the ligamentum flavum (OLF) is rare, and its prognostic factors remain unclear. The authors retrospectively studied 24 patients with surgically treated thoracic OLF to delineate its prognostic factor. Methods. The clinical manifestations, radiological studies, surgical records, and pathological findings were reviewed. Preoperative and postoperative neurological data were reappraised using the American Spinal Injury Association and modified Japanese Orthopaedic Association (JOA) scoring systems. Spearman rank-correlation coefficients and nonparametric tests were used to analyze the correlations between the variables of patient characteristics, preoperative duration of symptoms, preoperative neurological status, associated spinal disorder(s) other than thoracic OLF, and the final functional outcome. Conclusions. Decompressive surgery is indicated in patients in whom symptomatic thoracic spinal cord compression is caused by intruding OLF. Magnetic resonance imaging can provide sufficient clues for the diagnosis of thoracic OLF. Higher preoperative modified JOA scores of 3 and 4 are positively correlated with better postoperative functional recovery than lower scores. Surgery should be performed as soon as possible before independent ambulatory function is impaired.