Surgery for thoracic myelopathy caused by ossification of the ligamentum flavum

Between January 1996 and December 2003, our department treated 16 patients (10 men and 6 women; average age 57.5 years) by performing a laminectomy for thoracic myelopathy caused by ossification of the ligamentum flavum (OLF). We followed up all patients for 36 to 86 months (mean follow-up time, 57.3 months). The mean (+/-standard deviation) Japanese Orthopaedic Association score increased from 5.0+/-1.4 points before the operation to 7.7+/-1.9 points at the last follow-up (p<0.01). The average values for pre-operative and post-operative kyphosis of the involved vertebrae were 5.8 degrees +/-4.1 degrees and 8.8 degrees +/-6.0 degrees , respectively; the mean increase in kyphosis was only 3.0 degrees +/-2.4 degrees . An intraoperative dural tear was the main complication and none of the patients developed severe neurological complications. We conclude that laminectomy was both effective and safe in the treatment of thoracic OLF, but it must be performed with great care because of frequent dural adhesions to the OLF. The increase in kyphosis after the laminectomy was minimal when most of the facet joints were left intact and when the patient followed a back extensor exercise program post-operatively.