We evaluated the operative results in 32 cases with ossification of the yellow ligament (OYL) in the thoracic spine using JOA score and Hirabayashi's method. All patients had had laminectomy at least a year previously. Preoperative average JOA score was 4.3 points, postoperative average JOA score was 8.0 points with an average improvement rate of 61.8%.
We devised four types of classification according to neurological symptoms, namely spastic spinal paralysis, flaccid paralysis, combined type and normal reflex type depending on the variety of deep tendon reflexes of the lower extremities. We then discussed the causative mechanisms such as various types of paralysis originating at the thoracolumbar junction.
In addition, we referred to the surgical indications for OYL by analysing the operative results.