Serial changes of herniated intervertebral discs after posterior lumbar discectomy: the relation between magnetic resonance imaging of the postoperative intervertebral discs and clinical outcome.

To evaluate the relation between the morphologic changes of postoperative intervertebral discs and the clinical outcome after posterior lumbar discectomy, the size of the bulging disc was analyzed prospectively on serial follow-up magnetic resonance images in 26 randomly selected patients. The bulging of postoperative intervertebral discs involved three patterns of reduction: early reduction (n = 15), gradual reduction (n = 6), and late reduction (n = 5). There was a significant difference in the serial changes of subjective symptoms and neurologic function among the three patterns. A late reduction of postoperative disc bulging could cause late recovery of subjective symptoms and neurologic disturbance.