Lumbar disc herniation associated with separation of the posterior ring apophysis: analysis of five surgical cases and review of the literature.

BACKGROUND

Separation of the posterior ring apophysis of an adjacent vertebral body can sometimes accompany lumbar intervertebral disc herniation. The condition can be both difficult to detect in conventional radiographs and is somewhat controversial to treat. Although there is general agreement on the frequent need for surgery, there is no consensus on the choice of operation. One procedure, posterior lumbar interbody fusion (PLIF), has never been examined for effectiveness.

METHOD

Computed tomography (CT) either or with discography (CTD) was compared to plane radiographs and magnetic resonance imaging (MRI) for its ability to reveal the fragmentation. Five cases were identified and the severity of the condition evaluated using the Japanese Orthopaedic Association's Assessment of Treatment for Low Back Pain (JOA score). The fragments were removed by impaction with a shoe shaped device and posterior lumbar interbody fusion (PLIF) was performed using autogenous iliac crest bone. A second evaluation using the JOA score was performed after a 4 to 5 year follow-up.

FINDINGS

CT identified the separation in all 5 cases while plain films showed the defect in two and MRI in none. JOA scores prior to surgery were between 5 and 19 (mean, 13) and between 25 and 29 (mean, 27.4) at follow-up. The scores represented a recovery of 80% to 100%t (mean, 89.4).

INTERPRETATION

CT and CT discography (CTD) are the diagnostic tools of choice for detecting this condition. Posterior lumbar interbody fusion (PLIF) is an effective procedure for patients who have low back pain due to lumbar disc herniation accompanied by a separation of the posterior ring apophysis.