Surgical treatment for posterior rim separation of the lumbar and sacral vertebrae

Abstract

Objective: The posterior rim separation of the lumbar and sacral vertebrae has been ascribed to various mechanisms. The procedure of operative treatment is still controversial. The authors' objective was to study the therapeutic methods of posterior vertebral rim separation.

Methods: Thirty-four patients, including 23 males and 11 females whose ages ranged from 24 to 65 years (mean 41.3 years), were treated for posterior vertebral rim separation by various methods. All patients had discectomy and removal of bony fragment. Wide fenestration or hemilaminectomy was performed for 24 type I-III lesions, laminectomy for four type II and one type III lesion, and bilateral fenestration for 5 of 17 type II lesions. Posterior lumbar interbody fusion (PLIF) was performed in 11 patients using autogenous iliac bone or poly (ether-ether-ketone) (PEEK) spacer implant.

Results: Follow-up studies were performed for all patients ranging from 11 months to 4.6 years with an average period of 2.7 years. There were no serious intra-operative or postoperative complications. Satisfactory results were achieved in all patients except two with type III lesions, mostly because of a long history of hypaesthesia of the leg and a drop foot. Eleven patients who had PLIF exhibited bony fusion at final follow-up.

Conclusions: Early operative treatment should be performed on patients after a brief trial of conservative treatment. A proper surgical operation must be based on the type and location of the separated bony fragment and clinical symptoms.

Keywords: Lumbar vertebrae; Posterior lumbar interbody fusion; Posterior rim separation; Sacral vertebrae.

Figure 1

Type II lesion, and posterior lumbar interbody fusion (PLIF) was performed at L _4–5. (a,b) Lateral flexion and extension radiographs reveal bony density projecting into the spinal canal at the lower L ₄ level (arrow). (c) Computed tomography. Crescent shaped fragment with osseous defect of the vertebral body. (d) Sagittal T ₂ weighted MRI showing evidence of cord compression opposite the L _4–5 disc level. (e, f) Anteroposterior and lateral radiographs one year after PLIF.

Figure 2

Type II lesion. (A) Plain radiograph. No recognizable fragment at the posterior superior margin of L ₅. (B,C) Computed tomography. Bony fragment and anterior Schmorl nodes (white arrow). (D) MRI showed L _4–5 disc prolapse and a small bony density projecting into the spinal canal. (E) Postoperative CT. The bony fragment has been completely removed.