Posterior lumbar interbody fusion via a unilateral approach

Abstract

This study sought to determine the outcomes of posterior lumbar interbody fusion (PLIF), via a unilateral approach, in selected patients who presented with unilateral leg pain and segmental instability of the lumbar spine. Patients with a single level of a herniated disc disease in the lumbar spine, unilateral leg pain, chronic disabling lower back pain (LBP), and a failed conservative treatment, were considered for the procedure. A total of 41 patients underwent a single-level PLIF using two PEEK (Poly-Ether-Ether-Ketone) cages filled with iliac bone, via a unilateral approach. The patients comprised 21 women and 20 men with a mean age of 41 years (range: 22 to 63 years). Two cages were inserted using a unilateral medial facetectomy and a partial hemilaminectomy. At follow-up, the outcomes were assessed using the Prolo Scale. The success of the fusion was determined by dynamic lumbar radiography and/or computerized tomography scanning. All the patients safely underwent surgery without severe complications. During a mean follow-up period of 26 months, 1 patient underwent percutaneous pedicle screw fixation due to persistent LBP. A posterior displacement of the cage was found in one patient. At the last follow up, 90% of the patients demonstrated satisfactory results. An osseous fusion was present in 85% of the patients. A PLIF, via a unilateral approach, enables a solid union with satisfactory clinical results. This preserves part of the posterior elements of the lumbar spine in selected patients with single level instability and unilateral leg pain.

Fig. 1

Diagrams depicting the steps of the PLIF via a unilateral approach. (A) After the retraction of the thecal sac and traversing nerve root to the midline, disc material and endplates are removed as much as possible in both the contralateral and ipsilateral sides. Before the cage insertion, the lamina and cortical bone from the iliac crest are grafted as much as possible into the contralateral and anterior sides of the intervertebral space. (B) The first cage filled with cancellous bone from the iliac crest is introduced to the intervertebral space. (C) The cage is carefully pushed to the contralateral side with the down-biting curettes and impactor. (D) The second cage was impacted to the ipsilateral side in the same manner. (E) Lastly, adequate impaction and complete hemostasis are performed.

Fig. 2

A 53-year-old woman presented with a 1-year history of LBP and radiating right leg pain. (A) Plain dynamogram revealing flexion instability at L4-5. (B-C) Spinal MRI showing a severe disc protrusion with degenerative disease at the same level. The patient underwent L4-5 PLIF using PEEK cage. (D) Plain radiograph obtained one and a half years after the surgery demonstrates a solid fusion. At the last follow-up visit, she has returned to daily activities without any symptoms.

Fig. 3

This case showed retropulsion of the inserted cage at 6 months postoperative. (A, B) Preoperative MRI showed degenerative disc herniation at L5/S1 segments. (C) At 6 months after PLIF, the cage migrated posteriorly and compressed the dural sac.