Background
Posterior lumbar interbody fusion (PLIF) is a fusion technique with reliable and rapid fusion results. The traditional technique describes the use of two cages filled with bone graft and inserted in a straight-ahead direction within the prepared disc space. Bone graft used is usually harvested from the posterior iliac crest. This study evaluates the use of a single cage inserted diagonally through unilateral discectomy and filled with bone fragments obtained from the local decompression procedure.
Patients and methods
Fourteen patients underwent pedicle screw-rod supplemented PLIF and spinal canal decompression for symptomatic spinal canal stenosis, instability, or spondylolisthesis refractive to conservative treatment. PLIF was performed using a single PEEK cage filled with impacted graft from the locally excised bone. The PEEK cage was inserted into the prepared intervertebral disc space in an oblique (diagonal) manner to obtain near-symmetrical end-plate loading across the midline.
Results
The mean follow-up period was 15 months. The mean duration of surgery was 170 and 225 min for single-level and double-level fusions, respectively. The mean volume of blood loss was 850 and 1050 ml for single-level and double-level fusions, respectively. The mean duration for hospital stay was 5 days. Postoperative radiographs showed a mean increase in the disc height by 24.4% and a mean increase in lordosis angle by 4.3°. Pain and functional scores showed marked improvement. The mean Visual Analog Scale decreased from 7.8 to 2.2. The mean Oswestry Disability Index decreased from 82 to 28. The mean Economic Prolo Scale was 3.2 whereas the Functional Prolo Scale was 3.8. Interbody fusion was assessed using lateral radiographs. Loss of demarcation of the bony end-plates with consolidation of graft through the cage was the indication of successful fusion. At final follow-up, 10 patients showed solid fusion, three patients showed delayed fusion, and one patient showed loss of reduction of spondylolisthesis after a traumatic incident and required a revision surgery. Yet, patients with delayed union did show similar improvement to those with early union on the Visual Analog Scale and Oswestry Disability Index.
Conclusion
The use of single unilateral and obliquely inserted PEEK cage is an effective safe procedure for interbody fusion that gives comparable results to the traditional double-cage technique while shortens the operative time, lowers the blood volume loss, and also lowers the cost for implants used without endangering reliability of the technique.