Modified posterior lumbar interbody fusion using a single cage with unilateral pedicle screws: a retrospective clinical study

BACKGROUND The traditional posterior lumbar interbody fusion (PLIF) technique usually involves implantation of two cages through a bilateral approach and bilateral laminectomy, which requires bilateral transpedicle screw fixation. The procedure itself has several negative impacts. Therefore, a modified PLIF procedure that includes insertion of a unilateral cage through the symptomatic side with supplementary unilateral pedicle screws has been conducted. MATERIALS AND METHODS Thirty-one patients with unilateral radiculopathy who were diagnosed with spinal stenosis along with degenerative disc disease and a herniated intervertebral disc with lumbar instability underwent a unilateral PLIF using a single cage and unilateral pedicle screws. The postoperative clinical evaluation was based on the visual analogue scale (VAS) and the Oswestry Disability Index (ODI) for back pain and leg pain at multiple time points following the surgery. Radiological assessments were performed with lateral plain radiographs taken preoperation, immediately postoperation, 1, 2, 3 and 6 months postoperation and at the most recent follow-up. RESULTS The patients all underwent a single-level fusion, and the mean duration for the surgeries was 94 min. The mean haemorrhage volume was 250 ml, and no blood transfusion was required for any of the cases. Twelve months postoperatively, all patients had achieved an Excellent or Good outcome (Excellent in 28 patients and Good in 3). The mean pain score was 6.8 prior to surgery and decreased to 2.3 at the 3-month postoperative examination. No significant complications or neurological deterioration occurred. None of the 31 patients appeared to have any fusion failure. No broken screw, screw loosening, significant cage migration or subsidence was observed in any of the cases. A mean increase in the intervertebral disc height of 3.14 mm from the preoperative measurement to the most recent follow-up examination was determined to be statistically significant (p = 0.05). CONCLUSIONS Conducting PLIF using the diagonal insertion of a single cage with supplemental unilateral transpedicular screw instrumentation enables sufficient decompression and solid interbody fusion to be achieved with minimal invasion of the posterior spinal elements. This technique is a more clinically secure, straightforward and cost-effective way to perform PLIF.