Abstract
Introduction: Since Briggs and Milligan1 first described posterior lumbar interbody fusion (PLIF) in 1944, posterior lumbar interbody fusion has been a controversial fusion technique. Reports regarding the safety, efficacy and fusion rates have varied greatly over the years. Modern pedicle screw instrumentation and the use of intervertebral spreaders / implants have provided a powerful technique for the restoration of spinal balance in degenerative deformity.
Since 1993, the author has performed over 400 posterior interbody fusions for a wide variety of degenerative, traumatic and neoplastic conditions. A review was undertaken of 362 consecutive patients who were managed with this technique between October 1993 and July 2001. The purpose of this review was to determine the efficacy and safety of the technique and in particular, to attempt to identify those factors, which have contributed to patient outcomes.
Methods: The first 86 patients underwent wide posterior decompression with resection of facet joints and interbody grafting using morcellised posterior elements and pedicle screw stabilisation. From February 1995, the interbody graft was supplemented with Carbon wedge shaped spacers bearing serrated upper and lower surfaces (Ramps). From July of 1996 (patient 170), the interbody graft was supplemented with posterior grafting, and from December 2000 with Autologous Growth Factor (AGF) treated graft.
Patient pre-operative, operative and post-operative data and complications and follow-up Surgeon Subjective Outcome Assessments (SSOA’s) were acquired prospectively. Questionnaires were administered seeking patient generated follow-up data, including Patient Subjective Outcome Assessment (PSOA).
Results: Follow-up data (SSOA ± PSOA) was available on 327 or 91% of patients. The data was for periods greater than 6 months in 64% of patients. PSOA data was available on 31% – mean follow-up time for these patients was 27.7 months (± 25.8). Average age at surgery was 56 years (± 16). Average number of levels operated was 1.5 (± 0.9). Average number of previous surgeries was 0.7 (± 1.0). 286 patients were private and 76 were compensation. 88 patients had no deformity while the remainder had some form of deformity, the most common of which were spondylolisthesis – 156 and scoliosis – 94.
Overall, private patients did much better (very good or excellent outcomes) than compensation ones: 76% vs. 57% (p < 0.002). Patients who underwent surgery for conditions associated with deformity did significantly better than those without: 80% vs. 57% (p < 0.01). The outcomes since the introduction of interbody serrated spacers and additional posterior grafting have been significantly improved: for private patients, 86% now vs. 62% (p < 0.002).
The introduction of ramps improved the non-union rate from 16.3% in the first 86 patients to 8.3% in the next 84. The addition of posterior grafting improved the non-union rate to 1.0% in the next 198 patients. There have been no non-unions since the introduction of AGF.
Serious complications included three deaths, five deep infections, eight early returns to theatre for radiculopathy, four partial and one complete foot drop, four CSF leaks and one pulmonary embolus. Of the patients surveyed, 123/131 or 94% considered the surgery worthwhile and 88% said that they would have it again, if necessary.
Discussion: Refinements in technique and improved patient selection have resulted in a significant improvement in clinical outcomes over the last eight years. While technically demanding, this PLIF technique now yields a high fusion rate, the ability to fully correct sagittal and coronal deformity and a high rate of good or excellent clinical outcomes: 86% in private patients.
The abstracts were prepared by Dr Robert J. Moore. Correspondence should be addressed to him at The Spine Society of Australia, Institute of Medical and Veterinary Science, The Adelaide Centre for Spinal Research, Frome Road, Adelaide, South Australia 5000
