Abstract
INTRODUCTION: Since Briggs and Milligan first described posterior lumbar interbody fusion (PLIF) in 1944, it has been a controversial technique. However, modern pedicle screw instrumentation and the use of intervertebral spreaders and implants have provided a powerful technique for the restoration of spinal balance in degenerative deformity.
This study assesses the functional outcomes and safety in a series of patients undergoing complete reduction and posterior interbody fusion (PLIF) of lumbosacral spondylolisthesis with interbody fusion spacers implanted using an Insert and Rotate technique.
METHODS: A prospective, non-randomised, observational study of pre- and post-operative data, in a series of 35 patients with lumbosacral degenerative or isthmic spondylolisthesis, between April 2001 and June 2002.
All patients underwent decompressive laminectomy followed by complete reduction of the spondylolisthetic deformity with the aid of intervertebral disc space spreaders and pedicle screw instrumentation. Wedge shaped spacers made from Carbon Fiber, Titanium mesh or PEEK plastic were then inserted on their sides and rotated 90 degrees to support the vertebral end plates prior to placing bone graft beside them, within the disc space.
Outcomes were measured using the Low Back Outcome Score (LBOS), SF-12, visual analogue pain scores (VAS) and patient satisfaction survey.
RESULTS: Of the 35 patients, 24 had degenerative spondylolisthesis and 11 were isthmic in type. 26 were Meyerding Grade I; seven were Grade II; one was Grade III and one was Grade IV. The indications for surgery included relief of foraminal stenosis in 26 and likely post-operative instability in 24. Average time of last follow-up was 7.4 ± 3.0 months. Data are available on 34 of the 35 patients at three months and 29 at six to twelve months (83%). Mean pre-operative VAS and LBOS were 5.1 ± 2.5 and 26.5 ± 16.9, respectively. Mean scores at last follow-up were 2.2 ± 2.4 and 45.6 ± 14.6 (p< 0.01 for both measures). At last follow-up, 30 of the 35 patients or 88.2% described their outcome as good or excellent. One patient considered himself worse. 91% said the procedure had been worthwhile but only 79% said they would have it again under similar circumstances.
There were no deaths. There were no interbody implant/PLIF related problems but five intraoperative problems related to pedicle screw placement with one screw loosening during slip reduction, requiring replacement. Post-operatively, three patients developed an ileus. One patient developed a probable wound infection with high fever which settled on antibiotics.
DISCUSSION: This series represents a recent subset of a much larger total series managed with this technique for symptoms associated with spondylolisthetic deformity (187 patients to date). The author has previously reported to the society on the clinical results of the technique but without the benefit of prospective pre-operative data. This smaller series appears to confirm the results of the earlier studies and suggests that PLIF using an Insert and Rotate technique can yield satisfactory clinical outcomes with high patient satisfaction and low levels of complications.
These abstracts were prepared by Dr Robert J. Moore. Correspondence should be addressed to him at Spine Society of Australia, Institute of Medical and Veterinary Science, The Adelaide Centre for Spinal Research, Frome Road, Adelaide, South Australia 5000.
