Retrospective radiographic analysis of anterior lumbar fusion for high grade lumbar spondylolisthesis.

BACKGROUND

High-grade spondylolisthesis (>50% slippage) is infrequently encountered in adults and frequently requires surgical treatment. The optimal surgical treatment is controversial with limited literature guidance as to optimal approach to treatment. An observational study to examine the technique and radiographic outcomes of adult patients treated with anterior lumbar interbody fusion (ALIF) and posterior percutaneous instrumentation for high-grade spondylolisthesis.

METHODS

ALIF was performed in 5 consecutive patients (3/5 female, 2/5 male) aged 29-67 years old who presented with low back pain and L5 radiculopathy. All patients failed conservative treatment and were treated with L4-5 and L5-S1 ALIF followed by posterior percutaneous L4-S1 pedicle screw and rod fixation. Pre- and postoperative clinical data was collected including L5-S1 posterior disk height in millimeters, millimeters of spondylolisthesis at L5-S1, degrees of segmental lordosis (L4-S1), lumbar lordosis (L1-S1), and lumbar lordosis pelvic incidence (LL-PI) mismatch.

RESULTS

Six weeks following surgery, no patient reported residual L5 radicular symptoms. At last follow up, patient satisfaction, according to Modified Macnab Criteria, was excellent in 4/5 patients and good in 1/5 patient. In the 4 patients with greater than 1 year radiographic follow up, fusion rate was 100% on computed tomography (CT). Mean increase in posterior disk height was 12.5 mm (range, 11.4-13.5 mm). Mean reduction in spondylolisthesis was 58.7% (range, 20.2-100%). Mean segmental (L4-S1) and overall (L1-S1) lumbar lordosis increased by 23.6% (range, 6.5-41.7%) and 16.6% (2.5-31.5%), respectively. Following surgery, LL-PI mismatch decreased from a mean of 16.4 to 10.2 degrees.

CONCLUSIONS

ALIF with posterior percutaneous instrumentation is a safe and effective treatment for high-grade lumbosacral spondylolisthesis in properly selected adults. This technique improves lumbar sagittal parameters and reduces spondylolisthesis. The indirect neural decompression from simultaneous disk height restoration and spondylolisthesis reduction may be associated with lower neurological injury rate compared to posterior-only. Future prospective study is needed to validate this hypothesis.