Friday, June 13, 2014
Limited vs. Full Curve Fusion in Degenerative Scoliosis
Degenerative lumbar scoliosis remains a challenge to spine surgeons, in part due to a lack of clear cut indications for surgery or the most appropriate surgical approach. Prior studies have shown similar or better clinical outcomes for focal decompression or focal decompression and fusion compared to full curve fusion, with higher rates of complications for full curve fusion.1 While surgeons prefer to limit surgery to the least invasive option that can result in good outcomes in this elderly population, there is concern that focal decompression and fusion can result in more rapid progression of the curve in the adjacent segments that are not corrected. In an attempt to determine if focal fusion results in more rapid development of radiographic adjacent segment pathology (RASP), Dr. Ha and his colleagues from South Korea reported the results of a retrospective cohort study in which they compared the rate of RASP and clinical outcomes between patients undergoing decompression and focal fusion compared to those who underwent decompression and fusion of the entire curve. Approximately 30 patients were in each group, and the limited fusion group was about 4 years older, was followed for about 16 months longer, and had worse baseline Oswestry Disability Index (ODI) and visual analog scale (VAS) scores compared to the full curve fusion patients. The limited fusion group had a greater incidence of RASP compared to the full curve fusion patients (41% vs. 13%, p=0.015). RASP in the limited fusion group tended to involve progression of the curve, while in the full curve fusion group RASP resembled the adjacent segment degeneration observed in the non-scoliotic population. Improvements in ODI and VAS scores were similar for the two treatment groups, though the full curve fusion patients had lower initial and final VAS scores. The numbers available for comparison were low, but the RASP patients had non-significant trends towards worse outcomes compared to the non-RASP patients. Re-operation rate was higher in the limited fusion group, with 4 patients undergoing re-operation compared to just 1 in the full curve group.
This paper supports the concept that complete correction of the coronal plane deformity will decrease the rate of ASP as the spine has better coronal balance. However, this is only one part of the equation that one must consider while making treatment decisions with patients. Notably absent from the paper is any discussion of complications, and one can assume that complications would be more common when performing full curve fusion. While preventing RASP with full curve correction is desirable, if it comes at the price of a markedly increased rate of complications, it may not be worth it. Given that the degree of improvement in clinical outcome scores is similar for the two approaches yet RASP is more common in the partial curve correction group, it is possible that factors other than RASP limited improvement in the full curve fusion group. Another notable aspect of this paper is that the patients had relatively mild scoliosis, with curves in the 15 degree range, so it is possible that many of these patients would have done well with a decompression alone. This paper certainly adds to the debate about the best operation for degenerative lumbar scoliosis, but without a randomized trial that allows for analysis of the pros and cons of the different approaches, treatment of this condition will continue to rely on the art rather than the science of medicine. Please read Dr. Ha’s paper in the June 1 issue. Does this paper change your approach to degenerative lumbar scoliosis? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor
1. Transfeldt EE, Topp R, Mehbod AA, Winter RB. Surgical outcomes of decompression, decompression with limited fusion, and decompression with full curve fusion for degenerative scoliosis with radiculopathy. Spine 2010;35:1872-5.