The Spine Blog

Friday, April 14, 2017

Posterolateral fusion vs. TLIF for Degenerative Spondylolisthesis

Debate over the best surgical technique for degenerative spondylolisthesis (DS) has been ongoing for over twenty years, with no single technique being universally adopted. While fusion has been considered a mainstay of treatment since Herkowitz and Kurz’s landmark paper in 1991,1 recent RCTs have called into question the need for a fusion.2,3 Assuming a fusion is favored for many patients, the best fusion technique remains unknown. The Spine Patient Outcomes Research Trial showed no differences in patient reported outcome measures among uninstrumented fusion, instrumented fusion, and interbody fusion, though this was not a randomized study.4 Despite the lack of strong evidence supporting interbody fusion for DS, this technique is one of the most frequently used in the United States.5 On this background, Dr. Challier and colleagues from France performed an RCT comparing decompression with posterolateral instrumented fusion (PLF) to decompression, posterolateral instrumented fusion, and transforaminal lumbar interbody fusion (TLIF). They randomized 60 patients with DS and followed them for two years. There were no significant differences in patient reported outcome measures (ODI, SF-36, VAS) for the two fusion groups, though there was a trend towards a greater improvement in ODI at two years for the TLIF group (28 point improvement vs. 19 point improvement, p=0.08). The TLIF group had a significantly higher radiographic fusion rate (93% vs. 43% according to Lenke classification). There were no significant differences in spinopelvic parameters. The reoperation rate was low in both groups (3/30 for PLF vs. 1/30 for TLIF). Based on these findings, the authors concluded that adding TLIF did not provide any clinically meaningful benefit.

The authors should be congratulated for performing a very well-designed RCT in an effort to answer an important clinical question. One of the most striking findings is that the fusion rate for the PLF group was so low. This seems likely related to Lenke’s definition of fusion, which required bridging bone over the transverse processes. Frequently, the most robust fusion in PLF using local bone graft is found across the facet joints rather than across the transverse processes, and facet fusion can only be detected using a CT scan. Multiple prior studies have suggested a much higher fusion rate (>80%) for single level instrumented PLF using local bone graft, though fusion definitions varied across these studies.6-8 The fact that there were no significant differences in patient reported outcomes suggests that the lack of intertransverse fusion in the PLF patients generally did not lead to worse outcomes. Another important limitation was that this study was relatively underpowered. Even though the TLIF group improved 9 points more on the ODI score, the difference was not significant. The MCID on the ODI is likely around 10 points, so this borders on a clinically important difference that was not statistically significant given the low number of patients enrolled. This paper adds to the evidence that exists suggesting that adding a TLIF does not significantly improve clinical outcomes for the average DS patient. However, DS represents a wide spectrum of pathology, ranging from patients with a low grade, stiff, stable slip with a collapsed disk space to those with a higher grade, hypermobile slip with a preserved disk. The ideal surgical technique likely varies depending on patient and radiographic characteristics, but we do not currently have evidence to support the use of different techniques in patients with different pathology. Until we do, surgeons will have to rely on their experience and judgment to perform the operation they believe best fits each patient.

Please read Dr. Challier’s article on this topic in the April 15 issue. Does this change how you view the use of TLIF for DS? Let us know by leaving a comment on The Spine Blog.

 

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCES

1.            Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. The Journal of bone and joint surgery 1991;73:802-8.

2.            Forsth P, Olafsson G, Carlsson T, et al. A Randomized, Controlled Trial of Fusion Surgery for Lumbar Spinal Stenosis. N Engl J Med 2016;374:1413-23.

3.            Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis. N Engl J Med 2016;374:1424-34.

4.            Abdu WA, Lurie JD, Spratt KF, et al. Degenerative spondylolisthesis: does fusion method influence outcome? Four-year results of the spine patient outcomes research trial. Spine (Phila Pa 1976) 2009;34:2351-60.

5.            Kepler CK, Vaccaro AR, Hilibrand AS, et al. National trends in the use of fusion techniques to treat degenerative spondylolisthesis. Spine (Phila Pa 1976) 2014;39:1584-9.

6.            Inage K, Ohtori S, Koshi T, et al. One, two-, and three-level instrumented posterolateral fusion of the lumbar spine with a local bone graft: a prospective study with a 2-year follow-up. Spine 2011;36:1392-6.

7.            Kang J, An H, Hilibrand A, Yoon ST, Kavanagh E, Boden S. Grafton and local bone have comparable outcomes to iliac crest bone in instrumented single-level lumbar fusions. Spine 2012;37:1083-91.

8.            Sengupta DK, Truumees E, Patel CK, et al. Outcome of local bone versus autogenous iliac crest bone graft in the instrumented posterolateral fusion of the lumbar spine. Spine (Phila Pa 1976) 2006;31:985-91.