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
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
3. Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus
Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis. N Engl J Med
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)
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.