Does fusion add value to decompression for lumbar spondylolisthesis?

Augmenting decompression surgery with instrumented fusion* does not seem to add benefit for patients with lumbar spinal stenosis (LSS) with degenerative spondylolisthesis, according to findings from the phase III NORDSTEN-DS** trial.

LSS caused by spondylolisthesis usually entails leg and back pain that could restrict function, hence impairing quality of life. [J Bone Joint Surg Br 1976;58:184-192] Surgical treatment is advised when conservative approaches fail to manage the pain. [Spine J 2016;16:439-448; N Engl J Med 2007;356:2257-2270]

“[L]ess invasive procedures that preserve the integrity of stabilizing structures of the spine are now commonly used … [However,] it is uncertain whether decompression surgery alone is noninferior to decompression with instrumented fusion,” said the researchers. “Spine surgeons may presume that slippage and dynamic instability at the level of spondylolisthesis are better treated with fusion.”

A total of 267 individuals (mean age 66 years, 69 percent female) with symptomatic LSS and single-level spondylolisthesis of ≥3 mm who have failed conservative management were randomized 1:1 to undergo decompression surgery with or without instrumented fusion. More than three-quarters of participants have been experiencing leg (~75 percent) and back (>80 percent) pain for >1 year. [N Engl J Med 2021;385:526-538]

At 2 years, the fractions of participants with reductions of at least 30 percent in ODI*** scores were similar between decompression-fusion and decompression alone, both in the modified intention-to-treat (73 percent vs 71 percent) and the per-protocol cohorts (76 percent in both arms). “[These suggest] noninferiority of decompression alone to decompression combined with fusion,” the researchers noted.

“Results for the secondary outcomes were generally in the same direction as those for the primary outcome,” they continued. These were reflected by the similar mean changes from baseline ODI (−21.3 vs −20.6), ZCQ^# (–0.98 vs –1.00 [symptom severity], –0.81 vs –0.85 [physical function], 0.00 vs 0.08 [patient satisfaction]), NRS^## for leg (–3.62 vs –3.84) and back pain (–2.94 vs –3.39), and EQ-5D-3L^### scores (0.34 vs 0.26) between decompression-fusion and decompression alone.

Decompression alone appeared to yield better outcomes than decompression-fusion in terms of other secondary outcomes, ie, shorter mean durations of surgery (104 vs 174 minutes) and hospital stay (3.3 vs 5.0 days), and fewer dural tears (5 percent vs 13 percent).

Conversely, reoperations were more frequent with decompression alone than decompression-fusion (12 percent vs 9 percent). However, no definitive conclusions can be made regarding this, as the trial was not powered to compare reoperation rates between arms, the researchers pointed out.

“[We also] cannot rule out the possibility that decompression alone may require a subsequent fusion. However, patients treated with decompression-fusion may also require further secondary surgeries (ie, hardware removal or surgery) at the adjacent lumbar level,” they pointed out. “Patients and surgeons may weigh a potentially higher risk of reoperation against the complexity and costs of surgical alternatives.”

“Two previous trials, both with a superiority design, have challenged the widespread use of instrumented fusion in the surgical treatment of degenerative spondylolisthesis. Our results were in accordance with the findings of one of these trials,” said the researchers.