Debate highlights consequences of fusions for ADS stopped at L5 vs S1

Issue: November/December 2014

LYON, France — Two spine surgeons debated the advantages and disadvantages of stopping fusions for adult degenerative scoliosis at L5 or extending them further to the sacrum or S1, at the EuroSpine Annual Meeting, here.

The surgeons said the need to achieve greater lordosis and a patient’s age were some reasons to carry out an extended fusion and possibly avoid subsequent revision surgery. In addition, they seemed to agree the final fused level ultimately depended on the patient’s situation, including disc height and sagittal balance.

Pierre Roussouly, MD, of Lyon, France, and Rune Hedlund, MD, of Gothenburg, Sweden, discussed key issues surgeons should consider when deciding where to end spine fusions in cases of adult degenerative scoliosis (ADS).

When he summarized the points that Roussouly and Hedlund raised, session moderator Josef G. Grohs, MD, said, “It is not a clear yes or no, black and white, but we have several shades of gray depending on the age, complication rate, the possibility of related revisions, elongations to the sacrum and possibly functional limitations.”

A response system used during the session showed at the outset, 52% of the audience would stabilize to L5 the patient in a case that Grohs showed. However, by the end of the debate, fewer supported fusion to only L5.

Roussouly, who favored extended fusions, said he is not “scared” to stop fusions for ADS at S1.

“It is not a rule,” he said.

Surgeons should avoid stopping the fusion at S1 in patients younger than 40 years, and Roussouly said he prefers fusing patients in that age group through L4 or L5.

In patients older than 40 years, the status of the L5-S1 level and of the sagittal balance is critical, he said. The surgeon must determine the pelvic incidence to make the right decision.

In patients older than 50 years “always stop on S1,” Roussouly said, otherwise the fusion could prove painful and need revising. The fixation must also be solid with good screw position. He reviewed the roles of plating and iliac fixation and mentioned a promising new fixation system he worked with that is still in early trials.

Using a plate may help easily reduce a frontal inclination of L4-5, Roussouly said. In a study of more than 1,500 patients he just completed, patients had excellent quality of life with good fusion and front and sagittal balance.

“I do not always fuse to the sacrum in ADS,” Hedlund said, noting L5-S1 could be a pain generator that may accelerate a patient’s symptoms.

He admitted, however, that going down to S1 does help achieve greater lumbar lordosis.

Hedlund’s main arguments against S1 fusion for ADS were that it overloads the adjacent level, fusion can affect function, the extensor muscles may be impacted and it can increase the cost of the procedure and the complication rates.

“The single most important factor why you should not do it: It simply does not improve the outcome,” he said.

Hedlund discussed a study in which there was a 75% complication rate in patients fused to S1 or the ilium and he also contends L5-S1 is important to some patients’ activities.

The cases for which Hedlund agreed there is a need to fuse to S1 are spondylolisthesis at L5 or when an L5-S1 decompression is required. But, due to the downsides he cited during the debate, he said surgeons should avoid S1 fusion whenever possible. – by Susan M. Rapp

Reference:

Hedlund R. I never fuse to the sacrum.

Roussouly P. I always fuse to the sacrum. Both presented at: EuroSpine Annual Meeting; Oct. 1-3, 2014; Lyon, France.

Disclosure: Hedlund is a consultant to/receives research support from K2M, Zimmer and Globus. Spine Surgery Today was unable to confirm Roussouly’s relevant financial disclosures.