Proper sagittal balance may correlate with better surgical outcomes

Several factors, including a patient’s age, can affect sagittal balance. According to spine surgeons who participated in a symposium on the subject of sagittal balance, a surgeon who takes spine, hip and pelvic alignment into consideration may be able improve the surgical outcomes of degenerative and deformity procedures.

At the International Society for the Study of the Lumbar Spine Annual Meeting, Serena S. Hu, MD, and Jean Charles LeHuec, MD, PhD, discussed the importance of sagittal balance and restoring it to improve surgical outcomes. J.N. Alastair Gibson, MD, FRCS(Ed), FRCS(Tr &Orth), MFSTEd,presented information about how surgical restoration of sagittal balance may not be appropriate in some patients and may be excessively invasive in other patients.

“Surgical outcomes for spine surgery are improved when spinal, pelvic and hip alignment is considered in both degenerate and deformity cases, and how we better understand these will help us better improve outcomes for our patients,” Hu said.

Sagittal imbalance in a patient can negatively affect the outcomes of a surgical procedure. But, how extensive the surgery required is to correct the imbalance must be carefully considered for the individual patient, according to Hu.

Sagittal balance is important

Patients with sagittal imbalance can have better outcomes from spine surgery when the surgery is successful at correcting their sagittal imbalance. For example, Hu said she saw a woman 18 years ago who sought a lumbar fusion for her lumbar scoliosis. The surgery went well, but she came back to Hu several years later with proximal junctional kyphosis (PJK).

To also treat what she recognized as the woman’s flat back, Hu performed a pedicle subtraction osteotomy, and despite the fact the patient was now 15 years older than she was when she underwent her original procedure, and it was a much larger surgery, the woman was happier with her condition postoperatively than after the original surgery.

“If you take someone’s abnormal pelvic tilt and improve it, you can improve their Oswestry Disability Index score, SRS-22R activity and SRS-22 appearance score. The sagittal vertical axis is the second most important, so you can improve more of those outcome scores. And, if you get their [pelvic incidence] PI-lumbar lordosis correlation improved, you can improve all of those factors in a clinically significant way,” she said.

Sagittal balance is not static

Sagittal balance is an active phenomena for patients. Pelvic incidence is static and does not change in a patient after adolescence, but sagittal balance is always changing as patients compensate, according to LeHuec.

The best course of action is to strive to achieve sagittal balance in patients, he said.

In terms of compensation, patients always try to rebalance their spines to keep their equilibrium. Therefore, sagittal balance is an active process. When patients have a fixed segment, the other levels can compensate, LeHuec said.

“The formula is roughly this one. Pelvic incidence is equal to lumbar lordosis. The second one [is] that two- thirds of the lumbar lordosis is included between L4 and S1 because the apex of the lumbar lordosis is always located along L4, between the bottom of L3 and the top of L5. So, L4 is the key vertebra for the lordosis. This is the reason why the best osteotomies are always performed at L4 and not L3, where it is easier. But, it is much more effective at L4,” he said.

Balance is a compromise

According to LeHuec, compensated balance is a compromise between sagittal alignment and active balance capacity.

In short fusions, balance factors can adapt by rebalancing the spinal lordosis at adjacent levels. In long fusions, there is increased adjacent segment disease due to frequent inappropriate sagittal alignment restoration. In addition, long fusion has limited capacity of compensation for rebalancing the spine, LeHuec said.

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Gibson said excessive sagittal balance intervention, for some patients, may be quite costly in the long-term. Often, elderly patients cannot tolerate a “haircut” let alone some of the procedures that Hu and LeHuec proposed using to correct sagittal balance, he said.

Complications due to balance

Pedicle subtraction osteotomy will restore balance, but it is recognized that significant complications, including PJK, will occur in more than two-thirds of elderly patients, Gibson said.

“In the elderly, complete restoration may be impossible and inadvisable. You are going to end up with a lot of surgeon stress, immense hospital costs and significant patient morbidity and possible mortality,” he said.

Perhaps the best course of action is to do nothing. Gibson suggested, noting elderly patients tend to compensate themselves by increasing their thoracic kyphosis, hyperextending the intervertebral spaces and ultimately adapting.

“Some of them just say the only thing bothering them is the pain down their leg. So, why not just give them a nerve root injection and see if it works. If it works, fine. If it does not, you can come back and do an open laminotomy or a minimally invasive endoscopic,” Gibson said.

Inserting a cage through a transforaminal approach at multiple levels will probably improve an elderly patient’s condition and may be associated with far fewer complications, he noted.

“Minimalist approaches through small incisions will almost certainly yield better end results,” Gibson said. – by Robert Linnehan

References:
Gibson JNA. Sagittal balance. A viewpoint – sagittal balance – Where is the evidence? Challenging excessive intervention.
Hu SS. Sagittal balance. An overview of sagittal balance and surgical principles.
LeHuec JC. A viewpoint – Striving to optimize sagittal balance is best!
All presented during Symposium #2 at: International Society for the Study of the Lumbar Spine Annual Meeting; June 8-12, 2015; San Francisco.

For more information:
J.N. Alastair Gibson, MD, FRCS(Ed), FRCS(TR&Orth), MFSTEd, can be reached at Royal Infirmary of Edinburgh, 51 Little France Cres; Edinburgh EH16 4SA, United Kingdom; email: j.n.a.gibson@blueyonder.co.uk.
Serena S. Hu, MD, can be reached at Stanford Spine Clinic 450 Broadway St MC 6342, Redwood City, CA 94063; email: shu3@stanford.edu.
Jean Charles LeHuec, MD, PhD, can be reached at Department of Orthopaedic and Traumatology, Bordeaux University Hospital, 12 rue Dubernat, Talence 33404, France; email: j-c.lehuec1@u-bordeaux2.fr.

Disclosures: Gibson reports he receives payments for teaching and travel from Joimax GmbH, for travel from Q-Spine UK and he receives publishing royalties from Saunders/Mosby-Elsevier. He reports he has stock in Spire Healthcare UK and is a council member for the Royal College of Surgeons of Edinburgh. Hu is a consultant for NuVasive, has received speakers’ fees from NuVasive and Stryker and is on the editorial board for Spine Deformity. LeHuec reports he receives travel expenses from Medtronic.