Surgeons met sagittal alignment goals in one-third of patients with adult spinal deformity
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CHICAGO — Results presented here showed surgeons met preoperative sagittal alignment goals in about one-third of patients with adult spinal deformities.
Justin S. Smith, MD, PhD, and colleagues used standardized forms to collect data among 266 patients with adult spinal deformities. Researchers required the operative surgeon to document sagittal alignment goals, including sagittal vertical axis (SVA), pelvic incidence to lumbar lordosis (PI-LL) mismatch and thoracic kyphosis, prior to each surgery.
“We compared the goal alignment parameters from the respective surgeons with the achieved alignment goals on follow-up X-rays,” Smith said in his presentation at the North American Spine Society Annual Meeting.
Smith noted about 66% of patients achieved the goals for SVA, PI-LL mismatch and thoracic kyphosis and about 33% of patients achieved all three goals following surgery. He added surgeons tended to undercorrect SVA and PI-LL and increase thoracic kyphosis.
Factors associated with failure to achieve the SVA goal included a greater BMI index, worse deformity at baseline, lower thoracic kyphosis and N-type Scoliosis Research Society-Schwab curve, according to Smith.
“For PI-LL mismatch, the factors that were associated with failure to achieve the goal included younger age of the patient, greater maximum coronal Cobb angle at baseline, lower pelvic tilt and lack of pelvic instrumentation,” Smith said.
Smith noted factors associated with failure to achieve the thoracic kyphosis goal included older patient age, greater SVA at baseline, the specific surgeon, use of surgical planning software, use of age-adjusted alignment criteria and early proximal junctional kyphosis.
Smith said 38% of surgeons used commercially available planning software, while the remaining surgeons used a simple workstation to plan their surgeries. He added 38% of surgeons employed age-adjusted alignment goals and 62% performed an individualized patient assessment of what the surgeon’s goals would be for alignment.
“For the multivariate factors, so these are independent factors associated with failure to achieve these alignment goals, for SVA [it] was greater preoperative SVA and lower preoperative thoracic kyphosis,” Smith said.
Independent factors associated with failure to achieve PI-LL mismatch goals included primary cases, three-column osteotomy, lack of iliac instrumentation and use of surgical planning software, according to Smith. He said adjusted alignment criteria and early proximal junctional kyphosis were independent factors associated with failure to achieve thoracic kyphosis goals.
“Lastly, for all three parameters, the independent factors associated with failure to achieve all three goals was use of surgical planning software and greater global malalignment in the sagittal and coronal planes,” Smith said.
Perspective
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The article from Justin S. Smith, MD, PhD, is interesting, particularly because I was surprised by the low percentage of surgeons who are meeting the acceptable outcome from an alignment standpoint. These are the best deformity surgeons in the world and we’re still only “getting it right,” so to speak, 25% of the time. I think it just proves that we still have a lot to learn about what we’re doing from an intraoperative corrections standpoint and how that translates into postoperative alignment.
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Smith JS, et al. Paper 51. Presented at: North American Spine Society Annual Meeting; Oct. 12-15, 2022; Chicago.
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