Correction surgery for adult spinal deformity improves not only spinopelvic alignment but also the three-dimensional alignment of the lower extremities.

Abstract

It is well known that correction surgery for adult spinal deformity (ASD) improves sagittal and coronal spinopelvic alignment, but the surgery effect on lower extremities (LE) is not well clarified. The aim of this study was to test the hypothesis that LE alignment also improves following spinopelvic correction surgery for ASD as a function of compensatory mechanism, and to clarify an effect of the severity of knee osteoarthritis (OA) on the improvement. We retrospectively evaluated spinopelvic alignment, hip knee ankle angle (HKA), knee flexion angle (KF), and severity of the knee OA in thirty-nine patients with ASD before, two weeks and three months after the surgery. The grade of knee OA was evaluated by Kellgren Lawrence grading, and classified grade 0 to 2 into mild, and 3, 4 into severe OA. All the values were compared by paired t test or Wilcoxon signed rank test with significant p value of <0.05. Following the surgery, not only spinopelvic, but also bilateral HKA and KF were significantly improved. HKA in mild OA side was more normalized compared to that in severe side. Although KF of both bilateral mild and bilateral severe OA groups improved, the improvement of mild group was more significant. The 3D alignment of LE improved following spinopelvic correction surgery. The improvement was inadequate in cases with severe knee OA.