Purpose: By using full body radiograph, the aim of the current study was to elucidate the expected degree of lower extremity compensatory change after long thoracolumbar realignment surgery with adult spinal deformity patient who had normal or only mild osteoarthritis on lower extremities.
Methods: Two novel parameters were used for assessment of regional compensation of the lower extremity. The Pearson correlation test was used to assess the correlation of postoperative changes of lower extremity compensation with the other spinopelvic parameters.
Results: Overall, 113 spinal deformity patients (mean age was 54.5 years) were recruited and the average number of fused vertebrae was 13.3 ± 3.5. Except pelvic tilt (PT), postoperative sacrum-femur angle (SF) changes showed only moderate correlation with all angular spinopelvic parameters (r = 0.323-0.374; p < .001 to p = .001). Also C7 sagittal vertical axis showed no significant correlation with SF (p = .584-.621). However, postoperative changes of sagittal femur-tibia angle (SFT) reported strong correlation with all parameters evaluated (r = 0.455-0.586; p < .001 to p = .046).
Conclusion: For adult spinal deformity patients who had normal or only mild osteoarthritis on the lower extremities underwent long thoracolumbar realignment surgery, the surgeon could expect improvement of compensatory change of the knee with correction of spinopelvic parameters. However, the degree of hip compensation improvement was relatively difficult to predict than that of the knee, except PT.
Keywords: Adult spinal kyphotic deformity; EOS; lower extremity compensation; thoracolumbar realignment surgery.