Postoperative Treatment and Variables

During and after surgery, antibiotics were administered to prevent infection, and the patient's condition was closely monitored. The drainage tube was removed based on the drainage fluid output within 2 days postoperatively (< 40 mL/24 h), and the patient was instructed to wear a waist belt and engage in weight‐bearing activities. Immediately following the surgery, lumbar spine computed tomography (CT), anterior and posterior lateral X‐ray films of the lumbar spine, and magnetic resonance imaging were performed. Follow‐up radiographs of the anteroposterior and lateral views of the lumbar spine were repeated 3 months postoperatively and at the final follow‐up visit. The Cobb angle, lumbar lordosis (LL) angle, sacral slope (SS), average intervertebral height (AIH), slip percentage (SP), slip angle (SA), and L1 plumb line to S1 distance (LASD) were among the radiographic measures. The intervertebral space fusion status was assessed using the Bridwell criteria during the final follow‐up, with grades I and II denoting successful fusion. Lumbar spine CT was performed if the fusion status could not be determined. The visual analogue scale (VAS), Oswestry disability index (ODI), and Japanese Orthopaedic Association (JOA) scoring systems were used to evaluate clinical results.

Three independent investigators not involved in the surgery performed clinical outcome evaluation and data recording. Measurements of the spinal pelvic and deformity parameters were based on radiographs. Every measurement was double‐checked by two observers, and the analysis was based on the average results. The measurement methods for the sagittal plane spinal radiographic parameters were as follows:

Sagittal plane spinal imaging parameter measurement methods. (A) Slip percentage (SP): the slip distance between the upper and lower vertebrae divided by the anteroposterior diameter of the lower vertebra multiplied by 100%. (B) Slip angle (SA): the angle between the lower endplate of the upper vertebra with slip and the upper endplate of the lower vertebra. (C) Average intervertebral height: the average height of the most anterior and posterior intervertebral discs. (D) Cobb angle: the angle between the perpendicular lines drawn on the upper and lower endplates of the upper and lower vertebrae. The upper and lower endplates refer to the vertebrae with maximum inclination toward the concave side of the scoliosis. (E) Lumbar lordosis (LL) angle: Cobb angle between the upper endplates of L1 and S1. Sacral slope (SS): the angle between the line parallel to the upper endplate of S1 and the horizontal line. L1 plumb line to S1 distance (LASD): The horizontal distance from the plumb line drawn from the center of L1 to the posterior superior corner of S1; LASD is positive when the plumb line is anterior to the sacral promontory and negative when the plumb line is posterior to the sacral promontory.