Postoperative changes in sagittal spinopelvic alignment in sitting position in adolescents with idiopathic thoracic scoliosis treated with posterior fusion: an initial analysis

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>Previous studies have reported spinal straightening and pelvic retroversion when changing from erect to sitting posture in patients with adolescent idiopathic scoliosis (AIS), which were thought to be related to low-back pain after sitting for long periods. However, the sitting sagittal alignment after posterior spinal fusion has not been evaluated. This study aims to assess the influence of posterior fusion surgery upon sitting sagittal spinopelvic alignment in adolescents with idiopathic thoracic curves (thoracic AIS [T-AIS]).</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>A total of 44 T-AIS patients (30 Lenke I and 14 Lenke II) from the authors’ center were included in this study. Preoperative and postoperative long-cassette lateral radiographs of the spine and pelvis were obtained with the patients in standing and sitting positions. Thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were measured on standing and sitting lateral radiographs. Patients were divided into selective thoracic fusion (STF) and nonselective thoracic fusion (NSTF) groups.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>At baseline, TK, LL, and SS decreased by 27.5%, 42.1%, and 31.1%, respectively, from the standing to the sitting position, while PT increased by 193.6%. After posterior spinal fusion, increased TK, LL, and SS and corresponding decreased PT were observed compared to baseline parameters in the sitting position. Comparison of postoperative sitting and standing values for the whole cohort showed that the mean LS and SS values were significantly lower in the sitting position (decreased by 14.0% and 13.9%, respectively, compared to standing), whereas the mean PT value was significantly greater (increased by 39.0%, compared to standing). Similar changes were also observed in the STF group: postoperatively the mean LL value was 15.6% lower in sitting than in standing, while the mean SS value was 11.5% lower. However, no obvious changes of the postoperative values in sitting were found in the NSTF group.</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>Nonselective thoracic fusion surgery in T-AIS patients diminished spinal straightening and pelvic retroversion during sitting. Reducing distal fusion levels was of special value in not only saving more lumbar mobility, but also preserving the function of pelvic posterior rotation.</jats:p></jats:sec>

The Standing and Sitting Spino‐Pelvic Sagittal Alignment in Patients with Instrumented Lumbar Fusion Might Correlate with Adjacent Segment Degeneration

“…This finding indicates that lumbosacral fixation might limit pelvic retroversion and spinal straightening in sitting positions. Zhu et al 12 . also reported that nonselective thoracic fusion would diminish spinal straightening and pelvic retroversion during sitting.…”

“…Some researchers have investigated postoperative adaption in patients after fusion surgery. Zhu et al 12 . documented that thoracic fusion could diminish the decrease in LL (14.0%) and SS (13.9%) during sitting position, compared with the preoperative status (42.1% decrease in LL and 31.1% decrease in SS) for adolescent idiopathic scoliosis (AIS).…”

Correlation of Acetabular Anteversion and Thoracic Kyphosis Postoperatively with Proximal Junctional Failure in Adult Spinal Deformity Fused to Pelvis

“…There were remarkable associations among spine, pelvis, and hip joints, namely compensatory mechanism in previous studies [17][18][19] . Moreover, those associated effects were notable during position changing 20,21 .…”

Do the three-dimensional parameters of brace-wearing patients with AIS change when transitioning from standing to sitting position? A preliminary study on Lenke I

“…This effect has also been demonstrated in patients undergoing surgical treatment. When the kyphosis is reduced, the lumbar spine compensates by reducing the lordosis to maintain the coordination of the thoracic and lumbar spine [ 37 ]. We showed that after wearing a brace, the whole spine became straight and the SVA moved forward in the sitting position, which was not reported in previous studies.…”