Study Design Retrospective matched cohort study. Objectives To investigate the association between body mass index (BMI) and postoperative cosmetic improvement in adolescent idiopathic scoliosis (AIS). Methods Among 737 female AIS patients, the 10th percentile of the raw BMI distribution was used to define “extremely low BMI”. Lenke type 1 patients with extremely low BMI were matched 1:1 to non-extremely low BMI patients by age, apical vertebra, and preoperative Cobb angle. Sex, Risser sign category, curve pattern and surgical approach were standardized through the inclusion criteria. Pre- and 1-year postoperative radiographic and cosmetic parameters and SRS-22 scores were compared using paired analyses accounting for matched-pair design. The primary outcome was the between-group difference in postoperative cosmetic improvement; all other analyses were prespecified as secondary or exploratory. Results The BMI threshold for extremely low BMI was 15.57 kg/m 2 . Radiographic correction was comparable between cohorts. However, the non-extremely low BMI group improved more in shoulder area indices (SAI1/SAI2), shoulder (SA) and axilla (AA) angles, right-left waist angle difference (RLWAD), and posterior superior iliac spine (PSIS) angle (all P < 0.05). The extremely low BMI group had lower SRS-22 self-image (3.3±0.6 vs. 4.2±0.8) and mental health (3.4±0.4 vs. 4.1±0.3) scores (both P ≤ 0.010). Fisher’s r-to-z test showed significantly weaker or directionally different radiographic–cosmetic correlations in the extremely low BMI group (P<0.05). Conclusions Extremely low BMI was associated with poorer cosmetic improvement, worse self-image, and weaker radiographic–cosmetic correlations, suggesting a wider discrepancy between radiographic correction and cosmetic improvement.
Study Design Literature review with clinical recommendation. Objective Provide a concise curation of recent literature in interbody fusions at the lumbo-sacral junction. Methods Literature is graded based on the integration of scientific methodology and expert opinion. Results Article 1: ALIF with and without posterior instrumentation, Conditional recommendation: ALIF is comparable to 360 fusions in well selected patients. Article 2: ALIF+Perc Screws v. MIS TLIF at L5-S1, Conditional recommendation: use ALIF in cases where higher lordosis correction is needed, Article 3: L4-S1 ALIF v. TLIF with grade 1-2 osteotomy, Conditional recommendation: use ALIF in cases where higher lordosis correction is needed. Article 4: The Deformity TLIF, Conditional recommendation: additional corrective maneuvers (grade 2 osteotomy, rod compression, anterior placement of the cage in the disc, hinged motorized operative table) can aid in achieving lordosis correction. Article 5: Revision rates in isthmic spondylolisthesis, Conditional recommendation: interbody use and 360 fusions decrease revision rates. Article 6: ALIF v. TLIF for isthmic spondylolisthesis , Conditional recommendation: use ALIF+Perc screws when an anterior approach is feasible. Conclusions Segmental alignment matters, even in short segment constructs. Patients who require large magnitude correction are likely better served with an anterior approach as the literature consistently shows greater lordosis change with ALIF compared to TLIF. Appropriate lordosis is possible with TLIF, but surgeons must implement additional technical steps. For anterior fusions, supplemental fixation reduces the nonunion risk, but may not be necessary in a narrow subset of stable listhesis with good bone quality.
Study Design Retrospective cohort study. Objectives To assess the influencing factors of the distal add-on when selecting the touched vertebra (TV) as the lowest instrumented vertebra (LIV) in thoracic idiopathic scoliosis (IS). Methods A total of 96 thoracic IS patients who underwent deformity correction with LIV = TV were retrospectively analyzed to evaluate the distal add-on. Patients were divided into the DA group and the non-DA group. Radiological variables included coronal (Cobb’s angle, coronal balance, sacral slanting angle, and L4 vertebral tilt), sagittal (sagittal vertical axis, thoracic kyphosis, and lumbar lordosis), and axial parameters (vertebral rotation angle). Results When selecting the TV as the LIV, the occurrence rate of distal add-on was 20.8% (20 of 96) at a mean follow-up of 3 years. The mean number of remnant motion segments was significantly higher in the DA group (4.7) compared to the non-DA group (3.8) ( P < 0.001). The difference in the vertebral rotation angle between the lumbar apex and the TV level was significantly higher in the DA group (6.6°) than in the non-DA group (1.3°) ( P < 0.001). Multivariate logistic regression analysis demonstrated that the distal add-on was significantly associated with remnant motion segments (OR = 3.69, 95% CI: 1.03–13.18) and the vertebral rotation discrepancy (OR = 4.09, 95% CI: 1.98–8.43). Conclusions Greater vertebral rotation discrepancy between the LIV and lumbar apex was consistently associated with distal add-on when the TV was selected as the LIV, suggesting that three-dimensional rotational mismatch may contribute to residual distal add-on risk.
