Motion preservation and deformity correction in Lenke 1 C adolescent idiopathic  scoliosis: selective versus non-selective thoracic fusion.

Abstract

The central surgical question in Lenke 1C adolescent idiopathic scoliosis (AIS) is whether to extend fixation to include the compensatory thoracolumbar/lumbar (TL/L) curve (nonselective thoracic fusion, NSTF) or to limit instrumentation to the thoracic spine and rely on spontaneous lumbar correction (selective thoracic fusion, STF). NSTF achieves more predictable coronal correction but sacrifices lumbar motion segments. Whether this radiographic advantage translates into superior patient-reported outcomes remains unresolved. Prior syntheses have not quantified surgical extent differences or adequately characterized the structural sources of extreme heterogeneity in patient-reported data. A PRISMA-compliant systematic review and meta-analysis were conducted (search: January 2025, updated April 2025; PubMed, Scopus, Web of Science; no language restriction). Ten studies met inclusion criteria and were evaluated within an outcome-specific eligibility framework; pool composition for each outcome was determined by data quality verification (extractable mean ± SD) and baseline comparability. The radiographic pool comprised strictly verified Lenke 1C studies [1, 2], k = 2 primary, extended to k = 3 in sensitivity analysis with [3] Lenke 1C subgroup). A parallel fused-level pool [3, 4], k = 2) quantified surgical extent. SRS-22/22R/22r domain scores were pooled descriptively across k = 3 studies. Coronal decompensation was analyzed categorically (k = 3). All pooled estimates used random-effects models [5]. Leave-one-out sensitivity analyses were performed for all primary estimates. NSTF was associated with greater postoperative TL/L radiographic correction (primary pool: MD + 7.8°; 95% CI 2.12-13.41°; I² = 79.9%; p = 0.006; k = 2), with directional stability confirmed across all contributing studies in sensitivity analysis (k = 3: MD + 7.1°; 95% CI 4.08-10.03°; I² = 59.9%). STF was associated with preservation of significantly more lumbar motion segments (pooled MD: - 2.9 vertebrae; 95% CI - 4.81 to - 0.90; I² = 92.5%; p = 0.004; k = 2), providing the first pooled quantitative estimate of surgical extent differences between procedures. Coronal decompensation rates were not significantly different (OR: 1.60; 95% CI 0.82-3.12; I² = 6.3%; p = 0.17; k = 3). Pooled SRS domain analysis did not demonstrate a consistent difference between procedures for any domain; all pooled MDs fell below the MCID of 0.2 points (k = 3 per domain). Extreme heterogeneity (I² 82-99% for five of six domains) means these estimates are descriptive summaries, not reliable effect estimates. A large contemporary prospective cohort [6], n = 255) demonstrated significantly better lumbar flexibility in STF patients at 5 years without a corresponding SRS advantage for either group. Across ten studies evaluated within an outcome-specific eligibility framework, NSTF achieves greater TL/L radiographic correction in Lenke 1C AIS, while STF preserves a clinically meaningful number of lumbar motion segments. Available evidence did not demonstrate a consistent patient-reported outcome advantage for either procedure, though extreme heterogeneity substantially limits the interpretive value of pooled estimates. The trade-off between structural correction and motion preservation should be central to individualized preoperative decision-making. Prospective multicenter studies with pre-specified outcomes, standardized instruments, and long-term follow-up are needed.