Predicting Factors at Skeletal Maturity for Curve Progression and Low Back Pain in Adult Patients Treated Nonoperatively for Adolescent Idiopathic Scoliosis With Thoracolumbar/Lumbar Curves: A Mean 25-year Follow-up.

Study Design: A retrospective, long-term follow-up study.

Objective: We aimed to clarify the predicting factors at skeletal maturity for future curve progression and low back pain (LBP) in adolescent idiopathic scoliosis (AIS) with thoracolumbar/lumbar (TL/L) curve.

Summary Of Background Data: TL/L curves are likely to progress after skeletal maturity and cause LBP.

Methods: Of 147 patients treated nonoperatively for AIS with TL/L curve, 56 (55 females; average age at the time of survey, 39.5 ± 7.1 years; average follow-up duration after maturity, 24.9 ± 6.9 years) completed questionnaires, including the visual analogue scale (VAS) for LBP and Oswestry disability index (ODI). Forty-nine patients underwent a radiological examination, and 48 underwent lumbar magnetic resonance imaging (MRI).

Results: The mean Cobb angle of the TL/L curve increased from 37.3° ± 7.5° to 47.8° ± 12.6° (0.41° ± 0.39° per year). The factors at skeletal maturity that were associated with the annual progression of the TL/L curve included a cranially located apical vertebra, and great apical vertebral translation and L3 tilt. In addition, the VAS for LBP was positively correlated with L4 tilt, and the ODI was positively correlated with L4 tilt and apical vertebral rotation. Multivariate analyses and receiver-operating characteristic curves demonstrated that L3 tilt at skeletal maturity independently predicted a curve progression ≥0.5° per year (odds ratio [OR], 1.17), while L4 tilt at skeletal maturity independently predicted a VAS ≥3 cm (OR, 1.20) and ODI ≥21% (OR, 1.25) in adulthood, with a cutoff value of approximately 16° for each factor. Moreover, lumbar disc degeneration on MRI was associated with L4 tilt at skeletal maturity and LBP in adulthood.

Conclusion: Great L3 and L4 tilt at skeletal maturity, especially those >16°, are predictors of future curve progression and LBP in adulthood, respectively. For adolescent patients with these risk factors, periodic follow-ups into adulthood should be considered.

Level Of Evidence: 4.