This landmark prospective natural history study followed 219 patients with untreated adolescent idiopathic scoliosis for an average of 39.3 years. It defines curve-specific adult progression rates, pulmonary risk thresholds, back pain prevalence, and mortality compared against matched population controls. The core question: what actually happens to untreated AIS patients over a lifetime?
Two 1968 studies (Nachemson; Nilsonne and Lundgren) reported doubled mortality and 30–60% disability in untreated scoliosis, driving aggressive surgical recommendations. Both cohorts mixed idiopathic with paralytic, congenital, and tuberculosis-related curves — conditions with far worse inherent prognoses than pure AIS.
This paper, restricted entirely to adolescent idiopathic scoliosis with 39-year follow-up, showed near-normal mortality and functional outcomes. When counseling a family about an untreated 45° thoracic curve, use this data: most patients work, marry, and have children at population-average rates.
The 50° surgical threshold for thoracic fusion comes directly from this paper's progression data. Curves in the 50–80° range at skeletal maturity progress an average of 11° per decade. Enough to enter pulmonary risk territory over a lifetime. That mechanistic link between natural history and operative indication is what this paper established.
For pulmonary counseling: reassure families that clinically significant respiratory limitation in non-smokers does not appear until the curve approaches 100–120°. A 70° thoracic curve at skeletal maturity is not a pulmonary emergency. But it will likely progress, and that progression is the argument for surgery.
This landmark prospective natural history study followed 219 patients with untreated adolescent idiopathic scoliosis for an average of 39.3 years. It defines curve-specific adult progression rates, pulmonary risk thresholds, back pain prevalence, and mortality compared against matched population controls. The core question: what actually happens to untreated AIS patients over a lifetime?
Two 1968 studies (Nachemson; Nilsonne and Lundgren) reported doubled mortality and 30–60% disability in untreated scoliosis, driving aggressive surgical recommendations. Both cohorts mixed idiopathic with paralytic, congenital, and tuberculosis-related curves — conditions with far worse inherent prognoses than pure AIS.
This paper, restricted entirely to adolescent idiopathic scoliosis with 39-year follow-up, showed near-normal mortality and functional outcomes. When counseling a family about an untreated 45° thoracic curve, use this data: most patients work, marry, and have children at population-average rates.
The 50° surgical threshold for thoracic fusion comes directly from this paper's progression data. Curves in the 50–80° range at skeletal maturity progress an average of 11° per decade. Enough to enter pulmonary risk territory over a lifetime. That mechanistic link between natural history and operative indication is what this paper established.
For pulmonary counseling: reassure families that clinically significant respiratory limitation in non-smokers does not appear until the curve approaches 100–120°. A 70° thoracic curve at skeletal maturity is not a pulmonary emergency. But it will likely progress, and that progression is the argument for surgery.