Rib hump and supine angle as prognostic factors for mild scoliosis.

A retrospective study was conducted on 262 patients with minor idiopathic scoliosis, having supine angles of less than 30 degrees and rib humps of less than 30 mm at the first examination. The initial radiographic measurement of the Cobb supine angle and rib hump height, recorded during a bending test performed on subjects in a sitting position, was correlated with the rate of scoliosis progression. Scoliosis progression was estimated graphically from an angle diagram established by monitoring untreated patients for 7 months to several years, depending on the rate of progression before treatment. More than 95% of the patients with initial supine angles of more than 17 degrees or rib humps greater than 11 mm suffered from progressive scoliosis. The importance of the size of the supine angle, rib-hump height, scoliotic pattern, and state of maturation for the progression rate are analyzed. Knowledge of these parameters can be used to make individual prognoses for approximately 95% of these subjects.