Surgical assessment of the proximal thoracic curve in adolescent idiopathic scoliosis

Abstract

Existing predictive signs as available in current literature may miss potential proximal thoracic (PT) curve deterioration and shoulder imbalance, following selective main thoracic (MT) curve correction in adolescent idiopathic scoliosis (AIS). The present study is an attempt to evaluate and complement these signs, through a retrospective study of 56 AIS patients who underwent correction and fusion from 1986 till 2003 with follow-up 4–16 years. Forty-nine had fusion of MT curve, 7 of MT and PT. Cotrel–Dubousset instrumentation in 45, Luque in 12. Preoperative data: MT 50° (40°–80°), PT 25° (0°–50°), shoulder elevation from −4 cm (right) to 2 cm (left), clavicle angle from −14° to 5°, PT bending correction from 0 to 100% and T1 tilt from −15° to 14°. We introduced the first rib index (FRI), i.e., the difference between the diameter of right and left first rib arch as a percentage of the sum of both diameters, averaging from −22.7 to 14.3%. (Minus signs refer to or predict right, while positive left shoulder elevation.) Evaluation included all predictive parameters as related principally to postoperative left shoulder elevation ≥1 cm, patient satisfaction and surgeon fulfillment. Postoperative correction MT curve 53% (23–83%) and PT 35% (0–100%). One progressive paraplegic started 40 min following normal wake-up test. Immediate decompression, full recovery. Three cases with wound infection recovered after late removal of instrumentation. Loss of correction ≥10° in five. Fifteen had postoperative persisting left shoulder elevation ≥1 cm. Seven of these expressed dissatisfaction. Statistically FRI proved valuable predictive factor always in combination with previously described signs. We concluded that a postoperative left shoulder elevation ≥2 cm is a potential cause of dissatisfaction and may be prevented with thorough validation of all predictive signs, principally the FRI.