Correction of idiopathic scoliosis using the H-frame system.

To determine the effectiveness of posterior H-frame instrumentation for the surgical treatment of idiopathic scoliosis, 36 patients were studied. The patients underwent surgery between 1989 and 1993 and were evaluated for curve correction, hump correction, vertebral rotation, fusion level and complications. Average age at surgery was 19 years. Duration of follow-up averaged 2.5 years. Mean primary curve correction in patients with a King type I curve was 44.8% (n = 4) and in patients with a type II curve 67.3% (n = 9). Patients with King type III (n = 17) and IV (n = 6) curves achieved respective mean curve corrections of 67.8% and 63.9%. During follow-up there was a mean correction loss of 0.8% in type I, 5.4% in type II, 10.1% in type III and 2.4% in type IV curves. No significant derotation of the primary curves was noted. Rib hump correction and rotational changes of the unfused compensatory curves were significant. Fusion levels extended beyond L2 in six cases. Major neurological problems did not occur. Pseudoarthrosis developed in one patient and imbalance in two patients. The H-frame system satisfactorily achieves curve and rib hump correction with little correction loss.