Abstract
Introduction: The aim of this study is to compare the efficacy of the AO Universal Spine System (AO USS) with Harrington-Luque instrumentation for the treatment of King type II idiopathic scoliosis.
Methods/Results: A retrospective analysis was performed on two groups of patients with King II adolescent idiopathic scoliosis. The first group consisted of 40 consecutive patients treated with Harrington-Luque instrumentation between 1990 and 1993. The second group consisted of 25 consecutive patients treated with AO USS instrumentation between 1994 and 1996. The groups were well matched with respect to age, sex and curve severity. Inclusion criteria were patients over the age of 12 years with a King II curve pattern and a Cobb angle of greater than 40°. Half of the patients in each group underwent anterior release prior to posterior fusion. All patients were followed up six monthly for 18 months. The thoracic curve, lumbar curve, kyphosis and lordosis were measured using the Cobb method.
The mean pre-operative thoracic and lumbar curves were 62° and 43.9° respectively in the Harrington group and 57.5° and 35.9° in the AO USS group. On average 11.4 levels were fused in the Harrington group compared to 10.9 levels in the AO USS group. The mean post-operative correction of the thoracic curve in the AO USS group of 64% was significantly greater than the 51% achieved in the Harrington group (p< 0.005). At 18 months there was a 7% loss of correction in the Harrington group and 9% in the AO USS group. The correction of lumbar curve of 41% in the Harrington group and 46% in the AO USS group at 18 months was not significantly different. In the sagittal plane the AO USS group had significantly better preservation of the lumbar lordosis but there was no difference in kyphosis correction. Blood loss was similar in both groups. Mean operative time of 132 minutes in the AO USS group was shorter than the mean time of 153 minutes in the Harrington group (p< 0.05). Two hooks in the Harrington group became dislodged and two in the AO group. There were no neurological complications in either group. All the patients in both groups achieved a solid fusion.
Conclusion: AO USS is a safe and effective instrumentation system for the treatment of King type II adolescent idiopathic scoliosis. Correction of the thoracic curve is superior to that achieved with Harrington-Luque instrumentation and operative time is shorter. AO USS enables better preservation of the lumbar lordosis than Harrington-Luque. There is no difference in blood loss, complication rate and fusion rates between the two techniques. It has become our instrumentation system of choice for this group of patients.
Abstracts prepared by Mr J. Dorgan. Correspondence should be addressed to him at the Royal Liverpool Children’s Hospital, Alder Hey, Eaton Road, Liverpool L12 2AP, UK
President’s Lecture: Natural history and management of Congenital Kyphosis and Kyphoscoliosis M.J. McMaster, Edinburgh, Scotland, UK
Greg Houghton Lecture: Idiopathic Scoliosis – Alternatives to traditional surgery R.R. Betz, Philadelphia, USA
Instructional Lecture:New thoughts on the treatment of paralytic scoliosis R.R. Betz, Philadelphia, USA
Keynote Lectures: Idiopathic Scoliosis – How to manage the patient R.A. Dickson, Leeds, UK
Concave or convex approach for Kyphoscoliosis J. Dubousset, Paris, France Surgery or bracing for moderate AIS. How long term follow-up studies change your perspective A. Nachemson, Göteborg, Sweden
