Abstract
In order to overcome high intra-observer and inter-observer reliability, there is a new classification system for Adolescent Idiopathic Scoliosis (AIS). The type C (King II) of this system describes pronounced lumbar curves in which the center sacral vertical line (CSVL) lies outside the lumbar apical vertebra on the concavity of the curve. It has been proposed that selective anterior thoracic fusion (ATF) is not possible in these cases because of insufficient spontaneous correction of the lumbar curve or postoperative lumbar progression. This retrospective study analyses the results of a group of patients who received selective ATF for type C curves. The purpose of the study was to analyze the ability of the new classification system to predict the outcome of anterior thoracic fusion in the combined AIS type Lenke C, and to define predictive parameters revealed in the study.
From 1989 to 1994, 407 patients underwent anterior fusion for scoliotic deformities of different etiologies. There were 174 patients with anterior thoracic fusion. Twenty-one patients (< 19 years old) had combined AIS with a Risser sign < 5 with the criteria of a Lenke type C curve. Fourteen patients had a minimum follow-up of two years. The parameter analysis included coronal and sagittal corrections. Horizontalisation of lumbar and thoracic endvertbrae and correction of both curves were measured on pre-op bending and Cotrel traction films.
Fourteen female patients with a mean age of 15.4 years were followed for an average time period of 3.3 years. Mean correction of the lumbar curve and the thoracic curve was 46.0% (±18.5) and 54.7% (±16.4) respectively. Patients with preoperative horizontalisation on Cotrel traction films of the lumbar endvertebra of less than 6° had an average correction of the lumbar curve of 60.1% (±8.1) and an average loss of correction of 3.6% (±14.6); those with more than 5° had 27.2% (±9.7) and 19.4%(±11.5) respectively. Horizontalisation of the thoracic endvertebra of less than 10° on preoperative Cotrel traction films had an average correction of the lumbar curve of 62.7% (±8.7) and −2.8% (±10.4) loss of correction; those with more than 9° had 44.6%(±13) and 12.8%(±13.6) respectively. Preoperative correction of more than 50% of the thoracic curve on Cotrel traction films had an average correction of the lumbar curve of 53.1% (±18.3); loss of lumbar correction was −1.9% (±8.9); less than 50% had 38.9% (±15.7) and 22 % (±10.7) respectively.
Patients with combined AIS and pronounced lumbar curves (type C) can be treated with selective anterior thoracic fusion. Horizontalisation of the thoracic and lumbar endvertebrae and correction of the thoracic curve on preoperative Cotrel traction films have an important predictive value for the unfused lumbar curve and are superior to bending films in this context.
The abstracts were prepared by David P. Davlin. Correspondence should be addressed to him at the Orthopedic Clinic Bulovka, Budínova 2, 18081 Prague 8, Czech Republic.
