PREOPERATIVE SPINAL MOBILITY AND RESULT OF SURGICAL CORRECTION IN THORACIC ADOLESCENT IDIOPATHIC SCOLIOSIS (AIS)

Abstract

Objective: To evaluate the final result of surgical correction of AIS depending on preoperative spinal mobility and the type of procedure.

Summary of background data: To our knowledge no report has clearly demonstrated the role of different types of surgery in the final result of correction of deformed thoracic spine in AIS.

Materials and Methods: This is a retrospective, clinical study of patients with AIS and thoracic curves treated with CDI (hooks only) in the department of spinal surgery for children and adolescents of Russian Republican Spinal Centre from 1996 to 2005. Inclusion criteria included:

1. diagnosis of AIS King type II and III,

2. younger than 21 years,

3. not operated before.

A total of 247 patients met the inclusion criteria and they were divided in two groups:

• thoracic curve less than 90° and

• more than 90°.

In the group (A) there were 168 patients (male/female – 11/157, mean age 15.3 years), in the group (B) – 79 patients (male/female – 8/71, mean age 15.5 years). Coronal curve flexibility was assessed on supine side-bending AP radiographs. According the type of surgical technique the patients were divided in four groups:

• I - CDI correction

• II - CDI + skeletal traction

• III - anterior apical release with interbody fusion and CDI

• IV - anterior apical release, skeletal traction and CDI.

All the operations in the groups III and IV were performed in one session.

Results: In the group (A) mean thoracic curve before surgery was 66.8°, on the side-bending films 42.9° and after surgery 26.0°. The corresponding data according the type of surgery are presented in Table1.

So, CDI adds only 9.1° to side-bending correction (Gr. I) and skeletal traction gives 5.8° more (Gr. II). Anterior release with CDI improves preoperative correction by 14.7° (Gr. III) and the same procedure with skeletal traction – by 30.0° (Gr. IV). Consequently the part of the skeletal traction varies from 5.8° to 6.2°. Anterior release in its turn gives 14.7° of additional correction per se and 20.9° with skeletal traction.

In the group (B) mean thoracic curve before surgery was 109°, on the side-bending films 90.6° and after surgery 54°. The corresponding data according the type of surgery are presented in Table 2.

So, CDI adds 26.3° to side-bending correction (Gr.I) and skeletal traction gives only 1.9° more (Gr.II). Anterior release with CDI improves preoperative correction by 25.9° (Gr.III) and the same procedure with skeletal traction – by 40.6° (Gr.IV). Consequently the part of the skeletal traction varies from 1.9° to 14.7°. Anterior release in its turn does not give additional correction per se and 12.2° – with skeletal traction.

Conclusion: Our study supports the data of Delonne et al. (1998) that the instrumentation per se does not play the principal role in achieving final correction in AIS surgery. Skeletal traction and anterior release are of great importance as well. The second deduction is that curve correction is defined mainly by the volume of surgical procedure not by the preoperative mobility on side-bending films.