Fourth-generation spinal instrumentation: experience with adolescent idiopathic scoliosis at a tertiary care hospital in Pakistan

OBJECTIVE To evaluate the radiological and functional outcome of surgical treatment of adolescent idiopathic scoliosis using fourth-generation posterior spinal instrumentation at The Aga Khan University, Karachi, Pakistan. DESIGN Case series. PLACE AND DURATION OF STUDY The Aga Khan University Hospital after a minimum of 2 years postoperatively. PATIENTS AND METHODS A total of 20 patients with adolescent idiopathic scoliosis were recruited into the study and evaluated for radiological and functional outcome. The study period was from 2000 to 2005. Radiological outcome was assessed using Cobb angle measurement pre and postoperatively, hence assessing percentage correction. The lower instrumented vertebra was taken as the neutral vertebra and the level was recorded. Functional outcome was determined using the Scoliosis Research Society patient administered questionnaire. All patients were called to the clinic and asked to fill in the form. Those patients who were out of the city were mailed the forms and requested via telephone to complete and return. RESULTS Of the 20 patients operated on, twelve were female and eight were male. The average age at operation was 12.7 years. The mean Cobb angle was 69° preoperatively and 20° postoperatively, representing a percentage correction of 71%. The average duration of follow-up was 3.6 years. There was one major complication involving neurological injury post-op and two minor complications involving wound infection. The average Scoliosis Research Society score (on a scale of 1-5, with 5 being best) for pain was 4.5, self-image was 4.2, functional status was 4.1, mental status was 3.8, and satisfaction was 4.4. There was no relationship between the percentage correction of scoliosis and the functional outcome. Those patients with a high preoperative Cobb angle tended to have a better outcome for functional and mental status postoperatively. There was no relation between the lower instrumented vertebra and functional outcome. CONCLUSION In the correct indications, fourth-generation posterior instrumentation and fusion is a reliable and satisfactory technique to treat adolescent idiopathic scoliosis.