Background: Congenital scoliosis is a developmental disorder defined as a lateral curvature of the spine. Its progressive trend and complications, such as cosmetic problems, pain and pulmonary symptoms, have put scoliosis as an important skeletal deformity that should be corrected. One of the currently accepted methods of treatment is posterior spinal fusion (PSF) that may be performed with or without instrumentation. However, the use of implants in conjunction with PSF in congenital spine deformity has been debated over the past three decades primarily because of increased risk of neurological deficit and implant displacement. The aim of this study was to compare short-term and long-term outcomes of spinal fusion with and without posterior instrumentation in congenital scoliosis.

Methods: In this historical cohort study, 41 patients with congenital scoliosis were recruited. All patients underwent PSF surgery between 1977 and 1996. They were divided into two groups according to the use of instrumentation: 22 congenital scoliotic patients who were treated by PSF without any instrumentation (group A), and 19 instrumented PSF patients (group B). Instrumentation was mostly performed using the Harrington rod. The major curve angle was measured before surgery, two weeks and one year after PSF surgery and at the end of the follow-up period.

Results: The mean baseline curve angles were 66.3° and 69.1° in groups A and B, respectively. The mean Cobb angles one year after PSF were 43.1° and 38.4° in groups A and B, respectively. The mean follow-up period was 8 years (SD=3) and, at the end of this period, the final Cobb angles were 47.3° and 39.4° in groups A and B, respectively. Therefore, the final angle correction was 28.7% in patients without instrumentation and 43% in patients with instrumentation. The mean loss of correction was 5.5% and 4.3% in groups A and B, respectively. The final curve angles was significantly more corrected for those patients in whom instrumentation was used than those without instrumentation (p<0.05).

Conclusion: The treatment of congenital scoliosis can be very challenging despite the benefits of modern surgeries and instrumentation methods. The results of our study demonstrate that the application of an implant with PSF surgery may lead to increased improvement of the scoliotic curvature in the short-term and long-term periods, as well as a decrease in the loss of correction and the rate of reoperation. In addition, the low incidence of complications in our study indicates the safety of the posterior instrumentation for the treatment of congenital scoliosis.