A Comparison of Monoaxial Pedicle Screws Versus Polyaxial Pedicle Screws in Posterior Fusion Surgery for Adolescent Idiopathic Scoliosis (Lenke Type 1).

Background Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity in adolescents, characterized by a three-dimensional curvature of the spine with unknown etiology. Surgical intervention is indicated in progressive curves, particularly in Lenke type 1 patterns, to achieve deformity correction, spinal balance, and long-term stability. Objective The objective of this study is to compare the clinical and radiological outcomes of mono-axial versus poly-axial pedicle screw constructs in posterior spinal fusion surgery for AIS Lenke type 1, with particular emphasis on deformity correction, and operative parameters. Patients and methods This hospital-based prospective comparative study was conducted at the Faculty of Medicine, Al-Azhar University Hospital, Assiut. The study included 30 patients with AIS who attended the outpatient clinic and were indicated for posterior scoliosis correction surgery during the study period. Patients were enrolled after fulfilling the inclusion criteria and were divided into two groups according to the type of pedicle screw instrumentation used. All patients were evaluated and compared regarding demographic data (age, sex), clinical presentation, radiological parameters, operative details, and postoperative outcomes. Results This study included 30 patients with AIS Lenke type 1, divided equally into mono-axial and poly-axial pedicle screw groups (n=15 each). The mean ages were 13.87 years in the monoaxial group and 14.33 years in the polyaxial group with no statistical differences (p=0.386). Women represented 93.3% of patients in both groups, with no statistically significant difference in gender distribution (p=1.000, χ²=0.00). There was no statistically significant difference between the two groups regarding operative duration (p=0.907) or intraoperative blood loss (p=0.411). Radiological outcomes showed significant postoperative improvement in both groups; however, no statistically significant difference was found between mono-axial and poly-axial screws in preoperative or postoperative major Cobb angle (p=0.439 and p=0.670, respectively), apical vertebral translation (p=0.966 preoperatively and p=0.501 postoperatively), or T1-S1 spinal height (p=0.884 preoperatively and p=0.874 postoperatively). VAS and Oswestry Disability Index improved postoperatively in both groups, with no statistically significant difference between the examined groups (p>0.05). Conclusion In patients with moderate Lenke type 1 AIS treated with posterior segmental pedicle screw instrumentation and rod derotation, monoaxial and polyaxial pedicle screw constructs produced comparable radiographic correction and clinical outcomes in our series.