Do low-density screws influence pelvic incidence in adolescent idiopathic scoliosis correction?

Background: Low-density screw constructs yield significant radiographic and clinical improvements with reduced risk of neurological complications. This study aimed to investigate the relationship between coronal Cobb angle and pelvic incidence (PI) in the correction of adolescent idiopathic scoliosis (AIS) using a low-density construct, as well as the association between PI and functional outcomes.

Patients and methods: This prospective cohort study involved 60 posteriorly instrumented AIS patients, aged 10-16 years, with Cobb angles ranging from 45° to 90° of various Lenke types. Radiological assessments were conducted pre- and postsurgery at 1, 3, 6, 12, and 24 months. Functional evaluation utilized the Scoliosis Research Society score form (SRS-30).

Results: A positive correlation was observed between screw density and operation time, blood loss, and degree of correction with SRS change (P = 0.004). No correlation was found between screw density and hospital stay, loss of correction, correction rate, SRS change, change in PI, or Cobb angle.

Conclusions: Correction of AIS through a posterior approach using a low-density construct can lead to satisfactory curve correction, impacting spinopelvic parameters. However, PI alone does not directly influence patient functional outcomes assessed by SRS-30. Low-density implant constructs reduce operative time, blood loss, costs, and complication risks.