The placement of pedicular screws in spinal surgery has become the gold standard for scoliosis treatment. However, the use of sublaminar bands (SBs) on the apex of the curvature in idiopathic scoliosis (AIS) lowers the risk of neurological complications related to incorrect implementation of transpedicular screws into dysplastic pedicles without a cancellous channel. The latest research does not define a set of anatomical guidelines for applying SBs, nor does it use a dedicated classification system related to the structure of pedicles. The aim of this study was to assess the safety of the method and the correction attained through hypoplastic/aplastic pedicles when applying a hybrid instrumentation system to patients suffering from AIS Lenke type 1. Methods: Twenty patients were involved in a prospective, single-center, non-randomized case series study. The patients were assigned to the group "SCREWS" or "HYBRID" where SBs were used.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformation of the spine. The goal of the treatment is to achieve a reduction in deformity, restoring proper alignment and the best possible function of the spine. Pedicular screw placement in spinal surgery has become the gold standard for scoliosis reduction techniques in the last 30 years [6]. The screw-only systems are relatively safe, as various authors have proven. However, if implemented incorrectly, the screws increase the risk of damage to nervous or vascular structures and internal organs. The latest research does not define a set of anatomical guidelines for applying SBs, nor does it use a dedicated classification system related to the structure of pedicles. The aim of this study was to assess the safety of the method and the correction attained through hypoplastic/aplastic pedicles when applying a hybrid instrumentation system to patients suffering from AIS Lenke type 1. Methods: Twenty patients were involved in a prospective, single-center, non-randomized case series study. The patients were assigned to the group "SCREWS" or "HYBRID" where SBs were used. The inclusion criteria were this being the patients' first scoliosis operation due to AIS (Lenke type 1) and age under 18 years. The primary measured outcome involved correction efficacy, defined as the Cobb score baseline to endpoint change.

Inclusion Criteria:

• idiopathic scoliosis (AIS)
• Lenke type 1

Exclusion Criteria:

• AIS other than Lenke type 1 (neurogenic, congenial, or syndromic curvatures)
• abnormalities in the structure of the central nervous system in the MRI image
• advanced chronic respiratory or circulatory failure
• emergency surgery
• reoperation

Patients who qualified for scoliosis surgery in this center underwent X-ray imaging (AP, lateral, lateral bending view), computed tomography, and magnetic resonance imaging. Patients with a Cobb angle greater than 45 degrees (or 40 degrees in highly progressive cases) were considered eligible for the study. Based on the computed tomography assessment that was performed prior to the surgery, patients were assigned to one of two groups depending on the pedicle type on the apex of the thoracic curvature according to Watanabe pedicle's classification.

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