Double claw construct with hooks for proximal fixation in adolescent idiopathic scoliosis: a randomized controlled trial

Purpose: Proximal fixation in adolescent idiopathic scoliosis (AIS) surgery is a matter of discussion. All screw (AS) constructs provide better coronal correction than hybrid constructs, but high thoracic pedicle screw placement can be challenging. This study investigated whether an AS-construct provides better correction than a proximal double hook-claw (PH) construct. Methods: AIS patients undergoing posterior spinal fusion (PSF) were randomized to AS-construct or PH-construct from 2016 to 2020 with a two-year follow-up. Primary outcome is the main thoracic (MT) Cobb angle correction after two years. Secondary outcomes are thoracic kyphosis (TK), proximal junctional angle (PJA), proximal thoracic (PT) Cobb angle, SRS-22r, and complications after two years. Results: 60 patients (30 AS, 30 PH) were included. No baseline differences were found. Preoperative MT Cobb angle was 62° ± 11° (AS) vs. 65° ± 12° (PH). There was no statistical difference in MT Cobb angle after two years: 25° ± 9° (AS) vs. 27° ± 7° (PH) (p = 0.247). No difference in PT Cobb angle was found: 20° ± 9° (AS) vs. 21° ± 9° (PH) and TK: 23° ± 9° (AS) vs. 22° ± 7° (PH). SRS-22r improved in both groups with no statistical difference: 3.9 ± 0.5 to 4.3 ± 0.5 (AS) vs. 3.7 ± 0.5 to 4.3 ± 0.5 (PH). There were 13 complications (ten patients) in AS group and 17 (13 patients) in PH group, including 1 major complication in each group (deep wound infection). Conclusion: AS-construct does not provide better coronal Cobb correction after two years after surgery. A PH-construct is a reliable and safe option for proximal fixation AIS patients. TRN: NTR-NL5552 (2016). Trial registration: Overview of medical research in the Netherlands (OMON): NL-OMON43852.