Preliminary outcomes and complications of the posterior dynamic distraction device (ApiFix) in adolescent idiopathic scoliosis.

This study reports preliminary outcomes in coronal and sagittal spinal alignment and complications following posterior dynamic distraction device (PDDD) implantation (ApiFix) in adolescent idiopathic scoliosis (AIS) patients. A retrospective review of 11 AIS patients treated with PDDD between 2020 and 2022 was conducted. Radiographic parameters [Cobb angle, kyphosis, lordosis, and sagittal vertical axis (SVA)], trunk rotation, operative data, and SRS-22r were assessed preoperatively, postoperatively, and at latest follow-up. Complications and revisions were recorded. Eleven patients (Lenke 1: n = 6; Lenke 5: n = 5) with a mean follow-up of 37.35 ± 10.31 months were reviewed. Significant scoliosis improvement was achieved postsurgery and maintained at follow-up for both Lenke groups, but no further correction occurred after the initial postoperative period. Distal sagittal malalignment developed in eight patients; distal junctional kyphosis in 5 Lenke 1 patients (83%) and distal junctional lordosis in 3 Lenke 5 patients (60%). Kyphosis and lordosis returned to baseline, with SVA unchanged. Two patients (18%) required PDDD removal for deep infection. One with chronic pain and another with implant prominence required or were scheduled for conversion to posterior spinal fusion (PSF). Postoperatively, trunk rotation improved in 75% of patients. Patient satisfaction with scoliosis management improved, but the device cannot be strongly recommended based on these preliminary results. In conclusion, PDDD achieves good initial coronal correction but has a high rate of sagittal malalignment compared to PSF. Beyond the need for patient counselling regarding risks and further surgery, the implant's uncertain safety profile warrants the authors discontinuing it in clinical practice.