Outcomes of posterior spinal fusion in AIS: A minimally invasive vs. open technique analysis

Introduction: Posterior spinal fusion is the most popular surgical treatment for adolescent idiopathic scoliosis (AIS). Recent innovations in implant designs have facilitated minimally invasive (MISS) approaches. However, these techniques have not yet achieved widespread adoption for deformity correction. Research question: This study aimed to compare surgical, radiologic, and clinical outcomes in AIS patients treated with a minimally invasive transmuscular (MINI-OPEN) approach versus the traditional open (OPEN) approach. Material and methods: This single-center retrospective study analyzed prospectively collected data from the EUROSPINE Spine Tango Registry framework. Inclusion criteria were AIS, posterior fusion, major coronal Cobb angle <80°, and 10-30 years. Complications, blood loss, operative time, length of stay (LOS), and pre- and postoperative radiographs were evaluated. Patients completed the Core Outcome Measures Index (COMI) preoperatively and at 3, 12, and 24 months. Results: Seventy-one OPEN patients were compared with 39 MINI-OPEN patients. Blood loss was significantly lower in the MINI-OPEN group (350.0 (275.0-500.0) vs 1150 (600.0-1625.0)mL), whereas operative time was significantly longer (450 (389.0-522.0) vs 326.0 (259.0-403.0)minutes). LOS was nearly half as long in the MINI-OPEN as in the OPEN group (5.0 (4.0-6.0) vs 9.0 (8.0-11.0)days). Coronal curve correction (median reduction 77% MINI-OPEN vs 75% OPEN) and COMI improvements did not differ significantly between groups. Discussion and conclusion: The MINI-OPEN approach was associated with less blood loss and a shorter hospital stay but longer operative time compared with the OPEN approach while radiologic and patient-reported outcomes were similar. These findings support MINI-OPEN as a feasible soft-tissue-sparing strategy in AIS correction.