Pseudarthrosis and Reoperation Rates in Minimally Invasive Adult Spinal Deformity Correction

INTRODUCTION: Adult spinal deformity (ASD) has historically been corrected via open surgery (OS). Recent developments in minimally invasive surgery (MIS) have made ASD correction possible with less blood loss, shorter hospital stays, and fewer complications. However, it has been proposed that inherent exposure constraints in MIS approaches limit proximal construct fusion, resulting in pseudarthrosis and potentially proximal junctional kyphosis and failure. METHODS: We initially screened 66 abstracts in PubMed. Manuscripts were initially included if they described outcomes from an MIS to correct ASD, including those comparing outcomes between MIS and OS or hybrid open-MIS. Exclusion criteria included failure to mention pseudarthrosis and surgeries performed on 2 levels or fewer. After independent review by two authors, 10 papers were selected. Patient demographics, perioperative and postoperative characteristics were calculated. RESULTS: Within the 10 articles, 509 MIS patients were reviewed. The average age was 65.5 years; 64.8% were female. An average of 6 levels (4.2 - 11) were fused per patient. Perioperative characteristics include mean follow-up time of 26.9 months, mean estimated blood loss (EBL) of 527 mL, mean operating time (OT) of 297.9 minutes, and mean length of stay (LOS) of 7.7 days. Among manuscripts comparing MIS to OS, all reported a statistically significant lower EBL in MIS patients. Conversely, OT and LOS were less consistently reported as lower in MIS compared to OS. The overall proximal pseudarthrosis rate among MIS patients was 6.2%. Among patients with pseudarthrosis, 88.2% underwent revision. CONCLUSIONS: The results of this analysis demonstrate a measurable risk of pseudarthrosis when using MIS to treat ASD, overwhelmingly requiring reoperation. Considering this risk of pseudarthrosis and subsequent revision surgery against the benefits of MIS is crucial to evaluate surgical treatment options for patients with ASD.