O2130: Can High Drain Output be Predicted in Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis?

Background: In 2025, equipoise exists in the pediatric spine literature as to whether the placement of a drain changes outcomes in posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS). In 2003, Ecker et al. reported improved post-operative wound outcomes with placement of a subcutaneous drain. Yet in 2018, Lebel et al. reported no difference in complication rates between drained and non-drained groups. The orthopaedic community is moving away from subcutaneous drains, most recently in the adult arthroplasty literature in the setting of outpatient joint replacement. With AIS rapid recovery pathways accelerating post-operative inpatient recovery, our goal was to determine if patient or operative risk factors exist for predicting subcutaneous drain output to guide surgeons on who would benefit from a drain after PSF in AIS.

Methods: We conducted a retrospective analysis of patients between ages 10 and 18 who underwent PSF for AIS from 1/1/2016 to 12/1/2020. Patients with prior spinal surgery, neuromuscular diagnoses, or other co-morbidities were excluded. We compared mean subcutaneous drain output between three BMI groups: underweight ( < 18.49 kg/m2), healthy weight (18.5–24.99 kg/m2), and overweight (>25 kg/m2). Secondary analysis assessed the relationships between drain output and blood loss, operative time, and seroma.

Results: 230 total patients were included. Drain output in the underweight (281.1 mL), healthy weight (213.0 mL), and overweight (241.03 mL) groups were not significantly different (p=0.105). An operative time of greater than 286 minutes (p=0.04) or a blood loss of more than 300 mL (p=0.01) significantly increased the likelihood of high drain output (defined as ≥275 mL). A drain output of 275 mL or more was significantly associated with seroma formation (p=0.04). Drain output did not differ significantly between patients with or without wound dehiscence (p=0.2287) or post-operative infection (p=0.1972).

Conclusion: In AIS, pre-operative BMI cannot predict drain output. However, subcutaneous drain placement may help prevent seroma formation in AIS patients who undergo long and high-volume blood loss PSFs. Pediatric spine deformity surgeons are right to question the need for a subcutaneous drain following PSF in AIS.