Patient-perceived recovery after posterior spinal fusion: evaluating minimum clinically important difference (MCID) in adolescents with idiopathic scoliosis

BACKGROUND: Adolescent idiopathic scoliosis (AIS) affects 1-3% of children in the United States, with approximately 38,000 patients undergoing posterior spinal fusion (PSF) annually. The relationship between preoperative patient-reported outcomes, postoperative recovery, and long-term clinical significance remains unclear. This study assesses longitudinal changes in Scoliosis Research Society-22r (SRS-22r) scores. It evaluates clinical significance using the Minimum Clinically Important Difference (MCID) in AIS patients undergoing PSF. STUDY DESIGN: Retrospective study using prospectively collected data. METHODS: A retrospective study was conducted using prospectively collected data on AIS patients who underwent PSF at a single academic institution between 2012 and 2022. Patient-reported outcomes were assessed using the SRS-22r questionnaire at preoperative, 6-month, 1-year, and ≥ 2 years postoperative time points. MCID threshold achievements were determined using anchor-based criteria from Bago et al. The percentage of patients achieving MCID and predictors of MCID achievement were analyzed using logistic regression. RESULTS: A total of 161 patients (mean age 15.26 ± 2.15 years; 65.8% female) were included. At 1 year, MCID achievement ranged from 30.1% (Self-Image) to 43.4% (Mental Health). By ≥ 2 years, MCID rates declined in Pain (25.9%) and Self-Image (22.8%) but increased in Function/Activity (44.1%). Lower preoperative SRS-22r scores consistently predicted MCID achievement across all domains. A documented mental-health history reduced the likelihood of Pain MCID at 1 year, and larger postoperative Cobb angles independently decreased the odds of achieving Self-Image MCID at both follow-up points. Neighborhood opportunity (Child Opportunity Index) was not associated with outcomes. Sensitivity analyses demonstrated that complete-case ≥ 2 year MCID rates were consistently bounded by best- and worst-case values and closely approximated LOCF estimates, supporting robustness despite attrition. CONCLUSION: Meaningful postoperative improvement after PSF varies substantially by SRS-22r domain. Pain and mental-health gains occurred early and stabilized, whereas function demonstrated ongoing recovery, and self-image improved rapidly and remained stable. MCID achievement was most likely in patients with greater preoperative symptom burden, while mental-health history and residual postoperative deformity diminished domain-specific improvements. The stability of MCID patterns across sensitivity analyses reinforces the reliability of long-term findings. These results highlight the importance of incorporating psychological assessment, expectation management, and attention to postoperative alignment into perioperative care for AIS patients.