Who benefits from home-based exercise for adult spinal deformity? A prospective multicenter study on clinical and radiographic predictors.

Purpose: The prevalence of adult spinal deformity (ASD) is expected to exceed 60 million by 2050 due to an aging population and increased life expectancy. Despite advances in surgery, high complication rates and the economic burden highlight the need for effective non-surgical treatments. This study assesses the "Koshimagari Exercise," a self-exercise program for ASD patients, and aims to develop a classification system to identify those who would benefit most.

Methods: A prospective cohort study was conducted across 13 facilities, enrolling 144 participants from December 2020 to June 2022. The inclusion criteria were adults aged 50-80 years with chronic low back pain due to spinal deformities. Participants attended weekly physiotherapist-led exercise sessions and performed self-exercises at home three times a week, focusing on flexibility, functional improvement, trunk and back muscle strengthening, motor learning, and pain control. The primary outcome was the change in the Oswestry Disability Index (ODI) from baseline to 6 months post-intervention, with a 12-month follow-up. Clinical evaluations included health-related quality of life (HRQOL) assessments with ODI and EuroQol-5 Dimensions (EQ-5D), spinal alignment radiography, and magnetic resonance imaging of the paravertebral muscle (PVM) cross-sectional area.

Results: Of the 130 participants who provided written informed consent, 98 completed the 6-month follow-up. The study found that 42% of patients achieved a minimum clinically important difference (MCID) in ODI, with significant improvements in EQ-5D scores and LBP from baseline. Patients who achieved MCID had lower baseline body mass index and EQ-5D scores, and higher baseline ODI scores compared to those who did not. Logistic regression identified three significant predictors of MCID achievement: L4/S1 angle, the difference between standing and supine thoracolumbar kyphosis (ΔTLK), and the relative cross-sectional area (rCSA) of the PVM at L4/5. Based on these findings, a classification system was developed, dividing patients into Self-Exercise-Friendly and Self-Exercise-Limited groups, with a significant difference in ODI improvement observed between these groups at 6 months post-intervention.

Conclusion: The "Koshimagari Exercise," a novel self-exercise program for ASD, achieved an MCID in the ODI for 42% of patients. The classification system, incorporating L4/S1 angle, ΔTLK, and L4/5 rCSA, is associated with improvements in HRQOL and may help identify patients who are more likely to benefit from this home-based exercise program.