J Neurosurg Spine 43:609–615, 2025
This clinical study examines postoperative changes in Roussouly sagittal spinal profiles among 525 adult spinal deformity (ASD) patients and evaluates how shifts between Roussouly types influence mechanical complications and patient-reported outcomes up to two years after fusion surgery. Methods include radiographic classification (current SS-based and theoretical PI-based), HRQOL measures (ODI, SRS-22r, EQ-5D), and multivariate regression to link type changes with PJK/PJF and MCID attainment.
Key findings show 39–59% of patients experienced postoperative Roussouly shape changes, with certain transitions (R1→R2, R2→R4, R3→R4) associated with higher proximal junctional kyphosis/failure risk and R4→R3 linked to greatest mechanical complication risk. R2-mismatched patients had poorer ODI improvement and higher pelvic nonresponse, suggesting Roussouly matching should inform ASD surgical planning.
Roussouly Classification Changes: Postoperative changes in Roussouly sagittal profile are common after adult spinal deformity (ASD) surgery, with 39% of patients experiencing a change in Roussouly type at 6 weeks post-op; type 1 (R1) patients had the highest rate of change (59%) and type 4 (R4) the lowest (26.7%).
Mechanical Complication Risk: Certain Roussouly type changes significantly increase the risk of proximal junctional kyphosis (PJK) and mechanical complications, especially transitions from R1 to R2, R2 to R4, R3 to R4, and R4 to R3.
Health-Related Quality of Life (HRQOL): Overall, Roussouly type changes were not associated with significant differences in minimum clinically important difference (MCID) achievement for SRS-22r scores up to 2 years, except for a lower rate of ODI MCID attainment in R2-mismatched patients.
Surgical Invasiveness and Deformity Severity: R1 patients had the most severe baseline deformity and underwent more extensive surgery, which may contribute to higher rates of postoperative Roussouly type changes.
Matching Theoretical Roussouly Type: Only 48% of patients matched their theoretical (PI-based) Roussouly type postoperatively; those who matched, especially in the R2 group, had better functional outcomes and lower rates of pelvic nonresponse (PNR).
Clinical Implications: Maintaining or restoring the original Roussouly type during ASD surgery may reduce the risk of mechanical complications and improve early functional outcomes, particularly for R2 patients.
Limitations: The study was retrospective, single-center, and limited to 2-year follow-up, which may affect generalizability and long-term conclusions.
Surgical Planning: Accounting for Roussouly type changes and known risk factors (e.g., osteoporosis, advanced age) during surgical planning may help decrease postoperative complications.
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