Introduction: Restoring ASD patients’ ideal Roussouly type is reported to prevent mechanical complications. However, there remain patients with restored ideal Roussouly type who still suffer these complications.
Methods: ASD patients were stratified by matching ideal Roussouly types as described by Latouissat, with type 1 and 2 corresponding to pelvic incidence (PI) < 45°, type 3 to PI 45°–60°, and type 4 to PI > 60°. Patients matching ideal Roussouly types postoperatively and sustaining mechanical complications (Rouss+Mech+) were further isolated. Means comparisons tests were used to assess differences between both groups. Logistic regression analyses were used to analyze associations between Roussouly matching and various outcomes.
Results: 464 patients included (Age: 60.4 ± 14.9 years, BMI: 27.5 ± 5.8 kg/m2, CCI: 1.67 ± 1.66). 74% of patients were female. At baseline (BL), 8.2% of patients were type 1, 51.8% type 2, 26.6% type 3 and 13.2% type 4. 41.5% of patients matched ideal Roussouly (R) type (43.1% type 1, 30.4% type 2, 40.6% type 3 and 84.9% type 4, p< 0.001). Post-op, 50.7% of patients matched ideal R type (40.3% type 1, 43.4% type 2, 55.8% type 3 and 74.6% type 4, p< 0.001). At 2 years post-op, patients matching ideal R type experienced lower mechanical complications (13% vs 86%, p< 0.001). Mechanical complication rates by R type in patients matching ideal R type (Rouss+Mech+) were 11.1% in type 1, 13.9% type 2, 12.7% type 3 and 15.3% type 4, p=0.930). Factors associated with mechanical complications in Rouss+Mech+ were under-correction by persistent pelvic incidence-lumbar lordosis mismatch (OR 1.1, 95% CI 1.1-1.2, p< 0.001) and lower limb arthritis (OR 2.4, 1.2-4.9, p=0.024). Rouss+Mech+ had lower rates of matching in sagittal age-adjusted score compared to Rouss+Mech- at BL (27.3 vs 33.8%, p< 0.001), postop (27.3 vs 31.4%, p< 0.001), and at all timepoints up to 2 years. Rouss+Mech+ also had higher rates of reoperation at 2 years (58.3% vs 16.7%, p< 0.001).
Conclusion : Although uncommon, patients matched to ideal Roussouly shape still experience mechanical complications. Inadequate realignment and lower limb arthritis are associated with increased mechanical complications risk within two years.
.jpg)