Should Sagittal Spinal Alignment Targets for Adult Spinal Deformity Correction Depend on Pelvic Incidence and Age?

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Spine (Phila Pa 1976)


STUDY DESIGN: Retrospective analysis OBJECTIVE.: Determine whether deformity corrections should vary by pelvic incidence (PI).

SUMMARY OF BACKGROUND DATA: Alignment targets for deformity correction have been reported for various radiographic parameters. The T1 pelvic-angle (TPA) has gained in applications for ASD surgical-planning since it directly measures spinal alignment separate from pelvic- and lower-extremity compensation. Recent studies have demonstrated that ASD corrections should be age specific.

METHODS: A prospective database of consecutive ASD patients was analyzed in conjunction with a normative spine database. Clinical measures of disability included the Oswestry Disability Index (ODI) and SF-36 Physical Component Score (PCS). Baseline relationships between TPA, age, PI and ODI/SF-36 PCS scores were analyzed in the ASD and asymptomatic patients. Linear regression modeling was used to determine alignment targets based on PI and age-specific normative SF-36-PCS values.

RESULTS: 903 ASD patients (mean 53.7y) and 111 normative subjects (mean 50.7y) were included. Patients were subanalyzed by PI: low, medium, high (75); and age: elderly(>65y, n = 375) middle age(45-65y, n = 387) and young(18-45y, n = 141). TPA and SRS-Schwab parameters correlated with age and PI in ASD and normative subjects (r = .42, p < .0001). ODI correlated with PCS(r = .71, p < .0001). Linear regression analysis using age-normative SF-36-PCS values demonstrated that ideal spinopelvic alignment is less strict with increasing PI and age.

CONCLUSIONS: Targets for ASD correction should vary by age and PI. This is demonstrated in both asymptomatic and ASD subjects. Using age-normative SF-36 PCS values, alignment targets are described for different age and PI categories. High-PI patients do not require as rigorous realignments to attain age-specific normative levels of health status. As such, sagittal spinal alignment targets increase with increasing age as well as PI.


Clinical Institute

Orthopedics & Sports Medicine

Clinical Institute

Neurosciences (Brain & Spine)