280 - Full-Body Radiographic Analysis of Post-operative Deviations from Age-...

Oral Posters: Innovative Technologies

Presented by: B. Beaubrun - View Audio/Video Presentation (Members Only)

Author(s):

P. Passias(1), C. Jalai(1), B. Diebo(2), D. Cruz(1), G. Poorman(1), S. Horn(1), P. Zhou(1), B. Beaubrun(1), A. Buckland(1), L. Day(1), B. Liabaud(3), R. Lafage(3), A. Soroceanu(4), J. Baker(1), S. McClelland(1), J. Oren(1), T. Errico(1), F. Schwab(3), V. Lafage(3)

(1) NYU Hospital for Joint Diseases, Orthopaedic Surgery, New York, NY, United States
(2) SUNY Downstate, Orthopaedic Surgery, Brooklyn, NY, United States
(3) Hospital for Special Surgery, New York, NY, United States
(4) University of Calgary, Orthopaedic Surgery, Calgary, AB, Canada

Abstract

Background: Full-body stereographs for adult spinal deformity (ASD) have enhanced global deformity and lower-limb compensation associations. The advent of age-adjusted goals for classic ASD parameters (sagittal vertical axis [SVA], pelvic tilt [PT], spino-pelvic mismatch [PI-LL], has enabled individualized evaluation of successful versus failed realignment, though these remain to be radiographically assessed post-operatively. This study analyzes pre- and post-operative sagittal alignment to quantify patient-specific correction against age-adjusted goals, and presents differences in compensation in patients whose post-operative profile deviates from targets.

Methods: Single center retrospective review of ASD patients ≥18 years with biplanar full-body stereographic x-rays. Inclusion: ≥4 levels fused, complete baseline and early (≤6M) follow-up imaging. Correction groups generated at post-operative visit for actual alignment compared to age-adjusted ideal values for PT, PI-LL, and SVA derived from clinically-relevant formulas. Patients that matched (´Match´) an exact ±10 years threshold for age-adjusted targets were compared to unmatched cases (´Undercorrect´ or ´Overcorrect´). Comparison of spinal alignment and compensatory mechanisms (thoracic kyphosis [TK], hip extension [SFA], knee flexion [KA], ankle flexion [AA], pelvic shift [PS]) across correction groups were performed with ANOVA and paired t-tests.

Results: The SVA, PT, and PI-LL of 122 included patients improved at early post-operative visit (p< 0.001). Of lower-extremity parameters, KA and PS improved (p< 0.001), but SFA and AA were similar (p>0.170); GSA decreased overall, reflecting global post-operative correction (8.3° vs. 4.4°, p< 0.001). The rates of undercorrection to age-adjusted targets for each spino-pelvic parameter was 30.3% (SVA), 41.0% (PT), 43.6% (PI-LL). Compared to matched/overcorrected cases, undercorrections recruited increased posterior pelvic shift to compensate (p< 0.001); knee flexion was recruited in undercorrections for SVA and PT, while thoracic hypokyphosis was observed in PI-LL undercorrections. All undercorrected groups displayed a consequentially larger GSA (p< 0.001).

Conclusions: Global alignment cohort improvements were observed, and when comparing actual to age-adjusted alignment, undercorrections recruited pelvic and lower-limb flexion to compensate.

Level of evidence: III