596 - The Impact of Pre-operative Supine Radiographs on Surgical Strategy in...

Oral Posters: Adult Spinal Deformity

Presented by: J. Varghese - View Audio/Video Presentation (Members Only)


J. Varghese(1,2), A. Patel(1), B. Liabaud(1), C. Ames(3), J. Smith(4), J. Gum(5), C. Shaffrey(4), B. Diebo(1), R. Lafage(1), S. Bess(6), F. Schwab(1), V. Lafage(1), H.J. Kim(1), International Spine Study Group (ISSG)

(1) Hospital for Special Surgery, Spine Service, New York, NY, United States
(2) SUNY Downstate Medical Center, Department of Orthopaedic Surgery, Brooklyn, NY, United States
(3) San Francisco Medical Center, University of California, Department of Neurosurgery, San Francisco, NY, United States
(4) University of Virginia Medical Center, Department of Neurosurgery, Charlottesville, VA, United States
(5) Norton Leatherman Spine Center, Louisville, KY, United States
(6) NYU Langone Medical Center, Spine Division, Department of Orthopaedics, New York, NY, United States


Introduction: Adult Spinal Deformity (ASD) surgery is planned using standing radiographs. However, eliminating gravity in the operative (recumbent) position may dramatically alter spinal alignment and subsequently surgical plans. This study investigated the utility of supine radiographs to assess spinal flexibility and its impact on surgical strategy.

Purpose: To investigate the impact of spinal flexibility on surgical strategy in adult spinal deformity patients.

Method: Only ASD patients (pts) who underwent fusion from the pelvis to UIV = T9-L1 were included. Each patient had the following lateral radiographs: pre-op standing (ST), pre-op supine (SU), and 6-week post-op (Post). Pts were grouped based on surgical strategy: Yes-Osteotomy or No-Osteotomy. Demographic, surgical, and radiographic parameters (including pelvic incidence-lumbar lordosis mismatch [PI-LL]) were compared between groups using unpaired t-tests. Correction from spinal flexibility alone (%flexsupine) was assessed by DPI-LL from ST to SU divided by the total change from ST to Post (DPI-LL from ST to Post). %Flexsupine values range from 0% (no correction from SU positioning) to 100% (all correction from SU positioning).

Results: Yes-Osteotomy (n=32) and No-Osteotomy (n=27) had similar demographic and surgical data. Of all Yes-Osteotomy patients, 88% had a grade 2 osteotomy (mean = 3 per patient), 25% had a grade 3 osteotomy, while 12.5% had a grade 3 and grade 2 osteotomy. Post-op, No-Osteotomy and Yes-Osteotomy had similar alignment (Post PI-LL: 0.2° vs -3.1°; p=0.38). Standing alignments were similar between No-Osteotomy and Yes-Osteotomy (Table), but No-Osteotomy had a greater change in PI-LL from ST to SU (10° vs 5°, p=0.05). No-Osteotomy had a smaller change from SU to Post PI-LL than Yes-Osteotomy (5° vs 15.5°; p< 0.001). %flexsupine was greater in No-Osteotomy (66%) than Yes-Osteotomy (25%, p< 0.01) (See Figure) indicating the utility of the supine image in osteotomy utilization.

Conclusion: ASD patients requiring osteotomies had less flexibility in LL from supine positioning. No-Osteotomy patients still achieved adequate post PI-LL due to the flexibility in LL from supine positioning. Flexibility assessment via supine radiographs is a critical tool to guide use of osteotomies during planning for spinal realignment.