TITLE: Pre-operative pelvic parameters must be considered to achieve adequate sagittal
balance after lumbar osteotomy
AUTHORS (LAST NAME, FIRST NAME): Schwab, Frank J.1; Lafage, Virginie1; Shaffrey,
Christopher I.2; Farcy, Jean-Pierre C.1; Boachie-Adjei, Oheneba3; Shelokov, Alexis P.4; Hostin,
Richard 4; Hart, Robert A.5; Akbarnia, Behrooz A.6; O'Brien, Michael F.7; Burton, Douglas C.8;
Study Group, International Spine 9
INSTITUTIONS (ALL): 1. NYU Hospital for Joint Diseases, New York, NY, USA.
2. University of Virginia, Charlottesville, VA, USA.
3. Hospital for Special Surgery, New York, NY, USA.
4. Baylor Scoliosis Center, Plano, TX, USA.
5. Oregon Health Sciences University, Portland, OR, USA.
6. San Diego Center for Spinal Disorders, La Jolla, CA, USA.
7. Miami Children's Hospital, Miami, FL, USA.
8. University of Kansas Medical Center, Kansas City, KS, USA.
9. ISSG, San Diego, CA, USA.
ABSTRACT BODY:
Summary (80 words max): PSO procedure is now commonly used for realignment of
patients with marked sagittal mal-alignment. It is also commonly accepted that patients with
different sagittal deformities will require different surgical procedures. This study focuses on
patients with large pre-operative imbalance and aims to identify the key parameters that lead
to successful post-operative alignments based on pre-operative sagittal spino-pelvic
parameters. This study demonstrated that patients with large pre-operative pelvic tilt
required a larger PSO resection of reach an acceptable post-operative alignment
Introduction: Lumbar osteotomies are increasingly applied in the setting of adult sagittal
spinal deformity and may be effective in obtaining appropriate spino-pelvic re-alignment.
Additionally, it has been established that correction of global sagittal spinal balance improves
self reported clinical outcomes. The study aims to investigate the impact of pre-operative
radiographic spino-pelvic parameters on post-operative sagittal vertical axis offset (SVA) with
the hypothesis that patients with a larger pelvic tilt (PT) will require larger wedge resections
Methods: This is a multicenter consecutive retrospective review of 105 patients (mean age
54yo, 22M, 83F) who underwent lumbar PSO procedures for correction of major sagittal malalignment (mean pre SVA=14.3cm). Pre- and post-op free standing full length sagittal xrays
were analyzed for regional curves (LL, TK), pelvic parameters (PI, PT) and global balance
(SVA). Only patients with a pre-op SVA ranging from 10 to 20cm and with a post-op SVA less
than 5cm were retained. The group was subdivided by pre-op pelvic tilt (low/high, cutoff
=35°). Independent t-test analysis was used to determine differences in local/regional
correction required to achieve the desired SVA correction
Results: A total of 14 patients were identified in the low_PT group and 16 in the high_PT
group. There were no statistical differences in pre-op SVA, thoracic kyphosis (TK) and post-op
SVA. The low_PT group had a significant lower lumbar lordosis (12° vs 31°, p=0.002) and a
lower PT (23° vs 41°, p<0.001). Analysis of the surgical intervention demonstrated that
high_PT group required a larger osteotomy resection (resp. 29° and 20°, p<0.001) and a
larger regional change of lumbar lordosis (resp. +41° and+26°, p<0.001) to achieve an
acceptable post-op SVA (<5cm).
Conclusion: It has been accepted that improvements in surgical outcomes in patients with
sagittal malalignment relates to global and pelvic radiographic parameters. An understanding
of spino-pelvic alignment may help the surgeon during complex re-alignment procedures.
This study demonstrates that in the presence of increased pelvic retroversion (high PT), a
larger angular lumbar osteotomy and regional correction is required to obtain a satisfactory
post-operative SVA offset.