121 - MIS vs. Open Spinopelvic Fixation: Is There a Difference in Distal Junctional Failure Rates? A Propensity Score-Matched Analysis.

Saturday, June 3, 2023

11:20 AM – 11:22 AM

Location: Salons 13-15

Presenting Author (Person doing the Podium Present(s)

VA

Vardhaan Ambati, M.S.

Medical Student
UCSF
San Jose, California, United States

Co-Author(s)

TC

Timothy Chryssikos, MD, PhD

Spine Fellow
UCSF, California, United States
MT

Michael Tawil, BS

Medical Student
UCSF, United States
AD

Abraham Dada, B.A.

Medical Student
University of California, San Francisco, United States
RS

Ryan Sadjadi, M.Phil

Medical Student
UCSF, United States
AR

Alma Rechav Ben-Natan

United States
YS

Youssef Sibih

United States
MM

Mohamed Macki, MD, MPH

Spine Fellow
University of California, San Francisco
San Francisco, California, United States
AC

Andrew K. Chan, MD

Assistant Professor of Neurological Surgery (in Orthopaedic Surgery)
Columbia University
New York, New York, United States
SB

Sigurd Berven, MD

Professor in Residence
UC San Francisco
San Francisco, California, United States
DC

Dean Chou, MD

Columbia University, United States
AC

Aaron Clark, MD, PhD

Associate Professor
UCSF, United States
PM

Praveen V. Mummaneni, MD, MBA

Professor
University of California San Francisco
san francisco, California, United States

Submitter(s)

VA

Vardhaan Ambati, M.S.

Medical Student
UCSF
San Jose, California, United States

Introduction: There are no studies comparing distal junctional failure rates between patients undergoing open vs. MIS spinopelvic fixation.

Aims/

Objectives: To retrospectively compare rates of distal junctional pathology after MIS vs open spinopelvic fixation.

Methods: Patients undergoing MIS or open spinopelvic fixation at a single tertiary-care hospital between 2016-2021 were identified. MIS and open patients were propensity score-matched according to age, sex, BMI, unilateral versus bilateral iliac screws, and L5-S1 ALIF vs. TLIF vs. auto-fusion. We compared distal junctional failure rates (L5-S1 pseudarthrosis and hardware failure from L5 to the pelvis).

Results: After 1:2 propensity score-matching, the study cohort included 108 total cases, including 36 MIS (33.3%) and 72 open (66.7%) patients. There were 56 female patients (54.6%). Mean follow-up was 3.2 years. There were no significant differences between the MIS and open cohorts for age, sex, BMI, L5-S1 fusion (ALIF: 69.4% vs. 66.7%; TLIF: 23.6% vs. 25.0%; auto-fusion: 6.9% vs. 8.3%, p=0.95), number of pelvic screws per patient, unilateral vs. bilateral pelvic fixation (bilateral: 57.1% vs 50.0%, p=0.63), and BMP usage. The MIS cohort had lower mean sacral Hounsfield unit (188±56 vs. 220±58, p=0.01), shorter mean pelvic screw length (72.7±11.4 vs. 79.8±6.2, p< 0.001), fewer mean levels of fusion (4.1±1.0 vs. 5.9±2.9, p< 0.001), and lower rate of sacral-alar-iliac screws vs. iliac screws (sacral-alar-iliac: 13.9% vs. 40.3%; iliac: 83.3% vs. 50.0%; combination: 2.8% vs. 9.7%, p=0.004). There were no significant differences between the MIS and open cohorts for infection (5.6% vs. 8.3%, p=0.9), L5-pelvis hardware failure (2.8% vs. 8.3%, p=0.49), L5-S1 pseudarthrosis (2.8% vs. 5.6%, p=0.87), and reoperation for distal junctional failure (2.8% vs. 5.6%,p=0.87). The MIS cohort had lower pelvic incidence (51.2±11.6 vs. 59.0±14.3, p=0.006) and lower postoperative sacral slope (32.1±9.8 vs. 36.6±10.4, p=0.036) and lumbar lordosis (40.7±11.5 vs. 51.8±13.9, p< 0.001). There were no significant differences in pre- or post-operative PI-LL mismatch between the open and MIS cohorts. Patients in either cohort who developed L5-S1 pseudarthrosis had higher pelvic incidence (74.8±11.9 vs. 55.5±13.4, p=0.002), pre-operative pelvic tilt (35.6±11.6 vs. 25.3±11.2,p=0.049), and both pre- (36.6±8.1 vs. 15.9±15.0, p=0.003) and post-operative (23.8±6.4 vs. 7.5±16.1, p=0.03) PI-LL mismatch.

Conclusion: This study shows that both open and MIS spinopelvic fixation are associated with low rates of distal junctional failure, suggesting that MIS pelvic fixation does not appear to be inferior to open pelvic fixation.