808 - Dynamic Instability is Underestimated on Standing Flexion-Extension films when compared to Prone CT Imaging

Thursday, February 22, 2024

5:00 PM – 6:30 PM EDT

Presenting Author(s)

MC

Michael C. Chiang, MD

Resident physician
Spaulding Rehabilitation Hospital / Harvard Medical School
Cambridge, Massachusetts, United States

Co-Author(s)

AJ

Albert Jiao, MD

Resident physician
Brigham and Women's Hospital
Boston, Massachusetts, United States
JM

Jacob Mandell, MD

Attending physician
Brigham and Women's Hospital
Boston, Massachusetts, United States
MM

Melvin Makhni, MD

Resident physician
Brigham and Women's Hospital
Boston, Massachusetts, United States
Zacharia Isaac, MD

Division Chief, spine care and pain management
Spaulding rehabilitation
Charlestown, Massachusetts, United States

Objectives: We performed a retrospective study evaluating the incidence and degree of L4-5 anterior spondylolisthesis in patients with standard supine MRI, standing radiographs, and prone CT. We hypothesize that prone CT imaging will provide greater sensitivity for instability compared to standing or supine positions.

Design: Single center retrospective cohort study between 2014 - 2022

Results: We identified 102 patients with L4-5 anterolisthesis. The mean difference in anterolisthesis among imaging modalities were 2.7 ± 1.8 mm between CR and CT (p < 0.001), 1.8 ± 1.4 mm between CR and MRI (p < 0.001), and 1.6 ± 1.4 mm between CT and MRI (p = 0.252). Ninety two of 102 patients (90.2%) showed greater anterolisthesis on CR compared to CT, 72 of 102 (70.6%) comparing CR to MRI, and 27 of 102 (26.5%) comparing CT to MRI. We found that 17.6% of patients exhibited ≥ 3 mm anterior translation comparing CR with MRI, whereas 38.2% patients were identified comparing CR with CT imaging (χ2 test p = 0.0009, post-hoc Fisher’s exact test p = 0.0006 between CR and CT). Only 5.9% of patients had comparable degrees of instability between flexion-standing.

Conclusions: CT imaging revealed the greatest degree of single L4-5 segmental instability compared to flexion-extension radiographs.