Sitting With or Without Wedge-Shaped Cushion After Lumbar Spinal Fusion

Author(s): Florian Wanivenhaus, MD, Christoph Johannes Laux, MD, David Ephraim Bauer, MD, Christina Wanivenhaus, MD, José Miguel Spirig, MD, Michael Betz, MD, Nadja A Farshad Amacker, MD, Mazda Farshad, MD MPH

Introduction:

Transition from standing to sitting significantly decreases lumbar lordosis (LL). Fusion of lumbar segments eliminates motion and therefore, adjacent mobile segments are recruited during transition from standing to sitting to compensate. Prescription of a wedge-shaped seat cushion to retain LL while seated is a common practice. However, its effect has not been evaluated before and after posterior lumbar spinal fusion (PSF).

Methods:

Patients undergoing PSF at a single academic institution between May 2022 and August 2023 were included in the study. Radiographic spinopelvic parameters were measured in the standing, relaxed sitting, and sitting on a wedge-shaped cushion positions before and after surgery.

Results:

Twenty patients were included for analysis (female to male, 11:9). Mean age was 67 ± 10 years. Mean body mass index was 26.3 ± 3.3 kg/m². Median LL significantly decreased before the surgery from the standing 43° (33.5-49.5°) to the sitting positions with and without a cushion (24° (13-32°) vs 25° (8.5-34.5°); p<.001). After surgery LL also significantly decreased from the standing 38° (32- 47°) to the sitting positions with and without a cushion (26° (16.5-36°) vs 26° (19-38°); p<.001). But there was no significant difference in LL between the sitting positions without and with a cushion before and after the surgery 1° (-2-4°) and -2 (-4-2°), respectively.

Conclusions:

Sitting significantly decreases lumbar lordosis and increases pelvic tilt, but use of a wedge-shaped seat cushion does not alter lumbar lordosis compared with regular sitting before or after fusion surgery.