Effect of a Mattress on Lumbar Spine Alignment in Supine Position in Healthy Subjects: An MRI Study
Study by Jacopo A. Vitale, Stefano Borghi, Tito Bassani, Carmelo Messina, Luca M. Sconfienza and Fabio Galbusera (Schulthess Klinik, Zurich; University of Milan; IRCCS Istituto Ortopedico Galeazzi, Milan)
MRI Study of 20 Adults · European Radiology Experimental (Vol. 7, Article 47) · DOI: 10.1186/s41747-023-00361-w
Key Takeaway
Lying on a Mattress Changed the Lower Back Curve by a Few Degrees
What was tested: 20 healthy adults had MRI scans of the lower spine while lying on their backs, once on a medium-firm foam mattress and once on the rigid scanner table (Vitale et al., 2023).
What the numbers showed: On the mattress, the inward curve of the lower back was 2.9 degrees larger and the tilt at the base of the spine was 2.0 degrees larger. The authors call these changes "small but statistically significant".
What this means for you: A mattress changes how your lower spine sits compared with a hard surface, but only by a few degrees. The study tested one mattress for a short time in people without back pain, so it cannot tell you which firmness or brand to buy.
Key Numbers
How the Study Was Done
Researchers in Italy and Switzerland scanned 20 healthy adults, 10 women and 10 men, with an average age of 32. Each person had an MRI scan of the lower spine while lying on their back on a mattress, and another while lying on the rigid scanner table. Each person also had a standing X-ray of the spine (Vitale et al., 2023).
The mattress was a medium-firm, single layer of polyurethane foam, 22 cm thick, supplied by the Italian maker Dorelan. The team measured angles that describe the shape of the lower spine. These included the inward curve of the lower back (lordosis, measured from the L1 to L5 vertebrae) and the sacral slope, which is the tilt of the bone at the base of the spine.
What the Study Compared
Medium-Firm Foam Mattress
Lower back curve 2.9 degrees larger and sacral slope 2.0 degrees larger than on the rigid table.
Rigid Scanner Table
The comparison surface. Each person's scan here was compared with their own scan on the mattress.
What the Study Found
On the mattress, the lower back curve from L1 to L5 was 2.9 degrees larger (p < 0.001) and the sacral slope was 2.0 degrees larger (p < 0.001) than on the rigid table. The angle between the last lumbar vertebra and the sacrum (L5 to S1) was 1.6 degrees smaller (p = 0.008). The full curve from L1 to S1 was 2.0 degrees larger in men only (p = 0.006) (Vitale et al., 2023).
The authors conclude that using a mattress causes "small but statistically significant changes" in the angles of the lower spine when lying on the back. The study did not compare different firmness levels, and it did not measure pain or sleep.
The study was supported by a grant from Dorelan, which also provided the mattress, and by the Italian Ministry of Health. Two of the authors reported being paid as scientific consultants by Dorelan. The authors state that the company took no part in the design, data collection, analysis or interpretation (full paper).
How to Apply This Study When Choosing a Mattress
What it tells you: A mattress changes the shape of your lower spine a little compared with a hard surface.
This study compared one foam mattress with a rigid table, so it cannot tell you which firmness is best. For firmness and back pain, see the Kovacs 2003 trial, which compared firm and medium-firm mattresses in people with back pain.
Study Scope and Limitations
20 healthy adults, one mattress, lying on the back only, and scans taken over a short time rather than after a night of sleep. The authors list these limits themselves. The mattress maker funded the study and paid two of the authors as consultants.
Primary Citation
Vitale, J. A., Borghi, S., Bassani, T., Messina, C., Sconfienza, L. M., & Galbusera, F. (2023). Effect of a mattress on lumbar spine alignment in supine position in healthy subjects: an MRI study. European Radiology Experimental, 7, 47. https://doi.org/10.1186/s41747-023-00361-w