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Review
. 2025 Jul;34(7):2511-2521.
doi: 10.1007/s00586-025-09044-z. Epub 2025 Jun 13.

Relationships between psoas muscle index, lumbar lordosis, and chronic low back pain in middle-aged and elderly people

Bin Zhang  1   2 , Peng Song  1   2 , Chao Ma  1   2 , Yan Xu  1   2 , Yan Yuan  3   4
Affiliations
Review

Relationships between psoas muscle index, lumbar lordosis, and chronic low back pain in middle-aged and elderly people

Bin Zhang et al. Eur Spine J. 2025 Jul.

Abstract

Purpose: The Psoas Muscle Index (PMI) has emerged as a rapid assessment method for evaluating psoas muscle quality. In recent years, chronic low back pain (CLBP) and lumbar lordosis (LL) have been significant areas of research interest. However, there is a notable gap in the literature, with no studies investigating the relationship between PMI and CLBP, nor any research examining the potential interconnections among PMI, LL, and CLBP. This study aimed to describe the cross-sectional relationships among these three factors.

Methods: This retrospective study analyzed data from 976 patients with low back pain and 120 healthy individuals aged 45 or older who reported no history of low back pain. Ultimately, the final analysis included 230 middle-aged and elderly subjects (aged 45 or older). The Subjects were divided into the CLBP group (duration > 1 year) and the control group(no low back pain at all). This study selected the PMI(cross-sectional area of psoas major muscle at L4/height2, cm2 /m2 ) at the level of the upper endplate of the fourth lumbar vertebra (L4), closer to common LBP sites, for assessment. PMI and lumbar lordotic angle (LLA) measurements were compared between the CLBP and control groups using an independent T-test. Subsequently, a correlation analysis was performed to examine the relationship between these two indicators.

Results: The PMI of men and women in the CLBP group (males:7.3 ± 1.6; females:5.9 ± 1.1) was significantly lower than that of the control group (males:8.0 ± 1.4; females:6.8 ± 1.1) (p < 0.05). The LLA was decreased in the CLBP group compared to the control group (males: 22.9°±7.6° vs. 37.0 ± 6.9; females: 22.7 ± 10.1 vs. 33.1 ± 7.0) (p < 0.001). Furthermore, no correlation between PMI and LLA was observed in both male (r = 0.091, p = 0.002) and female (r = 0.073, p < 0.003) subjects.

Conclusion: There is a significant cross-sectional association among PMI, LL, and CLBP. This indicates a potential interaction between reduced PMI and altered LL, which may contribute to CLBP development.

Keywords: Chronic low back pain; Lordosis; Psoas muscle index.

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Conflict of interest statement

Declarations. Conflict of interest: None.

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