The Association Between Sagittal Plane Alignment and Disc Space Narrowing of Lumbar Spine in Farmers

OBJECTIVE: To investigate whether lumbar lordosis (LL) and lumbar segmental lordosis (LSL) are related to sex, age, low back pain (LBP), and lumbar disc space narrowing (DSN). METHODS: A total of 569 farmers were recruited. In lateral spine radiograph, LL (L1–L5) and LSL (L1, L2, L3, L4, and L5) were measured using Cobb’s method. The differences in LSL values (ΔLSL) according to the presence or absence of a DSN were calculated as LSL(DSN) – LSL(noDSN) for each DSN level. RESULTS: In male, the lateral spine radiograph showed significantly greater L4-LSL and L5-LSL and smaller L1-LSL and L2-LSL compared to female. LLs in the 50–59 and ≥60 years age groups were significantly smaller compared to those in the <50 years age group. In subjects with LBP, LL and L4-LSL were significantly smaller than in those without. The ΔLSLs at the disc level with DSN showed the greatest decrease: L1-ΔLSL (Δ-3.99°), L2-ΔLSL (Δ-3.31°), L3-ΔLSL (Δ-2.87°), L4-ΔLSL (Δ-3.31°), and L5-ΔLSL (Δ-4.44°) in L1/2, L2/3, L3/4, L4/5, and L5/S1 DSN, respectively. Conversely, distant ΔLSLs were inversely increased: L1-LSL (Δ0.75°) with L4/5 DSN and L2-LSL (Δ0.94°) with L5/S1 DSN. CONCLUSION: Sagittal plane alignment was significantly associated with sex, age, LBP, and DSN. LSLs around the levels of DSN were decreased, and there was compensational increase of LSL distant to the DSN to maintain the overall LL.