Objectives: Decreased lumbar lordosis is known to be associated with lumbar spinal stenosis and low back pain. Increased lordosis was associated with increased subsidence and less favorable outcome after spinal fusion operation. We aimed to investigate whether the lumbar lordosis, lumbar segmental lordosis, and sacral slope are related with lumbar disc height changes.
Study design: Total 590 farmers in Gangwon-do, South Korea were recruited. Twenty-one subjects were excluded due to history of spine surgery, 569 farmers were included in final analysis. The average age of subject was 58 years old, and the average period of agriculturing was 26 years. The percentage of people with back pain was about 75%.
Methods: Spine radiograph was obtained in standing posture. A disc height change (DHC) was defined if there is a difference of 25% or more, with compare to two adjacent discs. We defined 1) lumbar lordosis (LL) as the angle between the cranial end plate of L1 and the cranial end plate of S1, using Cobb’s method in the neutral position of lumbar X-ray; 2) lumbar segmental lordosis (LSL) as angle from the cranial endplates of adjacent vertebrae using Cobb’s method, described as L1-2, L2-3, L3-4, L4-5, and L5-S1, respectively; 3) sacral slope (SS) as the angle between the horizontal line and the cranial sacral end plate tangent.
Results: Lumbar DHCs were most frequently observed in L5-S1 (69.6%) and L4-5 (45.7%). DHCs in L1-4 was 55 (9.7%) in L1-2, 79 (13.9%) in L2-3, and 35 (23.7%) in L3-41. The average of LL was 49.8 degree. The largest proportion of LL was L5-S1 LSL, which was 20.4 degree (41% of LL), and the second largest lordosis was in L4-5, which is 12.6 degree (25% of LL). Thus L4-S1 accounted for a total of 66% of LL. The average of SS was 34 degree. In the presence of DHC at any level between L1-S1, LL and SS was statistically significant decreased compared to not having DHC (p<0.05). In the presence of L1-2 DHC, LSL was significantly decreased at L1-2, L2-3, L3-4, and L4-5 LSL, with the largest change in L1-2 (Δ3.99). In the presence of L2-3 DHC, LSL was significantly decreased at L1-2, L2-3, L3-4, and L4-5 LSL with the largest change in L2-3 (Δ3.31). In the presence of L3-4 DHC, LSL was significantly decreased at L3-4 and L4-5 LSL with the largest change in L3-4 (Δ2.87). In the presence of L4-5 DHC, LSL was significantly decreased at L4-5 and L5-S1 LSL with the largest change in L4-5 (Δ3.31) while L1-2 LSL was increased inversely (Δ-0.75). In the presence of L5-S1 DHC, LSL was significantly decreased at L5-S1 LSL (Δ4.44) while L2-3 LSL was increased contrarily (Δ-0.94).
Conclusions: Lumbar lordosis was occurred about 66% at L4-5, L5-S1 level. Lumbar DHC was also most commonly observed at that two lower levels. In the presence of DHC, both LL and SS were decreased. The decrease of lordosis was mostly occured around the level of DHC. In contrary, LSL at distant level was increased in the presence of L4-5 and L5-S1 DHC. |
