Table 1 Relationship between quantitative measures of lower lumbar spinal canal
Variables | L3–4 | L4–5 | L5–S1 | |
|---|---|---|---|---|
Degree of the dural sac compression at disc level (%) | Â | Â | Â | |
 Min–Max | 86.0–96.0 | 86.0–95.0 | 85.0–95.0 | |
78.0–84.0 | 77.0–84.0 | 76.0–84.0 | ||
69.0–74.0 | 67.0–75.0 | 65.0–74.0 | ||
17.0–64.0 | 24.0–64.0 | 42.0–64.0 | ||
Mid-sagittal AP diameter of dural sac at disc level (mm) | Â | Â | Â | |
 0 | Min–Max | 16.0–19.0 | 16.8- 20.3 | 17.3–22.1 |
 1 | 15.5–16.3 | 14.8–16.3 | 15.0–17.0 | |
 2 | 13.5–15.0 | 13.8–15.3 | 14.0–15.5 | |
 3 | 11.5–13.0 | 10.8–12.5 | 11.0–12.6 | |
The cross-sectional area of the dural sac (mm2) | Â | Â | Â | |
 0 | Min–Max | 180–31 | 190–302 | 190–374 |
 1 | 158–188 | 160–198 | 164–193 | |
 2 | 115–160 | 118–158 | 119–155 | |
 3 | 60–106 | 31–105 | 90–107 | |
Rt. LSC height for grades of right LSC (mm) | Â | Â | Â | |
 0 | Min–Max | 5.2–8.3 | 5.0–7.0 | 5.2–9.0 |
 1 | 3.1–4.8 | 3.5–4.5 | 4.0–4.8 | |
 2 | 1.7–3.0 | 1.5–3.4 | 1.7–3.4 | |
 3 | 0.0–1.3 | 0.0–1.5 | 0.0–1.4 | |
Lt. LSC height for grades of left LSC (mm) | Â | Â | Â | |
 0 | Min–Max | 5.2–7.5 | 5.5–7.4 | 5.0–8.8 |
 1 | 3.2–4.8 | 3.5–4.9 | 4.0–4.8 | |
 2 | 2.0–4.8 | 1.7–3.4 | 1.6–3.4 | |
 3 | 0.0–1.5 | 0.0–1.5 | 0.0–1.5 | |
Diameter of right intervertebral foramen for grades of Rt. lumbar foraminal stenosis (mm) | Â | Â | Â | |
 0 | Min–Max | 9.5–14.0 | 9.2–13.0 | 8.5–14.0 |
 1 | 8.3–9.0 | 7.1–8.9 | 7.0–8.3 | |
 2 | 4.4–7.0 | 4.2–7.0 | 4.2–6.5 | |
 3 | 3.5–3.9 | 2.7–3.3 | 2.7–3.2 | |
Diameter of left intervertebral foramen for grades of Lt. lumbar foraminal stenosis (mm) | Â | Â | Â | |
 0 | Min–Max | 9.5–13.6 | 9.0–13.6 | 8.5–13.0 |
 1 | 8.2–9.3 | 7.5–8.5 | 6.6–8.2 | |
 2 | 4.6–7.4 | 4.3–7.0 | 4.5–6.5 | |
 3 | 3.3–3.7 | 2.6–3.2 | 2.6–3.3 | |