Video S1 An example of motion segments in an asymptomatic volunteer where the TI-Index and AVI-Index are within normal limits at all levels. Rotation (degrees): 7.4 at L3–4, 14.6 at L4–5, 14.4 at L5–S1. Translation (% endplate width): 5.1 at L3–4, 7.7 at L4–5, 4.0 at L5–S1. TI-Index: 0.6 at L3–4, 0.0 at L4–5, 0.7 at L5–S1. AVI-Index: 0.0 at L3–4, 0.4 at L4–5, 1.0 at L5–S1.

Video S2 An example of motion segments with an abnormal TI-Index. Rotation (degrees): 9.4 at L3–4, 12.1 at L4–5. Translation (% endplate width): 11.2 at L3–4, 12.7 at L4–5. TI-Index: 4.4 at L3–4, 4.1 at L4–5. AVI-Index: −2.1 at L3–4, 0.6 at L4–5.

Video S3 An example of motion segments with an abnormal TI-Index. Rotation (degrees): 6.1 at L3–4, 9.7 at L4–5, 13.3 at L5–S1. Translation (% endplate width): 11.0 at L3–4, 12.3 at L4–5, 7.9 at L5–S1. TI-Index: 5.7 at L3–4, 4.6 at L4–5, 2.5 at L5–S1. AVI-Index: −0.6 at L3–4, 0.1 at L4–5, −2.7 at L5–S1.

Video S4 An example of a motion segment with abnormal AVI-Index. Rotation (degrees): 0.6 at L3–4, 4.6 at L4–5, 2.3 at L5–S1. Translation (% endplate width): 0.2 at L3–4, 2.9 at L4–5, 0.6 at L5–S1. TI-Index: −0.1 at L3–4, 0.3 at L4–5, 0.1 at L5–S1. AVI-Index: 1.2 at L3–4, 7.6 at L4–5, 0.6 at L5–S1.