Fig. 4

A case with matched Roussouly type. A 60-year-old female with lumbar spinal stenosis and isthmic spondylolisthesis at L3–4 and L4–5, the theoretical Roussouly shape was type 3 based on the PI of 57° (A, B). She underwent pedicle screw fixation from L3 to L5, and posterolateral inter-transverse process fusion at L3–4 and TLIF at L4–5. The upright lateral radiograph showed that PT was 20°, SS was 37°, LL was 49°, DL was 35°, LDI was 71%, lumbar apex was L4, and inflexion point was L1 (indicating the type 3 shape and a matched status, C). At 5-year follow-up, she reported being well. The upright lateral radiograph and MRI showed no signs of ASD (D, E). PI pelvic incidence, PT pelvic tilt, SS sacral slope, LL lumbar lordosis, DL distal lordosis, LDI lordosis distribution index, TLIF transforaminal lumbar interbody fusion, MRI magnetic resonance imaging, ASD adjacent segment disease