Fig. 1

Example of a patient who underwent deformity correction surgery using the P-A-P procedure; (a) T-score of -4.8; (l) The sagittal spinopelvic parameters on preoperative whole-spine X-ray were as follows: SVA, 262.3 mm; LL, 20.25°; TLK, 36.04°; PI, 45.47°; and PI − LL mismatch, 65.72°; (b, c) The measurements of LL on flexion and extension radiographs were − 19.86° and − 27.18°, respectively; (d-g, thick arrow) Computed tomography (CT) illustrated the grades of facet joint osteoarthritis using the Pathria grading scale as follows: (III-III), (III-III), (II-III), (III-III), respectively; (h-k) Index segmental lordosis significantly increased after surgery, and cage subsidence was not observed; (m) Postoperative two-year X-ray showed a well-maintained optimal sagittal alignment (SVA, 36.86 mm; LL, -56.02°; TLK, 14.66°; PI, 48.49°; and PI − LL mismatch, 7.53°)