Measurements of spinal sagittal parameters were illustrated in Fig. 1 , covering: (1) T1 slope (T1S), the angle between the superior endplate of T1 and the horizontal line; (2) thoracic kyphosis (TK), the Cobb angle between the superior endplate of T4 and the inferior endplate of T12; (3) LL, the Cobb angle between the superior endplates of both L1 and S1; (4) sacral slope (SS), the angle between the superior endplate of the sacrum and the horizontal line; (5) pelvic tilt (PT), the angle between the line linking the midpoint of the superior endplate of S1 and the center of the femoral heads and vertical line; (6) PI, the angle between the line linking the midpoint of the superior endplate of S1 and the center of the femoral heads and the line vertical to the superior endplate of the sacrum; (7) SVA, the distance between the posterosuperior corner of S1 and the vertical line from the C7 body center; (8) segmental lumbar lordosis (SLL), the Cobb angle between the superior endplate of L4 and the inferior endplate of L5; and (9) slip percentage (SP), the ratio of the interval between two extended lines of the posterior aspect of L4 and L5 to the length of the superior endplate of L5. The ratio of PT to PI (PT/PI) suggests the degree of pelvic compensation [17 (link)].![]()
Measurements of sagittal parameters enrolled in the present study.
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