Table 1 Spinopelvic alignment parameters definitions and their normative ranges/values

Cervical lordosis (CL)

The angle between the lines tangent to the posterior aspect of C₂ and C₇ vertebral bodies [80].

20° − 35° [81]

Thoracic kyphosis (TK)

The angle between the superior endplate of T₅ and the superior endplate of T₁₂ [16].

20° − 45° [82]

Lumbar lordosis (LL)

The angle between the superior endplate of L₁ and the superior endplate of S₁ [16].

So wide (30° − 80° using the Cobb method) [83]

Lumbar scoliosis

A lateral curvature of the lumbar spine with torsion of the spine and a disturbance of the sagittal profile [84]. Lumbar scoliosis is measured using the Cobb angle, which is the angle between the two most tilted vertebrae of a given scoliotic curve as measured on a coronal radiograph [85].

Cobb angle > 10° in skeletally mature patients [86]

T₁ spinopelvic inclination (T₁Spi)

The angle between the line drawn from the centroid of T₁ and the center of the bicoxofemoral axis and the vertical plumb line [87].

−13° − + 5° (average = − 4.67°) [88]

Pelvic tilt (PT)

The angle between the vertical line and line joining the middle of sacral endplate to the center of the bicoxofemoral axis [89].

13° (6°) [90]

T₁ pelvic angle (TPA)

The angle between the line from the femoral head axis to the centroid of T₁ and the line from the femoral head axis to the middle of the S₁ endplate [88].

−6° − + 25° (average = 8.28°) [88]

Sacral slope (SS)

The angle between the superior endplate of S₁ and a horizontal reference on sagittal imaging of the lumbosacral spine [89].

Approximately 33° − 49° (average = 41°) [90]

Pelvic incidence (PI)

The angle between the line perpendicular to the sacral endplate at its midpoint and the line connecting this point to the axis of the femoral heads [89]. Pelvic incidence = sacral slope + pelvic tilt [56].

Approximately 45° − 65° (average = 55°) [90]

Pelvic inclination angle (PIA)

The angle between the line connecting the anterior boarder of the sacral promontory with the upper border of the symphysis and a horizontal line [91].

60° [91]

Anterior pelvic plane angle (APP)

The angle between the vertical line and the line connecting the pubic symphysis and the bilateral anterior superior iliac spine midpoint (anterior pelvic plane) [16, 57].

−5° − + 5° [16]

Sagittal vertical axis (SVA)

Distance between the C₇ plumb line and the postero-superior edge of S₁ [92].

< 30 mm [93]

Spinosacral angle (SSA)

The SSA angle is defined by the angle connecting the center of the C₇ vertebra to the center of the S1 endplate and the line parallel to the superior S₁ endplate [94].

135° (8°) [94]

Cup/ acetabular (lateral) inclination (CI)

The angle between the transverse axis and the articular side of the acetabular cup. Measurement of this angle can be done by drawing a line through the medial and lateral margins of the cup and measuring the angle with the transischial tuberosity line [95].

30° − 50° [75]

Functional cup (acetabular) inclination (FI)

The angle between the pelvic longitudinal axis and the acetabular axis when this is projected onto the coronal plane [29].

43.7° − 55.9° [96]

Sagittal plane cup anteversion (CA)

The angle between the line tangent to the anterior and posterior edges of the acetabulum and the horizontal plane [97]. In the transverse plane, it is the angle formed by the line tangent to the anterior and posterior edges of the acetabulum and the sagittal axis [97].

5° − 25° [30]

Functional cup (acetabular) anteversion (FCA)

The angle can be calculated using the Lewinnek’s formula: cup anteversion angle = arc sin (D₁/D₂). D₁ is the distance of the short axis of an ellipse drawn perpendicular to the long axis of the acetabular component and D₂ is the distance of the long axis [31].

It depends on several variables such as planned inclination, planned anteversion, standing pelvic tilt, and sitting pelvic tilt [98]