Table 1 Description of the measured parameters with their respective normative values and range
Parameter | Description and clinical relevance | Normative values | range |
|---|---|---|---|
SS [41] | The angle between the sacral endplate (S1) and the horizontal. In asymptomatic subjects, SS correlates with PI (r = 0.81). | 41° ±8° | – |
PT [41] | The angle between a line form the center of the femoral head axis to the midpoint of the sacral plate and the vertical line. PT reveals a compensatory mechanism and increases with loss of LL. PT correlates with patient reported outcomes (disability). | 13° ±6° | −4.7 to 27° |
PI [25] | The angle between a line from the center of the femoral head axis to the midpoint of the sacral plate and the perpendicular line to the sacral plate. PI is a morphological parameter, fixed in adults, and determines spine-pelvic alignment. PI=PT + SS | 51.9° ± 10° | 35° to 85° |
PI-LL [42] | the difference between PI an LL. Estimates the “lack of lordosis” and correlates with disability patient reported outcomes HQRoL | −8° ± °9° | −25° to 15° |
LL (L1-S1) [43] | The angle between the upper endplate of L1 and sacral endplate. | 60.9° ± 12° | 31° to 88° |
TK (T2-T12) [41] | The angle between the caudal endplate of T12 and the cranial endplate of T2. | −40.6° ± 10° | 0° to − 69° |
SVA [44] | The horizontal offset from a plumbline dropped from C7 to the postero-superior corner of S1. SVA strongly correlates to clinical outcomes. | −0.5 ± 25 mm | -60 mm to + 65 mm |
T1SPI [45] | The angle between vertical and a line from the center of the femoral head axis to the center of the T1 vertebral body. T1SPI assesses the global spino-pelvic alignment and correlates with clinical outcomes. | −1.35° ± 2.7° | −9.16° to 7.2° |
TPA [46] | The angle formed by the center of the sacral endplate, the center of the femoral head axis, and the center of T1 vertebral body. TPA strongly correlates with HRQOL, PT and SVA. | 7.7° ± 7° | −6° to 23° |
T1 Slope [47] | The angle between the horizontal line and cranial endplate of T1. T1 Slope defines the orientation of the cervical spine and highly correlates with SVA and TK. | 26° ± 10° | 14° to 38° |
CL (C2-C7) [3] | The angle between the caudal endplate of C2 and the caudal endplate of C7. CL increases with positive sagittal malalignment in order to maintain horizontal gaze. | 5° ± 12° | −10° to 22° |
cSVA (C2-C7 SVA) [2] | The horizontal offset from the plumbline dropped from C2 to the postero-superior corner of C7. cSVA is a descriptor of cervical sagittal deformity. | 26 ± 11 mm | 12 mm to 40 mm |
C2-T3 | The angle between the caudal endplate of C2 and the caudal endplate of T3. | – | – |
C2-T3 SVA | The horizontal offset from the plumb line dropped from C2 to the postero-superior corner of T3 | – | – |
C2-T1 – H [22] | Involves drawing lines that are parallel to the posterior surfaces of all cervical vertebral bodies from C2 to T1 and then summing the segmental angles for an overall cervical curvature angle. The Harrison method is a precise method of quantifying cervical curvature. | about 41.8° | – |
C2 Slope | The angle between the horizontal line and cranial endplate of C2. C2 Slope defines the orientation of upper cervical spine. | – | – |
C0 Slope | The angle between the horizontal and cranial ring of C0. C0 Slope defines the orientation of upper cervical spine. | – | – |
MGSlope [48] | The angle between the horizontal line and a line connecting the posterior aspect of the hard palate and the opisthion. | 1.8° ± 6.3° | – |