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Table 1 Descriptions of the measurements and implant failure

From: Can posterior stand-alone expandable cages safely restore lumbar lordosis? A minimum 5-year follow-up study

Category Parameter Definition
Local factor Segmental angle [11] Angle between the perpendicular line of the lower endplate of the upper vertebra and upper endplate of the lower vertebra
Segmental translation [11] Forward or backward slippage on a lateral radiograph
Lumbar factor Short lumbar lordosis [5] Cobb angle between the upper endplate of the fused vertebra and lower endplate of the fused vertebra
Whole lumbar lordosis [5] Cobb angle between the upper endplate of L1 and the lower endplate of L5
Spinopelvic factor Pelvic incidence [12] Angle between the perpendicular line to the mid-point of the upper sacral endplate and mid-point of both femoral heads
Pelvic tilt [12] Angle between the vertical line from the femoral head and center of the sacral endplate
Sacral slope [12] Angle between the vertical line and superior sacral endplate
Global sagittal balance Thoracic kyphosis [12] Angle between the T4 upper endplate and T12 lower endplate
Sagittal vertical axis [12] Distance from the vertical line of the C7 body to the inferior lateral corner of the L5 body
Sagittal balance [12] Sagittal vertical axis line located within 5 cm
Implant failure Subsidence [13] Greater or equal to 2 mm loss of height
Pseudoarthrosis [6] Bony non-union between two vertebrae
Proximal junctional kyphosis [6] Proximal junction Cobb angle of at least 10° greater than the preoperative angle
Screw malposition [6] Perforated pedicular screw